ENZND / Viskase Holdings, Inc. - SEC Dosyaları, Yıllık Rapor, Vekil Beyanı

Viskase Holdings, Inc.
US ˙ OTCPK
BU SEMBOL ARTIK AKTİF DEĞİL

Temel İstatistikler
LEI 529900VN48L8QCMVPV36
CIK 727510
SEC Filings
All companies that sell securities in the United States must register with the Securities and Exchange Commission (SEC) and file reports on a regular basis. These reports include company annual reports (10K, 10Q), news updates (8K), investor presentations (found in 8Ks), insider trades (form 4), ownership reports (13D, and 13G), and reports related to the specific securities sold, such as registration statements and prospectus. This page shows recent SEC filings related to Viskase Holdings, Inc.
SEC Filings (Chronological Order)
Bu sayfa, başka bir yerde sunduğumuz mülkiyet başvuruları hariç, SEC Dosyalarının tam ve kronolojik bir listesini sunmaktadır.
May 5, 2026 EX-4.1

Section 382 Rights Agreement Dated as of May 5, 2026 by and between VISKASE HOLDINGS, INC. CONTINENTAL STOCK TRANSFER & TRUST COMPANY as Rights Agent TABLE OF CONTENTS

Exhibit 4.1 Section 382 Rights Agreement Dated as of May 5, 2026 by and between VISKASE HOLDINGS, INC. and CONTINENTAL STOCK TRANSFER & TRUST COMPANY as Rights Agent TABLE OF CONTENTS Page # Section 1. Certain Definitions 1 Section 2. Appointment of Rights Agent 11 Section 3. Issue of Rights Certificates 11 Section 4. Form of Rights Certificates 13 Section 5. Countersignature and Registration 14 S

May 5, 2026 8-A12G

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 VISKASE HOLDINGS, INC. (Exact name of registran

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 VISKASE HOLDINGS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 22-2372868 (IRS Employer Identification No.) 333 East Butterfie

May 5, 2026 EX-99.1

Viskase Holdings, Inc. Adopts Tax Benefits Preservation Plan to Protect its NOL Assets and Shareholder Value

Exhibit 99.1 Viskase Holdings, Inc. Adopts Tax Benefits Preservation Plan to Protect its NOL Assets and Shareholder Value Lombard, Illinois, May 5, 2026 – Viskase Holdings, Inc. (formerly known as Enzon Pharmaceuticals, Inc.) (the “Company”) today announced that its Board of Directors (the “Board”) adopted a tax benefits preservation plan (the “Section 382 Rights Plan”) designed to protect the ava

May 5, 2026 EX-3.1

CERTIFICATE OF DESIGNATION SERIES A-2 JUNIOR PARTICIPATING PREFERRED STOCK VISKASE HOLDINGS, INC. Pursuant to Section 151 of the General Corporation Law of the State of Delaware

Exhibit 3.1 CERTIFICATE OF DESIGNATION OF SERIES A-2 JUNIOR PARTICIPATING PREFERRED STOCK OF VISKASE HOLDINGS, INC. Pursuant to Section 151 of the General Corporation Law of the State of Delaware The undersigned do hereby certify that the following resolution was duly adopted by the Board of Directors of Viskase Holdings, Inc., a Delaware corporation (the “Company”), on April 30, 2026: RESOLVED, t

May 5, 2026 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 30, 2026 VISKASE HOLDINGS,

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 30, 2026 VISKASE HOLDINGS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Number)

May 4, 2026 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2026 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number: 0

May 1, 2026 EX-99.1

VISKASE COMPANIES, INC. AND SUBSIDIARIES CONSOLIDATED BALANCE SHEETS (Amounts in thousands of U.S. dollars, except for number of shares and per share amounts)

Exhibit 99.1 CONSOLIDATED FINANCIAL STATEMENTS OF VISKASE COMPANIES, INC. AND SUBSIDIARIES 1. Financial Statements - Report of Independent Certified Public Accountants - Consolidated Balance Sheets as of December 31, 2025 and 2024 - Consolidated Statements of Operations for the years ended December 31, 2025, 2024 and 2023 - Consolidated Statements of Comprehensive (Loss) Income for the years ended

May 1, 2026 8-K/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K/A CURRENT REPORT (AMENDMENT NO.1) Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 26, 2026

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K/A CURRENT REPORT (AMENDMENT NO.1) Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 26, 2026 VISKASE HOLDINGS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Comm

May 1, 2026 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 29, 2026 VISKASE HOLDINGS,

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 29, 2026 VISKASE HOLDINGS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Number)

May 1, 2026 EX-99.2

UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION

Exhibit 99.2 UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION Introduction On March 26, 2026 (the “Closing Date”), Viskase Holdings Inc. (formerly known as Enzon Pharmaceuticals, Inc.) (the “Combined Company”) consummated the previously announced transactions pursuant to the Agreement and Plan of Merger, dated as of June 20, 2025, by and among Enzon Pharmaceuticals Inc. (“Enzon”), EPSC

April 29, 2026 10-K/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K/A (Amendment No. 1)

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K/A (Amendment No. 1) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the Fiscal Year Ended December 31, 2025 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file numbe

April 21, 2026 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 16, 2026 VISKASE HOLDINGS,

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 16, 2026 VISKASE HOLDINGS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Number)

April 21, 2026 EX-10.1

SEVENTH AMENDMENT TO CREDIT AGREEMENT

Exhibit 10.1 Execution Version SEVENTH AMENDMENT TO CREDIT AGREEMENT THIS SEVENTH AMENDMENT TO CREDIT AGREEMENT (this “Amendment”), dated as of April 16, 2026, is by and among VISKASE COMPANIES, LLC (f/k/a VISKASE COMPANIES, INC.), a Delaware limited liability company (the “Borrower”), the other Subsidiary Guarantors party hereto, the Lenders party hereto and BANK OF AMERICA, N.A., as administrati

April 16, 2026 EX-16.1

April 16, 2026

Exhibit 16.1 April 16, 2026 Securities and Exchange Commission 100 F Street, N.E. Washington, DC 20549 Ladies and Gentlemen: We have read Item 4.01 of Form 8-K dated April 16, 2026 of Viskase Holdings, Inc. and are in agreement with the statements contained therein as it regards our firm. We have no basis to agree or disagree with other statements of the registrant contained in Item 4.01. Sincerel

April 16, 2026 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 14, 2026 VISKASE HOLDINGS,

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 14, 2026 VISKASE HOLDINGS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Number)

April 15, 2026 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 10, 2026 VISKASE HOLDINGS,

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 10, 2026 VISKASE HOLDINGS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Number)

March 26, 2026 EX-3.1

CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION Enzon Pharmaceuticals, Inc. (Pursuant to Section 242 of the General Corporation Law of the State of Delaware)

Exhibit 3.1 CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF Enzon Pharmaceuticals, Inc. (Pursuant to Section 242 of the General Corporation Law of the State of Delaware) ENZON PHARMACEUTICALS, INC. (the “Corporation”), a corporation organized and existing under and by virtue of the General Corporation Law of the State of Delaware (the “DGCL”), does hereby certi

March 26, 2026 EX-99.1

Enzon Pharmaceuticals Completes Merger with Viskase Companies, Inc. Combined company will operate as Viskase Holdings, Inc.

Exhibit 99.1 Enzon Pharmaceuticals Completes Merger with Viskase Companies, Inc. Combined company will operate as Viskase Holdings, Inc. LOMBARD, Illinois, March 26, 2026 (GLOBE NEWSIRE) - Enzon Pharmaceuticals, Inc. (OTCQB: ENZN), (“Enzon,” or the “Company”), today announced the completion of the previously announced merger pursuant to which Viskase Companies, Inc. (OTC Pink Limited: VKSC) (“Visk

March 26, 2026 EX-3.2

CERTIFICATE OF ELIMINATION OF SERIES A-1 JUNIOR PARTICIPATING PREFERRED STOCK OF VISKASE HOLDINGS, INC. ______________________________________________________________________ Pursuant to Section 151(g) of the General Corporation Law of the State of D

Exhibit 3.2 CERTIFICATE OF ELIMINATION OF SERIES A-1 JUNIOR PARTICIPATING PREFERRED STOCK OF VISKASE HOLDINGS, INC. Pursuant to Section 151(g) of the General Corporation Law of the State of Delaware VISKASE HOLDINGS, INC. (formerly known as Enzon Pharmaceuticals, Inc.), a corporation organized and existing under the laws of the State of Delaware (the “Corporation”), in accordance with the provisio

March 26, 2026 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 26, 2026 VISKASE HOLDINGS,

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 26, 2026 VISKASE HOLDINGS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Number)

March 25, 2026 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 25, 2026 ENZON PHARMACEUTIC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 25, 2026 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Nu

March 25, 2026 SC TO-I/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 9) ENZON PHARMACEUTICALS, INC. (Name of Subject Compan

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 9) ENZON PHARMACEUTICALS, INC. (Name of Subject Company and Filing Persons (Issuer)) Series C Non-Convertible Redeemable Preferred Stock (Title of Class of Securities) 293904702 (CUSIP Number of Class of

March 25, 2026 425

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 25, 2026 ENZON PHARMACEUTIC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 25, 2026 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Nu

March 25, 2026 EX-99.(A)(1)(L)

Enzon Announces Completion of the Exchange Offer Relating to Series C Non-Convertible Redeemable Preferred Stock

EXHIBIT (a)(1)(L) Enzon Announces Completion of the Exchange Offer Relating to Series C Non-Convertible Redeemable Preferred Stock Cranford, New Jersey – March 25, 2026 – Enzon Pharmaceuticals, Inc.

March 24, 2026 EX-3.2

CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION Enzon Pharmaceuticals, Inc. (Pursuant to Section 242 of the General Corporation Law of the State of Delaware)

Exhibit 3.2 CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF Enzon Pharmaceuticals, Inc. (Pursuant to Section 242 of the General Corporation Law of the State of Delaware) ENZON PHARMACEUTICALS, INC. (the “Corporation”), a corporation organized and existing under and by virtue of the General Corporation Law of the State of Delaware (the “DGCL”), does hereby certi

March 24, 2026 EX-3.2

CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION Enzon Pharmaceuticals, Inc. (Pursuant to Section 242 of the General Corporation Law of the State of Delaware)

Exhibit 3.2 CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF Enzon Pharmaceuticals, Inc. (Pursuant to Section 242 of the General Corporation Law of the State of Delaware) ENZON PHARMACEUTICALS, INC. (the “Corporation”), a corporation organized and existing under and by virtue of the General Corporation Law of the State of Delaware (the “DGCL”), does hereby certi

March 24, 2026 425

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 20, 2026 ENZON PHARMACEUTIC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 20, 2026 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Nu

March 24, 2026 EX-3.1

CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION Enzon Pharmaceuticals, Inc. (Pursuant to Section 242 of the General Corporation Law of the State of Delaware)

Exhibit 3.1 CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF Enzon Pharmaceuticals, Inc. (Pursuant to Section 242 of the General Corporation Law of the State of Delaware) ENZON PHARMACEUTICALS, INC. (the “Corporation”), a corporation organized and existing under and by virtue of the General Corporation Law of the State of Delaware (the “DGCL”), does hereby certi

March 24, 2026 EX-99.1

Enzon Announces Reverse Stock Split

Exhibit 99.1 Enzon Announces Reverse Stock Split CRANFORD, N.J., March 24, 2026 (GLOBE NEWSWIRE) - Enzon Pharmaceuticals, Inc. (OTCQB: ENZN) (“Enzon” or the “Company”), today announced that the previously approved 1-for-100 reverse stock split will become effective on March 24, 2026, at 4:30 pm, Eastern Time (the “Effective Time”), and the Company’s common stock is expected to begin trading on a r

March 24, 2026 SC TO-I/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 8) ENZON PHARMACEUTICALS, INC. (Name of Subject Compan

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 8) ENZON PHARMACEUTICALS, INC. (Name of Subject Company and Filing Persons (Issuer)) Series C Non-Convertible Redeemable Preferred Stock (Title of Class of Securities) 293904702 (CUSIP Number of Class of

March 24, 2026 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 20, 2026 ENZON PHARMACEUTIC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 20, 2026 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Nu

March 24, 2026 8-A12G/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 11 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 11 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation or organization) 22-2372868 (I.R.S. Empl

March 24, 2026 EX-99.1

Enzon Announces Reverse Stock Split

Exhibit 99.1 Enzon Announces Reverse Stock Split CRANFORD, N.J., March 24, 2026 (GLOBE NEWSWIRE) - Enzon Pharmaceuticals, Inc. (OTCQB: ENZN) (“Enzon” or the “Company”), today announced that the previously approved 1-for-100 reverse stock split will become effective on March 24, 2026, at 4:30 pm, Eastern Time (the “Effective Time”), and the Company’s common stock is expected to begin trading on a r

March 24, 2026 EX-3.1

CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION Enzon Pharmaceuticals, Inc. (Pursuant to Section 242 of the General Corporation Law of the State of Delaware)

Exhibit 3.1 CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF Enzon Pharmaceuticals, Inc. (Pursuant to Section 242 of the General Corporation Law of the State of Delaware) ENZON PHARMACEUTICALS, INC. (the “Corporation”), a corporation organized and existing under and by virtue of the General Corporation Law of the State of Delaware (the “DGCL”), does hereby certi

March 24, 2026 EX-4.1

ELEVENTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent

EXHIBIT 4.1 ELEVENTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. and CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent This ELEVENTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT (this “Eleventh Amendment”) is made and entered into March 23, 2026, and is effective immediately, by and between Enzon Pharmaceuticals, Inc., a Delaware corporation

March 24, 2026 EX-4.1

ELEVENTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent

EXHIBIT 4.1 ELEVENTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. and CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent This ELEVENTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT (this “Eleventh Amendment”) is made and entered into March 23, 2026, and is effective immediately, by and between Enzon Pharmaceuticals, Inc., a Delaware corporation

March 19, 2026 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 19, 2026 ENZON PHARMACEUTIC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 19, 2026 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Nu

March 19, 2026 EX-99.(A)(1)(J)

Enzon Announces Extension of Exchange Offer Relating to Series C Non-Convertible Redeemable Preferred Stock

EXHIBIT (a)(1)(J) Enzon Announces Extension of Exchange Offer Relating to Series C Non-Convertible Redeemable Preferred Stock Cranford, New Jersey – March 19, 2026 – Enzon Pharmaceuticals, Inc.

March 19, 2026 425

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 19, 2026 ENZON PHARMACEUTIC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 19, 2026 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Nu

March 19, 2026 SC TO-I/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 7) ENZON PHARMACEUTICALS, INC. (Name of Subject Compan

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 7) ENZON PHARMACEUTICALS, INC. (Name of Subject Company and Filing Persons (Issuer)) Series C Non-Convertible Redeemable Preferred Stock (Title of Class of Securities) 293904702 (CUSIP Number of Class of

March 18, 2026 8-A12G/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 10 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 10 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation or organization) 22-2372868 (I.R.S. Empl

March 18, 2026 EX-4.1

TENTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent

EXHIBIT 4.1 TENTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. and CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent This TENTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT (this “Tenth Amendment”) is made and entered into March 18, 2026, and is effective immediately, by and between Enzon Pharmaceuticals, Inc., a Delaware corporation (the “Com

March 18, 2026 425

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 18, 2026 ENZON PHARMACEUTIC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 18, 2026 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Nu

March 18, 2026 EX-4.1

TENTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent

EXHIBIT 4.1 TENTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. and CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent This TENTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT (this “Tenth Amendment”) is made and entered into March 18, 2026, and is effective immediately, by and between Enzon Pharmaceuticals, Inc., a Delaware corporation (the “Com

March 18, 2026 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 18, 2026 ENZON PHARMACEUTIC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 18, 2026 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Nu

March 16, 2026 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 16, 2026 ENZON PHARMACEUTIC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 16, 2026 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Nu

March 16, 2026 EX-99.(A)(1)(I)

Enzon Announces Extension of Exchange Offer Relating to Series C Non-Convertible Redeemable Preferred Stock

EXHIBIT (a)(1)(I) Enzon Announces Extension of Exchange Offer Relating to Series C Non-Convertible Redeemable Preferred Stock Cranford, New Jersey – March 16, 2026 – Enzon Pharmaceuticals, Inc.

March 16, 2026 SC TO-I/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 6) ENZON PHARMACEUTICALS, INC. (Name of Subject Compan

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 6) ENZON PHARMACEUTICALS, INC. (Name of Subject Company and Filing Persons (Issuer)) Series C Non-Convertible Redeemable Preferred Stock (Title of Class of Securities) 293904702 (CUSIP Number of Class of

March 16, 2026 425

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 16, 2026 ENZON PHARMACEUTIC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 16, 2026 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Nu

March 11, 2026 EX-4.1

NINTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent

EXHIBIT 4.1 NINTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. and CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent This NINTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT (this “Ninth Amendment”) is made and entered into March 10, 2026, and is effective immediately, by and between Enzon Pharmaceuticals, Inc., a Delaware corporation (the “Com

March 11, 2026 EX-99.(A)(1)(H)

Enzon Announces Extension of Exchange Offer Relating to Series C Non-Convertible Redeemable Preferred Stock

Exhibit (a)(1)(H) Enzon Announces Extension of Exchange Offer Relating to Series C Non-Convertible Redeemable Preferred Stock Cranford, New Jersey – March 11, 2026 – Enzon Pharmaceuticals, Inc.

March 11, 2026 SC TO-I/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 5) ENZON PHARMACEUTICALS, INC. (Name of Subject Compan

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 5) ENZON PHARMACEUTICALS, INC. (Name of Subject Company and Filing Persons (Issuer)) Series C Non-Convertible Redeemable Preferred Stock (Title of Class of Securities) 293904702 (CUSIP Number of Class of

March 11, 2026 8-A12G/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 9 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 9 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation or organization) 22-2372868 (I.R.S. Emplo

March 11, 2026 425

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 10, 2026 ENZON PHARMACEUTIC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 10, 2026 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Nu

March 11, 2026 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 10, 2026 ENZON PHARMACEUTIC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 10, 2026 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Nu

March 11, 2026 EX-4.1

NINTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent

EXHIBIT 4.1 NINTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. and CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent This NINTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT (this “Ninth Amendment”) is made and entered into March 10, 2026, and is effective immediately, by and between Enzon Pharmaceuticals, Inc., a Delaware corporation (the “Com

March 9, 2026 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 9, 2026 ENZON PHARMACEUTICA

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 9, 2026 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Num

March 9, 2026 SC TO-I/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 4) ENZON PHARMACEUTICALS, INC. (Name of Subject Compan

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 4) ENZON PHARMACEUTICALS, INC. (Name of Subject Company and Filing Persons (Issuer)) Series C Non-Convertible Redeemable Preferred Stock (Title of Class of Securities) 293904702 (CUSIP Number of Class of

March 9, 2026 425

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 9, 2026 ENZON PHARMACEUTICA

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 9, 2026 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File Num

March 9, 2026 EX-99.(A)(1)(G)

Enzon Announces Extension of Exchange Offer Relating to Series C Non-Convertible Redeemable Preferred Stock

Exhibit (a)(1)(G) Enzon Announces Extension of Exchange Offer Relating to Series C Non-Convertible Redeemable Preferred Stock Cranford, New Jersey – March 9, 2026 – Enzon Pharmaceuticals, Inc.

March 3, 2026 424B3

PROSPECTUS FOR ISSUANCE OF UP TO 7,935,878 SHARES OF COMMON STOCK IN THE MERGER PROSPECTUS FOR OFFER TO EXCHANGE SHARES OF SERIES C PREFERRED STOCK COMMON STOCK

Filed pursuant to Rule 424(b)(3) and 424(c) Registration File No. 333-293019 PROSPECTUS SUPPLEMENT (to Prospectus dated January 30, 2026) PROSPECTUS FOR ISSUANCE OF UP TO 7,935,878 SHARES OF COMMON STOCK IN THE MERGER PROSPECTUS FOR OFFER TO EXCHANGE SHARES OF SERIES C PREFERRED STOCK FOR COMMON STOCK This prospectus supplement (this “Prospectus Supplement”) supplements the information in the pros

March 3, 2026 SC TO-I/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 3) ENZON PHARMACEUTICALS, INC. (Name of Subject Compan

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 3) ENZON PHARMACEUTICALS, INC. (Name of Subject Company and Filing Persons (Issuer)) Series C Non-Convertible Redeemable Preferred Stock (Title of Class of Securities) 293904702 (CUSIP Number of Class of

March 2, 2026 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the Fiscal Year Ended December 31, 2025 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number: 001-12957 Enzon P

March 2, 2026 EX-4.1

DESCRIPTION OF ENZON PHARMACEUTICALS, INC.’S REGISTERED SECURITIES

EXHIBIT 4.1 DESCRIPTION OF ENZON PHARMACEUTICALS, INC.’S REGISTERED SECURITIES The following description of the common stock, $0.01 par value (“Common Stock”), of Enzon Pharmaceuticals, Inc. (“us”, “our”, or the “Company”) and the Series A-1 Junior Participating Preferred Stock Purchase Rights (the “Rights”) is a summary. This summary is not complete and is subject to and qualified in its entirety

March 2, 2026 EX-21.1

ENZON PHARMACEUTICALS, INC. Subsidiaries of Registrant

EXHIBIT 21.1 ENZON PHARMACEUTICALS, INC. Subsidiaries of Registrant Subsidiary State or Other Jurisdiction of Incorporation SCA Delaware Ventures, Inc. EPSC Acquisition Corp. Delaware

February 27, 2026 EX-99.(A)(1)(F)

Enzon Announces Extension of Exchange Offer Relating to Series C Non-Convertible Redeemable Preferred Stock

Exhibit (a)(1)(F) Enzon Announces Extension of Exchange Offer Relating to Series C Non-Convertible Redeemable Preferred Stock Cranford, New Jersey – February 27, 2026 – Enzon Pharmaceuticals, Inc.

February 27, 2026 EX-4.1

EIGHTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent

Exhibit 4.1 EIGHTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. and CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent This EIGHTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT (this “Eighth Amendment”) is made and entered into February 27, 2026, and is effective immediately, by and between Enzon Pharmaceuticals, Inc., a Delaware corporation (th

February 27, 2026 425

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 27, 2026 ENZON PHARMACEU

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 27, 2026 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File

February 27, 2026 SC TO-I/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 2) ENZON PHARMACEUTICALS, INC. (Name of Subject Compan

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 2) ENZON PHARMACEUTICALS, INC. (Name of Subject Company and Filing Persons (Issuer)) Series C Non-Convertible Redeemable Preferred Stock (Title of Class of Securities) 293904702 (CUSIP Number of Class of

February 27, 2026 EX-4.1

EIGHTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent

Exhibit 4.1 EIGHTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. and CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent This EIGHTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT (this “Eighth Amendment”) is made and entered into February 27, 2026, and is effective immediately, by and between Enzon Pharmaceuticals, Inc., a Delaware corporation (th

February 27, 2026 8-A12G/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 8 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 8 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation or organization) 22-2372868 (I.R.S. Emplo

February 27, 2026 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 27, 2026 ENZON PHARMACEU

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 27, 2026 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File

February 26, 2026 SC 14F1

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14F-1 Information Statement Pursuant to Section 14(f) of the Securities Exchange Act of 1934 and Rule 14f-1 Thereunder Commission file number: 000-12957 ENZON PHARMACEUT

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14F-1 Information Statement Pursuant to Section 14(f) of the Securities Exchange Act of 1934 and Rule 14f-1 Thereunder Commission file number: 000-12957 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its corporate charter) Delaware (State or other jurisdiction of incorporation or organization) 2

February 11, 2026 SC TO-I/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 1) ENZON PHARMACEUTICALS, INC. (Name of Subject Compan

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 1) ENZON PHARMACEUTICALS, INC. (Name of Subject Company and Filing Persons (Issuer)) Series C Non-Convertible Redeemable Preferred Stock (Title of Class of Securities) 293904702 (CUSIP Number of Class of

February 11, 2026 425

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 11, 2026 ENZON PHARMACEU

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 11, 2026 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File

February 11, 2026 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 11, 2026 ENZON PHARMACEU

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 11, 2026 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 000-12957 (Commission File

January 30, 2026 EX-FILING FEES

Table 1: Transaction Valuation

Calculation of Filing Fee Tables Table 1: Transaction Valuation Transaction Valuation Fee Rate Amount of Filing Fee Fees to be Paid 1 $ 7.

January 30, 2026 EX-99.10

NOTICE OF GUARANTEED DELIVERY OF SHARES OF SERIES C PREFERRED STOCK OF ENZON PHARMACEUTICALS, INC. Pursuant to the Prospectus/Consent Solicitation/Offer to Exchange, dated January 28, 2026 Instructions for Use

 Exhibit 99.10 NOTICE OF GUARANTEED DELIVERY OF SHARES OF SERIES C PREFERRED STOCK OF ENZON PHARMACEUTICALS, INC. Pursuant to the Prospectus/Consent Solicitation/Offer to Exchange, dated January 28, 2026 Instructions for Use Unless defined herein, terms used in this Notice of Guaranteed Delivery shall have definitions set forth in the Prospectus/Consent Solicitation/Offer to Exchange, dated Januar

January 30, 2026 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): January 30, 2026 ENZON PHARMACEUT

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): January 30, 2026 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission File

January 30, 2026 EX-99.11

LETTER TO BROKERS, DEALERS, COMMERCIAL BANKS, TRUST COMPANIES AND OTHER NOMINEES Offer To Exchange Shares of Series C Preferred Stock of Enzon Pharmaceuticals, Inc. for Shares of Common Stock of Enzon Pharmaceuticals, Inc.

 Exhibit 99.11 LETTER TO BROKERS, DEALERS, COMMERCIAL BANKS, TRUST COMPANIES AND OTHER NOMINEES Offer To Exchange Shares of Series C Preferred Stock of Enzon Pharmaceuticals, Inc. for Shares of Common Stock of Enzon Pharmaceuticals, Inc. THE OFFER (AS DEFINED BELOW) AND WITHDRAWAL RIGHTS WILL EXPIRE AT ONE MINUTE AFTER 11:59 P.M., EASTERN TIME, ON FEBRUARY 27, 2026, OR SUCH LATER TIME AND DATE TO

January 30, 2026 EX-99.13

Enzon Announces Commencement of Exchange Offer Relating to Series C Non-Convertible Redeemable Preferred Stock in Connection With Viskase Merger

Exhibit 99.13 Enzon Announces Commencement of Exchange Offer Relating to Series C Non-Convertible Redeemable Preferred Stock in Connection With Viskase Merger Cranford, New Jersey – January 30, 2026 – Enzon Pharmaceuticals, Inc. (OTCQB: ENZN) (“Enzon” or the “Company”), today announced that it has commenced an exchange offer (the “Offer”) involving its Series C Non-Convertible Redeemable Preferred

January 30, 2026 S-4/A

As filed with the U.S. Securities and Exchange Commission on January 30, 2026

As filed with the U.S. Securities and Exchange Commission on January 30, 2026 Registration No. 333-293019 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 AMENDMENT NO. 1 TO FORM S-4 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation

January 30, 2026 EX-99.9

LETTER OF TRANSMITTAL OFFER TO EXCHANGE SHARES OF SERIES C NON-CONVERTIBLE REDEEMABLE PREFERRED STOCK OF ENZON PHARMACEUTICALS, INC. Shares of Common Stock of Enzon Pharmaceuticals, Inc. (subject to the terms and conditions described in the prospectu

 Exhibit 99.9 LETTER OF TRANSMITTAL OFFER TO EXCHANGE SHARES OF SERIES C NON-CONVERTIBLE REDEEMABLE PREFERRED STOCK OF ENZON PHARMACEUTICALS, INC. for Shares of Common Stock of Enzon Pharmaceuticals, Inc. (subject to the terms and conditions described in the prospectus/consent solicitation/offer to exchange and this letter of transmittal) The Depositary and Exchange Agent for the offer is: If deli

January 30, 2026 EX-99.12

LETTER TO CLIENTS OF BROKERS, DEALERS, COMMERCIAL BANKS, TRUST COMPANIES AND OTHER NOMINEES Offer To Exchange Shares of Series C Preferred Stock of Enzon Pharmaceuticals, Inc. for Shares of Common Stock of Enzon Pharmaceuticals, Inc.

 Exhibit 99.12 LETTER TO CLIENTS OF BROKERS, DEALERS, COMMERCIAL BANKS, TRUST COMPANIES AND OTHER NOMINEES Offer To Exchange Shares of Series C Preferred Stock of Enzon Pharmaceuticals, Inc. for Shares of Common Stock of Enzon Pharmaceuticals, Inc. THE OFFER (AS DEFINED BELOW) AND WITHDRAWAL RIGHTS WILL EXPIRE AT ONE MINUTE AFTER 11:59 P.M., EASTERN TIME, ON FEBRUARY 27, 2026, OR SUCH LATER TIME A

January 30, 2026 8-A12G/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 7 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 7 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation or organization) 22-2372868 (I.R.S. Emplo

January 30, 2026 EX-4.1

SEVENTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent

EXHIBIT 4.1 SEVENTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. and CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent This SEVENTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT (this “Seventh Amendment”) is made and entered into January 30, 2026 and is effective immediately, by and between Enzon Pharmaceuticals, Inc., a Delaware corporation (t

January 30, 2026 424B3

CONSENT SOLICITATION PROSPECTUS FOR ISSUANCE OF UP TO 7,935,878 SHARES OF COMMON STOCK IN THE MERGER PROSPECTUS FOR OFFER TO EXCHANGE SHARES OF SERIES C PREFERRED STOCK COMMON STOCK

TABLE OF CONTENTS  Filed Pursuant to Rule 424(b)(3)  Registration No. 333-293019 PROSPECTUS CONSENT SOLICITATION PROSPECTUS FOR ISSUANCE OF UP TO 7,935,878 SHARES OF COMMON STOCK IN THE MERGER PROSPECTUS FOR OFFER TO EXCHANGE SHARES OF SERIES C PREFERRED STOCK FOR COMMON STOCK Dear Enzon Stockholders: On behalf of the board of directors (the “Enzon Board”) of Enzon Pharmaceuticals, Inc. (“Enzon”),

January 30, 2026 SC TO-I

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (Name of Subject Company and Filing Perso

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE TO TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (Name of Subject Company and Filing Persons (Issuer)) Series C Non-Convertible Redeemable Preferred Stock (Title of Class of Securities) 293904702 (CUSIP Number of Class of Securities) Richar

January 28, 2026 EX-99.9

LETTER OF TRANSMITTAL OFFER TO EXCHANGE SHARES OF SERIES C NON-CONVERTIBLE REDEEMABLE PREFERRED STOCK ENZON PHARMACEUTICALS, INC. Shares of Common Stock of Enzon Pharmaceuticals, Inc. (subject to the terms and conditions described in the prospectus/c

Exhibit 99.9 LETTER OF TRANSMITTAL OFFER TO EXCHANGE SHARES OF SERIES C NON-CONVERTIBLE REDEEMABLE PREFERRED STOCK OF ENZON PHARMACEUTICALS, INC. for Shares of Common Stock of Enzon Pharmaceuticals, Inc. (subject to the terms and conditions described in the prospectus/consent solicitation/offer to exchange and this letter of transmittal) The Depositary and Exchange Agent for the offer is: If deliv

January 28, 2026 EX-10.25

EMPLOYMENT AGREEMENT

Exhibit 10.25 EMPLOYMENT AGREEMENT This EMPLOYMENT AGREEMENT, dated as of November , 2025 (the “Employment Agreement”), is entered by and between Viskase Companies, Inc., a Delaware corporation (the “Company”), and Thomas D. Davis (the “Executive”) and (except as provided in Section 2.1) is effective December 1, 2025 (the “Effective Date”). In consideration of the mutual covenants contained herein

January 28, 2026 EX-10.23

Exhibit 10.23

Exhibit 10.23

January 28, 2026 EX-10.12

VISKASE COMPANIES, INC. Management Incentive Plan for Fiscal Year 2024

Exhibit 10.12 VISKASE COMPANIES, INC. Management Incentive Plan for Fiscal Year 2024 I. PURPOSE The Viskase Companies, Inc. Management Incentive Plan (the “Plan”) has been established for Fiscal Year 2024 for those Participants defined under Section III below. The purpose of this Plan is to provide additional compensation to Participants for their contribution to the achievement of the objectives

January 28, 2026 EX-99.5

Consent to Reference in Registration Statement

Exhibit 99.5 January 23, 2026 Enzon Pharmaceuticals, Inc. 200 Commerce Drive, Suite 135 Cranford, NJ 07016 Consent to Reference in Registration Statement Enzon Pharmaceuticals, Inc. (the “Company”) has filed a Registration Statement on Form S-4, as amended, with the Securities and Exchange Commission under the Securities Act of 1933, as amended (the “Securities Act”), as of the date hereof. In con

January 28, 2026 EX-10.15

FOURTH AMENDMENT TO CREDIT AGREEMENT

Exhibit 10.15 FOURTH AMENDMENT TO CREDIT AGREEMENT THIS FOURTH AMENDMENT TO CREDIT AGREEMENT (this “Amendment”), dated as of July 25, 2025, is by and among VISKASE COMPANIES, INC., a Delaware corporation (the “Borrower”), the other Subsidiary Guarantors party hereto, the Lenders party hereto and BANK OF AMERICA, N.A., as administrative agent (in such capacity, the “Administrative Agent”). Capitali

January 28, 2026 EX-10.31

LIMITED WAIVER AND SIXTH AMENDMENT TO CREDIT AGREEMENT

Exhibit 10.31 Execution Version LIMITED WAIVER AND SIXTH AMENDMENT TO CREDIT AGREEMENT THIS LIMITED WAIVER AND SIXTH AMENDMENT TO CREDIT AGREEMENT (this “Amendment”), dated as of January 23, 2026, is by and among VISKASE COMPANIES, INC., a Delaware corporation (the “Borrower”), the other Subsidiary Guarantors party hereto, the Lenders party hereto and BANK OF AMERICA, N.A., as administrative agent

January 28, 2026 EX-3.8

State of Delaware

Exhibit 3.8 State of Delaware Secretary of State Division of Corporations Delivered 04:14 PM 10/07/2020 FILED 04:14 PM 10/07/2020 SR 20207703755 – File Number 757401 CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF VISKASE COMPANIES, INC. Viskase Companies, Inc. (the “Corporation”), organized and existing under and by virtue of the General Corporation Law of the

January 28, 2026 EX-10.8

FIRST AMENDMENT TO CREDIT AGREEMENT

Exhibit 10.8 FIRST AMENDMENT TO CREDIT AGREEMENT THIS FIRST AMENDMENT TO CREDIT AGREEMENT (this “Amendment”), dated as of August 13, 2021, is by and among VISKASE COMPANIES, INC., a Delaware corporation (the “Borrower”), the other Subsidiary Guarantors party hereto, the Lenders party hereto and BANK OF AMERICA, N.A., as administrative agent (in such capacity, the “Administrative Agent”).Capitalize

January 28, 2026 EX-10.20

Viskase Companies, Inc. 333 East Butterfield Road, Suite 400, Lombard, Illinois, 60561 USA Phone: (630) 874-0700 Fax: (630) 874-0176

Exhibit 10.20 June 7, 2024 Delivered via Email Jan Stevens [*****] Dear Jan: On behalf of Viskase Companies, Inc. (“Company” or “Viskase”), I am pleased to present you with the following job offer: Title: Vice President of Quality and Technology Reporting to: You will report directly to Tim Feast, President and CEO Location This role is a remote position, with occasional visits to the corporate of

January 28, 2026 EX-99.6

Consent to Reference in Registration Statement

Exhibit 99.6 January 23, 2026 Enzon Pharmaceuticals, Inc. 200 Commerce Drive, Suite 135 Cranford, NJ 07016 Consent to Reference in Registration Statement Enzon Pharmaceuticals, Inc. (the “Company”) has filed a Registration Statement on Form S-4, as amended, with the Securities and Exchange Commission under the Securities Act of 1933, as amended (the “Securities Act”), as of the date hereof. In con

January 28, 2026 EX-10.22

Viskase Companies, Inc. 333 East Butterfield Road, Suite 400, Lombard, Illinois, 60561 USA Phone: (630) 874-0700 Fax: (630) 874-0176

Exhibit 10.22 January 30, 2025 Joseph Marigliano [*****] Dear Joseph: On behalf of Viskase Companies, Inc. (“Viskase” or the “Company”), I am pleased to present you with the following job offer: Title: Vice President, Business Management Primary Focus: You will perform such services as requested by the Company’s President & CEO. Unless otherwise directed, your primary focus will be to drive global

January 28, 2026 EX-10.9

SECOND AMENDMENT TO CREDIT AGREEMENT

Exhibit 10.9 SECOND AMENDMENT TO CREDIT AGREEMENT THIS SECOND AMENDMENT TO CREDIT AGREEMENT (this “Amendment”), dated as of August 10, 2022, is by and among VISKASE COMPANIES, INC., a Delaware corporation (the “Borrower”), the other Subsidiary Guarantors party hereto, the Lenders party hereto and BANK OF AMERICA, N.A., as administrative agent (in such capacity, the “Administrative Agent”). Capital

January 28, 2026 EX-10.29

FIFTH AMENDMENT TO CREDIT AGREEMENT

Exhibit 10.29 Execution Version FIFTH AMENDMENT TO CREDIT AGREEMENT THIS FIFTH AMENDMENT TO CREDIT AGREEMENT (this “Amendment”), dated as of October 10, 2025, is by and among VISKASE COMPANIES, INC., a Delaware corporation (the “Borrower”), the other Subsidiary Guarantors party hereto, the Lenders party hereto and BANK OF AMERICA, N.A., as administrative agent (in such capacity, the “Administrativ

January 28, 2026 EX-10.11

VISKASE COMPANIES, INC. 2022 LONG-TERM INCENTIVE PLAN For the Performance Period September 6, 2022 – September 5, 2027

Exhibit 10.11 VISKASE COMPANIES, INC. 2022 LONG-TERM INCENTIVE PLAN For the Performance Period September 6, 2022 – September 5, 2027 I. PURPOSE AND STRUCTURE The Company’s (as defined below) 2022 Long-Term Incentive Plan (the “Plan”) is designed to drive a culture focused on long-term company performance. The Plan is intended to deliver “pay-for-performance” through a potential long-term incentive

January 28, 2026 EX-10.27

EMPLOYMENT CONTRACT FOR AN INDEFINITE PERIOD SEPTEMBER 23, 2025 Viskase GmbH R.M. Schouten

Exhibit 10.27 EMPLOYMENT CONTRACT FOR AN INDEFINITE PERIOD SEPTEMBER 23, 2025 Between Viskase GmbH and R.M. Schouten CONTENTS Clause Page 1. Start date and position 3 2. Place of work 4 3. Duration and termination 4 4. Salary and holiday allowance 5 5. Working hours and overtime 5 6. Travel and expenses 5 7. Holidays 6 8. Sickness 6 9. Pensions 6 10. Confidentiality 6 11. Documents and company pro

January 28, 2026 EX-3.7

AMENDED AND RESTATED BYLAWS VISKASE COMPANIES, INC. (hereinafter called the “Corporation”) (As amended and restated through August 10, 2017) ARTICLE I

Exhibit 3.7 AMENDED AND RESTATED BYLAWS OF VISKASE COMPANIES, INC. (hereinafter called the “Corporation”) (As amended and restated through August 10, 2017) ARTICLE I OFFICES Section 1.Registered Office. The registered office of the Corporation shall be in the City of Wilmington, County of New Castle, State of Delaware. Section 2.Other Offices. The Corporation may also have offices at such other pl

January 28, 2026 EX-99.8

CONSENT OF ALVAREZ & MARSAL VALUATION SERVICES, LLC

Exhibit 99.8 CONSENT OF ALVAREZ & MARSAL VALUATION SERVICES, LLC January 28, 2026 Special Committee of the Board of Directors Viskase Companies, Inc. 333 East Butterfield Road, Suite 400 Lombard, Illinois 60148-5679 RE: prospectus/consent solicitation/offer to exchange of Enzon Pharmaceuticals, Inc. (“Enzon”) and Viskase Companies, Inc. (“Viskase”), which forms part of the Registration Statement o

January 28, 2026 EX-99.10

NOTICE OF GUARANTEED DELIVERY OF SHARES OF SERIES C PREFERRED STOCK OF ENZON PHARMACEUTICALS, INC. Pursuant to the Prospectus/Consent Solicitation/Offer to Exchange, dated January 28, 2026 Instructions for Use

Exhibit 99.10 NOTICE OF GUARANTEED DELIVERY OF SHARES OF SERIES C PREFERRED STOCK OF ENZON PHARMACEUTICALS, INC. Pursuant to the Prospectus/Consent Solicitation/Offer to Exchange, dated January 28, 2026 Instructions for Use Unless defined herein, terms used in this Notice of Guaranteed Delivery shall have definitions set forth in the Prospectus/Consent Solicitation/Offer to Exchange, dated January

January 28, 2026 EX-99.4

Consent to Reference in Registration Statement

Exhibit 99.4 January 23, 2026 Enzon Pharmaceuticals, Inc. 200 Commerce Drive, Suite 135 Cranford, NJ 07016 Consent to Reference in Registration Statement Enzon Pharmaceuticals, Inc. (the “Company”) has filed a Registration Statement on Form S-4, as amended, with the Securities and Exchange Commission under the Securities Act of 1933, as amended (the “Securities Act”), as of the date hereof. In con

January 28, 2026 EX-99.7

The Special Committee of the Board of Directors

Exhibit 99.7 The Special Committee of the Board of Directors Enzon Pharmaceuticals, Inc. 20 Commerce Drive, Suite 135 Cranford, NJ 07016 Dear Special Committee: We hereby consent to the inclusion of our opinion letter, dated October 21, 2025, to the Special Committee of the Board of Directors of Enzon Pharmaceuticals, Inc. (“Enzon”) as Annex C to, and reference to such opinion letter under the hea

January 28, 2026 EX-10.28

SECURITIES PURCHASE AGREEMENT

Exhibit 10.28 EXECUTION COPY SECURITIES PURCHASE AGREEMENT This Securities Purchase Agreement (this “Agreement”) is entered into as of December 30, 2025, by and between Viskase Companies, Inc. (the “Company”), and American Entertainment Properties Corp., a Delaware corporation (“Purchaser”). RECITALS WHEREAS, the Company wishes to sell to the Purchaser, and the Purchaser wishes to purchase from th

January 28, 2026 EX-99.3

Consent to Reference in Registration Statement

Exhibit 99.3 January 23, 2026 Enzon Pharmaceuticals, Inc. 200 Commerce Drive, Suite 135 Cranford, NJ 07016 Consent to Reference in Registration Statement Enzon Pharmaceuticals, Inc. (the “Company”) has filed a Registration Statement on Form S-4, as amended, with the Securities and Exchange Commission under the Securities Act of 1933, as amended (the “Securities Act”), as of the date hereof. In con

January 28, 2026 EX-10.10

EMPLOYMENT AGREEMENT

Exhibit 10.10 EMPLOYMENT AGREEMENT This EMPLOYMENT AGREEMENT, dated as of August 4, 2022 (the “Employment Agreement”), is entered by and between Viskase Companies, Inc., a Delaware corporation (the “Company”), and Timothy P. Feast (the “Executive”) and (except as provided in Section 2.1) is effective September 6, 2022 (the “Effective Date”). In consideration of the mutual covenants contained herei

January 28, 2026 EX-10.26

Viskase Companies, Inc. 333 East Butterfield Road, Suite 400, Lombard, Illinois, 60561 USA Phone: (630) 874-0700 Fax: (630) 874-0176

Exhibit 10.26 December 8, 2025 Via Electronic Delivery John Plescia [*****][*****] Email: [*****][*****] Dear John: On behalf of Viskase Companies, Inc. (“Company” or “Viskase”), I am pleased to present you with the following job offer: Title: Vice President and General Manager, Americas Reporting to: You will report directly to Tom Davis, President, and CEO Location Viskase Corporate HQs, Lombard

January 28, 2026 EX-FILING FEES

Security Type

Calculation of Filing Fee Tables S-4 ENZON PHARMACEUTICALS, INC. Table 1: Newly Registered and Carry Forward Securities ☐Not Applicable Security Type Security Class Title Fee Calculation or Carry Forward Rule Amount Registered Proposed Maximum Offering Price Per Unit Maximum Aggregate Offering Price Fee Rate Amount of Registration Fee Carry Forward Form Type Carry Forward File Number Carry Forward

January 28, 2026 EX-99.2

Consent to Reference in Registration Statement

Exhibit 99.2 January 23, 2026 Enzon Pharmaceuticals, Inc. 200 Commerce Drive, Suite 135 Cranford, NJ 07016 Consent to Reference in Registration Statement Enzon Pharmaceuticals, Inc. (the “Company”) has filed a Registration Statement on Form S-4, as amended, with the Securities and Exchange Commission under the Securities Act of 1933, as amended (the “Securities Act”), as of the date hereof. In con

January 28, 2026 EX-99.12

LETTER TO CLIENTS OF BROKERS, DEALERS, COMMERCIAL BANKS, TRUST COMPANIES AND OTHER NOMINEES Offer To Exchange Shares of Series C Preferred Stock Enzon Pharmaceuticals, Inc. Shares of Common Stock Enzon Pharmaceuticals, Inc.

Exhibit 99.12 LETTER TO CLIENTS OF BROKERS, DEALERS, COMMERCIAL BANKS, TRUST COMPANIES AND OTHER NOMINEES Offer To Exchange Shares of Series C Preferred Stock of Enzon Pharmaceuticals, Inc. for Shares of Common Stock of Enzon Pharmaceuticals, Inc. THE OFFER (AS DEFINED BELOW) AND WITHDRAWAL RIGHTS WILL EXPIRE AT ONE MINUTE AFTER 11:59 P.M., EASTERN TIME, ON [], 2026, OR SUCH LATER TIME AND DATE TO

January 28, 2026 EX-10.21

Viskase Companies, Inc. 333 East Butterfield Road, Suite 400, Lombard, Illinois, 60561 USA Phone: (630) 874-0700 Fax: (630) 874-0176

Exhibit 10.21 September 13, 2024 Via Electronic Delivery Marcelo Passos [*****] [email protected] Dear Marcelo: On behalf of Viskase Companies, Inc. (“Company” or “Viskase”), I am pleased to present you with the following job offer: Title: Vice President and General Manager Americas Reporting to: You will report directly to Tim Feast, President, and CEO Location Remote, Home-Based office in

January 28, 2026 EX-10.17

Viskase Companies, Inc. 333 East Butterfield Road, Suite 400, Lombard, Illinois, 60561 USA Phone: (630) 874-0700 Fax: (630) 874-0176

Exhibit 10.17 May 4, 2022 Joseph D King [*****] Dear Joe: On behalf of Viskase Companies, Inc. (“Company” or “Viskase”), I am pleased to present you with the following job offer, subject to review and approval of Viskase Board of Directors’ Compensation Committee: Title: Senior Vice President, General Counsel and Secretary Reporting to: Kees Bras, President and CEO Location: Lombard, IL - Corporat

January 28, 2026 EX-10.7

CREDIT AGREEMENT Dated as of October 9, 2020 VISKASE COMPANIES, INC., as the Borrower, CERTAIN SUBSIDIARIES OF THE BORROWER PARTY HERETO, as the Guarantors, BANK OF AMERICA, N.A., as Administrative Agent, Swingline Lender and L/C Issuer, THE LENDERS

Exhibit 10.7 CREDIT AGREEMENT Dated as of October 9, 2020 among VISKASE COMPANIES, INC., as the Borrower, CERTAIN SUBSIDIARIES OF THE BORROWER PARTY HERETO, as the Guarantors, BANK OF AMERICA, N.A., as Administrative Agent, Swingline Lender and L/C Issuer, and THE LENDERS PARTY HERETO BMO HARRIS BANK N.A., as Syndication Agent TRUIST BANK, as Documentation Agent BOFA SECURITIES, INC., and BMO CAPI

January 28, 2026 EX-10.30

SECURITIES PURCHASE AGREEMENT

Exhibit 10.30 EXECUTION COPY SECURITIES PURCHASE AGREEMENT This Securities Purchase Agreement (this “Agreement”) is entered into as of January 23, 2026, by and between Viskase Companies, Inc. (the “Company”), and American Entertainment Properties Corp., a Delaware corporation (“Purchaser”). RECITALS WHEREAS, the Company wishes to sell to the Purchaser, and the Purchaser wishes to purchase from the

January 28, 2026 EX-3.6

The First State

Exhibit 3.6 Delaware Page 1 The First State I, JEFFREY W. BULLOCK, SECRETARY OF STATE OF THE STATE OF DELAWARE, DO HEREBY CERTIFY THE ATTACHED ARE TRUE AND CORRECT COPIES OF ALL DOCUMENTS FILED FROM AND INCLUDING THE RESTATED CERTIFICATE OR A MERGER WITH A RESTATED CERTIFICATE ATTACHED OF “VISKASE COMPANIES, INC.” AS RECEIVED AND FILED IN THIS OFFICE. THE FOLLOWING DOCUMENTS HAVE BEEN CERTIFIED: R

January 28, 2026 S-4

As filed with the U.S. Securities and Exchange Commission on January 28, 2026.

Table of Contents As filed with the U.S. Securities and Exchange Commission on January 28, 2026. Registration No. 333- UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM S-4 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware 2836 22-2372868 (State or other jurisdiction of inco

January 28, 2026 EX-10.19

Viskase Companies, Inc. 333 East Butterfield Road, Suite 400, Lombard, Illinois, 60561 USA Phone: (630) 874-0700 Fax: (630) 874-0176

Exhibit 10.19 March 15, 2024 Via Electronic Delivery Armando Herrera [*****] Dear Armando: On behalf of Viskase Companies, Inc. (“Company” or “Viskase”), I am pleased to present you with the following job offer: Title: Vice President, Global Human Resources Reporting to: You will report directly to Joe King, Senior Vice President, General Counsel and Secretary Location Corporate HQs, Lombard, IL S

January 28, 2026 EX-10.18

Viskase Companies, Inc. 333 East Butterfield Road, Suite 400, Lombard, Illinois, 60561 USA Phone: (630) 874-0700 Fax: (630) 874-0176

Exhibit 10.18 December 19, 2022 Thomas Holz [*****] Dear Tom: On behalf of Viskase Companies, Inc. (“Viskase” or the “Company”), I am pleased to present you with the following job offer, subject to review and approval of the Compensation Committee of Viskase’s Board of Directors: Title: Vice President and Chief Financial Offer Reporting to: Tim Feast, President and CEO Location: Lombard, IL – Corp

January 28, 2026 EX-10.13

LIMITED WAIVER AND THIRD AMENDMENT TO CREDIT AGREEMENT

Exhibit 10.13 LIMITED WAIVER AND THIRD AMENDMENT TO CREDIT AGREEMENT THIS LIMITED WAIVER AND THIRD AMENDMENT TO CREDIT AGREEMENT (this “Amendment”), dated as of February 14, 2025, is by and among VISKASE COMPANIES, INC., a Delaware corporation (the “Borrower”), the other Subsidiary Guarantors party hereto, the Lenders party hereto and BANK OF AMERICA, N.A., as administrative agent (in such capacit

January 28, 2026 EX-10.16

Fourth Amendment Fee Letter Viskase Companies, Inc.

Exhibit 10.16 Execution Version Confidential July 25, 2025 Viskase Companies, Inc. 333 East Butterfield Road Suite 400 Lombard, Illinois 60148-5679 Attn: Michael Blecic Fourth Amendment Fee Letter Viskase Companies, Inc. Ladies and Gentlemen: Reference is made that certain Fourth Amendment to Credit Agreement, dated as of July 25, 2025 (the “Fourth Amendment”) which amends that certain Credit Agre

January 28, 2026 EX-99.11

LETTER TO BROKERS, DEALERS, COMMERCIAL BANKS, TRUST COMPANIES AND OTHER NOMINEES Offer To Exchange Shares of Series C Preferred Stock Enzon Pharmaceuticals, Inc. Shares of Common Stock Enzon Pharmaceuticals, Inc.

Exhibit 99.11 LETTER TO BROKERS, DEALERS, COMMERCIAL BANKS, TRUST COMPANIES AND OTHER NOMINEES Offer To Exchange Shares of Series C Preferred Stock of Enzon Pharmaceuticals, Inc. for Shares of Common Stock of Enzon Pharmaceuticals, Inc. THE OFFER (AS DEFINED BELOW) AND WITHDRAWAL RIGHTS WILL EXPIRE AT ONE MINUTE AFTER 11:59 P.M., EASTERN TIME, ON [ ], 2026, OR SUCH LATER TIME AND DATE TO WHICH WE

January 28, 2026 EX-10.32

Fifth Amendment Fee Letter Viskase Companies, Inc.

Exhibit 10.32 Execution Version Confidential October 10, 2025 Viskase Companies, Inc. 333 East Butterfield Road Suite 400 Lombard, Illinois 60148-5679 Attn: Michael Blecic Fifth Amendment Fee Letter Viskase Companies, Inc. Ladies and Gentlemen: Reference is made that certain Fifth Amendment to Credit Agreement, dated as of October 10, 2025 (the “Fifth Amendment”) which amends that certain Credit A

December 23, 2025 8-A12G/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 6 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 6 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation or organization) 22-2372868 (I.R.S. Emplo

December 23, 2025 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): December 23, 2025 ENZON PHARMACEU

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): December 23, 2025 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission File

December 23, 2025 EX-4.1

SIXTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent

Exhibit 4.1 SIXTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. and CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent This SIXTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT (this “Sixth Amendment”) is made and entered into December 23, 2025 and is effective immediately, by and between Enzon Pharmaceuticals, Inc., a Delaware corporation (the “C

December 19, 2025 EX-10.26

Viskase Companies, Inc. 333 East Butterfield Road, Suite 400, Lombard, Illinois, 60561 USA Phone: (630) 874-0700 Fax: (630) 874-0176

Exhibit 10.26 December 8, 2025 Via Electronic Delivery John Plescia [*****][*****] Email: [*****][*****] Dear John: On behalf of Viskase Companies, Inc. (“Company” or “Viskase”), I am pleased to present you with the following job offer: Title: Vice President and General Manager, Americas Reporting to: You will report directly to Tom Davis, President, and CEO Location Viskase Corporate HQs, Lombard

December 19, 2025 EX-10.12

VISKASE COMPANIES, INC. Management Incentive Plan for Fiscal Year 2024

Exhibit 10.12 VISKASE COMPANIES, INC. Management Incentive Plan for Fiscal Year 2024 I. PURPOSE The Viskase Companies, Inc. Management Incentive Plan (the “Plan”) has been established for Fiscal Year 2024 for those Participants defined under Section III below. The purpose of this Plan is to provide additional compensation to Participants for their contribution to the achievement of the objectives

December 19, 2025 EX-10.20

Viskase Companies, Inc. 333 East Butterfield Road, Suite 400, Lombard, Illinois, 60561 USA Phone: (630) 874-0700 Fax: (630) 874-0176

Exhibit 10.20 June 7, 2024 Delivered via Email Jan Stevens [*****] Dear Jan: On behalf of Viskase Companies, Inc. (“Company” or “Viskase”), I am pleased to present you with the following job offer: Title: Vice President of Quality and Technology Reporting to: You will report directly to Tim Feast, President and CEO Location This role is a remote position, with occasional visits to the corporate of

December 19, 2025 EX-10.23

Company: Enzon Pharmaceuticals, Inc. Fri Dec 19 2025 04:11 Document: 25-21156-2 S-4/enzn_Ex10_23.pdf (v0.1) Page: 2/16 Company: Enzon Pharmaceuticals, Inc. Fri Dec 19 2025 04:11 Document: 25-21156-2 S-4/enzn_Ex10_23.pdf (v0.1) Page: 3/16 Company: Enz

Exhibit 10.23 Exhibit 10.23 Company: Enzon Pharmaceuticals, Inc. Fri Dec 19 2025 04:11 Document: 25-21156-2 S-4/enznEx1023.pdf (v0.1) Page: 1/16 Company: Enzon Pharmaceuticals, Inc. Fri Dec 19 2025 04:11 Document: 25-21156-2 S-4/enznEx1023.pdf (v0.1) Page: 2/16 Company: Enzon Pharmaceuticals, Inc. Fri Dec 19 2025 04:11 Document: 25-21156-2 S-4/enznEx1023.pdf (v0.1) Page: 3/16 Company: Enzon Pharma

December 19, 2025 EX-10.13

LIMITED WAIVER AND THIRD AMENDMENT TO CREDIT AGREEMENT

Exhibit 10.13 LIMITED WAIVER AND THIRD AMENDMENT TO CREDIT AGREEMENT THIS LIMITED WAIVER AND THIRD AMENDMENT TO CREDIT AGREEMENT (this “Amendment”), dated as of February 14, 2025, is by and among VISKASE COMPANIES, INC., a Delaware corporation (the “Borrower”), the other Subsidiary Guarantors party hereto, the Lenders party hereto and BANK OF AMERICA, N.A., as administrative agent (in such capacit

December 19, 2025 DRS

As confidentially submitted to the Securities and Exchange Commission on December 19, 2025.

TABLE OF CONTENTS As confidentially submitted to the Securities and Exchange Commission on December 19, 2025.

December 19, 2025 EX-3.6

AMENDED AND RESTATED CERTIFICATE OF INCORPORATION VISKASE COMPANIES, INC.

Exhibit 3.6 Delaware Page 1 The First State I, JEFFREY W. BULLOCK, SECRETARY OF STATE OF THE STATE OF DELAWARE, DO HEREBY CERTIFY THE ATTACHED ARE TRUE AND CORRECT COPIES OF ALL DOCUMENTS FILED FROM AND INCLUDING THE RESTATED CERTIFICATE OR A MERGER WITH A RESTATED CERTIFICATE ATTACHED OF “VISKASE COMPANIES, INC.” AS RECEIVED AND FILED IN THIS OFFICE. THE FOLLOWING DOCUMENTS HAVE BEEN CERTIFIED: R

December 19, 2025 EX-10.8

FIRST AMENDMENT TO CREDIT AGREEMENT

Exhibit 10.8 FIRST AMENDMENT TO CREDIT AGREEMENT THIS FIRST AMENDMENT TO CREDIT AGREEMENT (this “Amendment”), dated as of August 13, 2021, is by and among VISKASE COMPANIES, INC., a Delaware corporation (the “Borrower”), the other Subsidiary Guarantors party hereto, the Lenders party hereto and BANK OF AMERICA, N.A., as administrative agent (in such capacity, the “Administrative Agent”).Capitalize

December 19, 2025 EX-10.19

Viskase Companies, Inc. 333 East Butterfield Road, Suite 400, Lombard, Illinois, 60561 USA Phone: (630) 874-0700 Fax: (630) 874-0176

Exhibit 10.19 March 15, 2024 Via Electronic Delivery Armando Herrera [*****] Dear Armando: On behalf of Viskase Companies, Inc. (“Company” or “Viskase”), I am pleased to present you with the following job offer: Title: Vice President, Global Human Resources Reporting to: You will report directly to Joe King, Senior Vice President, General Counsel and Secretary Location Corporate HQs, Lombard, IL S

December 19, 2025 EX-10.25

EMPLOYMENT AGREEMENT

Exhibit 10.25 EMPLOYMENT AGREEMENT This EMPLOYMENT AGREEMENT, dated as of November , 2025 (the “Employment Agreement”), is entered by and between Viskase Companies, Inc., a Delaware corporation (the “Company”), and Thomas D. Davis (the “Executive”) and (except as provided in Section 2.1) is effective December 1, 2025 (the “Effective Date”). In consideration of the mutual covenants contained herein

December 19, 2025 EX-10.7

CREDIT AGREEMENT Dated as of October 9, 2020 VISKASE COMPANIES, INC., as the Borrower, CERTAIN SUBSIDIARIES OF THE BORROWER PARTY HERETO, as the Guarantors, BANK OF AMERICA, N.A., as Administrative Agent, Swingline Lender and L/C Issuer, THE LENDERS

Exhibit 10.7 CREDIT AGREEMENT Dated as of October 9, 2020 among VISKASE COMPANIES, INC., as the Borrower, CERTAIN SUBSIDIARIES OF THE BORROWER PARTY HERETO, as the Guarantors, BANK OF AMERICA, N.A., as Administrative Agent, Swingline Lender and L/C Issuer, and THE LENDERS PARTY HERETO BMO HARRIS BANK N.A., as Syndication Agent TRUIST BANK, as Documentation Agent BOFA SECURITIES, INC., and BMO CAPI

December 19, 2025 EX-10.9

SECOND AMENDMENT TO CREDIT AGREEMENT

Exhibit 10.9 SECOND AMENDMENT TO CREDIT AGREEMENT THIS SECOND AMENDMENT TO CREDIT AGREEMENT (this “Amendment”), dated as of August 10, 2022, is by and among VISKASE COMPANIES, INC., a Delaware corporation (the “Borrower”), the other Subsidiary Guarantors party hereto, the Lenders party hereto and BANK OF AMERICA, N.A., as administrative agent (in such capacity, the “Administrative Agent”). Capital

December 19, 2025 EX-10.17

Viskase Companies, Inc. 333 East Butterfield Road, Suite 400, Lombard, Illinois, 60561 USA Phone: (630) 874-0700 Fax: (630) 874-0176

Exhibit 10.17 May 4, 2022 Joseph D King [*****] Dear Joe: On behalf of Viskase Companies, Inc. (“Company” or “Viskase”), I am pleased to present you with the following job offer, subject to review and approval of Viskase Board of Directors’ Compensation Committee: Title: Senior Vice President, General Counsel and Secretary Reporting to: Kees Bras, President and CEO Location: Lombard, IL - Corporat

December 19, 2025 EX-10.27

EMPLOYMENT CONTRACT FOR AN INDEFINITE PERIOD SEPTEMBER 23, 2025 Viskase GmbH R.M. Schouten

Exhibit 10.27 EMPLOYMENT CONTRACT FOR AN INDEFINITE PERIOD SEPTEMBER 23, 2025 Between Viskase GmbH and R.M. Schouten CONTENTS Clause Page 1. Start date and position 3 2. Place of work 4 3. Duration and termination 4 4. Salary and holiday allowance 5 5. Working hours and overtime 5 6. Travel and expenses 5 7. Holidays 6 8. Sickness 6 9. Pensions 6 10. Confidentiality 6 11. Documents and company pro

December 19, 2025 EX-10.11

VISKASE COMPANIES, INC. 2022 LONG-TERM INCENTIVE PLAN For the Performance Period September 6, 2022 – September 5, 2027

Exhibit 10.11 VISKASE COMPANIES, INC. 2022 LONG-TERM INCENTIVE PLAN For the Performance Period September 6, 2022 – September 5, 2027 I. PURPOSE AND STRUCTURE The Company’s (as defined below) 2022 Long-Term Incentive Plan (the “Plan”) is designed to drive a culture focused on long-term company performance. The Plan is intended to deliver “pay-for-performance” through a potential long-term incentive

December 19, 2025 EX-3.7

AMENDED AND RESTATED BYLAWS VISKASE COMPANIES, INC. (hereinafter called the “Corporation”) (As amended and restated through August 10, 2017) ARTICLE I

Exhibit 3.7 AMENDED AND RESTATED BYLAWS OF VISKASE COMPANIES, INC. (hereinafter called the “Corporation”) (As amended and restated through August 10, 2017) ARTICLE I OFFICES Section 1. Registered Office. The registered office of the Corporation shall be in the City of Wilmington, County of New Castle, State of Delaware. Section 2. Other Offices. The Corporation may also have offices at such other

December 19, 2025 EX-10.18

Viskase Companies, Inc. 333 East Butterfield Road, Suite 400, Lombard, Illinois, 60561 USA Phone: (630) 874-0700 Fax: (630) 874-0176

Exhibit 10.18 December 19, 2022 Thomas Holz [*****] Dear Tom: On behalf of Viskase Companies, Inc. (“Viskase” or the “Company”), I am pleased to present you with the following job offer, subject to review and approval of the Compensation Committee of Viskase’s Board of Directors: Title: Vice President and Chief Financial Offer Reporting to: Tim Feast, President and CEO Location: Lombard, IL – Corp

December 19, 2025 EX-10.21

Viskase Companies, Inc. 333 East Butterfield Road, Suite 400, Lombard, Illinois, 60561 USA Phone: (630) 874-0700 Fax: (630) 874-0176

Exhibit 10.21 September 13, 2024 Via Electronic Delivery Marcelo Passos [*****] [email protected] Dear Marcelo: On behalf of Viskase Companies, Inc. (“Company” or “Viskase”), I am pleased to present you with the following job offer: Title: Vice President and General Manager Americas Reporting to: You will report directly to Tim Feast, President, and CEO Location Remote, Home-Based office in

December 19, 2025 EX-10.15

FOURTH AMENDMENT TO CREDIT AGREEMENT

Exhibit 10.15 FOURTH AMENDMENT TO CREDIT AGREEMENT THIS FOURTH AMENDMENT TO CREDIT AGREEMENT (this “Amendment”), dated as of July 25, 2025, is by and among VISKASE COMPANIES, INC., a Delaware corporation (the “Borrower”), the other Subsidiary Guarantors party hereto, the Lenders party hereto and BANK OF AMERICA, N.A., as administrative agent (in such capacity, the “Administrative Agent”). Capitali

December 19, 2025 EX-10.16

Fourth Amendment Fee Letter Viskase Companies, Inc.

Exhibit 10.16 Execution Version Confidential July 25, 2025 Viskase Companies, Inc. 333 East Butterfield Road Suite 400 Lombard, Illinois 60148-5679 Attn: Michael Blecic Fourth Amendment Fee Letter Viskase Companies, Inc. Ladies and Gentlemen: Reference is made that certain Fourth Amendment to Credit Agreement, dated as of July 25, 2025 (the “Fourth Amendment”) which amends that certain Credit Agre

December 19, 2025 EX-10.22

Viskase Companies, Inc. 333 East Butterfield Road, Suite 400, Lombard, Illinois, 60561 USA Phone: (630) 874-0700 Fax: (630) 874-0176

Exhibit 10.22 January 30, 2025 Joseph Marigliano [*****] Dear Joseph: On behalf of Viskase Companies, Inc. (“Viskase” or the “Company”), I am pleased to present you with the following job offer: Title: Vice President, Business Management Primary Focus: You will perform such services as requested by the Company’s President & CEO. Unless otherwise directed, your primary focus will be to drive global

December 19, 2025 EX-3.8

CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF VISKASE COMPANIES, INC.

Exhibit 3.8 State of Delaware Secretary of State Division of Corporations Delivered 04:14 PM 10/07/2020 FILED 04:14 PM 10/07/2020 SR 20207703755 – File Number 757401 CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF VISKASE COMPANIES, INC. Viskase Companies, Inc. (the “Corporation”), organized and existing under and by virtue of the General Corporation Law of the

December 19, 2025 EX-10.10

EMPLOYMENT AGREEMENT

Exhibit 10.10 EMPLOYMENT AGREEMENT This EMPLOYMENT AGREEMENT, dated as of August 4, 2022 (the “Employment Agreement”), is entered by and between Viskase Companies, Inc., a Delaware corporation (the “Company”), and Timothy P. Feast (the “Executive”) and (except as provided in Section 2.1) is effective September 6, 2022 (the “Effective Date”). In consideration of the mutual covenants contained herei

November 12, 2025 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2025 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file numbe

October 24, 2025 425

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): October 24, 2025 ENZON PHARMACEUT

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): October 24, 2025 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission File

October 24, 2025 EX-10.1

FIRST AMENDMENT TO THE SUPPORT AGREEMENT

Exhibit 10.1 FIRST AMENDMENT TO THE SUPPORT AGREEMENT This FIRST AMENDMENT TO THE SUPPORT AGREEMENT (this “Amendment”), dated as of October 24, 2025, is by and among Enzon Pharmaceuticals, Inc., a Delaware corporation (“Enzon”), Viskase Companies, Inc., a Delaware corporation (“Viskase”), Icahn Enterprises Holdings L.P., a Delaware limited partnership (“IEH”), American Entertainment Properties Cor

October 24, 2025 EX-10.1

FIRST AMENDMENT TO THE SUPPORT AGREEMENT

Exhibit 10.1 FIRST AMENDMENT TO THE SUPPORT AGREEMENT This FIRST AMENDMENT TO THE SUPPORT AGREEMENT (this “Amendment”), dated as of October 24, 2025, is by and among Enzon Pharmaceuticals, Inc., a Delaware corporation (“Enzon”), Viskase Companies, Inc., a Delaware corporation (“Viskase”), Icahn Enterprises Holdings L.P., a Delaware limited partnership (“IEH”), American Entertainment Properties Cor

October 24, 2025 EX-99.1

Enzon and Viskase Announce Amendment to Merger Agreement Enzon and Viskase stockholders will respectively own 45% and 55% of the combined company

Exhibit 99.1 Enzon and Viskase Announce Amendment to Merger Agreement Enzon and Viskase stockholders will respectively own 45% and 55% of the combined company Cranford, New Jersey and Lombard, Illinois, October 24, 2025 – Enzon Pharmaceuticals, Inc. (OTCQB: ENZN) (“Enzon” or the “Company”) and Viskase Companies, Inc. (OTC Pink Limited: VKSC) (“Viskase”) today announced that they have entered into

October 24, 2025 EX-2.1

FIRST AMENDMENT TO THE AGREEMENT AND PLAN OF MERGER

Exhibit 2.1 Execution Version FIRST AMENDMENT TO THE AGREEMENT AND PLAN OF MERGER This FIRST AMENDMENT TO THE AGREEMENT AND PLAN OF MERGER, dated as of October 24, 2025 (this “Amendment”), is by and among Enzon Pharmaceuticals, Inc., a Delaware corporation (“Enzon”), EPSC Acquisition Corp., a Delaware corporation (“Merger Sub”), and Viskase Companies, Inc., a Delaware corporation (“Viskase” and, t

October 24, 2025 EX-2.1

FIRST AMENDMENT TO THE AGREEMENT AND PLAN OF MERGER

Exhibit 2.1 Execution Version FIRST AMENDMENT TO THE AGREEMENT AND PLAN OF MERGER This FIRST AMENDMENT TO THE AGREEMENT AND PLAN OF MERGER, dated as of October 24, 2025 (this “Amendment”), is by and among Enzon Pharmaceuticals, Inc., a Delaware corporation (“Enzon”), EPSC Acquisition Corp., a Delaware corporation (“Merger Sub”), and Viskase Companies, Inc., a Delaware corporation (“Viskase” and, t

October 24, 2025 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): October 24, 2025 ENZON PHARMACEUT

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): October 24, 2025 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission File

October 24, 2025 EX-99.1

Enzon and Viskase Announce Amendment to Merger Agreement Enzon and Viskase stockholders will respectively own 45% and 55% of the combined company

Exhibit 99.1 Enzon and Viskase Announce Amendment to Merger Agreement Enzon and Viskase stockholders will respectively own 45% and 55% of the combined company Cranford, New Jersey and Lombard, Illinois, October 24, 2025 – Enzon Pharmaceuticals, Inc. (OTCQB: ENZN) (“Enzon” or the “Company”) and Viskase Companies, Inc. (OTC Pink Limited: VKSC) (“Viskase”) today announced that they have entered into

September 30, 2025 EX-4.1

FIFTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent

Exhibit 4.1 FIFTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. and CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent This FIFTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT (this “Fifth Amendment”) is made and entered into September 30, 2025 and is effective immediately, by and between Enzon Pharmaceuticals, Inc., a Delaware corporation (the “

September 30, 2025 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): September 30, 2025 ENZON PHARMACE

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): September 30, 2025 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission Fil

September 30, 2025 8-A12G/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 5 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 5 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation or organization) 22-2372868 (I.R.S. Emplo

August 14, 2025 8-A12G/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 4 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 4 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation or organization) 22-2372868 (I.R.S. Emplo

August 14, 2025 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2025 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number 001

August 14, 2025 EX-4.1

Fourth Amendment to the Section 382 Rights Agreement, dated as of August 13, 2025, by and between Enzon Pharmaceuticals, Inc. and Continental Stock Transfer & Trust Company.

Exhibit 4.1 FOURTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. and CONTINENTAL STOCK TRANSFER & TRUST COMPANY, as Rights Agent This FOURTH AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT (this “Fourth Amendment”) is made and entered into August 13, 2025 and is effective immediately, by and between Enzon Pharmaceuticals, Inc., a Delaware corporation (the “

June 23, 2025 EX-2.1

Agreement and Plan of Merger, dated as of June 20, 2025, by and between Enzon Pharmaceuticals, Inc., EPSC Acquisition Corp. and Viskase Companies, Inc.

Exhibit 2.1 Execution Version AGREEMENT AND PLAN OF MERGER by and between ENZON PHARMACEUTICALS, INC., EPSC ACQUISITION CORP., and VISKASE COMPANIES, INC. Dated as of June 20, 2025 TABLE OF CONTENTS Page Article I The Merger 3 Section 1.1 The Merger 3 Section 1.2 Closing 3 Section 1.3 Effective Time 4 Section 1.4 Effects of the Merger 4 Section 1.5 Constituent Documents 4 Section 1.6 Directors and

June 23, 2025 8-K

Regulation FD Disclosure, Entry into a Material Definitive Agreement, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): June 20, 2025 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission File Num

June 23, 2025 EX-2.1

Agreement and Plan of Merger, dated as of June 20, 2025, by and between Enzon Pharmaceuticals, Inc., EPSC Acquisition Corp., and Viskase Companies, Inc.

Exhibit 2.1 Execution Version AGREEMENT AND PLAN OF MERGER by and between ENZON PHARMACEUTICALS, INC., EPSC ACQUISITION CORP., and VISKASE COMPANIES, INC. Dated as of June 20, 2025 TABLE OF CONTENTS Page Article I The Merger 3 Section 1.1 The Merger 3 Section 1.2 Closing 3 Section 1.3 Effective Time 4 Section 1.4 Effects of the Merger 4 Section 1.5 Constituent Documents 4 Section 1.6 Directors and

June 23, 2025 EX-10.1

Support Agreement, dated as of June 20, 2025, by and between Icahn Enterprises Holdings L.P. and certain of its affiliates, Enzon Pharmaceuticals, Inc. and Viskase Companies, Inc.

Exhibit 10.1 Execution Version SUPPORT AGREEMENT This SUPPORT AGREEMENT, dated as of June 20, 2025 (this “Agreement”), is made by and among: (i) Enzon Pharmaceuticals, Inc., a Delaware corporation (“Enzon”); (ii) Viskase Companies, Inc., a Delaware corporation (“Viskase”); and (iii) Icahn Enterprises Holdings L.P., a Delaware Limited Partnership (“IEH”), American Entertainment Properties Corp., a

June 23, 2025 EX-10.1

Support Agreement, dated as of June 20, 2025, by and between Icahn Enterprises Holdings L.P. and certain of its affiliates, Enzon Pharmaceuticals, Inc. and Viskase Companies, Inc.

Exhibit 10.1 Execution Version SUPPORT AGREEMENT This SUPPORT AGREEMENT, dated as of June 20, 2025 (this “Agreement”), is made by and among: (i) Enzon Pharmaceuticals, Inc., a Delaware corporation (“Enzon”); (ii) Viskase Companies, Inc., a Delaware corporation (“Viskase”); and (iii) Icahn Enterprises Holdings L.P., a Delaware Limited Partnership (“IEH”), American Entertainment Properties Corp., a

June 23, 2025 EX-99.1

Enzon and Viskase Enter into Merger Agreement Enzon and Viskase stockholders will respectively own approximately 15.9% and 84.1% of the combined company

Exhibit 99.1 Enzon and Viskase Enter into Merger Agreement Enzon and Viskase stockholders will respectively own approximately 15.9% and 84.1% of the combined company Cranford, New Jersey and Lombard, Illinois, June 20, 2025 – Enzon Pharmaceuticals, Inc. (OTCQX: ENZN) (“Enzon” or the “Company”) and Viskase Companies, Inc. (OTC Pink Limited: VKSC) (“Viskase”) announced that they have entered into a

June 23, 2025 425

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): June 20, 2025 ENZON PHARMACEUTICA

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): June 20, 2025 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission File Num

June 23, 2025 EX-99.1

Enzon and Viskase Enter into Merger Agreement Enzon and Viskase stockholders will respectively own approximately 15.9% and 84.1% of the combined company

Exhibit 99.1 Enzon and Viskase Enter into Merger Agreement Enzon and Viskase stockholders will respectively own approximately 15.9% and 84.1% of the combined company Cranford, New Jersey and Lombard, Illinois, June 20, 2025 – Enzon Pharmaceuticals, Inc. (OTCQX: ENZN) (“Enzon” or the “Company”) and Viskase Companies, Inc. (OTC Pink Limited: VKSC) (“Viskase”) announced that they have entered into a

May 9, 2025 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2025 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number 00

April 28, 2025 10-K/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K/A (Amendment No. 1)

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K/A (Amendment No. 1) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the Fiscal Year Ended December 31, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file numbe

April 28, 2025 EX-19.1

Insider Trading Policy

Exhibit 19.1 Corporate Policy Manual Page No.: 1 of 9 Title: Insider Trading Effective Date: July 21, 2006, revised September 27, 2012 and April 25, 2025 Policy No.: CPM-CP-102.03 Applies to: All employees, officers and Board members of Enzon Pharmaceuticals 1.INTRODUCTION AND PURPOSE: 1.1.Since the common stock of Enzon Pharmaceuticals, Inc. (“Enzon” or the “Company”) is publicly traded, the Comp

April 1, 2025 8-A12G/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 3 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 3 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation or organization) 22-2372868 (I.R.S. Emplo

April 1, 2025 8-K

Entry into a Material Definitive Agreement, Material Modification to Rights of Security Holders, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 31, 2025 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission File Nu

April 1, 2025 EX-4.1

Third Amendment to the Section 382 Rights Agreement, dated as of March 31, 2025, by and between Enzon Pharmaceuticals, Inc. and Continental Stock Transfer & Trust Company (incorporated herein by reference to Exhibit 4.1 of the Company’s Current Report on Form 8-K filed with the SEC on April 1, 2025).

Exhibit 4.1 THIRD AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. and CONTINENTAL STOCK TRANSFER & TRUST COMPANY as Rights Agent THIS THIRD AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT (this “Third Amendment”) is made and entered into March 31, 2025 and is effective immediately, by and between Enzon Pharmaceuticals, Inc., a Delaware corporation (the “Compa

February 21, 2025 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the Fiscal Year Ended December 31, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number: 001-36435 Enzon P

February 21, 2025 EX-21.1

Subsidiaries of Registrant

EXHIBIT 21.1 ENZON PHARMACEUTICALS, INC. Subsidiaries of Registrant Subsidiary State or Other Jurisdiction of Incorporation SCA Delaware Ventures, Inc.

February 21, 2025 EX-4.1

Description of Enzon Pharmaceuticals, Inc.’s Registered Securities

EXHIBIT 4.1 DESCRIPTION OF ENZON PHARMACEUTICALS, INC.’S REGISTERED SECURITIES The following description of the common stock, $0.01 par value (“Common Stock”), of Enzon Pharmaceuticals, Inc. (“us”, “our”, or the “Company”) and the Series A-1 Junior Participating Preferred Stock Purchase Rights (the “Rights”) is a summary. This summary is not complete and is subject to and qualified in its entirety

January 10, 2025 8-K

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): January 7, 2025 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission File N

December 27, 2024 8-K

Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): December 18, 2024 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission File

November 5, 2024 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file numbe

October 1, 2024 8-K

Submission of Matters to a Vote of Security Holders

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): September 26, 2024 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission Fil

August 19, 2024 SC 13D/A

ENZN / Enzon Pharmaceuticals, Inc. / ICAHN CARL C - SC 13D/A Activist Investment

SC 13D/A 1 tm2421713d3sc13da.htm SC 13D/A SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 14)* Enzon Pharmaceuticals, Inc. (Name of Issuer) Common Stock, No par value (Title of Class of Securities) 293904108 (CUSIP Number) Jesse Lynn, Esq. Icahn Capital LP 16690 Collins Avenue, Suite PH-1 Sunny Isles Beach, FL 33160 (3

August 8, 2024 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number 001

August 8, 2024 ARS

ARS

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the Fiscal Year Ended December 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number: 001-36435 Enzon Pharmaceuticals, In

August 8, 2024 DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant x Filed by a Party other than the Registrant ¨ Check the appropriate box: ¨ Preliminary Proxy Statement ¨ Confidential, For Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ¨ Definitive Proxy State

August 8, 2024 DEF 14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒ Filed by a party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, For Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☒ Definitive Proxy State

July 29, 2024 PRE 14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒ Filed by a party other than the Registrant ☐ Check the appropriate box: ☒ Preliminary Proxy Statement ☐ Confidential, For Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☐ Definitive Proxy State

July 11, 2024 8-K/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K/A (Amendment No. 1) CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): July 2, 2024

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K/A (Amendment No. 1) CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): July 2, 2024 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (

July 2, 2024 8-K

Shareholder Director Nominations

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): July 2, 2024 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission File Numb

June 14, 2024 8-K

Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): June 10, 2024 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission File Num

May 22, 2024 8-K

Entry into a Material Definitive Agreement, Material Modification to Rights of Security Holders, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 16, 2024 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission File Numb

May 22, 2024 EX-4.1

Second Amendment to the Section 382 Rights Agreement, dated as of May 16, 2024, by and between Enzon Pharmaceuticals, Inc. and Continental Stock Transfer & Trust Company (incorporated herein by reference to Exhibit 4.1 of the Company’s Current Report on Form 8-K filed with the SEC on May 22, 2024).

Exhibit 4.1 SECOND AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. and CONTINENTAL STOCK TRANSFER & TRUST COMPANY as Rights Agent THIS SECOND AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT (this “Second Amendment”) is made and entered into May 16, 2024 and is effective immediately, by and between Enzon Pharmaceuticals, Inc., a Delaware corporation (the “Comp

May 22, 2024 8-A12G/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 2 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 2 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation or organization) 22-2372868 (I.R.S. Emplo

May 10, 2024 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number 00

April 26, 2024 10-K/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K/A (Amendment No. 1)

ENZN UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K/A (Amendment No. 1) x ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the Fiscal Year Ended December 31, 2023 OR ¨ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number: 001-36435

March 20, 2024 EX-21.1

Subsidiaries of Registrant

EXHIBIT 21.1 ENZON PHARMACEUTICALS, INC. Subsidiaries of Registrant Subsidiary State or Other Jurisdiction of Incorporation SCA Delaware Ventures, Inc.

March 20, 2024 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the Fiscal Year Ended December 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number: 001-36435 Enzon P

March 20, 2024 EX-4.1

Description of Enzon Pharmaceuticals, Inc.’s Registered Securities

Exhibit 4.1 DESCRIPTION OF ENZON PHARMACEUTICALS, INC.’S REGISTERED SECURITIES The following description of the common stock, $0.01 par value (“Common Stock”), of Enzon Pharmaceuticals, Inc. (“us”, “our”, or the “Company”) and the Series A-1 Junior Participating Preferred Stock Purchase Rights (the “Rights”) is a summary. This summary is not complete and is subject to and qualified in its entirety

January 5, 2024 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): December 31, 2023 ENZON PHARMACEU

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): December 31, 2023 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission File

November 9, 2023 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file numbe

August 7, 2023 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number 001

June 14, 2023 8-K

Submission of Matters to a Vote of Security Holders

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): June 8, 2023 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission File Numb

May 5, 2023 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number 00

April 20, 2023 DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant x Filed by a Party other than the Registrant ¨ Check the appropriate box: ¨ Preliminary Proxy Statement ¨ Confidential, For Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ¨ Definitive Proxy State

April 20, 2023 ARS

ARS

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10-K ց ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the Fiscal Year Ended December 31, 2022 OR տ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number: 001-36435 Enzon Pharmaceuticals, I

April 20, 2023 DEF 14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, For Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☒ Definitive Proxy State

February 16, 2023 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10-K

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.

February 16, 2023 EX-4.1

Description of Enzon Pharmaceuticals, Inc.’s Registered Securities

Exhibit 4.1 DESCRIPTION OF ENZON PHARMACEUTICALS, INC.’S REGISTERED SECURITIES The following description of the common stock, $0.01 par value (“Common Stock”), of Enzon Pharmaceuticals, Inc. (“us”, “our”, or the “Company”) and the Series A-1 Junior Participating Preferred Stock Purchase Rights (the “Rights”) is a summary. This summary is not complete and is subject to and qualified in its entirety

February 16, 2023 EX-21.1

Subsidiaries of Registrant

EXHIBIT 21.1 ENZON PHARMACEUTICALS, INC. Subsidiaries of Registrant Subsidiary State or Other Jurisdiction of Incorporation SCA Delaware Ventures, Inc.

January 6, 2023 8-K

Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): December 31, 2022 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission File

November 9, 2022 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

? ? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 ? FORM 10-Q ? (Mark One) ? QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 ? For the quarterly period ended September 30, 2022 ? OR ? ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 ? For the transition period from? ? to? ? ? Commission fi

August 4, 2022 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

? ? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 ? FORM 10-Q ? (Mark One) ? QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 ? For the quarterly period ended June 30, 2022 ? OR ? ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 ? For the transition period from? ? to? ? ? Commission file nu

June 15, 2022 8-K

Submission of Matters to a Vote of Security Holders

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): June 9, 2022 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission File Numb

April 26, 2022 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

? ? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 ? FORM 10-Q ? (Mark One) ? QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 ? For the quarterly period ended March 31, 2022 ? OR ? ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 ? For the transition period from? ? to ? Commission file numb

April 26, 2022 EX-10.2

Form of Indemnification Agreement for members of the Board of Directors **

Exhibit 10.2 INDEMNIFICATION AGREEMENT THIS INDEMNIFICATION AGREEMENT (this ?Agreement?) is entered into effective as of April , 2022 by and between Enzon Pharmaceuticals, Inc., a Delaware corporation (the ?Company?), and (?Indemnitee?) effective immediately. Capitalized terms used in this Agreement that are not otherwise defined in this Agreement have the meanings ascribed to such terms in the Co

April 22, 2022 DEF 14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

? UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ? Filed by a Party other than the Registrant ? Check the appropriate box: ? Preliminary Proxy Statement ? ? Confidential, For Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ? ? Definitive Proxy

April 22, 2022 DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant x Filed by a Party other than the Registrant ? Check the appropriate box: ? Preliminary Proxy Statement ? Confidential, For Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ? Definitive Proxy State

February 25, 2022 EX-10.7

First Amendment to the Second Amended and Restated By-Laws, effective February 24, 2022

Exhibit 10.7 FIRST AMENDMENT TO THE SECOND AMENDED AND RESTATED BY-LAWS OF ENZON PHARMACEUTICALS, INC. On February 24, 2022, the Board of Directors of Enzon Pharmaceuticals, Inc., a Delaware corporation (the ?Corporation?), unanimously approved and adopted the following amendment to the Corporation?s Second Amended and Restated By-Laws (the ?By-Laws?) to be effective immediately: 1. Section 3.2 of

February 25, 2022 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10-K

? UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10-K ? ? ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 ? For the Fiscal Year Ended December 31, 2021 OR ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 ? For the transition period from to Commission file number: 001-36435 Enzon Pharmaceut

February 25, 2022 EX-3.5

Independent Contractor Agreement, effective as of February 24, 2022, between Enzon Pharmaceuticals, Inc. and Richard L. Feinstein **

Exhibit 3.5 INDEPENDENT CONTRACTOR AGREEMENT This Independent Contractor Agreement (the ?Agreement?) is effective as of February 24, 2022 (the ?Effective Date?) by and between Richard L. Feinstein, CPA (?Feinstein?) and Enzon Pharmaceuticals, Inc. (?Enzon?), pursuant to which Feinstein is being engaged to serve as Enzon?s Chief Executive Officer, Chief Financial Officer and Secretary. This Agreeme

February 25, 2022 EX-21.1

Subsidiaries of Registrant

EXHIBIT 21.1 ENZON PHARMACEUTICALS, INC. Subsidiaries of Registrant Subsidiary State or Other Jurisdiction of Incorporation SCA Ventures, Inc. Delaware ?

February 25, 2022 EX-4.1

Description of Enzon Pharmaceuticals, Inc.’s Registered Securities

Exhibit 4.1 DESCRIPTION OF ENZON PHARMACEUTICALS, INC.?S REGISTERED SECURITIES The following description of the common stock, $0.01 par value (?Common Stock?), of Enzon Pharmaceuticals, Inc. (?us?, ?our?, or the ?Company?) and the Series A-1 Junior Participating Preferred Stock Purchase Rights (the ?Rights?) is a summary. This summary is not complete and is subject to and qualified in its entirety

November 5, 2021 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

? ? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 ? FORM 10-Q ? (Mark One) ? QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 ? For the quarterly period ended September 30, 2021 ? OR ? ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 ? For the transition period from to ? Commission file num

August 5, 2021 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

? ? ? UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 ? FORM 10-Q ? (Mark One) ? QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 ? For the quarterly period ended June 30, 2021 ? OR ? ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 ? For the transition period from to ? Commission file number 0

June 8, 2021 EX-4.1

First Amendment to the Section 382 Rights Agreement, dated as of June 4, 2021 and effective as of June 2, 2021, by and between Enzon Pharmaceuticals, Inc. and Continental Stock Transfer & Trust Company.

Exhibit 4.1 FIRST AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT by and between ENZON PHARMACEUTICALS, INC. and CONTINENTAL STOCK TRANSFER & TRUST COMPANY as Rights Agent THIS FIRST AMENDMENT TO THE SECTION 382 RIGHTS AGREEMENT (this ?First Amendment?) is made and entered into June 4, 2021, and is effective as of June 2, 2021, by and between Enzon Pharmaceuticals, Inc., a Delaware corporation (the

June 8, 2021 8-K

Entry into a Material Definitive Agreement, Material Modification to Rights of Security Holders, Financial Statements and Exhibits, Submission of Matters to a Vote of Security Holders

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): June 2, 2021 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission File Numb

June 8, 2021 8-A12G/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 1 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A Amendment No. 1 FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation or organization) 22-2372868 (I.R.S. Emplo

May 4, 2021 10-Q

Quarterly Report - FORM 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q (Mark One) x QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2021 OR ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number 001-36435 Enzon Phar

April 14, 2021 DEF 14A

- DEF 14A

TABLE OF CONTENTS UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A? Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ? Filed by a Party other than the Registrant ? Check the appropriate box: ? Preliminary Proxy Statement ? ? Confidential, For Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ? ?

April 14, 2021 DEFA14A

- DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant x Filed by a Party other than the Registrant ? Check the appropriate box: ? Preliminary Proxy Statement ? Confidential, For Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ? Definitive Proxy State

April 2, 2021 PRE 14A

- PRE 14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant x Filed by a Party other than the Registrant ? Check the appropriate box: x Preliminary Proxy Statement ? Confidential, For Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ? Definitive Proxy State

February 23, 2021 EX-21.1

Subsidiaries of Registrant

EXHIBIT 21.1 ENZON PHARMACEUTICALS, INC. Subsidiaries of Registrant Subsidiary State or Other Jurisdiction of Incorporation SCA Ventures, Inc. Delaware

February 23, 2021 10-K

Annual Report - FORM 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K x ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the Fiscal Year Ended December 31, 2020 OR ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number: 001-36435 Enzon Pharmaceuticals, In

February 23, 2021 EX-4.1

Description of Enzon Pharmaceuticals, Inc.’s Registered Securities

Exhibit 4.1 DESCRIPTION OF ENZON PHARMACEUTICALS, INC.?S REGISTERED SECURITIES The following description of the common stock, $0.01 par value (?Common Stock?), of Enzon Pharmaceuticals, Inc. (?us?, ?our?, or the ?Company?) and the Series A-1 Junior Participating Preferred Stock Purchase Rights (the ?Rights?) is a summary. This summary is not complete and is subject to and qualified in its entirety

January 4, 2021 8-K

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): December 30, 2020 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission File

January 4, 2021 EX-99.1

Enzon Pharmaceuticals, Inc. CEO Andrew Rackear to Retire; Richard L. Feinstein, Enzon’s CFO, to Assume Position of CEO and Remain CFO

Exhibit 99.1 Enzon Pharmaceuticals, Inc. CEO Andrew Rackear to Retire; Richard L. Feinstein, Enzon’s CFO, to Assume Position of CEO and Remain CFO Jan 4, 2021 CRANFORD, N.J., Jan. 04, 2021 (GLOBE NEWSWIRE) - Enzon Pharmaceuticals, Inc. (OTC:ENZN) announced today that Andrew Rackear has communicated to the Board his intent to retire from his role as the Company’s Chief Executive Officer effective F

December 21, 2020 8-K

Submission of Matters to a Vote of Security Holders - FORM 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): December 18, 2020 ENZON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation) 001-36435 (Commission File

November 24, 2020 424B3

36,056,636 Shares of Common Stock

Filed pursuant to Rule 424(b)(3) Registration No. 333-250031 PROSPECTUS 36,056,636 Shares of Common Stock This prospectus relates to the possible resale of up to 36,056,636 shares of our common stock, par value $0.01 per share (the “Shares”), by Icahn Capital LP, together with its affiliates, that are identified as the selling stockholders in this prospectus or in supplements to this prospectus, w

November 18, 2020 CORRESP

-

November 18, 2020 VIA EDGAR SUBMISSION U.S. Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.E. Washington, D.C. 20549 Re: Enzon Pharmaceuticals, Inc. (the “Company”) Registration Statement on Form S-1 (File No. 333-250031) (the “Registration Statement”) Dear Ladies and Gentlemen: Pursuant to Rule 461 of the Securities Act of 1933, as amended (the “Securities Act”

November 17, 2020 TEXT-EXTRACT

-

United States securities and exchange commission logo November 17, 2020 Andrew Rackear Chief Executive Officer and Secretary Enzon Pharmaceuticals, Inc.

November 17, 2020 LETTER

LETTER

United States securities and exchange commission logo November 17, 2020 Andrew Rackear Chief Executive Officer and Secretary Enzon Pharmaceuticals, Inc.

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