# EDGAR Filing Document

**Accession Number:** 0000727510
**File Stem:** 0001193125-25-249981
**Filing Date:** 2025-10
**Character Count:** 15664
**Document Hash:** 6677051dea56b66d26b2362d6630b694
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-25-249981.hdr.sgml**: 20251024

**ACCESSION NUMBER**: 0001193125-25-249981

**CONFORMED SUBMISSION TYPE**: SCHEDULE 13D/A

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20251024

**DATE AS OF CHANGE**: 20251024

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** ENZON PHARMACEUTICALS, INC.
- **CENTRAL INDEX KEY:** 0000727510
- **STANDARD INDUSTRIAL CLASSIFICATION:** BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 222372868
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-35587
- **FILM NUMBER:** 251416357

**BUSINESS ADDRESS:**
- **STREET 1:** 20 COMMERCE DRIVE, SUITE 135
- **CITY:** CRANFORD
- **STATE:** NJ
- **ZIP:** 07016
- **BUSINESS PHONE:** 732-980-4500

**MAIL ADDRESS:**
- **STREET 1:** 20 COMMERCE DRIVE, SUITE 135
- **CITY:** CRANFORD
- **STATE:** NJ
- **ZIP:** 07016

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** ENZON PHARMACEUTICALS INC
- **DATE OF NAME CHANGE:** 20060324

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** ENZON PHARMACEUTICALS  INC
- **DATE OF NAME CHANGE:** 20021211

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** ENZON PHARMACEUTICAL  INC
- **DATE OF NAME CHANGE:** 20021210
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** ICAHN CARL C
- **CENTRAL INDEX KEY:** 0000921669
- **STANDARD INDUSTRIAL CLASSIFICATION:** UNKNOWN SIC - 0000 [0000]
- **ORGANIZATION NAME:** CF
- **EIN:** 000000000
- **STATE OF INCORPORATION:** FL
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A

**BUSINESS ADDRESS:**
- **STREET 1:** C/O ICAHN ENTERPRISES L.P.
- **STREET 2:** 16690 COLLINS AVE., PH-1
- **CITY:** SUNNY ISLES BEACH
- **STATE:** FL
- **ZIP:** 33160
- **BUSINESS PHONE:** 305-422-4145

**MAIL ADDRESS:**
- **STREET 1:** C/O ICAHN ENTERPRISES L.P.
- **STREET 2:** 16690 COLLINS AVE., PH-1
- **CITY:** SUNNY ISLES BEACH
- **STATE:** FL
- **ZIP:** 33160

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** ICAHN CARL C ET AL
- **DATE OF NAME CHANGE:** 19950612

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## SCHEDULE 13D

### Under the Securities Exchange Act of 1934

**(Amendment No. 17)**

**ENZON PHARMACEUTICALS, INC.**

*(Name of Issuer)*

**Common Stock, par value $0.01 per share**

*(Title of Class of Securities)*

**293904108**

*(CUSIP Number)*

**Jesse Lynn, Esq.**<br>Icahn Capital LP, 16690 Collins Avenue<br>Suite PH-1<br>Sunny Isles Beach FL 33160<br>305-442-4000

*(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)*

**10/24/2025**

*(Date of Event Which Requires Filing of this Statement)*

| **CUSIP No.** | **293904108** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**CARL C ICAHN** | Name of reporting person<br>**CARL C ICAHN** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**OO** | Source of funds (See Instructions)<br>**OO** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[x] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[x] | |
| 6 | Citizenship or place of organization<br>**X1** | Citizenship or place of organization<br>**X1** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**36056636.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**36056636.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**36056636.00** | Aggregate amount beneficially owned by each reporting person<br>**36056636.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**48.6%** | Percent of class represented by amount in Row (11)<br>**48.6%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

**Comment for Reporting Person:** The Reporting Person may also be deemed to beneficially own shares of Preferred Stock.

| **CUSIP No.** | **293904108** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**ICAHN ENTERPRISES HOLDINGS L.P.** | Name of reporting person<br>**ICAHN ENTERPRISES HOLDINGS L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**OO** | Source of funds (See Instructions)<br>**OO** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[x] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[x] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**36056636.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**36056636.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**36056636.00** | Aggregate amount beneficially owned by each reporting person<br>**36056636.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**48.6%** | Percent of class represented by amount in Row (11)<br>**48.6%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

**Comment for Reporting Person:** The Reporting Person may also be deemed to beneficially own shares of Preferred Stock.

| **CUSIP No.** | **293904108** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**ICAHN ENTERPRISES G.P. INC.** | Name of reporting person<br>**ICAHN ENTERPRISES G.P. INC.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**OO** | Source of funds (See Instructions)<br>**OO** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[x] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[x] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**36056636.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**36056636.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**36056636.00** | Aggregate amount beneficially owned by each reporting person<br>**36056636.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**48.6%** | Percent of class represented by amount in Row (11)<br>**48.6%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**CO** | Type of Reporting Person (See Instructions)<br>**CO** | |

---

**Comment for Reporting Person:** The Reporting Person may also be deemed to beneficially own shares of Preferred Stock.

**Item 1. Security and Issuer**

**(a) Title of Class of Securities:**
Common Stock, par value $0.01 per share

**(b) Name of Issuer:**
ENZON PHARMACEUTICALS, INC.

**(c) Address of Issuer's Principal Executive Offices:**
20 Commerce Drive (Suite 135), Cranford, NJ, 07016

This statement constitutes Amendment No. 17 to the Schedule 13D relating to the shares of Common Stock, par value $0.01 per share (the "Shares"), issued by Enzon Pharmaceuticals, Inc., a Delaware corporation (the "Issuer"), and amends the Schedule 13D relating to the Shares filed on March 14, 2008 (as previously amended, the "Original 13D"), on behalf of the Reporting Persons (as defined in Item 2 of Amendment No. 16 to the Schedule 13D). Capitalized terms used herein and not otherwise defined have the respective meanings ascribed thereto in the Original 13D.

**Item 4. Purpose of Transaction**

Item 4 of the Original 13D is hereby amended and supplemented as follows:

Amendment to the Agreement and Plan of Merger of the Issuer and Viskase

On October 24, 2025, the Issuer, Merger Sub, and Viskase entered into an amendment to the Merger Agreement (the "Merger Agreement Amendment"). Pursuant to the terms of the Merger Agreement Amendment, the parties to the Merger Agreement agreed, among other things, to the following:

(i) an adjustment to the exchange ratio as calculated under the Merger Agreement for the exchange of each share of Viskase Common Stock issued and outstanding immediately prior to the Merger (other than shares held by holders that properly exercise dissenters rights, shares held in treasury, and shares held by the Issuer, Merger Sub, or a wholly owned subsidiary of Viskase, the Issuer, or Merger Sub) into Shares, such that the current Viskase stockholders will own 55% of the combined company following the Merger;

(ii) an adjustment to the exchange ratio for the exchange of each share of the Issuer's Series C Preferred Stock for Shares, to be based upon the 20-day volume weighted average price of the Shares prior to the execution of the Merger Agreement Amendment (the "20-Day VWAP");

(iii) a reduction in the minimum amount of cash that the Issuer is required to have at Closing;

(iv) the Issuer effecting a 1-for-100 reverse stock split with respect to all Shares prior to the effective time of the Merger;

(v) an extension to the date on which either party may terminate the Merger Agreement if the Merger has not yet occured from 11:59 p.m. Eastern Time on December 31, 2025 to 11:59 p.m. Eastern Time on March 31, 2026;

(vi) with respect to each of the Issuer and Merger Sub (each, a "Waiving Party"), waive, consent to and release (a) any inaccuracy in, breach of or failure to comply with any representation, warranty, covenant or agreement of Viskase in the Merger Agreement, to the extent known to such Waiving Party as of the date of the Merger Agreement Amendment (each, a "Viskase Breach") and (b) any fact, event, circumstance or condition giving rise to a Viskase Breach, in each case to the extent known to such Waiving Party as of the date of the Merger Agreement Amendment and occurring or existing on or prior to such date; and

(vii) a modification to the definition of "Viskase Material Adverse Effect" in the Merger Agreement to provide that, if the Issuer, Merger Sub or any of their respective representatives knew of the material facts of a matter prior to the date of the Merger Agreement Amendment, then no effect, change, event or occurrence arising out of, or resulting from such facts shall constitute a Viskase Material Adverse Effect for all purposes under the Merger Agreement; provided that, for the avoidance of doubt, a Viskase Material Adverse Effect may result from facts that the Issuer, Merger Sub or any of their respective representatives become aware of after the date of the Merger Agreement Amendment

The foregoing description does not purport to be complete, and is qualified in its entirety by reference to the complete text of the Merger Agreement Amendment, a copy of which is attached as Exhibit 99.1 hereto and incorporated herein by reference.

IEH Support Agreement

In connection with the execution and delivery of the Merger Agreement Amendment, on October 24, 2025 Icahn Enterprises Holdings and certain of its affiliates entered into an amendment to the IEH Support Agreement (the "Support Agreement Amendment") with the Issuer and Viskase. Pursuant to the terms of the IEH Support Agreement (as amended by the Support Agreement Amendment), Icahn Enterprises Holdings agreed to, among other things, (i) deliver or cause the delivery of written consents with respect to all of the issued and outstanding Shares held by Icahn Enterprises Holdings and its affiliates approving the Merger and the amendment to the Issuer's certificate of incorporation, and (ii) exchange all of the shares of Series C Preferred Stock held by Icahn Enterprises Holdings and its affiliates into Shares prior to the consummation of the Merger, based on the full liquidation preference of such shares of Series C Preferred Stock and the 20-Day VWAP.

The foregoing description does not purport to be complete, and is qualified in its entirety by reference to the complete text of the Support Agreement Amendment, a copy of which is attached as Exhibit 99.2 hereto and incorporated herein by reference.

**Item 6. Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer.**

Item 6 of the Original 13D is hereby amended and supplemented as follows:

The disclosure set forth in Item 4 of this Schedule 13D is incorporated herein by reference.

### SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** CARL C ICAHN

**Signature:** /s/ Carl C. Icahn

**Name/Title:** Carl C. Icahn

**Date:** 10/24/2025

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** ICAHN ENTERPRISES HOLDINGS L.P.

**Signature:** /s/ Ted Papapostolou

**Name/Title:** Ted Papapostolou, Chief Financial Officer

**Date:** 10/24/2025

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** ICAHN ENTERPRISES G.P. INC.

**Signature:** /s/ Ted Papapostolou

**Name/Title:** Ted Papapostolou, Chief Financial Officer

**Date:** 10/24/2025