Enzon Pharmaceuticals Inc - ENZN stock

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OTC Symbol: ENZN | OTC Tier: OTCQX U.S.


Enzon Pharmaceuticals, Inc. and its subsidiaries are involved in the marketing of drug products, with PegIntron being their primary marketed drug, and they also have a marketing agreement pertaining to the Vicineum drug.[1] The company currently operates as a public company acquisition vehicle, with the goal of utilizing a previous accrued net operating loss carryforward.[2]


Enzon Pharmaceuticals, Inc. was founded in 1981. The company has its origins in Piscataway, New Jersey, where it was established with a focus on biopharmaceutical research and development. Originally known as Enzon, Inc., the company later adopted the name Enzon Pharmaceuticals, Inc. The company was founded with the goal of developing innovative therapies and drug products, particularly in the field of biotechnology. Over the years, the company's research efforts centered on the development of novel drug delivery technologies and therapeutic products targeting various medical conditions.[3]

The company's primary focus is on developing and commercializing therapeutics for various medical conditions, particularly in the field of oncology and hematology. The company's early years were marked by research and development efforts to create novel therapeutic agents, particularly utilizing PEGylation technology. PEGylation involves attaching polyethylene glycol (PEG) molecules to existing drugs, which can enhance their pharmacokinetic properties, improve efficacy, and reduce side effects.[3]

In the 1980s and 1990s, Enzon Pharmaceuticals made significant progress in developing PEGylated drugs and delivery systems. One of their most notable achievements was the development of PEGylated adenosine deaminase (brand name Adagen®), which was approved by the U.S. Food and Drug Administration (FDA) in 1990 for the treatment of severe combined immunodeficiency (SCID), a rare genetic disorder.[3]

Enzon Pharmaceuticals continued to expand its portfolio of PEGylated products and technologies over the years. Some of their other PEGylated drugs included Oncaspar® (pegaspargase) for the treatment of acute lymphoblastic leukemia (ALL) and DepoCyt® (cytarabine liposome injection) for the treatment of lymphomatous meningitis.[3]

In addition to their focus on PEGylation, Enzon Pharmaceuticals also engaged in collaborations and partnerships with other biopharmaceutical companies and research institutions to advance their drug development programs. As with many biopharmaceutical companies, Enzon Pharmaceuticals experienced ups and downs over the years, including shifts in its strategic focus and portfolio. At times, the company divested assets or spun off specific business units to concentrate on core areas.[3]

According to recent SEC filings, the company has no clinical operations and limited corporate operations, and there is no intention of resuming clinical development activities. In 2020, the company became a public company acquisition vehicle.[4]



One of the significant achievements of Enzon Pharmaceuticals was the development and marketing of PegIntron, an important drug product used to treat certain viral infections and cancers. PegIntron is a pegylated interferon-alpha product designed to enhance its effectiveness and prolong its activity in the body. Enzon Pharmaceuticals also entered into a marketing agreement related to the drug Vicineum, further expanding its portfolio of therapeutic products.[3]


Vicineum is a drug approved for the treatment of non-muscle invasive bladder cancer and was developed by Sesen, Inc.[4]

  1. Yahoo Finance. ENZN Stock Profile. Retrieved on 10/29/2023.
  2. enzon.com. Company Overview - About. Retrieved on 12/3/2023.
  3. 3.0 3.1 3.2 3.3 3.4 3.5 Wikipedia. Enzon Pharmaceuticals. Retrieved on 10/29/2023.
  4. 4.0 4.1 SEC.gov. Enzon Pharmaceuticals 10Q for the period ending 9/30/2023. November 3, 2023.

The page is authored by: Wisdom Tree