United Therapeutics acquires Massachusetts biotech company

United Therapeutics, a biotechnology company with co-headquarters and manufacturing facilities in Research Triangle Park, has acquired a Boston-area biotech company to boost its efforts in regenerative medicine and organ transplantation.

United acquired Thymmune Therapeutics of Cambridge, Mass., for $140 million in cash plus potential payments of up to $160 million if certain clinical and regulatory milestones are achieved by the end of 2031.

Thymmune is a privately held, preclinical-stage company developing scalable, regenerative thymic cell therapies for the potential treatment of post-transplant organ tolerance, immunodeficiencies and autoimmune diseases.

“Thymmune’s platform complements United Therapeutics’ broader mission to expand the supply of transplantable organs, building on our UThymoKidney clinical development program and our growing strength in immunomodulatory therapeutics,” said Martine Rothblatt, Ph.D., chairperson and chief executive officer of United Therapeutics. “By restoring or modulating T-cell receptor diversity, Thymmune’s technology could make fundamental contributions to human health care and potentially resolve the root causes of dozens of life-threatening diseases.”

The thymus is a small gland that sits in the upper chest, behind the sternum and in front of the heart. It is a critical organ for the development and proper function of key parts of the immune system, including training T-cells, which are essential for fighting infections and other diseases. 

Thymmune has a proprietary process for converting human-induced pluripotent stem cells into thymic cells, which ─ once inside the body ─ mature into cell types that can restore healthy T-cell function.

Thymmune’s lead drug candidate, THY-100, is in preclinical development for congenital athymia, an ultra-rare and life-threatening condition in which infants are born without a functional thymus. Animal studies have shown that treatment with THY-100 results in the formation of a neo-thymus that is capable of facilitating T-cell development. 

The clinical proof of concept and further development of THY-100 have the potential to broaden thymic regenerative medicine approaches for transplant tolerance, serious immune-mediated diseases, and enhanced longevity for older adults with diminished T-cell function.

“Thymmune was founded to harness the biology of the thymus to restore immune function for patients with serious immune-mediated diseases,” said Stan Wang, M.D., Ph.D., chief executive officer and founder of Thymmune Therapeutics. “United Therapeutics shares our conviction that regenerative medicine can transform the lives of patients, and we believe its leadership in organ alternatives and cell-based technologies makes it the ideal partner to advance our platform toward broad clinical impact.”

United Therapeutics was founded by Rothblatt in 1996 under the name Lung Rx. Her goal was to discover a cure for her daughter's life-threatening, rare disease, pulmonary arterial hypertension. Today, the company focuses more broadly on treatments for rare diseases and alternatives to expand the supply of transplantable organs. 

United Therapeutics has five approved drugs on the market and several more drugs and devices in development, all for treating pulmonary diseases. The company expects to file for regulatory approval of ralinepag, a potential treatment for pulmonary arterial hypertension, by the end of this year following positive Phase 3 clinical trial results announced in May. 

The company is also developing regenerative medicine applications for xenotransplants, organ transplantation, and organ alternatives for diseased lungs, kidneys, livers, and hearts.

In May, United Therapeutics received clearance from the U.S. Food and Drug Administration to begin a small clinical study of its investigational UHeart, a pig heart with 10 gene edits, intended for human implantation. The study will enroll up to two patients initially.

Following FDA review of available safety and efficacy data from the two transplants, the study may then be further expanded, with the intent to support a Biologics License Application with the FDA.

“Moving a porcine-derived heart into human clinical trials represents another defining advancement for the field of xenotransplantation,” said Kristina DeSmet, Ph.D., DABT, senior director of product development at United Therapeutics. “The heart is one of the most complex solid organs to transplant, and proceeding into the clinic reflects years of coordinated scientific progress. For United Therapeutics, this milestone represents our third clinical trial in xenotransplantation and underscores the breadth of our platform, spanning end-stage renal disease and now life-threatening heart disease. Together, these programs reinforce our commitment to expanding transplant options for patients who currently have no other alternatives.”

United Therapeutics has about 1,400 employees at seven sites in the United States and Canada, including office, lab, warehouse, and manufacturing facilities in Research Triangle Park. The company reported nearly $3.2 billion in product revenue in 2025. Its shares are traded on the Nasdaq stock exchange under the symbol UTHR.

United Therapeutics is the first publicly traded biotech or pharmaceutical company to operate as a public benefit corporation. The legal designation requires a company to balance financial returns to shareholders with a stated social or environmental mission.