Pasatru™ (garetosmab-grts) First and Only FDA-approved Treatment Demonstrating Reduction in New Heterotopic Ossification (HO) Lesions and Clinician-Assessed Flare-ups in a Placebo-controlled Trial in Adults with Fibrodysplasia Ossificans Progressiva (FOP)

FOP is an ultra-rare genetic disorder characterized by rogue bone formation that infiltrates muscles, tendons, ligaments and other connective tissues, resulting in significant disability

Approval based on results from the OPTIMA trial demonstrating a 90% or greater reduction in new HO lesions at 56 weeks with a dramatic reduction in clinician-assessed flare-ups in adults with FOP

TARRYTOWN, N.Y. , Aug. 19, 2026 (GLOBE NEWSWIRE) -- Regeneron Pharmaceuticals, Inc. (NASDAQ: REGN) today announced the U.S. Food and Drug Administration (FDA) has granted approval for Pasatru ™ (garetosmab-grts) to reduce formation of new heterotopic ossification (HO) lesions and clinician-assessed flare-ups in adults with fibrodysplasia ossificans progressiva (FOP). Recognizing the significant mobility challenges faced by many people with FOP, Pasatru can be administered across a range of care settings, including home infusion where appropriate. The recommended starting dosage is based on weight at 10 mg/kg and is given intravenously over 60 minutes once monthly (every four weeks) but may be decreased to a 3 mg/kg infusion over 60 minutes once monthly if not tolerated. Pasatru is a VelocImmune ® -derived, fully human monoclonal antibody that blocks Activin A, a protein that Regeneron scientists discovered to be critical in the development of HO lesions in people with FOP.

FOP is an ultra-rare genetic disorder in which muscles, tendons, ligaments and other connective tissues are progressively infiltrated by rogue bone formation, a process known as HO. HO of the jaw, spine, hip and rib cage can make basic actions such as speaking, eating, walking or breathing difficult, and the dysfunction of these structures can lead to escalating loss of mobility. Worldwide, approximately 900 people are diagnosed with FOP, and most patients are wheelchair-bound by age 30 with the median age of survival being 56.

“For people living with FOP, every irregular new bone formation is a step toward disability and potential loss of mobility,” said Dr. Kathryn Dahir , Professor in the Department of Internal Medicine , Division of Endocrinology , Diabetes, and Metabolism at Vanderbilt University , and a primary investigator for the OPTIMA trial. “With the ability to reduce the number of new bone lesions and flare-ups, we now have a new treatment that can positively affect patients.”

“FOP is a relentless, restrictive condition that severely impacts the lives of those diagnosed and their families,” said Michelle Davis , Executive Director of the International FOP Association . “This approval is monumental for our community, providing a vital new therapy that can have a significant impact on the life of someone with FOP."

Pasatru was granted approval based on efficacy and safety data from the positive Phase 3 OPTIMA trial evaluating Pasatru in adults with FOP. At 56 weeks, both doses of Pasatru, 10 mg/kg (n=23) and 3 mg/kg (n=19), met the primary endpoint and were highly efficacious in reducing the total number of new HO lesions as compared to placebo (n=21), demonstrating a 90% (2 lesions vs. 19 lesions) and 94% (1 lesion vs. 19 lesions) reduction, respectively, as assessed by computed tomography (CT) scan. The number of clinician-assessed flare-ups during this time, a key secondary endpoint, were 9 for Pasatru 10 mg/kg (88% reduction compared to placebo), 53 for Pasatru 3 mg/kg (15% reduction compared to placebo), and 66 for placebo. Changes in the proportion of patients with patient-reported flare-ups through week 56 were not significantly different between placebo and Pasatru treatment groups. At 56 weeks, among all 63 people who participated in the trial, serious treatment-emergent adverse events occurred in 2 patients treated with 10 mg/kg Pasatru, 1 patient treated with 3 mg/kg Pasatru, and 2 patients treated with placebo. The most common adverse reactions occurring in ≥10% of adults with FOP treated with Pasatru 10 mg/kg or 3 mg/kg were abscess, acne, increased hair growth, madarosis (loss of eyebrows), oral ulcers, epistaxis (nosebleeds), folliculitis, paronychia (nail infection), and rash.

“The approval of Pasatru is the culmination of decades of pioneering research that Regeneron has pursued alongside the FOP community, rooted in our discovery of the role that Activin A plays in driving this disease,” said George D. Yancopoulos , M.D., Ph.D., Board co-Chair, President and Chief Scientific Officer at Regeneron . “People living with FOP have needed a new treatment option for this devastating condition far too long, much like many others living with a rare disease. This unprecedented milestone embodies our broader mission to continue delivering new options for those who have long faced limited treatment options and our relentless commitment to bringing scientific breakthroughs to families, no matter the prevalence of the condition they manage.”

Regeneron is committed to supporting people living with rare diseases. Regeneron’s myRARE™ program offers resources to help patients and healthcare providers, including product information, insurance benefit verification, and information about potential financial support. To learn about myRARE, visit myRARE.com or call 1-833-4my-RARE (1-833-469-7273).

In the European Union, a regulatory submission for Pasatru is currently under review by the European Medicines Agency . Additional regulatory submissions are planned in countries around the world, including Japan . Pasatru previously received Fast Track designation and Orphan Drug Designation from the FDA, as well as Orphan Designation by the European Medicines Agency in the European Union and the Ministry of Health, Labour and Welfare in Japan .

About the OPTIMA Clinical Trial OPTIMA is a Phase 3, multi-center, multinational trial to assess the efficacy of Pasatru on the reduction of heterotopic bone formation and flares, as well as its safety, tolerability, and pharmacokinetics, in patients with active FOP.

The trial enrolled 63 participants aged 18 years and older who have any FOP-causing variant of type I Activin A receptor (ACVR1), exhibited FOP disease activity or progression of HO lesions, and had a cumulative analogue joint involvement scale (CAJIS) score at screening of ≤19. CAJIS is a scoring tool used by clinicians to assess the degree of joint involvement, with higher scores representing a greater degree of disease severity (scale: 0 to 30). Eligible participants were randomized to receive intravenously administered Pasatru 10 mg/kg, Pasatru 3 mg/kg, or placebo once every four weeks for 56 weeks. Following this, participants could elect to then continue their originally assigned treatment in a double-blind extension phase for at least 84 weeks or discontinue treatment and enter an observation-only arm.

During the treatment period, efficacy was evaluated through whole body CT scans for HO lesions, physician and patient assessment of flare-ups, utilization of CAJIS to rate joint functionality, and observances of change in disease severity. Safety assessment includes reports of adverse events, measurement of vital signs, physical examination, and coagulation testing.

A Phase 3 trial of Pasatru in adolescents and children with FOP, OPTIMA 2, is planned to begin later this year. For more information, visit the  Regeneron clinical trials website , contact clinicaltrials@regeneron.com or call +1 844-734-6643.

About Pasatru Regeneron has been engaged in FOP research for decades and helped to provide fundamental insights into the biology and natural history of the disease. Regeneron scientists discovered that  Activin A plays a key role in FOP  by driving HO, the main pathology of FOP . Pasatru is a  VelocImmune -derived, fully human monoclonal antibody that binds and neutralizes Activin A, which is involved in the development of heterotopic bone in people with FOP.

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