PTC Therapeutics is expanding its prospects in rare disease, winning a bankruptcy auction for a Sangamo Therapeutics gene therapy that’s already on a fast path to regulatory review by the FDA.
The PTC bid amounts to $111 million up front, the companies announced after Wednesday’s market close. Warren, New Jersey-based PTC is responsible for up to $100 million more in milestone payments tied to the regulatory progress of the therapy, isaralgagene civaparvovec (code name ST-920). A rolling FDA submission is expected to be complete in the fourth quarter of this year. If approved, PTC said this therapy could launch in 2027.
ST-920 was developed to treat Fabry disease, an inherited metabolic disorder in which mutations in the GLA gene result in deficiency of alpha-galactosidase A, an enzyme needed to break down a particular type of fat called globotriaosylceramide (Gb3). Accumulation of Gb3 in tissues and organs leads to problems such as diminished sweat production, heat intolerance, skin blemishes, and vision problems. Fabry can also cause kidney and heart complications. An estimated 11,000 people in the U.S. have Fabry. The treatment options for this disease are enzyme replacement therapy and Galafold, a drug from Amicus Therapeutics, now a subsidiary of BioMarin Pharmaceutical.
The available Fabry therapies are chronic treatments. ST-920 could bring patients the option of a one-time treatment. This Sangamo therapy delivers a functioning version of the GLA gene to liver cells to enable long-term production of the deficient enzyme. In an open-label Phase 1/2 study that enrolled adults with Fabry disease, Sangamo reported improvement on measures of kidney function at 52 weeks as well as evidence of favorable effect according to other measures of the disorder. Last December, Sangamo initiated a rolling submission seeking accelerated FDA approval.
ST-920 is the most advanced therapeutic candidate remaining from what was once a robust Sangamo pipeline. The biotech had neuroscience programs partnered with Biogen and Novartis and a hemophilia A gene therapy partnership with Pfizer. Biogen and Novartis terminated their respective alliances in 2023. The Pfizer partnership ended last year, and Sangamo’s search for a new partner on this program turned up empty. In regulatory filings, Sangamo said its financial circumstances led it to consider filing for bankruptcy protection.
Sangamo announced in June it was exploring strategic alternatives. Later that month, the company filed for Chapter 11 bankruptcy. An agreement was reached with Astellas Pharma as the “stalking horse” bidder for the Fabry program, setting a baseline $50 million bid for this gene therapy, inclusive of potential milestone payments.
PTC focuses on therapies for rare disease. The company already has regulatory and commercial experience in gene therapy through Kebilidi, which was approved in 2024 for treating aromatic L-amino acid decarboxylase (AADC) deficiency, a rare inherited enzyme deficiency that affects the brain. Speaking during a Wednesday evening conference call, PTC CEO Matthew Klein said Sangamo’s Fabry gene therapy represents a unique opportunity to add a program at the regulatory review stage without needing to build up significant capabilities. He added that PTC already has in-house Fabry know-how from commercial leaders at the company with specific experience marketing the approved Fabry therapies. Industry interest in this Sangamo gene therapy went beyond Astellas and PTC.
“It was a competitive process, there were multiple bidders,” Klein said. “In fact, the auction took over two days, just to give you an idea how competitive it was and how much interest there was in this asset.”
Beyond the FDA submission for ST-920, Klein said PTC plans to seek regulatory approval for this gene therapy in other countries. The bankruptcy court still needs to approve the asset acquisition, which must also pass antitrust review. PTC expects to complete the transaction late in the current quarter or early in the fourth quarter of this year.
Sangamo was able to offload other assets. Eli Lilly’s $50 million bid was the only one for certain platform technologies for use in neurology. The bid also covers ST-506, program in preclinical development for prion disease. In addition, Sangamo selected bidders for certain tools and equipment for a total of $2.5 million.
Sangamo filed for bankruptcy in the U.S. Bankruptcy Court for the District of Delaware, case number 26-10989. As of June 30, the company reported $153 million in total assets and $130.4 million in total liabilities.
Photo: Mykola Velychko, Getty Images
