Astellas Pharma has done some spring cleaning of its pipeline, dropping two phase 1 candidates and slamming the brakes on a troubled gene therapy.
The Japanese drugmaker has halted development of its gene therapy AT132, also known as resamirigene bilparvovec, for a rare muscle disorder that mostly affects young boys called X-linked myotubular myopathy.
Moving away from AT132 will cost Astellas 16.4 billion yen (around $103 million), the company announced in an April 27 release. Astellas will instead pursue a new gene therapy for the rare disease, ASP2957, which is being studied in a phase 1/2 open-label trial that’s currently enrolling.
“The impairment was not due to safety and does not reflect a change in the scientific rationale, clinical data generated to date or the planned follow-up activities,” as Astellas spokesperson told Fierce Biotech. “We still plan to complete an additional 5-year long-term follow-up for patients currently enrolled, and we look forward to announcing further data readouts from the ASPIRO clinical trial.”
AT132 has long been dogged by safety concerns. The therapy caused four deaths in an earlier trial due to liver failure, with the FDA slapping a hold on the candidate as a result. AT132 originally came from Astellas’ $3 billion buy of Audentes Therapeutics back in 2019.
ASP2957 uses a muscle-targeting AAV capsid, as did AT132, but Astellas’ new candidate showed “high muscle specificity and reduced liver targeting” in preclinical studies, Naoki Okamura, Astellas’ president and CEO, said on an April 27 call with investors.
“This enables clinical study initiation at a dose level about 100-fold lower compared to AT132,” Okamura added. “With the progress of ASP2957, we decided on a strategic hold for AT132. Moving forward, we will focus on the development of ASP2957.”
Astellas licensed ASP2957 from Kate Therapeutics in 2023, about a year before Kate was acquired by Novartis for $1.1 billion.
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Astellas recently inked a deal with Dyno Therapeutics to up its muscle delivery game, paying $15 million upfront for a novel adeno-associated virus capsid designed to shuttle therapies into the tough-to-reach tissue.
In addition to pausing development of AT132, Astellas has also fully given up on two phase 1 candidates, according to the company’s 2025 financial results (PDF) released on April 27. These are ASP5502, a small molecule STING inhibitor for Sjögren’s syndrome, and ASP1570, a cancer candidate currently being trialed in a phase 1/2 solid tumor study.
Astellas had previously confirmed to Fierce that it had terminated a phase 1 study of ASP5502, with a spokesperson promising that the asset’s status would be “disclosed at the appropriate time.”
“The termination of the ASP5502 and ASP1570 clinical trials was a business decision and not related to safety observed in the studies,” an Astellas spokesperson confirmed to Fierce. “At Astellas, we continuously evaluate our pipeline strategy in order to focus our resources and accelerate the most promising assets.”
