Another Astellas gene therapy trial paused by FDA after side effect report

Dive Brief:

• The Food and Drug Administration has halted clinical testing of an experimental gene therapy from Astellas Pharma due to safety concerns, the company said Monday, marking the latest setback to its plans to develop gene-based medicines.
• The regulator stopped an early-stage study of an Astellas treatment for Pompe disease, a rare and inherited metabolic disorder, after a patient developed peripheral sensory neuropathy. Though an investigator graded the side effect as mild in severity, it was judged serious due to its “medical significance,” Astellas said.
• The FDA is seeking more information about the event, according to the statement. Astellas, meanwhile, said it will track the patient to gather more data and closely monitor others on treatment.

Dive Insight:

Astellas paid $3 billion to acquire Audentes Therapeutics in December 2019 planning, like many of its peers, to capitalize on advances in gene therapy research. The deal came months after the FDA had approved the second gene therapy for an inherited disease, and had indicated it was preparing for an influx of applications.

Safety worries and clinical setbacks have slowed the field’s progress since, however. Last year, the FDA convened a panel of experts to discuss ways for gene therapy developers to mitigate health risks. A number of companies, among them Pfizer, UniQure and Bluebird bio, had safety concerns crop up in 2021.

In each of those cases, the developers’ treatments were eventually cleared by regulators and research continued. Bluebird could win U.S. approval of two rare disease treatments by September. A Pfizer Duchenne muscular dystrophy trial has restarted with new safeguards, and the FDA is currently reviewing UniQure’s hemophilia gene therapy.

Astellas’ problems have persisted, however. Testing of one program acquired in the Audentes deal, for children with a rare neuromuscular disease, was paused multiple times over the past two years following the deaths of four study participants. Three other experimental treatments for Duchenne muscular dystrophy were scrapped as well, contributing to $700 million in impairment charges recently recorded by the Japanese drugmaker for its gene therapy assets.

Still, Astellas says it remains committed. Earlier this month, it opened a manufacturing facility in North Carolina, noting in a statement that the plant represents its “continued dedication” to gene therapy. The company has 16 programs in development across four therapeutic areas.

“Admittedly, Astellas has already been forced to impair some Audentes-linked intangibles, and may book further impairments this year,” wrote Stephen Barker, an analyst at Jefferies, in a March note to clients. “But these expenses will look like small change if Astellas can translate its leadership in gene therapy manufacturing into clinical and commercial-stage leadership.”

Only two of Astellas’ gene therapies are in human testing, though. With the announcement Monday, both are now on hold.

The latest hold involves a gene therapy called AT845, which Astellas is developing for late-onset Pompe disease. Pompe, which causes muscle weakness and breathing problems, is typically treated with medications that replace the protein that’s missing in people who have the condition with a synthetic version. AT845 is meant to fix the problem with a one-time treatment.

In early February, the company said the first four patients treated in its early-stage trial didn’t experience any serious side effects.

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