Adverum shares halved after trial patient goes blind in one eye after experimental gene therapy

Dry eye
(YaroslavKryuchka/Getty Images)

Adverum Biotechnologies saw its shares down more than 51% after-hours Wednesday night after a patient it was testing a gene therapy on for a common eye condition went blind in the treated eye.

This happened 30 weeks after initial treatment with a high-dose of its therapy, known as ADVM-022, and for the treatment of diabetic macular edema.

The patient, who was given a single intravitreal injection, later “developed hypotony [increased pressure in the eye], with panuveitis [major inflammation of the eye] and loss of vision in the treated eye,” the biotech said in a statement.

Adverum said it “has decided to immediately unmask” the test, a phase 2 made up of 36 patients and known as INFINITY, “to better understand this event and to help identify and manage any similar potential risk to other patients in this study.”

The test finished patient dosing at the end of last year. The biotech is also “conducting a thorough review of data from the ADVM-022 program” and will report what it finds.

This comes after a slew of gene therapy trial halts in the U.S. over the past 12 months for both manufacturing and safety issues, though since the start of the year, a growing number of these holds have been lifted by the FDA, including just this week for Voyager Therapeutics and uniQure.

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“The safety of every patient who is participating in our clinical studies with our gene therapy is the utmost priority for us at Adverum,” said Laurent Fischer, M.D., CEO of Adverum. “We are fully committed to thoroughly assessing this case and ongoing monitoring of this patient and all patients treated with ADVM-022 with our investigators, data monitoring committee (DMC), scientific advisory board, and healthcare authorities.”