The US Food and Drug Administration (FDA) has placed a partial hold on Avidity Biosciences’ Phase I/II Marina clinical trial of AOC 1001 in adult myotonic dystrophy type 1 (DM1) patients.

With the latest development, enrolment of new subjects will be paused.

The partial hold comes after the company reported a serious adverse event in a single subject in the 4mg/kg arm of the trial.

Avidity is in talks with the regulatory agency and trial investigator to evaluate the cause of the adverse event.

All required steps for rapidly resolving the partial clinical hold on new subject enrolment are being adopted, the company said.

To date, the trial has enrolled nearly 40 subjects in the MARINA and MARINA open-label extension (MARINA-OLE) trials.

All subjects who are currently receiving AOC 1001 or a placebo can continue to take the treatment, but no new patients will be enrolled until the FDA lifts the partial clinical hold.

In addition, all subjects in the MARINA trial could progress to the MARINA-OLE to receive AOC 1001 as scheduled.

Avidity plans to carry out an initial analysis of safety, tolerability, and key biomarkers in nearly half of the MARINA trial participants in the fourth quarter of this year. 

AOC 1001 is a lead product candidate of the company.

Avidity president and CEO Sarah Boyce said: “The safety of participants enrolled in our clinical studies is our first priority.

“We are doing a thorough analysis and will work diligently with the FDA and the trial investigator to follow the progress of this participant and to resume new participant enrolment as soon as we can.

“We continue to look forward to the preliminary assessment of the MARINA study in Q4 and, with our two recent IND clearances, we are now advancing AOC 1020 for FSHD, and AOC 1044 for DMD into the clinic this year as planned.”

A progressive neuromuscular ailment, DM1 currently has no approved therapy options.