A drug safety group has delivered a positive analysis for a Sarepta Therapeutics-licensed RNA medicine, with the same study also hitting an enrollment target, triggering a $200 milestone payment due to partner Arrowhead Pharmaceuticals.
Today, Sarepta shared updates on SRP-1003, a small interfering RNA (siRNA) therapeutic being studied in a phase 1/2 trial for type 1 myotonic dystrophy (DM1).
Two groups receiving escalating doses have already wrapped, and a third cohort is now fully enrolled—a milestone that has prompted a $200 million payment to Arrowhead. Sarepta said the milestone payment will be made within 60 days.
The biopharma also announced a positive review from a pre-specified drug safety committee for the trial, enabling the company to launch additional dose escalation groups. Patients are currently being dosed in a fourth cohort, and there are plans to start dosing in a final group early next year.
Since market open, Sarepta’s stock has risen 5% from $17.76 per share to $18.71.
Leerink Partners analysts view the update as positive when considering prior occurrences of safety signals and clinical holds for DM1 treatment candidates and oligonucleotides.
“As we have frequently seen safety as a speed bump for other DM1 therapies, as well as oligonucleotides broadly, we view the incremental safety update favorably for the SRP-1003 program,” a Nov. 24 Leerink Partners note reads. The firm cited a 2022 hold on Avidity Biosciences’ phase 1/2 trial after a serious adverse event and on PepGen’s phase 2 Duchenne muscular dystrophy study in 2023.
“As these siRNA assets from Arrowhead use a unique skeletal muscle targeting platform, referred to as the Targeted RNAi Molecule (TRiM) platform, safety has been a focus for investors,” Leerink Partners wrote about Sarepta.
Back in November of last year, Sarepta paid Arrowhead $500 million upfront, while also investing $325 million, to secure rights to seven programs. In addition, the pact requires Sarepta to pay $50 million a year for five years and includes $300 million in milestone payments associated with the DM1 study’s enrollment.
In July, Arrowhead hit the first enrollment target in the phase 1/2 and received regulatory approval to start dose escalation in the same study, triggering a $100 million milestone payment.
In August, Sarepta said it would sell off Arrowhead shares to stretch its cash runway, plus ink a share transfer to pay off half of the $100 million milestone payment obligation. At the time, Sarepta told Fierce that it still had to pay Arrowhead the remaining $50 million.
The new announcement follows the summer’s dramatic saga that stemmed from multiple deaths among patients who had received one of Sarepta’s gene therapies. The company launched a major layoff round in July and weighed further efficiency measures the following month in an attempt to address its 2027 debt obligations, which stood at $1 billion-plus at the time. Since then, Sarepta has refinanced a large chunk of the 2027 debt.
Under July's restructuring, Sarepta discarded several pipeline gene therapies and elevated siRNA as the main focus of its pipeline going forward.