Sarepta touts clean data for commercial grade Duchenne gene therapy, clearing key hurdle to PhIII
After a trial flop and an unexpected detour, Sarepta says its gene therapy for Duchenne muscular dystrophy looks ready to get back on the Phase III track.
A review of preliminary safety and expression data from 11 patients suggests that the material manufactured with their updated commercial process spurred consistent production of dystrophin, the biotech reported, while maintaining a clean side effect profile. The study, SRP-9001-103, was the first to test Sarepta’s commercial grade process in patients.
The plan is to take these results to the FDA for a meeting before the end of June, and kickstart its much-anticipated Phase III soon after.
“We feel very very good where we are,” CEO Doug Ingram said on an investor call.
Investors clearly did too, sending shares $SRPT up 12.60% to $84.60.
Sarepta was supposed to go into Phase III earlier. But in September, the FDA knocked back their plans, raising concerns about the potency assays they were using for the pivotal study and commercial supply. And then the last trial, 102, failed the functional endpoint.
The company quickly resolved the assay issue as well as one of the things that Ingram said confounded the 102 results: an “improbable imbalance” in the baseline characteristics of a certain patient cohort. The other? Titering variability within the doses — which is what 103 is designed to clean up.
More specifically, Sarepta changed the way they measured the how much AAV they were dosing, switching from the traditional qPCR method to a linear PCR method.
Looking at biopsies at week 12, they found comparable biomarker results — whether in terms of dystrophin expression, dystrophin positive fibers or intensity — said CSO Louise Rodino-Klapac.
Count Baird analyst Brian Skorney in the “extremely encouraged” camp.
The continued absence of severe adverse events bodes well for Sarepta even as it falls behind Pfizer in initiating a Phase III, he added:
By our count, this marks over 60 patients who have been treated with AAVrh74 to date (4 in Study 101, 41 in Study 102, 11 in Study 103, and 6 LGMD2E patients), which we believe makes it highly unlikely that the fact that AAVrh74-based gene therapy has not resulted in complement activation is due to random chance. While there were two SAEs in this study (1 increased liver enzymes and 1 nausea/vomiting) overall we view these side effects as easily manageable and not life-threatening. All told, we view the absence of complement activation in Sarepta’s program as a key differentiating factor as compared to Pfizer’s and Solid’s AAV9-based assets which have been plagued with these adverse events.