GenSight has a gene therapy mystery on its hands, which is about the last thing it wanted at the end of Phase III.
Assessing the 48-week data from its first pivotal test of a treatment for Leber Hereditary Optic Neuropathy — or LHON, a rare genetic disease that causes blindness — investigators pulled out a meaningful improvement in sight in their one treated eye.
The mystery: The other eyes that received a sham therapy did just as well with their eyesight. Exactly as well.
That makes the Phase III study of GS010 a failure, and rather than stay to try and solve the mystery, investors bailed, driving down the EuroNext stock $SIGHT down by 34%.
One of the reasons why the early gene therapy pioneers like GenSight picked hereditary eye diseases to go after first is that the eye is a contained unit, limiting off-target effects. But GenSight’s Paris-based CEO Bernard Gilly says that as only a fraction of patients historically see a spontaneous improvement in eyesight, he’s wondering if the therapy injected into one eye delivers an unexpected benefit to the other.
At the same time, GenSight touted a hit on a retinal biomarker for the disease, which they claimed as evidence that the therapy had an impact separate from the sham.
“The fact that structural measures of the retina showed such a large statistical difference with treatment is compelling and objective evidence that this gene therapy protects the integrity of many retinal ganglion cells from the damage of LHON,” commented company co-founder José-Alain Sahel.
That’s a messy argument, with the company arguing that it appeared the therapy improved sight for both eyes, but only hit the secondary biomarker in the treated eye.
The company — which tried and failed to make it onto Nasdaq — will be left looking for more data to analyze from its next two Phase III studies, which are upcoming. But easy explanations will be hard to come by.
The best place to read Endpoints News? In your inbox.
Comprehensive daily news report for those who discover, develop, and market drugs. Join 33,900+ biopharma pros who read Endpoints News by email every day.Free Subscription