Sio Gene Therapies posts positive PhI/II data in rare pediatric disease, the first readout since its name change
A little over a month after a full company rebrand, the Biotech Formerly Known as Axovant has its first data readout under its new moniker.
Tuesday’s interim look comes from Sio Gene Therapies’ GM1 gangliosidosis program, where the ex-Vant says it saw positive safety and efficacy outcomes in a small Phase I/II trial. The results mark what CEO Pavan Cheruvu hopes can provide a new foundation in rare pediatric diseases as Sio seeks to move past an epic Alzheimer’s fail just a few years ago.
“This is truly a cornerstone of the approach we hope to take going forward as we consider pipeline development and expansion,” Cheruvu told Endpoints News, “and is really the first instance where we see promising new data coming out at, admittedly, an early time point, but that we think builds upon the strong scientific foundation that we’ve put in place at Sio.”
Investors took the news in stride, with Sio $SIOX shares shooting up about 45% after the closing bell Tuesday.
There are two types of GM1 gangliosidosis, an inherited genetic disease that falls under the lysosomal storage disorder umbrella. If left untreated, the lack of a key enzyme allows for waste material to build up in cells and cause their early destruction.
The program, called AXO-AAV-GM1, is an AAV9-based gene therapy Sio acquired back in December 2018 from the University of Massachusetts Medical School as it was undergoing its shift in strategy. Designed to introduce functional copies of the mutated GLB1 gene, the candidate aims to reverse the enzyme deficiency, preventing the progressive death of cells over time.
Sio’s results come from the six-month follow-up period for the low-dose cohort of the trial, which enrolled five patients between 32 and 68 months old. Cheruvu was mainly looking for good safety results as, given the rare nature of the disease, these were the first patients dosed with a gene therapy of any kind, he said. Sio found no serious treatment-related side effects and the therapy was well-tolerated.
In terms of efficacy, Sio looked at the change in serum enzyme activity from baseline, or how concentrated an enzyme is within a patient’s cells, after six months. The five patients saw an average increase of 110%, which amounted to a restoration of 38% of normal enzyme activity. Cheruvu said that in other similar storage diseases, like Tay-Sachs and Sandhoff diseases, restoring anywhere from 10% to 20% typically correlates with long-term benefits.
“[These diseases] act as proxies for GM1 gangliosidosis; they’re linked by an underlying biochemical and cellular pathway,” Cheruvu said.
With its first data as Sio, the biotech will continue to push AXO-AAV-GM1 through the dose escalation period and ultimately into a larger trial. Sio has already dosed the first two patients in the higher dose cohort and is hoping to see safety and efficacy levels maintained in the low-dose through the next readout at the 12-month mark.
The results also mark something of a win for Cheruvu, who took on the responsibility of cleaning up the Alzheimer’s mess despite joining the company after the fallout. When Sio announced its rebranding last month, the CEO proclaimed, “We’re not a vant any longer,” emphasizing that Vivek Ramaswamy’s Roivant biotech smorgasbord was no longer a majority stakeholder (it still owns a roughly 30% stake in the company and holds two board seats).
Sio’s pediatrics programs are part of a two-pronged focus — Cheruvu also noted the company is looking at some high-risk, high-reward candidates in Parkinson’s. And though AXO-AAV-GM1 is still in its early stages, Cheruvu is confident in the therapy’s potential.
“As we build the program, we hope to have a more expedited approval process around this product,” Cheruvu said. “We know there’s a predictable natural history of decline in these kids, and if we can maintain stability, maintain milestones that have already been gained, that could be a basis for a significant discussion with regulators.”