Sanofi’s brain-penetrant GCS inhibitor venglustat met the primary endpoint and three of four key secondary endpoints in the Phase 3 LEAP2MONO study in type 3 Gaucher disease, showing superiority to enzyme replacement therapy on neurologic measures at 52 weeks (global test p=0.007 across SARA modified total score and RBANS). Systemic outcomes were maintained at parity with ERT, with comparable changes in spleen and liver volume and hemoglobin. In the 43-patient, double-blind, double-dummy trial, safety was consistent with prior studies; the most common adverse events on venglustat versus ERT were headache (14.3% vs 18.2%), nausea (14.3% vs 4.5%), splenomegaly (14.3% vs 0), and diarrhea (14.3% vs 0). Separately, the Phase 3 PERIDOT trial in Fabry disease did not meet its patient-reported primary endpoint, despite pain reductions in both arms; the CARAT study evaluating left ventricular mass index remains ongoing.
The core development is Sanofi’s plan to file globally for venglustat in GD3, positioning an oral, CNS-penetrant substrate reduction therapy against biweekly intravenous ERT in a population with no approved treatments for neurologic manifestations. LEAP2MONO enrolled adolescents and adults who had been stabilized on ERT for systemic disease and randomized them 1:1 to daily venglustat or continued ERT with double-dummy controls. While the press release did not disclose absolute effect sizes on SARA or RBANS, the head-to-head superiority signal on neurologic function over 52 weeks, alongside non-inferiority on systemic measures, sets up a potential monotherapy switch scenario.
Strategically, this is an expansionary yet self-disruptive move. Sanofi already leads in Gaucher with Cerezyme and Cerdelga and just secured a U.S. label expansion allowing Cerezyme use in non-CNS GD3 based on real-world evidence. A successful venglustat filing would migrate a subset of stabilized GD3 patients from infusion centers to an oral regimen, pressuring the ERT franchise but addressing a long-standing CNS gap ERT cannot reach. The Fabry miss underscores the risk of hinging pivotal outcomes on patient-reported tools in heterogeneous, small rare disease populations; Sanofi’s hedge with CARAT’s cardiac structural endpoint reflects a broader trend toward anchoring programs in more objective measures when PROs are volatile.
For sites and CROs, LEAP2MONO validates the feasibility of complex, double-dummy rare disease trials with neurologic batteries and CSF/plasma biomarker collection in adolescents and adults. If approved, care pathways could shift: infusion center volumes may decline for GD3, while clinics will need workflows for neurocognitive assessments, adherence monitoring, and long-term neurologic follow-up on an oral SRT. Regulators will scrutinize endpoint validation and clinical meaningfulness in GD3 neurology, the durability of benefit beyond one year, and whether systemic control is maintained without ERT outside a tightly selected population. The recent RWE-driven Cerezyme expansion signals openness to alternative evidence streams, which could influence post-marketing requirements and label scope.
The next inflection points are the open-label phase readout for durability and biomarker trajectories (CSF and plasma GL1/lyso-GL1), detailed effect sizes on SARA and RBANS, and subgroup analyses including pediatrics from age 12. Review agencies may probe whether monotherapy is sufficient across the GD3 spectrum or if sequencing with ERT is warranted. Pricing and access will test payer appetite for replacing infusions with an oral therapy that tackles CNS disease; adherence oversight and potential REMS-like controls could surface. In Fabry, CARAT will determine whether the program retains a cardiovascular foothold after the PRO miss. More broadly, the GD3 outcome will be watched as a litmus test for brain-penetrant substrate reduction strategies across lysosomal diseases where ERT cannot cross the blood–brain barrier.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
