First Werner helicase drug shows durable tumour responses in Phase 1

A first-in-class drug that shuts down the DNA-repair enzyme Werner helicase produced durable partial responses and a high disease-control rate in patients with microsatellite-instability or mismatch-repair-deficient solid tumours, according to Phase 1 results published Tuesday in Nature Medicine from a trial led by researchers at The University of Texas MD Anderson Cancer Center.

VVD-133214 (formerly RO7589831), developed with Vividion Therapeutics after early Roche backing, is the first covalent Werner helicase inhibitor in the clinic. Among 66 efficacy-evaluable patients — a heavily pretreated group, 95.5 per cent of whom had already received immune checkpoint therapy — seven had radiologic partial responses across multiple cancer types, and the disease-control rate was 74.2 per cent. Median duration of response was 10.2 months; five of seven responders were still responding at data cutoff. Safety in 88 patients was mostly grade 1–2 nausea, vomiting and diarrhea; three patients discontinued for adverse events. Lead investigator Timothy Yap said the data validate Werner helicase as an actionable target for patients with few options after immunotherapy fails.

Roughly 40 to 70 per cent of patients with MSI/dMMR solid tumours never respond to checkpoint inhibitors or later relapses. Follow-on trials are already open: a Phase 1b pairing the drug with bevacizumab in post-immunotherapy metastatic colorectal cancer, and a Phase 2 combining it with pembrolizumab in treatment-naïve metastatic colorectal disease. Canadian oncology centres that already sequence MSI status for immunotherapy eligibility will watch whether WRN inhibition becomes the next synthetic-lethal standard beside PARP inhibitors — a rare new lever when checkpoint drugs stall.