VIR-5818

VIR-5818 (AMX-818, SAR446309) is a masked T-cell engager (PRO-XTEN dual-masked TCE) from Amunix Pharmaceuticals, with Sanofi as acquirer, Vir Biotechnology as licensee and Merck Sharp & Dohme as partner. A HER2-targeted T-cell engager with PRO-XTEN masks that are removed by proteases in tumours. Its furthest stage is phase 1, for HER2-expressing locally advanced or metastatic solid tumours. ClinicalTrials.gov registers it in one study linked below. Phase 1/2 NCT05356741 recruiting under Vir; updated dose-escalation data expected 2H 2026 (Vir Q2 2026 release). Whether it works in people has not been established unless a trial below reports it.