GSK partner Hansoh Pharmaceutical Group announced on July 10 that its pivotal ARTEMIS-008 trial evaluating risvutatug rezetecan (Ris-Rez) in Chinese patients with advanced or relapsed small-cell lung cancer met its overall survival primary endpoint, delivering what the companies described as statistically significant and clinically meaningful improvement over topotecan. The result marks the first Phase III overall survival win reported for any B7-H3-targeted antibody-drug conjugate (ADC) across any tumor type, providing the class with its first pivotal proof of concept. It also supports GSK's broader global program.
The randomized ARTEMIS-008 Phase III trial compared risvutatug rezetecan with topotecan in Chinese patients with advanced or relapsed SCLC. The trial met its primary endpoint of overall survival and also improved progression-free survival, while demonstrating a safety profile consistent with previous studies. Hazard ratios and median survival data were not disclosed.
Risvutatug rezetecan is a fully human anti-B7-H3 monoclonal antibody conjugated to a topoisomerase I inhibitor payload. B7-H3 is broadly expressed across SCLC tumors, and the ADC mechanism delivers cytotoxic payload directly to tumor cells following receptor-mediated internalization — a distinct approach from both the checkpoint inhibitors and the bispecific T-cell engager now approved in this indication.
In terms of the competitive context: Amgen's Imdelltra (tarlatamab), the first-in-class B7-H3/CD3 bispecific antibody, received full FDA approval in November 2025 for relapsed ES-SCLC and European Commission approval in June 2026, establishing itself as the leading second-line option. Jazz Pharmaceuticals' Zepzelca (lurbinectedin) holds accelerated FDA approval in the same setting. Risvutatug rezetecan would enter as an ADC — a mechanism class not yet approved in SCLC — and carries a different safety profile from tarlatamab, which requires step-up dosing and hospitalization for cytokine release syndrome management.