GSK reports global phase Ib Ris‑Rez data in relapsed extensive‑stage SCLC

Efficacy

In the phase Ib dose‑optimisation portion of EMBOLD PanTumour‑101, risvutatug rezetecan achieved a confirmed objective response rate of 61% at 8 mg/kg (11/18; 95% CI 35.7–82.7) versus 32% at 6 mg/kg (7/22; 95% CI 13.9–54.9). The analysis included 50 patients with relapsed (2L+) extensive‑stage small cell lung cancer who had received a median of two prior therapies; enrolment in the dose‑optimisation portion was ongoing at data cut‑off.

Safety

At a median follow‑up of 100.5 days the safety profile was manageable. Grade 3 or higher treatment‑related adverse events were observed in 42% of patients receiving 8 mg/kg and 15% of those receiving 6 mg/kg, with haematological events being the most common. The overall rate of interstitial lung disease was 2% (1/50) and the case was grade 2.

Trial context and next steps

The findings will be presented at ESMO 2026 and supported selection of the 8 mg/kg dose currently being evaluated in GSK’s global phase III EMBOLD SCLC‑301 study. EMBOLD PanTumour‑101 is a global, open‑label phase Ia/b study randomising relapsed ES‑SCLC patients to 6 mg/kg or 8 mg/kg intravenously every three weeks; the analysed population included patients with prior topoisomerase‑1 inhibitor or tarlatamab exposure and patients with brain or liver metastases.

External comparator

GSK stated these global phase Ib data build on a statistically significant overall survival benefit recently reported in Hansoh’s pivotal Chinese phase III ARTEMIS‑008 study in SCLC.