GSK Lung Cancer Drug Risvutatug Rezetecan Posts 61% Response Rate in Global Phase 1b Trial

GSK's experimental antibody-drug conjugate risvutatug rezetecan, known as Ris-Rez, achieved a 61% confirmed response rate in a phase 1b global trial of patients with relapsed extensive-stage small cell lung cancer. At the higher dose of 8 milligrams per kilogram, 11 of 18 evaluable patients responded to treatment, compared with a 32% response rate, or 7 of 22 patients, at the lower 6 milligram per kilogram dose.

Ris-Rez is an antibody-drug conjugate designed to deliver cancer-killing agents directly to tumor cells by targeting the B7-H3 protein, which is highly expressed across more than ten solid tumor types. GSK said the phase 1b results support its decision to use the higher dose in its ongoing global phase III EMBOLD SCLC-301 study. The safety profile was described as manageable, though serious treatment-related adverse events occurred in 42% of patients at the higher dose, compared with 15% at the lower dose, including one case of moderate interstitial lung disease.

The new data add to a growing body of evidence for Ris-Rez. Earlier late-stage data from Chinese patients showed the drug reduced the risk of death by 54% versus topotecan, with patients surviving a median of 18.5 months compared with 10.3 months on the comparator. GSK has stated ambitions to develop Ris-Rez across more than 40 indications by 2040.