GSK's experimental lung cancer drug achieves 61% confirmed response rate
Key Facts
GSK said in results announced in October 2026 that its experimental small-cell lung cancer drug risvutatug rezetecan achieved a confirmed objective response rate of 61% at the higher dose. The rate was 32% at the lower dose in a comparison within the dose-optimization program for the drug, which is being developed globally. The doses used were 8 mg/kg and 6 mg/kg of body weight, according to the company's statement on the early-stage study. The analysis included 50 patients randomly assigned to the two doses in an open-label study. Median follow-up in this analysis was 100.5 days, as the company continues to evaluate the drug in small-cell lung cancer.
Participants had received a median of two prior treatments before enrolling in the study, according to GSK's statement. The sample also included patients with brain or liver metastases among the group covered by the early results analysis. On safety, the company said hematologic events were the most common treatment-related adverse events among participants. The incidence of interstitial lung disease recorded in the safety analysis was 2%, according to the results announced by the company. GSK described the reported lung disease case as "moderate" and classified it as grade two in its assessment of adverse event severity.
The results follow GSK's announcement in September 2026 that the drug reduced the risk of death by 54% compared with topotecan in a pivotal Chinese study. Median overall survival among patients who received the experimental drug in that study was 18.5 months, according to the company's statement on its results. In the comparison group receiving topotecan, median overall survival was 10.3 months, according to the same statement. The drug also recorded a response rate of 58.3% in an assessment by an independent committee within the Chinese study. The response rate in the topotecan group was 12.6%, in the comparison the company announced alongside the overall survival results.
Risvutatug rezetecan targets the B7-H3 protein using a monoclonal antibody, according to GSK's description of the experimental drug's composition. The antibody is linked to a topoisomerase inhibitor in a construct combining the antibody with a drug payload. The drug received orphan drug designation for small-cell lung cancer from Japan's Ministry of Health, Labour and Welfare. It also received U.S. breakthrough therapy designation for relapsed or refractory disease following platinum-based chemotherapy, according to a separate company statement. The U.S. designation aims to accelerate the development and review of drugs that may offer an improvement over available treatments for patients.
GSK holds global development and commercialization rights to the drug under an exclusive licensing agreement with Hansoh, according to the statement on the agreement. These rights exclude mainland China, Hong Kong, Macau and Taiwan from the geographic scope of the company's license. The agreement provided for an upfront payment of $185 million as part of the disclosed financial terms for obtaining rights to the drug. Hansoh is also eligible for milestone payments that could total $1.525 billion over the course of the agreement. The license includes tiered royalties on net sales once the drug is commercialized, alongside the upfront payment and potential milestone payments.
The global late-stage study of the drug in patients with relapsed small-cell lung cancer began in August 2025, according to GSK. The company said in its September statement that it expected pivotal data from the global study in the year following that statement. Regarding the current dose-optimization analysis, it said longer follow-up of participants was needed to characterize the durability of treatment response. The company scheduled the dose-optimization results poster presentation for October 26 at the 2026 European Society for Medical Oncology congress. The presentation is scheduled during the poster session from 12:00 to 12:45 Central European Time, according to the company's announced program.