GSK partner Hansoh reports another phase 3 win for priority ADC

Biotech GSK partner Hansoh reports another phase 3 win for priority ADC By Nick Paul Taylor Jul 28, 2026 8:20am GSK Hansoh Pharma antibody-drug conjugates osteosarcoma Hansoh Pharmaceutical has guided its GSK-partnered, B7-H3-directed antibody-drug conjugate (ADC) to another phase 3 win in China. Weeks after reporting a victory in small-cell lung cancer (SCLC), Hansoh revealed that a phase 3 trial of the ADC in relapsed osteosarcoma was tied to significantly longer progression-free survival than chemotherapy, hitting the primary endpoint. The study compared the ADC, risvutatug rezetecan (ris-rez), to chemotherapy in people who had progressed or relapsed after receiving at least two prior lines of systemic therapy. Sharing Hansoh’s findings, GSK said “consistent benefit” was seen across secondary endpoints, including overall survival, while no new safety signals were identified. Reflecting on the results during a media call to discuss the company's second-quarter earnings, GSK CEO Luke Miels said: “Any day you do something that helps kids with cancer is a good day.” The partners have yet to share data on any of the endpoints, but Hansoh is confident enough in the results to start preparing a regulatory submission in China. The success of the Chinese clinical trial bodes well for Embold Sarcoma-202, a global phase 1b/2 trial that GSK is running to evaluate ris-rez in previously treated unresectable advanced or metastatic sarcomas, including osteosarcoma. Osteosarcoma, which mainly affects children and young adults, is a bone cancer with a global incidence of about 3.4 cases per million people per year. Chemotherapy is the established first-line treatment, but options are limited for people who relapse and particularly for people who progress after two lines of therapy. GSK started its global trial, which is also enrolling people with soft tissue sarcoma, last month. The study is part of an attempt to move ris-rez beyond second-line SCLC. GSK began a phase 3 trial in that SCLC indication last year. Second-line SCLC is the lead indication, but Tony Wood, Ph.D., GSK’s chief scientific officer, used an April earnings call to discuss the planned expansion of the ris-rez program. GSK is planning multiple phase 3 trials, “including in genitourinary cancers, which start later this year,” Wood said at the time. GSK’s focus mirrors the indications that Daiichi Sankyo and Merck & Co. are prioritizing for their rival B7-H3 ADC, ifinatamab deruxtecan (I-DXd). The FDA accepted a filing for review of I-DXd in second-line SCLC in April. Daiichi and Merck are also running phase 3 trials in prostate cancer and esophageal squamous cell carcinoma. Despite trailing its rivals, GSK has previously identified ris-rez and a sibling ADC as “priority assets.” GSK Hansoh Pharma antibody-drug conjugates osteosarcoma Biotech Clinical Data