GSK's B7-H3 ADC cuts osteosarcoma progression risk by 67% in Chinese phase 3 trial

A phase 3 study in China evaluated GSK's B7-H3‑directed antibody‑drug conjugate, risvutatug rezetecan (ris‑rez), in patients with relapsed osteosarcoma. The trial met its primary endpoint, showing a 67% reduction in the risk of disease progression or death compared with standard chemotherapy.

The Artemis‑011 trial enrolled 122 patients aged 12 and older who had failed second‑line therapies. Participants received either ris‑rez or a gemcitabine‑docetaxel regimen. Median progression‑free survival was 5.5 months for the ADC versus 1.5 months for chemotherapy.

Grade 3 or higher treatment‑related adverse events occurred in 93% of patients on ris‑rez and 83% on chemotherapy, with hematologic toxicities most common. Discontinuations due to adverse events were 4% for the ADC and 2% for the chemotherapy arm.

These results provide the first robust evidence that B7‑H3‑targeted ADCs can improve outcomes in a disease area with few effective options, potentially paving the way for regulatory submissions and broader use.