Ris-Rez Shows Progression-free Survival Gain in ARTEMIS-011 Osteosarcoma Trial

GSK has reported positive results from Hansoh's ARTEMIS-011 pivotal phase III trial in China, which evaluated the investigational B7-H3-directed antibody-drug conjugate Ris-Rez against gemcitabine and docetaxel chemotherapy in patients whose osteosarcoma had progressed or relapsed after at least two prior systemic therapy lines. The trial met its primary endpoint of Independent Review Committee-assessed progression-free survival, and the data will support a Hansoh regulatory submission in China. GSK Press Releases report.

The Primary Endpoint and What the Numbers Show

According to GSK, Ris-Rez reduced the relative risk of disease progression or death by 67% compared with chemotherapy. Median progression-free survival, assessed by an Independent Review Committee, was 5.5 months with Ris-Rez versus 1.4 months with chemotherapy. The late-breaking results were presented during a Presidential Symposium session at the European Society for Medical Oncology Congress 2026.

Our analysis is confined to the reported progression-free survival endpoint; readers should not interpret it as proof of a cure or an overall-survival improvement. GSK describes the improvement as statistically significant and clinically meaningful. ARTEMIS-011 was a multicentre, randomised, open-label phase III study conducted by Hansoh Pharma in patients in China.

Related coverage: Biopharma research.

Safety Findings at the Studied Dose

Grade 3 or higher treatment-related adverse events occurred in 93% of patients receiving Ris-Rez at the studied dose and 83% of those receiving chemotherapy. GSK said the most common Grade 3 or higher treatment-related adverse events in both arms were haematologic events, and that safety findings were consistent with prior findings in this tumour type.

These figures indicate that high-grade treatment-related adverse events were common on both arms of the trial. They are not evidence that the investigational agent is free of toxicity, and they do not establish that it is suitable for all patients; the findings apply to the dose studied in this China trial.

Related coverage: Clinical development.

A Submission in China, Not an Approval

GSK says the results will support a regulatory submission by Hansoh in China. Our assessment is that the planned submission should not be presented as an approval. GSK holds exclusive rights to develop and commercialise Ris-Rez outside mainland China, Hong Kong, Macau and Taiwan.

GSK described this as Hansoh's second positive phase III study for Ris-Rez in China, adding to a growing body of evidence across difficult-to-treat solid tumours. The China data are being generated under Hansoh's trial, while GSK's own global programme spans lung cancer, prostate cancer and other solid tumours.

Related coverage: Cancer research.

Global Development Runs on a Separate Track

GSK's global phase Ib/II EMBOLD Sarcoma-202 trial is a distinct study from ARTEMIS-011. It is evaluating Ris-Rez in previously treated unresectable advanced or metastatic sarcomas, including osteosarcoma. GSK said data from ARTEMIS-011 will help inform dose selection in a global population.

Our assessment is that the China findings should not be treated as established benefit in every population or as an overall-survival result. EMBOLD Sarcoma-202 remains ongoing, and GSK's phase III programme for Ris-Rez in other tumour types is separate from the osteosarcoma trial reported here.

Related coverage: Drug development.

What This Means for Practitioners

OUR recommendations: treat these findings as evidence from a single China-based, open-label phase III trial in a heavily pretreated population, reported by the licensor rather than an independent assessment by this publication. Do not present the 67% figure as longer survival or as a cure; it describes relative reduction in risk of progression or death, alongside a 5.5-month versus 1.4-month median progression-free survival. Note that Grade 3 or higher treatment-related adverse events affected 93% of Ris-Rez recipients at the studied dose. Frame any discussion as investigational pending regulatory review, and reserve judgment on global applicability until EMBOLD Sarcoma-202 data are available.