Risvutatug rezetecan reduced the risk of progression or death by 67% versus chemotherapy in the ARTEMIS-011 Phase III relapsed osteosarcoma trial.
Written By: Malavatu Satvika, PharmD
Reviewed By: Pharmacally Editorial Team
GSK and Hansoh Pharmaceutical Group have reported positive Phase III results for risvutatug rezetecan (Ris-Rez), an investigational B7-H3-targeted antibody-drug conjugate (ADC), in patients with relapsed or refractory osteosarcoma in China. In the ARTEMIS-011 trial, Ris-Rez significantly improved progression-free survival (PFS) compared with gemcitabine plus docetaxel after at least two prior lines of systemic therapy. The findings provide evidence of antitumour activity in a setting with limited treatment options, although immature overall-survival data and frequent serious adverse events remain important considerations.
ARTEMIS-011: Trial Design
ARTEMIS-011 was a multicentre, randomised, open-label Phase III study conducted in China. It enrolled 122 patients whose osteosarcoma had relapsed or progressed after at least two prior lines of systemic therapy. Patients were randomised in a 2:1 ratio to receive Ris-Rez at 12 mg/kg intravenously every three weeks or gemcitabine plus docetaxel.
The chemotherapy regimen comprised gemcitabine 1,000 mg/m² on Days 1 and 8 and docetaxel 75 mg/m² on Day 8 of each three-week cycle. The primary endpoint was PFS assessed by independent central review. The reported analysis had a data cutoff of June 17, 2026, with a median follow-up of 7.1 months.
PFS: The Primary Efficacy Finding
The study met its primary endpoint. Median PFS was 5.5 months with Ris-Rez versus 1.4 months with chemotherapy (hazard ratio [HR], 0.33; 95% confidence interval [CI], 0.20–0.55; p<0.0001). This corresponds to a 67% reduction in the relative hazard of disease progression or death.
Investigator-assessed PFS supported the primary finding, with median PFS of 5.6 months versus 1.0 month (HR, 0.30; 95% CI, 0.19–0.50; p<0.0001). The consistency between independent and investigator assessments strengthens the evidence that Ris-Rez delayed disease progression in this population.
Tumour response results also favoured Ris-Rez. Independent review found an objective response rate of 15% versus approximately 2% with chemotherapy and a disease control rate of 76% versus 33%. Median duration of response with Ris-Rez was 7.6 months.
The 67% figure represents a relative reduction in the hazard of progression or death, not a 67-percentage-point increase in the proportion of patients remaining progression-free. The median PFS difference of 4.1 months describes outcomes between the treatment groups and does not predict an individual patient’s duration of benefit.
Overall Survival: Evidence Remains Immature
Overall-survival (OS) data were immature at the reported analysis, and median OS had not been reached in either group. The reported OS HR was 0.51 (95% CI, 0.21–1.23), indicating a numerical trend favouring Ris-Rez. However, the confidence interval includes 1, so these results do not establish a statistically significant OS benefit. Further follow-up is needed to determine whether the PFS improvement translates into longer survival.
Safety and Treatment Burden
Grade 3 or higher treatment-related adverse events occurred in 93% of patients receiving Ris-Rez and 83% receiving chemotherapy. Serious treatment-related adverse events occurred in 64% and 29%, respectively, and were predominantly haematological. Treatment-related adverse events led to treatment discontinuation in 4% of Ris-Rez recipients versus 2% of chemotherapy recipients.
One patient receiving Ris-Rez developed Grade 2 treatment-related interstitial lung disease, which resolved with supportive management. No Grade 5 treatment-related adverse events were reported in either group.
The safety findings highlight an important consideration in interpreting the efficacy results. Although treatment discontinuation rates were low, the high incidence of severe and serious adverse events indicates a substantial treatment burden. Longer follow-up and more detailed safety data will help clarify the implications for clinical monitoring and tolerability.
Regulatory Status
Hansoh reported that China’s National Medical Products Administration accepted the biologics licence application for Ris-Rez in osteosarcoma on September 24, 2026, and granted it Priority Review status. Acceptance of the application and Priority Review designation do not constitute marketing approval. GSK said the ARTEMIS-011 results would also inform its global development programme, including an ongoing Phase II trial in advanced osteosarcoma and soft tissue sarcoma.
Clinical Interpretation
ARTEMIS-011 provides statistically significant evidence that Ris-Rez improves progression-free survival (PFS) compared with gemcitabine plus docetaxel in heavily pretreated patients with relapsed or refractory osteosarcoma. The accompanying response results support antitumour activity, but the immature overall-survival (OS) data do not establish that the treatment extends survival.
The findings apply to the trial population in China and should not automatically be generalised to earlier treatment settings or other populations. The open-label design and relatively short follow-up are additional considerations when interpreting the results.
The key questions are whether the PFS benefit persists with longer follow-up, whether an OS benefit emerges, and how the efficacy findings balance against the observed safety burden.
Reference
Ris-Rez reduced risk of disease progression or death by 67% versus chemotherapy in patients with relapsed osteosarcoma in China, GSK, 26 October 2026
Study of HS-20093 Versus Gemcitabine in Combination with Docetaxel in Treatment of Osteosarcoma After Previous Second-line Treatment Failure, ClinicalTrials.gov ID NCT06935409
About the Writer
Malavatu Satvika (Linkedin) is a Pharm.D professional and aspiring healthcare medical writer with clinical exposure and research experience. Her interests include medical writing, drug safety, pharmaceutical research, and evidence-based healthcare communication. She has contributed to two research publications in pharmaceutical journals and has gained practical experience in prescription review, patient counselling, medication review, adverse drug reaction monitoring, drug information services, literature review, and clinical documentation through regular hospital training.
She has completed certifications in clinical research, ICH-GCP E6(R3), data management for clinical research, and congenital hypothyroidism. With a strong foundation in pharmacy, clinical practice, and scientific research, she aims to translate complex medical and pharmaceutical information into accurate, clear, and evidence-based healthcare content. She is also preparing to pursue a PhD and further develop her expertise in medical writing and pharmaceutical research.