Ris-Rez Hits PFS End Point in Phase 3 Osteosarcoma Trial

Risvutatug rezetecan (Ris-Rez), a B7-H3-targeted antibody-drug conjugate (ADC), met its primary end point of progression-free survival (PFS) in the phase 3 ARTEMIS-011 trial (NCT06935409) for patients with relapsed osteosarcoma, according to a news release from GSK.¹

The ARTEMIS-011 trial enrolled patients with osteosarcoma who had progressed or relapsed after at least 2 prior lines of systemic therapy. Ris-Rez demonstrated a statistically significant and clinically meaningful improvement in PFS compared with chemotherapy, and a consistent benefit was also observed across secondary end points, including overall survival (OS). The safety profile in ARTEMIS-011 was consistent with prior findings in this tumor type, and no new safety signals were identified.

The drug’s developer will use the ARTEMIS-011 data to support a regulatory submission in China.

The results follow recently reported pivotal data for Ris-Rez in advanced or relapsed small cell lung cancer (SCLC), where the phase 3 ARTEMIS-008 trial (NCT06498479) met its primary end point of OS compared with topotecan (Hycamtin), according to a separate GSK release.² That trial, also conducted in China, showed a consistent benefit across key secondary end points, including PFS, with a safety profile in line with previous findings. Together, the SCLC and osteosarcoma results make Ris-Rez, according to GSK, the only B7-H3-targeted ADC to deliver positive phase 3 outcomes across multiple tumor types.

“Building on recent pivotal data in small cell lung cancer, these results strengthen our confidence in the broad potential of Ris-Rez and validate B7-H3 as a promising target across multiple tumour types," Hesham Abdullah, MD, senior vice president and global head of oncology research and development at GSK, said in the release announcing the ARTEMIS-011 results.¹

This unmet need is also reflected in the regulatory path Ris-Rez has followed in osteosarcoma. The FDA granted the ADC breakthrough therapy designation in January 2025 for adult patients with relapsed or refractory osteosarcoma who progressed on at least 2 prior lines of therapy, according to a GSK release on the designation.³ That decision was supported by data from ARTEMIS-002 (NCT05830123), a phase 2, open-label, randomized, multicenter trial that enrolled approximately 60 patients with relapsed or refractory osteosarcoma and other unresectable bone and soft tissue sarcomas, including 42 patients with osteosarcoma; those results were presented at the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting.⁴

Ris-Rez is composed of a fully human anti-B7-H3 monoclonal antibody covalently linked to a topoisomerase inhibitor payload. Beyond the China-based ARTEMIS program, GSK is advancing EMBOLD Sarcoma-202 (NCT07602777), a global phase 1b/2 trial evaluating Ris-Rez in previously treated, unresectable advanced or metastatic sarcomas, including osteosarcoma, as part of a broader clinical development program spanning lung cancer, prostate cancer, and other solid tumors.

References

1. GSK's licensor Hansoh Pharma announces positive results from a second phase III trial for Ris-Rez in China. News release. GSK plc. July 28, 2026. Accessed July 28, 2026. https://tinyurl.com/ykv9pkmz
2. GSK’s licensor Hansoh Pharma announces positive phase III results for Ris-Rez in China patient population. News release. GSK plc. July 10, 2026. Accessed July 28, 2026. https://tinyurl.com/2bmnz24b
3. GSK's B7-H3-targeted antibody-drug conjugate, GSK'227, receives US FDA Breakthrough Therapy Designation in late-line relapsed or refractory osteosarcoma. News release. GSK plc. January 7, 2025. Accessed July 28, 2026. https://tinyurl.com/5d6v4xv6
4. Xie L, Xu, J, Liang X, et al. ARTEMIS-002: phase 2 study of HS-20093 in patients with relapsed or refractory osteosarcoma. J Clin Oncol. 2024;42(suppl 16):11507. doi: 10.1200/JCO.2024.42.16_suppl.11507