SHANGHAI, July 28, 2026—Hansoh Pharmaceutical Group Co., Ltd. (Hansoh Pharma, 03692.HK) today announces that risvutatug rezetecan (Ris-Rez/HS-20093), the Group’s proprietary B7-H3 directed antibody-drug conjugate (ADC), met the primary endpoint of progression-free survival (PFS) as assessed by the Independent Review Committee (IRC) in the pivotal Phase III clinical trial (ARTEMIS-011) in patients with osteosarcoma who had progressed or relapsed after receiving at least two prior lines of systemic therapy. Compared with chemotherapy, Ris-Rez demonstrated a statistically significant and clinically meaningful improvement in IRC-assessed PFS. Consistent benefits were also observed across secondary clinical endpoints, including overall survival (OS) and investigator-assessed PFS, further validating the potential clinical value of this drug in the treatment of advanced osteosarcoma. The safety profile was consistent with prior study findings, and no new safety signals were identified.

ARTEMIS-011 is a registrational Phase 3 clinical study conducted in patients with osteosarcoma. Its positive results mark another potential important breakthrough for B7-H3–directed ADC therapy in solid tumor treatment. Based on these findings, Hansoh Pharma will initiate discussions with the Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA) in the near term to advance preparations for a Biologics License Application (BLA) in China. Meanwhile, detailed data from the ARTEMIS-011 study will be presented at an upcoming international oncology congress.

These results build on the recent announcement of positive pivotal data for Ris-Rez in advanced or relapsed small-cell lung cancer, marking its positive phase III outcomes in two distinct tumour types. Ris-Rez is now the only B7-H3-targeted antibody-drug conjugate (ADC) to report positive phase III studies across multiple tumour settings.

Addressing Unmet Medical Needs — Breaking Through the Treatment Bottleneck in Advanced Osteosarcoma

Osteosarcoma is the most common malignant bone tumor, accounting for 35% of all malignant bone tumors, and has been included in the Second Batch of the Rare Disease Directory published by China’s National Health Commission ^[1]. With a median age at onset of 20 years, osteosarcoma is the most common primary malignant bone tumor in children and adolescents. Approximately 20–30% of patients with localized (non-metastatic) osteosarcoma and 80% of patients with metastatic osteosarcoma will progress to advanced disease (recurrent or metastatic), and the 5-year survival rate for patients with advanced osteosarcoma is only approximately 20% ^[2–3]. Globally, treatment options are limited for patients with recurrent or refractory osteosarcoma after first-line chemotherapy, with no clearly defined standard of care ^[4–5]. For patients who have progressed after second-line therapy, treatment options are even more limited, representing a substantial unmet medical need.

As the core ADC asset in Hansoh Pharmaceutical's B7-H3 portfolio, Ris-Rez is designed to precisely target the B7-H3 antigen on the surface of tumor cells and deliver a topoisomerase inhibitor payload directly into tumor cells. This directed approach aims to achieve potent tumor cell killing while significantly reducing systemic toxicity. In this ARTEMIS-011 study conducted in patients who had progressed or relapsed after receiving at least two prior lines of systemic therapy, Ris-Rez demonstrated a statistically significant and clinically meaningful improvement in IRC-assessed PFS, accompanied by a consistent benefit in the secondary endpoint of OS, and may provide a breakthrough new treatment option for this highly refractory tumor.

About Risvutatug Rezetecan

Risvutatug rezetecan is a Hansoh proprietary B7-H3–directed antibody-drug conjugate (ADC), comprising a fully human B7-H3 monoclonal antibody covalently linked to a topoisomerase inhibitor (TOPOi) payload. The product has entered Phase 3 clinical development in China for osteosarcoma, small cell lung cancer (SCLC), non-small cell lung cancer (NSCLC) and esophageal squamous cell carcinoma(ESCC), and is also being evaluated in multiple proof-of-concept (PoC) studies across additional indications, including head and neck cancer, prostate cancer, colorectal cancer, and other solid tumors. In December 2023, Hansoh Pharma granted GSK an exclusive worldwide license, excluding Chinese mainland, Hong Kong, Macau and Taiwan, to develop, manufacture and commercialize Ris-Rez. GSK is currently advancing Phase I to III clinical trials for the product overseas.

References

[1] Second Batch of the Rare Disease Directory, National Health Commission of the People's Republic of China, Guo Wei Yi Zheng Fa [2023] No. 26, September 18, 2023.

[2] Durfee RA, Mohammed M, Luu HH. Review of Osteosarcoma and Current Management. Rheumatol Ther. 2016 Dec;3(2):221-243. DOI: 10.1007/s40744-016-0046-y.

[3] Meltzer PS, Helman LJ. New Horizons in the Treatment of Osteosarcoma. N Engl J Med. 2021;385(22):2066-2076.

[4] National Comprehensive Cancer Network (NCCN). NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®): Bone Cancer. August 20, 2024. Version 1.2025. Accessed October 24, 2024. https://www.nccn.org/professionals/physician_gls/pdf/bone.pdf

[5] Chinese Society of Clinical Oncology (CSCO). CSCO Clinical Practice Guidelines: Bone and Soft Tissue Cancer (2024).