Hansoh's B7-H3 ADC Risvutatug Rezetecan Shows 18.5-Month Median OS in Relapsed SCLC

On the morning of September 13, 2026, during the first presidential session of the opening day of the 2026 World Conference on Lung Cancer, risvutatug rezetecan (development code: HS-20093), a B7-H3-targeted antibody-drug conjugate (ADC) independently developed by Hansoh Pharma, was presented as a late-breaking abstract and in an oral report. The data presented set a record for the longest overall survival in second-line treatment of small cell lung cancer, extending patient survival by 8.2 months compared with the current standard of care.

The presentation covered interim analysis results from the Phase III ARTEMIS-008 study of risvutatug rezetecan in relapsed small cell lung cancer. The study was a randomized, open-label Phase III trial that enrolled 461 patients, who were randomized 1:1 to receive risvutatug rezetecan or topotecan. The prespecified interim analysis, reviewed by an independent data monitoring committee, showed that the study met its primary endpoint of overall survival (OS). Topotecan is the current standard second-line treatment for small cell lung cancer. As of June 6, 2026, the median follow-up was 12.2 months.

In terms of specific data, median OS reached 18.5 months for risvutatug rezetecan and 10.3 months for topotecan. Median OS refers to the duration that half of patients survive and the other half die before, and is a core indicator in clinical trials used to measure the overall performance of a regimen. Compared with the current standard treatment, risvutatug rezetecan extended patient survival by 8.2 months. A consistent trend of OS benefit was observed across all prespecified subgroups, including platinum-resistant and platinum-sensitive disease, presence or absence of brain metastases, prior treatment with or without PD-(L)1 inhibitors, and limited-stage versus extensive-stage disease.

For progression-free survival (PFS), median PFS reached 7.2 months for risvutatug rezetecan and 3.0 months for topotecan. In terms of safety, the incidence of Grade 3 or higher treatment-related adverse events was 60.9% and 78.2% in the two groups, respectively. Risvutatug rezetecan is a B7-H3-targeted antibody-drug conjugate independently developed by Hansoh Pharma, composed of a fully human anti-B7-H3 monoclonal antibody conjugated to a topoisomerase I inhibitor payload via a cleavable tetrapeptide linker.

Lung cancer has among the highest incidence and mortality rates of all cancers globally and in China. Lung cancer can be divided into small cell lung cancer and non-small cell lung cancer. Small cell lung cancer accounts for approximately 10% to 15% of all lung cancer cases, a lower proportion than non-small cell lung cancer, but it is the most aggressive subtype of lung cancer, characterized by early widespread metastasis, easy recurrence, and poor prognosis. Small cell lung cancer can be divided into limited-stage and extensive-stage disease. Limited-stage disease is treated with surgery, concurrent chemoradiotherapy, and other modalities, with a 5-year survival rate of only 30% to 35%. Between 60% and 70% of small cell lung cancer patients are already at the extensive stage at diagnosis. Extensive-stage patients receive palliative treatment based mainly on chemotherapy, with a worse prognosis than limited-stage disease, a median survival of only 7 to 12 months, and a 2-year survival rate of approximately 22%.

Platinum-containing chemotherapy is the standard first-line treatment for small cell lung cancer, but the vast majority of patients relapse rapidly or develop resistance after first-line treatment, and second-line and later treatment options are extremely limited. Hansoh Pharma announced on September 2, 2026, that the marketing authorization application for risvutatug rezetecan for the treatment of small cell lung cancer that has failed prior platinum-containing therapy has been accepted by China's drug regulator and included in the priority review and approval procedure.