Japan Grants Orphan Designation To GSK’s Investigational Ris-Rez As Global Development Advances In Aggressive Lung Cancer

GSK plc has announced that its investigational antibody–drug conjugate risvutatug rezetecan (Ris-Rez) has been granted Orphan Drug Designation by the Japan Ministry of Health, Labour and Welfare for the treatment of small-cell lung cancer (SCLC). The decision follows encouraging early clinical data from the Phase I ARTEMIS-001 study, in which patients with extensive-stage SCLC achieved durable responses. This marks the sixth regulatory recognition for Ris-Rez, which is being explored across multiple solid tumours, including lung, prostate, and colorectal cancers.

Lung cancer remains the second most prevalent cancer in Japan, with SCLC accounting for roughly 10–15% of all cases. Around 70% of patients are diagnosed at the extensive stage, where the disease has already spread within the lungs or to distant organs. This advanced form is particularly aggressive, difficult to manage, and associated with limited treatment options. Relapse is common after first-line therapy, and patients receiving current standard treatments face a median overall survival of only about eight months.

Ris-Rez is a next-generation B7-H3-targeted antibody–drug conjugate that combines a fully human monoclonal antibody with a topoisomerase inhibitor payload to selectively target tumour cells. GSK plc secured exclusive global development and commercialisation rights from Hansoh Pharma, excluding certain Chinese regions. A global Phase III trial evaluating the therapy in relapsed extensive-stage SCLC was initiated in August 2025.

The therapy has accumulated multiple regulatory endorsements worldwide. These include Orphan Drug Designations from the U.S. Food and Drug Administration and the European Medicines Agency, as well as PRIME status from the EMA. Additionally, the US regulator has granted Breakthrough Therapy Designations for its potential use in relapsed or refractory extensive-stage SCLC and osteosarcoma, underscoring the treatment’s promise in hard-to-treat cancers.