Pharmaceutical company GSK plc (LSE: GSK) (NYSE: GSK) declared on Monday that it has received Orphan Drug Designation in Japan for its investigational antibody-drug conjugate, risvutatug rezetecan, for the treatment of small-cell lung cancer (SCLC), marking the sixth global regulatory designation for the asset.

This designation from Japan's Ministry of Health, Labour and Welfare is supported by early clinical data from the Phase I ARTEMIS-001 trial, which demonstrated durable responses in patients with extensive-stage SCLC (ES-SCLC). The condition remains highly aggressive, with limited treatment options, high relapse rates and a median overall survival of approximately eight months under current standard of care.

Risvutatug rezetecan is a B7-H3-targeted antibody-drug conjugate combining a fully human monoclonal antibody with a topoisomerase inhibitor payload. The therapy is being developed across multiple solid tumours, including lung, prostate and colorectal cancers, with a global Phase III trial in relapsed ES-SCLC initiated in August 2025.

GSK holds exclusive worldwide rights to the therapy outside Greater China under an agreement with Hansoh Pharma. In addition to the latest Japanese designation, the programme has received Orphan Drug and Breakthrough Therapy Designations from the US Food and Drug Administration, as well as Priority Medicines designation from the European Medicines Agency, supporting its potential as a novel treatment option in difficult-to-treat cancers.