GSK plc has announced that its investigational therapy risvutatug rezetecan (Ris-Rez), a B7-H3-targeted antibody-drug conjugate (ADC), has been granted Orphan Drug Designation (ODD) by Ministry of Health, Labour and Welfare for the treatment of small-cell lung cancer (SCLC).

The designation is supported by preliminary findings from the Phase I ARTEMIS-001 clinical trial, which demonstrated durable responses in patients with extensive-stage SCLC (ES-SCLC). This marks the sixth regulatory designation for Ris-Rez, underscoring its potential across multiple solid tumours, including lung, prostate and colorectal cancers.

Lung cancer remains the second most common cancer in Japan, with SCLC accounting for approximately 10–15 percent of cases. A majority of these patients present with extensive-stage disease, a highly aggressive form with limited treatment options and poor survival outcomes. Most patients relapse after initial therapy, and median overall survival with current standard treatments is around eight months.

Ris-Rez is a novel investigational ADC composed of a fully human anti-B7-H3 monoclonal antibody linked to a topoisomerase inhibitor payload, designed to deliver targeted cytotoxic therapy. GSK holds exclusive global development and commercialisation rights for the drug, excluding mainland China, Hong Kong, Macau, and Taiwan, following an agreement with Hansoh Pharma.

The company initiated a global Phase III trial in August 2025 to evaluate Ris-Rez in patients with relapsed ES-SCLC. To date, the therapy has received multiple regulatory recognitions, including orphan drug designations from the US Food and Drug Administration and the European Medicines Agency, as well as Breakthrough Therapy and PRIME designations for various cancer indications.

GSK stated that the latest designation highlights the urgent need for innovative therapies in aggressive cancers such as SCLC and reinforces its commitment to advancing targeted oncology treatments.