GSK’s ADC Risvutatug Rezetecan Earns FDA Orphan Drug Status for Small Cell Lung Cancer

GSK’s B7-H3 targeted antibody drug conjugate risvutatug rezetecan has received FDA Orphan Drug Designation for small cell lung cancer, supported by early ARTEMIS 001 data showing durable responses in extensive stage disease.

GSK’s investigational antibody-drug conjugate (ADC) risvutatug rezetecan, also known as GSK’227, has received FDA Orphan Drug Designation for the treatment of small-cell lung cancer. The designation is anchored in early findings from the phase I ARTEMIS-001 study, where the B7-H3-targeted ADC produced durable responses in patients with extensive-stage SCLC.

SCLC represents about 13 percent of all lung cancers in the US, and 70% of patients present with extensive-stage disease, a setting defined by widespread involvement within or beyond the lungs. Despite initial sensitivity to chemotherapy, most patients experience rapid relapse. The median overall survival after recurrence is roughly eight months and the five-year survival rate for extensive-stage SCLC hovers around 3 percent. Any therapy capable of generating prolonged responses therefore represents a potential advance.

Risvutatug rezetecan has now accumulated five regulatory designations across major agencies, reflecting continued confidence in its therapeutic potential. The new US designation follows recent Orphan Drug Designation from the European Medicines Agency for pulmonary neuroendocrine carcinoma, a category that includes SCLC.

Additional recognitions include PRIME status from the EMA for relapsed or refractory ES-SCLC and two Breakthrough Therapy Designations from the FDA for relapsed or refractory ES-SCLC and relapsed or refractory osteosarcoma. These regulatory actions underscore growing interest in B7-H3 as a drug target in solid tumours.

Risvutatug rezetecan is a fully human monoclonal antibody linked to a topoisomerase inhibitor payload. By targeting B7-H3, a surface protein expressed across several solid tumours, the ADC is designed to deliver cytotoxic therapy directly to malignant cells while limiting systemic exposure. GSK holds exclusive worldwide rights to develop and commercialise the molecule outside mainland China, Hong Kong, Macau, and Taiwan.

A global phase III trial evaluating risvutatug rezetecan in relapsed extensive-stage SCLC began enrolling patients in August 2025. Its results will be crucial in determining whether the early activity observed in ARTEMIS-001 can translate into meaningful clinical benefit at scale for a population with few remaining options.