GSK plc (LSE/NYSE: GSK) today announced a significant regulatory milestone for its promising oncology asset, risvutatug rezetecan (formerly GSK’227), a B7-H3-targeted antibody-drug conjugate (ADC). The US Food and Drug Administration (FDA) has granted the drug Orphan Drug Designation (ODD) for the treatment of small-cell lung cancer (SCLC).
The ODD is supported by encouraging preliminary clinical data from the Phase I ARTEMIS-001 trial, which demonstrated durable responses in patients suffering from extensive stage SCLC (ES-SCLC). This aggressive and rapidly progressing form of cancer accounts for approximately 70% of SCLC diagnoses, is notoriously difficult to treat, and is associated with a poor prognosis, with a 5-year survival rate of approximately 3%.
The Orphan Drug Designation is designed to encourage the development of drugs for rare diseases or conditions that affect fewer than 200,000 people in the US. With an estimated 29,500 new SCLC diagnoses in the US in 2025, the designation underscores the urgent need for new therapeutic options for this patient population, especially those who relapse after initial standard-of-care treatments.
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Risvutatug rezetecan is a novel investigational ADC composed of a fully human anti-B7-H3 monoclonal antibody linked to a topoisomerase inhibitor payload. This latest designation marks the fifth key regulatory milestone for the ADC, highlighting its transformational potential across various solid tumors. Risvutatug rezetecan has also previously received Breakthrough Therapy Designations from the FDA for relapsed or refractory ES-SCLC and osteosarcoma, and Priority Medicines (PRIME) Designation from the European Medicines Agency (EMA) for relapsed ES-SCLC.
GSK is accelerating the drug’s development, with a global Phase III trial (NCT07099898) for risvutatug rezetecan in relapsed ES-SCLC having commenced in August 2025. The company acquired exclusive worldwide rights (excluding Greater China) to the molecule from Hansoh Pharma.
GSK Secures Japan Orphan Drug Designation for Risvutatug Rezetecan in Small-Cell Lung Cancer
GSK’s risvutatug rezetecan has officially secured Orphan Drug Designation from Japan’s MHLW for the treatment of small-cell lung cancer (SCLC). Supported by durable response data […]
Targeting a Difficult-to-Treat Cancer
SCLC constitutes about 13% of all lung cancers, with an estimated 29,500 people in the US diagnosed in 2025. Approximately 70% of these patients present with extensive-stage disease, where the cancer has spread beyond the original site.
Risvutatug rezetecan is an investigational B7-H3-targeted ADC. It is composed of a fully human monoclonal antibody designed to selectively target the B7-H3 protein a common target found on the surface of many solid tumor cells, including SCLC, covalently linked to a topoisomerase inhibitor payload. This mechanism allows the drug to deliver a potent cytotoxic agent directly to the cancer cell, minimizing damage to surrounding healthy tissue.
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