The UK's Medicines and Healthcare products Regulatory Agency (MHRA) has approved serplulimab (Hetronifly) for treating adults with extensive-stage small cell lung cancer (ES-SCLC), marking the first anti-PD-1 monoclonal antibody approved in the UK for this aggressive cancer type. The approval, announced on June 20, 2025, addresses a significant unmet medical need for patients with limited treatment options and poor prognosis.
Clinical Significance and Mechanism
Small cell lung cancer represents a particularly challenging malignancy, accounting for 10-15% of all lung cancer cases and characterized by rapid growth and early metastasis. The disease typically develops in the lung airways and is often diagnosed at advanced stages when cancer has already spread throughout the lungs or to other body parts.
Serplulimab functions as a targeted immunotherapy that blocks the PD-1 receptor, which some cancer cells exploit to evade immune system detection. By inhibiting this pathway, the monoclonal antibody enhances the immune system's ability to recognize and destroy cancer cells more effectively.
Trial Results and Efficacy
The MHRA approval is based on results from a randomized, double-blind clinical trial involving 585 adults with extensive-stage SCLC who had not received prior treatment. The study compared serplulimab plus chemotherapy against placebo plus chemotherapy as first-line treatment.
Patients receiving serplulimab in combination with chemotherapy demonstrated significantly improved survival outcomes, living an average of 15.4 months compared to 10.9 months for those receiving chemotherapy with placebo. This represents a substantial improvement in overall survival for a cancer type historically associated with poor outcomes.
Treatment Protocol and Administration
Serplulimab is administered through intravenous infusion once every three weeks in combination with standard chemotherapy agents carboplatin and etoposide. Treatment can continue for as long as clinical benefit is observed, providing flexibility in patient management.
The European Society for Medical Oncology (ESMO) has scored serplulimab 4 out of 5 on their magnitude of clinical benefit scale (MCBS) for extensive-stage small cell lung cancer, reflecting the therapy's significant clinical value.
Regulatory Recognition and Global Approval
Julian Beach, MHRA Interim Executive Director of Healthcare Quality and Access, emphasized the importance of this approval: "As the first and only anti-PD-1 monoclonal antibody approved in the UK for small cell lung cancer, this marks an important new treatment option for patients with this aggressive type of lung cancer who currently have limited choices and face a poor prognosis."
The drug has also received marketing authorization from the European Commission for all 27 EU member states and European Economic Area countries, including Norway, Iceland, and Liechtenstein. Serplulimab previously received orphan drug designation from the European Commission in December 2022 for SCLC treatment, which was renewed in 2025.
Safety Monitoring and Availability
The MHRA has confirmed that serplulimab meets appropriate regulatory standards for safety, quality, and efficacy. As with all approved medications, the agency will maintain close safety monitoring through ongoing surveillance programs. Patients and healthcare providers can report suspected adverse effects through the Yellow Card scheme.
The marketing authorization was granted to Accord Healthcare Limited, with complete safety information available in the Patient Information Leaflet and Summary of Product Characteristics on the MHRA website within seven days of approval.
