Although both avelumab and radium-223 are approved for use in oncology, the combination will be tested for incurable stage 4 breast cancer.
A new clinical trial could bring hope to thousands of UK women living with Stage 4 breast cancer, which has only a 25% survival rate after 5 years. The trial, which is being funded by the Breast Cancer Now Catalyst Programme, aims to explore the combined effect of radium-223 and avelumab in patients with metastatic breast cancer. The monoclonal antibody avelumab, is already licensed for the treatment of metastatic Merkel cell carcinoma and advanced renal cell carcinoma. Its mode of action involves blockage of the protein, PD-L1 found on tumour cells. The PD-L1 protein decreases the immune system’s ability to kill cancer cells, hence blockage enables the immune system to recognise and destroy cancer cells. There is already some data that avelumab has an acceptable safety profile and clinical activity in a subset of patients with metastatic breast cancer.
Radium-223, brand name, Xofigo, is radiopharmaceutical and which is also licensed for use as either mono-therapy or in combination with luteinising hormone releasing hormone (LHRH) for the treatment of adult patients with metastatic castration-resistant prostate cancer (mCRPC), symptomatic bone metastases and no known visceral metastases. In patients with stage 4 breast cancer, the most common distal site for spreading is bone and which occurs in up to 51% of cases. Radium-223 selectively binds to areas of increased bone turnover in bone metastases and emits high-energy alpha particles which have a short range which limits damage to adjacent areas of tissue. Although radium-223 has not been used in metastatic breast cancer, a second on-going trial is examining feasibility and safety of combining radium-223 given on a 6-weekly schedule, in combination with orally administered capecitabine in breast cancer patients with bone metastases.
The avelumab and radium-223 trial is led by Professor Janet Brown at the University of Sheffield, and run by the Clinical Trials Research Unit at the University of Leeds. If successful, this combination of drugs could provide a new way to treat secondary breast cancer.
