Radiation enhancer improves survival in metastases treated with radiotherapy

Standard palliative treatment for brain metastases is corticosteroids and cranial radiotherapy. Median survival time is approximately 4-7 months. Hypoxic tumour cells are more resistance to DNA damage by ionising radiation, and may have a higher recurrence rate. This was a phase II, open-label, multicentre study of the efficacy and safety of the radiation enhancer RSR13. RSR13 is a synthetic allosteric modifier of haemoglobin, and decreases the haemoglobin oxygen binding affinity. This increases the release of oxygen from haemoglobin and so increases the tissue partial pressure of oxygen.1In this study, RSR13 was given intravenously by central venous access for 30 minutes concurrently with radiotherapy to 57 patients. Results were compared to data from the Radiation Therapy Oncology Group Recursive Partitioning Analysis Brain Metastases Database (RTOG BMD). Results showed increased survival for RSR13 treated patients compared to the RTOG BMD control group. Survival at six months, one year, and two years was 51%, 23%, and 11% compared to 35%, 15% and 3% for the control group (p = 0.0174). When exact match cases were compared, survival rates were 58%, 24%, 13% for those on RSR13 compared to 21%, 8% and 3% of the RTOG BMD patients.Only 14% of patients experienced serious adverse events related to their treatment. Most were predictable, dose related and due to mild, transient reductions in oxygen. The authors recommend giving supplemental oxygen by nasal cannula.Reference...