RSR13 plus cranial radiation therapy in patients with brain metastases: Comparison with the Radiation Therapy Oncology Group Recursive Partitioning Analysis Brain Metastases Database

Purpose: This phase II, open-label, multicenter study assessed the efficacy and safety of the potential radiation enhancer RSR13 plus cranial radiation therapy (RT) in patients with brain metastases. The primary end point was patient survival in comparison with the Radiation Therapy Oncology Group Recursive Partitioning Analysis Brain Metastases Database (RTOG RPA BMD). Patients and Methods: Eligibility criteria were age ≥ 18 years, Karnofsky performance score ≥ 70, and brain metastases with solid tumor histology. Patients received cranial RT, 30 Gy in 10 fractions of 3 Gy each, preceded by RSR13, 50 to 100 mg/kg intravenously over 30 minutes. Univariate and multivariate comparisons of survival and cause of death were made between class II study patients and RTOG BMD patients. Results: Fifty-seven RPA class II patients were enrolled. With a minimum follow-up of 24 months, the median survival time and 1- and 2-year survival rates were 6.4 months, 23%, and 11% for the RSR13-treated patients compared with 4.1 months, 15%, and 3% for the RTOG BMD patients (P = .0174). In an exact-matched case analysis (n = 38), median survival time for RSR13 patients was 7.3 months versus 3.4 months for the RTOG BMD patients (P = .006). There was a 54% reduction in the risk of death for RSR13 patients (P = .0267). RSR13-related adverse events of greater than or equal to grade 3 toxicity that occurred in more than one patient included hypoxia, headache, anemia, fatigue, hypertension, and intracranial hypertension. Conclusion: RSR13 plus cranial RT resulted in a significant improvement in survival, as well as a reduction in death due to brain metastases, compared with class II patients in the RTOG BMD.