ATIM-20. A RETROSPECTIVE STUDY EVALUATING THE SAFETY AND SURVIVAL OF THE COMBINATION OF PD-1 IMMUNE CHECKPOINT BLOCKADE AND BEVACIZUMAB IN RECURRENT GLIOBLASTOMA

Abstract

Abstract INTRODUCTION Immune checkpoint inhibitors (ICI) have demonstrated clinical efficacy in a variety of cancers. It is known that cancer including glioblastoma (GBM) induces an immunosuppression. Bevacizumab by normalizing blood vessels in the tumor can facilitate immune surveillance and potentially improve the efficacy of ICI in GBM patients. We analyze GBM patients with recurrent disease treated with ICI and bevacizumab. METHODS We retrospectively review records of patients diagnosed with recurrent GBM treated at our institution with Pembrolizumab or Nivolumab and bevacizumab and evaluate for tolerance and outcomes. RESULTS Twenty-one patients, 12 men and 9 women with median age 62 (range 36–78) and KPS 70 (range 60–90) were treated with a median of 10 ICI cycles (range 4–29) and 5 of bevacizumab (range 0–21). A total of 8 patients (38%) had immune-related adverse events (IRAE): 3 grade 1, 3 grade 2 and 2 grade 3. A patient with pneumonitis required cessation of ICI. Median OS for the 21 patients was 22 months (range 6–41). The 7 patients that had MGMT detected in their tumors had a median OS of 27 months (range 23–41) compared to a survival of 21 months (range 6–24) for the 13 patients that had MGMT undetected. One had undetermined MGMT and her OS was 21 months. The median survival for all the patients from onset of ICI was 10 months (range 1–25) and 10 of them (47.6%) survived > 12 months. DISCUSSION The development of IRAE was common but self-limiting, allowing continuation of the treatment in all but one patient. The combination of ICI and bevacizumab increased survival. Our data needs to be interpreted with caution, as it is a retrospective analysis of a small group of patients. However, these results warrant prospective studies using the combination of ICI and bevacizumab to treat recurrent GBM.