CBM-06IMMUNE BIOMARKER RESULTS FROM A TRIAL OF NIVOLUMAB ± IPILIMUMAB IN PATIENTS WITH RECURRENT GLIOBLASTOMA: CHECKMATE-143

Abstract

BACKGROUND: The prognosis for patients with glioblastoma (GBM) remains poor despite the availability of first-line therapies including surgery and chemoradiation. Recent evidence suggests that there are varying degrees of lymphocyte infiltration in GBM, and the composition may have prognostic significance. Expansion of regulatory T cells (CD4+FoxP3+, Treg) at the tumor site has been observed and is implicated in cancer-associated immunity in GBM. Immune checkpoint inhibitors, such as the fully human anti-PD-1 monoclonal antibody nivolumab, have shown promising antitumor activity in both solid tumors and preclinical glioma models. The CHECKMATE-143 study is evaluating nivolumab as monotherapy and in combination with ipilimumab (anti-CTLA-4) in patients with recurrent GBM (Cohorts 1 and 1b). As part of the initial phase of this study, T-cell maturation, activation, exhaustion, and effector function, as well as Treg frequencies and function and myeloid-derived suppressor cell frequencies were examined. METHODS: Analyses were performed on peripheral blood drawn from patients at pre-determined time points and upon tumor tissue samples obtained if resection was performed at the time of progression or suspected progression. Baseline and on-treatment samples were obtained from patients (n = 20) randomized 1:1 to receive either nivolumab 3 mg/kg Q2W or nivolumab 1 mg/kg + ipilimumab 3 mg/kg Q3W followed by nivolumab 3 mg/kg Q2W. Phenotypic analysis was determined by CyTOF and flow cytometry; Treg suppressive function by thymidine incorporation; cytokine release by multiplex immunoassay; and gene expression by RNAseq. RESULTS: Treatment-related changes in lymphocyte populations (including but not limited to T, B, and NK cells, granulocytes, and memory and effector T-cell subsets) in peripheral blood and resected tumor will be reported. CONCLUSIONS: Peripheral and tumor biomarker analyses of GBM subjects treated with checkpoint inhibitors will provide insights into treatment-related changes versus tumor progression.