BL-8040, a CXCR4 Antagonist, in Combination with Pembrolizumab and Chemotherapy for Pancreatic Cancer: the COMBAT trial

Abstract

Single agent immunotherapy has limited effect in pancreatic ductal adenocarcinoma (PDAC), underscoring the need to co-target alternative pathways. CXCR4 blockade promotes T-cell tumor infiltration and is synergistic with anti-PD1 therapy in PDAC mouse models. We conducted a phase IIa, open label, two-cohort study to assess the safety, efficacy and immunobiological effects of the CXCR4 antagonist BL-8040 (motixafortide) with pembrolizumab and chemotherapy in metastatic PDAC (NCT02826486). Primary outcome was objective response rate (ORR). Secondary outcomes were overall survival (OS), disease control rate (DCR) and safety. In cohort-1, 37 subjects with disease progression after one or more lines of chemotherapy received BL-8040 and pembrolizumab. The DCR was 34.5% in the evaluable population (modified intention to treat, mITT N=29) including nine patients (31%) with stable disease and one (3.4%) with partial response. Median OS was 3.3 months in the ITT population. Notably, in patients receiving study drugs as second-line mOS was 7.5 months. BL-8040 increased CD8+ effector T-cells tumor infiltration and decreased myeloid derived suppressor cells, and further decreased circulating Tregs. In a 22 patients expansion cohort-2 combining BL-8040 and pembrolizumab with standard second-line chemotherapy, ORR was 32%, DCR was 77%, with median duration of response of 7.8 months. These data suggest that CXCR4/PD-1 blockade may expand the benefit of chemotherapy in PDAC and warrant confirmation in subsequent randomized trial.