A phase I study to evaluate the safety and tolerability of SX-682 in combination with PD-1 inhibitor as maintenance therapy for unresectable pancreatic adenocarcinoma.

Abstract

TPS631 Background: Survival outcomes for advanced pancreatic ductal adenocarcinoma (PDAC) remain dismal despite improvements in systemic therapy regimens developed over the past decade. In addition, current first-line therapies result in cumulative cytopenias and neuropathy, highlighting the need for more effective, less toxic maintenance treatment strategies. There are currently no standard approved maintenance treatments for patients with PDAC not associated with BRCA or DNA-repair mutations. Pre-clinical data suggest a potential synergistic effect of combining blockade of CXC chemokine receptors (CXCR) with immunotherapy or chemotherapy in pancreatic cancer1,2. We are currently conducting a Phase I study (NCT04477343) evaluating SX-682, an oral CXCR1/2 inhibitor, and Nivolumab as maintenance treatment for advanced PDAC. Methods: This is an open-label, dose escalation Phase I clinical trial evaluating the combination of SX-682 and Nivolumab. Patients must have histologically confirmed unresectable PDAC and have completed at least 16 weeks of first-line chemotherapy with disease stability or treatment response at time of enrollment. Radiographically measurable disease must be present per iRECIST criteria. Patients receive a 3-week run-in phase of twice-daily dosing of SX-682, followed by combination of twice-daily dosed SX-682 and every 2-week Nivolumab (240 mg IV). Dose finding of SX-682 is performed using Bayesian optimal interval (BOIN) design to determine the maximum tolerated dose (MTD) when combined with Nivolumab. Pre-treatment and one on treatment (Day 28-35) biopsies are required for enrollment to evaluate change in tumor microenvironment immune cell composition by single cell-RNA sequencing, flow cytometry, RNA RT-qPCR, and IHC. The primary endpoint is to determine MTD; the key secondary endpoint is progression-free survival (PFS), defined as the time from enrollment to progression via iRECIST criteria or death. Nine of a planned 20 patients have been enrolled. Dose-level 1 (SX-682 50 mg BID) completed enrollment without dose-limiting toxicity (DLT). Dose-level 2, which commenced in June 2021, (SX-682 100 mg BID) is without DLTs, but has not completed enrollment at time of abstract submission. Nywening TM, Belt BA, Cullinan DR, et al. Targeting both tumour-associated CXCR2(+) neutrophils and CCR2(+) macrophages disrupts myeloid recruitment and improves chemotherapeutic responses in pancreatic ductal adenocarcinoma. 1) Gut. 2018;67(6):1112-1123. Steele CW, Karim SA, Leach JDG, et al. CXCR2 Inhibition Profoundly Suppresses Metastases and Augments Immunotherapy in Pancreatic Ductal Adenocarcinoma. 2) Cancer Cell. 2016;29(6):832-845. Clinical trial information: NCT04477343.