GOBLET study: Results of the safety run-in for first-line metastatic pancreatic ductal adenocarcinoma (PDAC) patients treated with pelareorep + modified FOLFIRINOX +/- atezolizumab.

730 Background: Immunotherapies are effective in only the small subset of metastatic PDAC patients with MSI-H or dMMR tumors. Pelareorep (pela) is a non-genetically modified, intravenously administered reovirus that selectively infects cancer cells. It stimulates the expansion of pre-existing tumor-infiltrating lymphocyte (TIL) clones, and it makes tumors visible to the immune system by upregulating interferon-induced gene expression including PD-L1, CXCL9, CXCL10, and CXCL11. PD-L1 upregulation also provides a basis for potential synergy between pela and immune checkpoint inhibitors. Pela combined with gemcitabine/nab-paclitaxel/atezolizumab showed promising tumor responses in mPDAC. Here, we are assessing the safety and preliminary efficacy of pela + mFOLFIRINOX +/- atezolizumab in a new cohort in the ongoing GOBLET study. Methods: GOBLET is a phase 1/2, open-label, Simon two-stage study in patients with advanced or metastatic GI cancers. In this new GOBLET cohort (Cohort 5), patients with newly diagnosed mPDAC are randomized to receive either pela + mFOLFIRINOX or pela + mFOLFIRINOX + atezolizumab. The primary endpoints are safety and objective response rate (ORR). In Stage 1, 15 evaluable patients will be enrolled in each arm. Both arms include a 3-6 patient safety run-in that must be successfully completed prior to opening the study to full enrollment. If pre-specified ORR success criteria are met, one or both arms may be advanced to Stage 2 during which 17 additional evaluable patients/per arm will be enrolled. Results: The 3-patient safety run-in for both arms of Cohorts 5 (6 patients total) have been enrolled, and all patients have completed the required 1-month evaluation period. Cohort 5 safety data have been reviewed by the independent Data Safety Monitoring Board (DSMB). The DSMB identified no safety signals attributable to the combination of pela and mFOLFIRINOX +/- atezolizumab and recommended that enrollment into these arms of Cohort 5 continue without modification. Reported adverse events are consistent with the known toxicities of the components of the treatment regimen. Tumor response results are pending. Conclusions: The results of the GOBLET Cohort 5 safety run-in indicate that pela can be given safely in combination with mFOLFIRINOX +/- atezolizumab to newly diagnosed mPDAC patients. Safety and efficacy of these combination therapies will continue to be monitored (Eudra-CT: 2020-003996-16). Clinical trial information: 2020-003996-16 .