Abstract
3017 Background: Metastasis to the peritoneal cavity is associated with end-stage disease in many cancers, including OC and CRC, both of which exhibit poor responses to checkpoint inhibitors. Locoregional treatment with oncolytic viruses may be used to improve the efficacy of checkpoint inhibitors at both treated and distant tumor sites. This study evaluates the combination of IP-administered ONCOS-102, an oncolytic adenovirus encoding for granulocyte macrophage colony stimulating factor (GMCSF), with systemic durvalumab, an anti PD-L1 antibody, in patients with peritoneal disease who have histologically confirmed OC or metastatic CRC and have failed prior standard therapies. Methods: This ongoing Phase 1/2, open-label study (NCT02963831) evaluates safety and antitumor/biologic activity of durvalumab (1500 mg IV, every 4 weeks x 12) + ONCOS-102 (IP, weekly x 6); cyclophosphamide is given pre first ONCOS-102 dose. Phase 1 uses a 3+3 design to evaluate the ONCOS-102 dose (1 or 3 x 1011 VP) to be given with durvalumab. Phase 2 evaluates the activity of the combination using Simon’s 2-stage MINIMAX design. Safety, response rate by RECIST 1.1, and immunological effects in tumors were evaluated for Phase 1; the current abstract reports on the phase 1 results. Results: Enrollment opened 7 Sep 2017; data cutoff, 1 Nov 2019. There were 17 patients treated in Phase 1: 8 CRC, 9 ovarian; 94% female; median age, 56 [37-77] years; ECOG PS0, 47%; ECOG PS1, 53%. There were no DLTs. Grade 3 treatment-related AEs included hypokalemia (n = 2); anemia, myocarditis, increased GGT, and influenza like illness (n = 1 each). There were 4 deaths due to PD. One patient had durable confirmed partial response and remains on treatment > 1 year; 4 patients had stable disease as best overall response. Two patients remained on treatment at data cutoff. Analysis of pre- and on-treatment tumor biopsies revealed changes in the tumor-infiltrating immune cells and PD-L1 expression, including an increase in tumor-infiltrating CD8 T cells in 5 of 11 evaluable patients. Conclusions: Combination of durvalumab and IP ONCOS-102 was safe, and no DLTs were observed. Preliminary analyses demonstrate evidence of biologic and clinical activity. Phase 2 enrollment is ongoing. Clinical trial information: NCT02963831 .