Durvalumab and tremelimumab in combination with FOLFOX in patients with RAS-mutated, microsatellite-stable, previously untreated metastatic colorectal cancer (MCRC): Results of the first intermediate analysis of the phase Ib/II MEDETREME trial.

3006 Background: Single agent PD-1/L1 inhibition are not effective in metastatic colorectal cancer (MCRC) with microsatellite stable tumors. However, signal of efficacy was shown using combo therapy of anti-PD-L1 and anti CTLA-4 in multitreated patients. FOLFOX regimen could induced immunogenic cell death and elimination of myeloid derived suppressor cells (MDSCs) thus leading to a potential positive effect on antitumor immune response. Methods: This is a single arm exploratory investigator-initiated trial planned to include 57 pts to receive mFOLFOX6 (6cycles) in combination with durvalumab (150mg/q2W) and tremelimumab (75mg/q4W). After 6 cycles of chemotherapy, patients are treated with durvalumab untils progression. Primary endpoint is 6 months’ progression-free survival rate. Secondary endpoints are response rate, tolerability and translational research evaluating tissue and blood immune parameter. Upon Simon’s design an efficacy intermediate analysis was planned after the 16th patient has passed 6 months. Results: As of 1st of January 2020 the 55/57 pts were enrolled and treated with the MEDETREME regimen at 8 French sites. The intermediate efficacy analysis was conducted on the 1st of January after a median of 13.4 months of treatment. The following adverse events were noted: asthenia (81.25%), neuropathy (87.5%), diarrhea (56.25%) and neutropenia (62.5%). Notable grade 3/4 (CTC AE 4.03) include asthenia (18.75%) diarrhea (12.5%) neutropenia (50%) and elevated blood pressure (25%). Most of adverse events were related to chemotherapy. It has been noted one cytolysis grade 3, one thyroid dysfunction grade 3 and one hypophysitis grade 3 related to immunotherapy. Median PFS was not reached. Progression free survival at 6 months was observed in 10/16 pts (62,5%) given 5 CR, 5 PR and 4 SD. Updated translational data will be presented at the meeting. Conclusions: The interim safety analysis has supported safety and efficacy of the MEDITREME regimen in first- line MCRC. Finally, results will be presented after maturation of follow up. Clinical trial information: NCT03202758 .