Objectives Novel therapies are needed for the treatment of pts with relapse/refractory disease following treatment with approved checkpoint inhibitors. COM701 is a 1st in class novel immune checkpoint inhibitor of PVRIG, part of the DNAM axis. Key primary objectives/endpoints: safety and tolerability of COM701 monotherapy and in combination with nivolumab (doublet), measured by the incidence of pts with adverse events (AEs) and dose-limiting toxicities (DLTs). The recommended dose for expansion of COM701 monotherapy and in combination with nivolumab. Key secondary objectives/endpoints: the preliminary antitumor activity of COM701 monotherapy and doublet in pts with selected tumor types (endometrial, ovarian, breast and lung cancer).

Methods Study design: dose escalation hybrid single subject accelerated titration design and 3+3 design. Key inclusion criteria: Age ≥18 yrs, histologically confirmed, advanced solid tumor and has exhausted all available standard therapy or not a candidate for available standard therapy, prior checkpoint inhibitor permissible. Key exclusion criteria: inflammatory pneumonitis, history of immune-related events that led to immunotherapy treatment discontinuation. We report on COM701 monotherapy dose escalation. Expansion cohorts will enroll pts with the selected tumor types (above). ClinicalTrials.gov Identifier: NCT03667716.

Results At time of this submission no DLTs observed up to 5th COM701 monotherapy dose level pt cohort.

Conclusions Study enrollment ongoing.

COM701 monotherapy safe and tolerable at the doses tested. Updated results will be presented at the meeting.