Dose Escalation Trial of Bexmarilimab (FP-1305) Plus Pembrolizumab in Non-Small Cell Lung Cancer

This study is an open label, Phase Ib, standard 3+3 dose escalation trial of bexmarilimab (FP-1305) plus pembrolizumab in 4 planned dose escalation cohorts in Non-Small Cell Lung Cancer (NSCLC) to determine the safety and tolerability of repeated doses of bexmarilimab plus pembrolizumab administered in three-week intervals (Q3W) (Figures 1 and 2) defined as treatment cycles. Bexmarilimab is a monoclonal antibody to common lymphatic endothelial and vascular endothelial receptor-1 (CLEVER-1), administered by IV infusion every 3 weeks. Pembrolizumab is a monoclonal antibody to programmed death-1 (PD-1), administered by 30-minute IV infusion every 3 weeks. When pembrolizumab and bexmarilimab are given on the same day, bexmarilimab is given before pembrolizumab. No pre-medication(s) is/are needed before infusion of either drug.

Dose levels will be escalated to determine the maximum tolerated dose (MTD) in trial subjects with NSCLC eligible for pembrolizumab as standard of care (SOC) treatment. The MTD level will be determined based on the occurrence of dose limiting toxicities (DLTs) by standard 3+3 escalation. For the purposes of DLT, only DLT attributable to or likely due to bexmarilimab are counted. DLTs clearly related to pembrolizumab do not count as DLTs for the purposes of dose escalation. The pre-determined dose levels in the dose escalation part are 0.1, 1.0, 3.0, 10.0, and 30 mg/kg, In Cohort 0, if the first dose at 0.1 mg/kg is tolerated, that patient will advance to Cohort 1 to finish the trial at the Cohort 1 bexmarilimab dose. Dose escalation within individual patients beyond Cohort 0 is not permitted.

Beyond the Level 0 dose level, each subject will be observed for three weeks for DLT (subject at Level 0 will advance to the next level after a 3-week observation period). In the absence of DLT, once three subjects have received the second dose at dose level (for example at Level 1), each of them with a minimum of three-week follow-up, the dose is escalated to the third dose level (in this example to Level 2). If a subject is withdrawn/discontinued for any reason or dies before the completion of Cycle 3, week 1, the withdrawn/discontinued subject must be replaced with a new subject enrolled at the same dose level until three subjects have reached the three-week follow-up and the dose escalation to the next level may occur.

The dose cannot be escalated to the next level before a three-week DLT period is reached for all the subjects at the current level. Beyond Level 0, if subjects fail to reach the three-week DLT window in a given cohort for any reason, they must be replaced, and the replacement subject will be observed accordingly before escalation can proceed. If a subject misses a dose in the DLT period that subject must be replaced so that each subject receives 2 doses of bexmarilimab in the DLT window.