This is a Phase 1/2a, multicenter, dose-finding, consecutive-cohort, open-label trial of BI-1206 in combination with pembrolizumab in subjects with advanced solid tumors who have previously received treatment with a PD-1/PD-L1 immune checkpoint inhibitor.

The trial will consist of 2 main parts: Phase 1 (with dose escalation cohorts and selection of the RP2D), and Phase 2a (with 3 expansion cohorts at the RP2D).

Subjects in each phase will initially receive 3 planned doses of therapy with BI-1206 in combination with pembrolizumab.

Subjects who show clinical benefit (CR, PR or SD) at the Week 9 Visit may continue on combination therapy. Starting at Week 10, these subjects will receive infusions every 3 weeks for up to 32 additional doses or up to 2 years from first dose of BI-1206 therapy or until progression.