GRWD5769, an oral ERAP1 inhibitor, combined with cemiplimab showed durable activity across multiple Phase 1b expansion cohorts in solid tumors with secondary anti–PD-1 resistance and in MSS-CRC. Results from the EMITT-1 program reported interim efficacy and longitudinal immune-translational findings across six completed cohorts. Interim data for 81 patients showed ORR of 10–33% and durable clinical benefit ranging from 26–57%, with median progression-free survival spanning 1.9–7.5 months by cohort. Safety was described as tolerable, with no observed safety signals and only one Grade 3 immune hepatitis event leading to drug discontinuation. Translational analyses indicated increased TCR repertoire diversity in responders and antigen-repertoire shifts consistent with ERAP1i-driven remodelling. Stage 2 expansions are ongoing to support a randomized Phase 2 study design.