152P TACTI-003 Cohort B: Eftilagimod alpha (Soluble LAG-3) and pembrolizumab in first-line recurrent or metastatic head & neck squamous cell carcinoma with PD-L1 negative

Eftilagimod alpha (E) is a soluble LAG-3 protein that binds to a subset of MHC class II molecules to mediate antigen presenting cell activation & T-cell (CD4/CD8) recruitment/activation. Prior results from a phase II study of E plus pembrolizumab (P) as a second-line therapy in recurrent or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) led to promising response rates across all PD-L1 strata (TACTI-002; NCT03625323). We report updated results from the PD-L1 negative (CPS <1) Cohort B of the TACTI-003 study in 1st line HNSCC (NCT04811027).