PROM1 and head and neck squamous cell carcinoma: Trispecific (CD16, IL-15, CD133) and tetraspecific (CD16, IL-15, EpCAM, CD133) NK cell engagers have also demonstrated appreciable anti-cancer efficacy against colorectal Caco-2 cells, as well as a panel of breast, prostate, HNSCC, CRC, and AML cell lines, respectively [267,268].