XS15-adjuvanted peptide vaccines have been evaluated so far in five clinical Phase I and Phase II trials (NCT04546841 (56), NCT04954469 (57), NCT04688385 (58), NCT04842513, NCT05937295), which documented the induction of a strong CD8+ and Th1 CD4+ T cell response against vaccine peptides after subcutaneous injection in healthy volunteers as well as in cancer patients. Here, CD4 is linked to cancer.