CD4 and cancer: Components associated with HLA class II peptide loading (the invariant chain [CLIP]), as well as the “peptide editors”, HLA-DMA/DMB/DOA/DOB also play a significant role in producing meaningful CD4+ T-cell responses (153, 168, 169) and are needed to present tumor antigen derived epitopes to CD4+ T-cells either by cancer cells directly or APCs in the TME cross-presenting tumor-associated antigens.