CD4 and melanoma: Representative flow cytometry data of CD4+ and CD8+ T cells treated with the different conditioned melanoma supernatants of one healthy donor are shown in Fig. 5B. The results of a total of six individual donors are depicted in Fig. 5C and D. We found that melanoma cells treated with epacadostat alone did not cause a significant inhibition of CD4+ and CD8+ T cell proliferation, while HPI-1 alone significantly reduced CD4+ (Fig. 5C) but not CD8+ T cell proliferation (Fig. 5D).