Further resembling Gc-/- mice, fecal transplants from WT mice that were fed with VitD3 high diet increased the therapeutic efficacy of anti-CTLA-4 and anti-PD-1 immune checkpoint blockade inhibitors in transplantable cancer models other than 5555 BrafV600E melanoma such as MCA-205 and MC38 (Fig. 3F, G, H). Here, CTLA4 is linked to melanoma.