GC and vitamin D deficiency: Vitamin D-binding protein (VDBP) sequesters vitamin D from T-cells and reduced serum VDBP is strongly associated with longer overall survival in advanced renal cancer patients treated with anti-PD-L1 ICB [225] consistent with an association between vitamin D deficiency, worse outcomes in patients with stage IV metastatic melanoma [226] and observations that vitamin D intake (around 1000 IU) before ICB therapy in melanoma patients reduced the risk of developing colitis by altering the Th1/Th2 ratio [227].