The objective response rate in advanced melanoma is greater if vitamin D levels are within the normal range.
Vitamin D is able to modulate both innate and adaptive immune responses. Furthermore, recent work suggests that vitamin D exerts anti-proliferative effects on tumour cells. In addition, the vitamin is able to up-regulate programmed death ligand 1 expression. This findings indicates the possibility for a synergic effect in combination with immune-checkpoint inhibitor therapy. But whether this could improve outcomes such as the objective response rate during advanced melanoma treatment remains unclear.
The current study explored the effect of vitamin D levels during anti-PD-1 immunotherapy with nivolumab or pembrolizumab in advanced, inoperable or metastatic melanoma. Serum levels of vitamin D in patients were either reduced (Group 1) or normal (Group 2). Researchers then compared the objective response rate, progression-free and overall survival between the two groups.
Objective response rate and vitamin D levels
Data were available for 200 patients. Among those in Group 1, the objective response rate (ORR) was significantly lower than for Group 2 (36.2% vs 56%, p = 0.011). Similarly, there was a shorter progression-free survival (5.75 vs 11.25 months, p = 0.037) and a lower complete response (7.8% vs 10.3%). Finally, while overall survival was lower in Group 1 than Group 2, this difference was non-significant (27 vs 31.5 months, p = 0.39).
The researchers suggest that vitamin D levels should be within the normal range during anti-PD-1 immunotherapy in advanced melanoma patients.