Vitamin D Status Is Associated With Immune Checkpoint Inhibitor Efficacy and Immune-related Adverse Event Severity in Lung Cancer Patients: A Prospective Cohort Study

Vitamin D (VitD) is potentially immunomodulatory, so here we aimed to explore the relationships between serum VitD levels, immune checkpoint inhibitor (ICI) efficacy, and immune-related adverse events (irAEs). Serum 25-hydroxyvitamin D [25(OH)D] levels were quantified before and after ICI treatment in prospectively enrolled patients with advanced lung cancers. Of 77 enrolled patients, 29 developed 42 irAEs. Baseline 25(OH)D levels of partial response (PRs) patients were significantly higher than non-PR patients (19.39 +/- 7.16 vs. 16.28 +/- 5.99 ng/mL, P=0.04). The area under the curve of 25(OH)D >15.73 ng/mL to identify PR was 0.63 (95% CI, 0.51-0.76, P=0.047), and baseline 25(OH)D levels >15.73 ng/mL (odds ratio: 2.93, 95% CI, 1.10-7.79, P=0.03) and prior targeted therapy (odds ratio: 0.30, 95% CI, 0.10-0.92, P=0.04) were independent predictors of PR as best efficacy by multivariable logistic regression. With respect to irAEs, baseline 25(OH)D levels were higher in grade 1 irAE patients than in grade 2/3/4 irAE patients (20.07 +/- 8.64 vs. 15.22 +/- 2.30 ng/mL, P=0.02). However, the area under the curve was only 0.56 (95% CI, 0.42-0.70, P=0.39) for a baseline 25(OH)D of 20.99 ng/mL for predicting irAE occurrence. There was a direct monotonic relationship and U-shaped relationship between baseline 25(OH)D levels and ICI efficacy and irAE occurrence, respectively. Overall survival was significantly different between VitD sufficient, insufficient, and deficient patients (log-rank P=0.01), which remained after adjustment in Cox proportional hazards regression models. Baseline 25(OH)D levels seem to be associated with ICI efficacy and prognosis, it might be helpful to assess the baseline VitD status, and supplementation with VitD might bring some benefit to enhance ICI efficacy and reduce moderate-severe irAEs.