Vitamin D may protect against colitis adverse events in patients taking immune checkpoint inhibitors

People with melanoma who take immune checkpoint inhibitors (ICIs) are less likely to develop colitis if they are taking vitamin D supplements at treatment initiation, a study published in the journal Cancer (22 June 2020) has suggested^[1]
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Researchers analysed data on 213 patients treated for melanoma with nivolumab and/or ipilimumab, or pembrolizumab between May 2011 and October 2017, 37 of whom developed ICI colitis. 

The team found that 34.1% of patients without colitis reported taking a vitamin D supplement at the time of treatment initiation, compared with 16.2% of patients with colitis.

In multivariate analysis, patients who were taking vitamin D supplements before initiating treatment had reduced odds of developing colitis (odds ratio [OR] 0.35; 95% confidence interval [CI] 0.1–0.9) compared with patients who were not taking vitamin D.

Vitamin D deficiency and immune dysregulation have been linked to the development of autoimmune colitis, but predictive markers for ICI-induced colitis are lacking, the researchers explained. They added that, to their knowledge, this was the first study to identify vitamin D as a protective factor against the development of ICI colitis.

“These results may suggest benefit in prophylactic use of vitamin D supplementation to prevent ICI colitis, as previously demonstrated in inflammatory bowel disease and graft-versus-host disease,” they concluded.