June 22 (UPI) -- Vitamin D might help prevent colitis, a common side effect linked with immunotherapy drugs for cancer, according to a study published Monday by the journal Cancer.
Patients who started a vitamin D supplement prior to beginning cancer treatment with one of several immune checkpoint inhibitor-based regimens were up to 65 percent less likely to develop colitis, an inflammatory reaction in the colon, the researchers found.
"Our findings of a link between vitamin D intake and reduced risk for colitis could potentially impact practice if validated in future prospective studies," study co-author Dr. Osama Rahma said in a statement.
"Vitamin D supplementation should be tested further to determine if it could be a safe, easily accessible, and cost-effective approach towards preventing immunotherapy's gastrointestinal toxicity and extending the effectiveness of immune checkpoint inhibitor treatment in cancer patients," said Rahma, a medical oncologist and cancer immunotherapy researcher at the Dana-Farber Cancer Institute and Harvard Medical School.
Colitis is a chronic digestive disease caused by inflammation of the inner lining of the colon. The inflammation may result from an infection, loss of blood supply, inflammatory bowel disease or invasion of the colon wall with collagen or lymphocytic white blood cells.
The accumulation of white blood cells is a sign of an immune system response. Immune checkpoint inhibitors -- including pembrolizumab, nivolumab and cemiplimab -- are designed to stimulate the immune system to attack cancer cells, according to the American Cancer Society.
By stimulating the immune system, however, these drugs may inadvertently cause colitis, research has shown. Previous studies have also found that vitamin D may affect the immune system in cases of autoimmune disorders and inflammatory bowel disease.
For the research, Rahma and colleagues assessed 213 patients with melanoma who received immune checkpoint inhibitors between 2011 and 2017. In all, 37, or 17 percent, developed colitis and 66, or 31 percent, took vitamin D supplements before starting cancer treatment, the researchers said.
Patients taking vitamin D were 65 percent less likely to develop colitis.
Researchers confirmed the findings on the role of vitamin D in preventing colitis in these patients in another group of 169 participants, of whom 49 developed colitis. In the validation group, use of vitamin D was linked with 54 percent lower odds of developing colitis, the researchers said.
"Immune checkpoint inhibitor-induced colitis can limit the use of such life-saving drugs leading to discontinuation of treatment," Rahma said.
"While it is one of the most common and severe adverse events of immunotherapy, there is a lack of understanding of the risk factors that could be modified to prevent colitis."