Researchers have launched a clinical trial to test an immunotherapy drug in patients who have both cancer and an autoimmune disease, such as rheumatoid arthritis, lupus, or multiple sclerosis. Immunotherapy drugs enhance the ability of the immune system to detect and kill tumor cells. In recent years, these therapies have benefited a growing number of patients, including some patients with advanced cancers. But doctors have not known whether immunotherapy is safe and effective for people who have both cancer and an autoimmune disease, because such patients have been excluded from clinical trials of immunotherapy drugs. “Having an overactive immune system is the main reason that many patients with both cancer and autoimmune diseases have not been included in hundreds of clinical trials of immunotherapy drugs,” said Hussein Tawbi, M.D., Ph.D., of the University of Texas MD Anderson Cancer Center and one of the lead investigators for the new trial. For many doctors who treat patients with both diseases, the lack of information on the effects of immunotherapy in such patients has led to a “clinical conundrum,” Dr. Tawbi continued. “As doctors, we have been afraid of using these drugs in patients with autoimmune diseases because we don’t have evidence that they are safe for these patients,” he added. “There’s no guidance on how to handle these cases.” The main concerns, Dr. Tawbi explained, are that “the immune-related side effects may be more severe in patients with both diseases, or that their autoimmune conditions may get much worse because of immunotherapy.” In addition, because these patients have been excluded from clinical trials, doctors don’t know “whether they may respond better [than other patients]—or possibly worse because they could be on therapy to suppress the immune system,” he added. The new clinical trial, which is sponsored by NCI, is intended to help researchers understand the potential harms and benefits of using immunotherapy in patients with certain autoimmune diseases. The trial could also yield insights into the biology of autoimmune diseases, which could help researchers explore new treatments, according to Dr. Tawbi. “This study is the first of its kind,” he said. “What we learn may allow us to extend the promise of immunotherapy in a safe manner to patients who have cancer and an existing autoimmune disease.” Between 10% and 30% of cancer patients have an autoimmune disease as well, so the results of the trial could have implications for many patients, said Elad Sharon, M.D., M.P.H., of NCI’s Cancer Therapy Evaluation Program and another leader of the study.