medwireNews: Researchers have characterized rheumatic immune-related adverse events (Rh-irAEs) that occur in patients with cancer who are undergoing treatment with immune checkpoint inhibitors.
“In addition to transforming oncology in the past few years, these drugs have given rheumatologists a new category of autoimmune disease to treat, and with over 1500 ongoing clinical trials I think this is a field that is only going to continue to grow,” Michael Richter (Mayo Clinic, Rochester, Minnesota, USA) told delegates at the 2018 ACR/ARHP Annual Meeting in Chicago, Illinois, USA.
In the study, which was also published in Arthritis & Rheumatology, Richter and colleagues analyzed the medical records from 1293 patients who received treatment with a checkpoint inhibitor – including pembrolizumab, nivolumab, ipilimumab, avelumab, and atezolizumab – at their institution between 2011 and 2018.
A total of 43 (3.3%) of these patients developed Rh-irAEs, as did 18 individuals who were treated with immune checkpoint inhibitors elsewhere and included in the study. Patients were followed up for an average of 86 weeks following Rh-irAE diagnosis.
The most commonly occurring Rh-irAE was inflammatory arthritis, affecting 34 patients, with an overall prevalence of 2% in the study population. The majority of patients who developed inflammatory arthritis were receiving pembrolizumab (55.9%), followed by nivolumab (20.6%) and ipilimumab (11.8%). In all, 62% of individuals who developed inflammatory arthritis received care from a rheumatologist, and most (76%) were treated with glucocorticoids, which were given for an average duration of 18 weeks.
“The good news is most of these patients were able to continue their cancer therapy,” with only three patients discontinuing immune checkpoint inhibitor treatment as a result of inflammatory arthritis, said Richter.
Almost half (47%) of patients with inflammatory arthritis experienced complete resolution of their Rh-irAE symptoms over the study period, while the remaining 53% experienced partial resolution with treatment.
The second most common Rh-irAE was myopathy, which affected 10 patients, giving an overall prevalence of 0.8%. All patients with a diagnosis of myopathy were treated with glucocorticoids; seven experienced complete resolution of symptoms, while two died due to complications related to bulbar myopathy and myocarditis, and one died from a cause unrelated to treatment. Richter noted that the majority of patients with myopathy required discontinuation of immune checkpoint inhibitor treatment.
The remaining 17 patients with Rh-irAEs were categorized as having other rheumatic syndromes, including connective tissue disease, vasculitis, polymyalgia-like syndrome, and flared pre-existing rheumatic diseases.
A total of 13 patients in the overall cohort had pre-existing rheumatic disease and five experienced flares during treatment with immune checkpoint inhibitors.
Together, these findings suggest that “Rh-irAEs likely represent a broad range of immunologic phenotypes,” concluded Richter.
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