Background/Purpose: Cancer immunotherapy is a newly-approved approach in the management of advanced malignancies. Immune checkpoint inhibitors (ICIs) are the most commonly used type of cancer immunotherapy and have been associated with an increasingly number of immune-related adverse events (irAEs), including a variety of rheumatologic manifestations, however information regarding prevalence and incidence of irAEs in Latin American population is scarce.

Methods: We designed a retrospective, cross-sectional study to identify the prevalence of rheumatologic irAEs in patients with cancer receiving ICIs during the study period, ranging from January 2014 to February 2018 in a single center. 

Results: Data from 140 subjects was included with a global prevalence of irAES of 38.6%, from which Rheumatic irAES were identified in 20 patients (14.3%). None of the patients had history of previous autoimmune disease. Mean age was 63 (+/- 11.3) years, 50% were female. The most common solid tumors were Lung and melanoma in 45 and 30%, respectively and 85% had metastatic disease. Patients received the following ICIs or combinations: Pembrolizumab in 45%, Nivolumab in 30%, Ipilimumab in 15% or Nivolumab + Ipilimumab in 10%. In order of frequency the following Rheumatologic irAEs were observed: Cutaneous (80%) (including lupus-like erythema), inflammatory arthritis (20%), myositis (5%), interstitial lung disease (5%), episcleritis (5%), nephritis (5%); Only four patients had available antinuclear antibodies with positive result. One patient developed a lupus-like syndrome with cutaneous, articular and renal involvement with negative antinuclear antibodies.  Additionally, other concomitant non-rheumatologic irAES were observed: conjunctivitis in 4 patients, thyroiditis in 1 patient, and severe thrombocytopenia in 1 patient. Of notice, only 2 of the rheumatologic irAES were considered severe and 80% were mild or moderated. And most patients were treated with topic or low dose systemic glucocorticoids and symptomatic treatment and none required treatment with DMARDs.

Conclusion: We performed one of the first epidemiologic reports of rheumatologic irAES in a Latin American Population. Patients showed a predominantly mild and moderated cutaneous and articular involvement. Emphasis on serological assessment may improve identification of these newly described manifestations in Latin American populations.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/rheumatic-immune-related-adverse-effects-from-checkpoint-inhibitor-immunotherapy-in-patients-with-solid-tumors-in-a-latin-american-population/