Background/Purpose: Cancer therapies that target immune checkpoints have gained a prominent role in the treatment of malignancy. These agents stimulate an impressive and sustained anti-tumour response, including complete remission in some patients. Despite their effectiveness, they can also result in off-target immune-related adverse events (irAEs) that can affect nearly every organ system, sometimes resulting in de novo rheumatic diseases. While glucocorticoids are the mainstay of therapy for rheumatic irAEs, there is concern among rheumatologists and oncologists that their use may blunt the anti-tumour response, and cause avoidable glucocorticoid-related side effects. However, there is little data on the differences in therapeutic approach and prescribing patterns to date. The purpose of this study was to describe glucocorticoid route and dosing, adverse event profile, and patient outcomes between patients initiated on glucocorticoids for rheumatic irAEs by oncologists versus rheumatologists.

Methods: This was a single center retrospective chart review. Adult patients who received an immune checkpoint inhibitor and were identified as having inflammatory arthritis as a rheumatic irAE or those with pre-existing inflammatory arthritis were included. Patients were divided into two groups according to whether they were initiated on glucocorticoid therapy by Oncology versus Rheumatology. Glucocorticoid route of administration, dose, and adverse event profile were recorded. Patient reported quality of life was captured via a standard Health Assessment Questionnaire (HAQ) that was completed at the time of initial assessment by Rheumatology and at 1 month follow up.

Results: 86 patient charts were reviewed. Mean age was 65 years old. 57 patients received glucocorticoid therapy for inflammatory arthritis. 22 (40%) patients were initiated on glucocorticoid therapy by Oncology, and 34 (60%) patients were initiated on glucocorticoid therapy by Rheumatology. Of the patients started on glucocorticoid therapy by Oncology, 22 (100%) were initiated on oral prednisone alone. Of those started on glucocorticoid therapy by Rheumatology, 24 (70%) patients were initiated on prednisone monotherapy, and 9 (26%) patients received intra-articular glucocorticoids without systemic glucocorticoids. Of those initiated on oral glucocorticoids, the average starting dose by Rheumatology was 15mg prednisone daily, while the average in Oncology was 47mg prednisone daily (p < 0.001). 18 patients experienced adverse events secondary to glucocorticoids, all of whom received oral prednisone. 4 (17%) patients initiated on glucocorticoids by Rheumatology experienced adverse events, compared with 14 (64%) of patients started on glucocorticoids by Oncology (p< 0.001).

Conclusion: The use of systemic glucocorticoids in the treatment of rheumatic irAEs is associated with glucocorticoid related adverse events. When treated in the Rheumatology setting, patients receive lower doses of systemic glucocorticoids with significantly fewer adverse events. This highlights the need for further education and collaboration between Rheumatology and Oncology to best manage this complex patient population.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/canadian-research-group-of-rheumatology-in-immuno-oncology-canrio-a-retrospective-chart-review-study-of-adults-with-inflammatory-arthritis-associated-with-cancer-immunotherapies/