Session: (1088–1122) Immunological Complications of Medical Therapy Poster
1097: Polymyalgia rheumatica and giant cell arteritis induced by immune checkpoint inhibitors: a systematic review and meta-analysis highlighting differences with the idiopathic forms
Disclosure(s): No financial relationships with ineligible companies to disclose
Background/Purpose: An altered immune tolerance disturbed by immune checkpoint inhibitors (ICIs) may contribute to new-onset polymyalgia rheumatica (PMR) and giant cell arteritis (GCA) in treated cancer patients. This systematic literature review (SLR) and meta-analysis synthesizes data on the characteristics of ICI-induced PMR and GCA, including pooled prevalence, demographic patterns, clinical features, and treatment-related outcomes. The aim is to present a large-scale meta-analysis offering insights into these syndromes and their potential differences from idiopathic forms. Methods: The SLR analyzed Medline and EMBASE databases up to July 2024, comparing ICI-induced PMR and GCA to their primary forms. For studies without direct comparisons, SLRs or large observational studies provided the data on primary PMR and GCA. A meta-analysis pooled prevalence, demographics, clinical features, and treatment outcomes when sufficient data were available. Results: From 1,237 abstracts, 46 were included, yielding 358 patients (314 with ICI-PMR and 44 with ICI-GCA).
ICI-PMR had a pooled prevalence of 0.3% [95% CI: 0.1%–1.2%] among ICI recipients. Patients were predominantly males (64% [95% CI: 54%–73%]), with a mean age of 71 years [95% CI: 68–74]. PD1/PDL1 blockers were used in 85% [95% CI: 80%–89%] of cases. Inflammatory pain in the girdles was universal (100%), however pelvic girdle involvement was explicitly reported in only 3 studies. Peripheral arthritis in ICI-PMR was present in 26% [95% CI: 9%–54%], and normal inflammatory markers were detected in 26% [95% CI: 15%–40%]. Glucocorticoids (GCs) completely improved symptoms in 83% of patients [95% CI: 66%–92%], with 13% [95% CI: 12%–34%] requiring DMARDs and 18% [95% CI: 9%–33%] experiencing relapses (Figure 1).
Two comparative studies explored differences between ICI vs primary PMR. Vermeulen et al suggested milder symptoms and better outcomes in ICI-PMR (Figure 1) while Fremont et al more frequent peripheral arthritis and higher DMARD use in the ICI group. However, the latter was a brief report with methodological limitations, warranting cautious interpretation.
ICI-GCA prevalence was 0.06% among ICI recipients. Male patients comprised 51% [95% CI: 36%–66%], with a mean age of 71 years [95% CI: 68–74]. About 50% [95% CI: 23%–77%] received anti-CTLA4 blockers (alone or with PD1 blockers), while the rest received PD1/PDL1 blockers. Clinical features included cephalic symptoms (85% [95% CI: 70%–93%]), permanent visual loss (23% [95% CI: 12%–39%]), and large-vessel involvement (62% [95% CI: 40%–80%]). High-dose GCs permitted remission in 95% [95% CI: 73%–99%], though 19% [95% CI: 7%–41%] experienced relapses and 10% [2% - 31%] required DMARDs (Figure 1). Conclusion: ICI-induced PMR and GCA may have distinct clinical profiles than idiopathic forms, potentially with milder symptoms and better treatment responses.
Large observational data and meta-analyses on primary forms suggest higher relapse rates and prolonged GC use [1,2], yet further robust comparative studies are needed to validate whether ICI-induced syndromes truly represent a distinct and less severe clinical entity.
