Background/Purpose: Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment, but their safety profile in patients with pre-existing autoimmune diseases, such as systemic lupus erythematosus (SLE), is not well characterized. Hematologic abnormalities are common in patients with SLE. Given the potential for ICIs to exacerbate immune-mediated adverse events, this study evaluated the risk of mortality and hematological adverse events in patients with cancer and pre-existing SLE treated with ICIs compared to matched patients without SLE.

Methods: We conducted a propensity score-matched cohort study using electronic health records from 101 U.S. healthcare organizations. Patients diagnosed with SLE (identified using International Classification of Diseases 10 codes) prior to cancer treatment and subsequently treated with ICIs (anti-PD-1/PD-L1 or CTLA-4) were matched 1:1 with non-SLE comparators based on demographics, comorbidities, cancer types, metastatic status, and prior cancer treatments. Outcomes of interest were a) hematologic abnormalities that were determined using laboratory measurements (i.e., defined by the presence of an abnormal lab value recorded after ICI initiation) and included pancytopenia, thrombocytopenia, anemia, neutropenia, and eosinophilia; and b) all-cause mortality. Cox proportional hazards models estimated the risk of hematological adverse events and all-cause mortality adjusting for above confounders.

Results: The analysis included 403 SLE patients and 403 matched non-SLE patients receiving ICIs. Mean age was 63.1 years; 77.8% were female and 68.7% White. Patients with pre-existing SLE demonstrated a significantly higher risk of developing pancytopenia (13.2% vs. 8.4%; HR=1.63, 95% CI: 1.06–2.5) and thrombocytopenia (50.9% vs. 42.4%; HR=1.25, 95% CI: 1.02–1.53). Risks of anemia, neutropenia, and eosinophilia did not differ significantly between groups. All-cause mortality was not significantly increased in patients with SLE compared to non-SLE controls (29.8% vs. 35.5%; HR=0.83, 95% CI: 0.65–1.06).

Conclusion: Cancer patients with pre-existing SLE receiving ICIs exhibit an increased risk of hematological adverse events, notably pancytopenia and thrombocytopenia, compared to matched controls without SLE. However, overall survival was comparable between both groups. These findings highlight the importance of vigilant hematological monitoring in this patient population and suggest the need for tailored management strategies when initiating ICI therapy in patients with SLE.

Figure 1: Forest plot of adjusted hazard ratios and 95% confidence intervals for hematological outcomes and all-cause mortality in cancer patients with pre-existing SLE treated with ICIs.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/mortality-and-hematological-adverse-events-in-patients-with-cancer-receiving-immune-checkpoint-inhibitors-impact-of-pre-existing-systemic-lupus-erythematosus/