Persistent immune-related adverse events after cessation of checkpoint inhibitor therapy: Prevalence and impact on patients' health-related quality of life.

Background: Immune checkpoint inhibitors (ICIs) may induce persistent immune-related adverse events (irAEs). We investigated persistent irAEs and implications on patients' lives compared to non-ICI-induced autoimmune diseases (AIs).

Methods: The multicentre, cross-sectional study comprised 200 patients with cancer ≥12 weeks after ICI cessation (ICI-patients) and 2705 patients with AIs (AI-patients), recruited in German outpatient clinics and support groups. The prevalence of persistent irAEs subdivided in long-term (12 weeks to <12 months) and chronic irAEs (≥12 months) since ICI discontinuation, health-related quality of life (HRQoL) using the EuroQol 5D-5L (EQ-Index/VAS score), and burden of autoimmune symptoms and respective therapies were assessed.

Results: Long-term/chronic irAEs occurred in 51.9%/35.5% of outpatient ICI-patients, including arthralgia (16.7%/16.1%), myalgia (13.0%/14.0%), hypothyroidism (11.1%/10.8%), xerostomia (7.4%/8.6%), vitiligo (13.0%/7.5%) and hypophysitis (9.3%/7.5%). ICI-patients with long-term/chronic irAEs reported clinically significantly reduced HRQoL compared to ICI-patients without long-term/chronic irAEs (EQ-Index score: 0.767/0.752 versus 0.920/0.923, p < 0.001/0.001; EQ-VAS score: 52.2/52.0 versus 63.6/74.7, p =/< 0.040/0.001). Multiple linear regression analyses confirmed clinically significant reductions in HRQoL scores by chronic irAEs (EQ-Index/VAS score: -0.163/-23.4, p < 0.001/0.001). HRQoL, burden of autoimmune symptoms and burden of respective therapies in ICI-patients with chronic irAEs were similar to AI-patients with non-exacerbated AIs. Patients with chronic irAEs felt inadequately informed about side-effects compared to patients without chronic irAEs (p < 0.001).

Conclusion: Persistent irAEs impose a significant burden on patients after ICI cessation. Especially in early tumour stages, risk-benefit ratios must be carefully evaluated, and patients need to be informed about potential long-term sequelae.