Safety of Immune Checkpoint Inhibitors for Cancer Treatment: Real-World Retrospective Data Analysis from Qatar (SAFE-ICI-Q study)

Nabil Elhadi Omar^1,2*Shereen Elazzazy^1,3Anas Hamad^1,3Mohamed Saad⁴Aya Alasmar¹Sahar M Nasser¹Maria Benkhadra¹Hebatalla M Affi¹Farah I Jibril¹Rawan Dawoud¹Mohamed S Hamid⁵Afnan Alnajjar¹Arwa O Sahal¹Amaal Gulied¹HAZEM ELEWA^1*

• ¹Pharmacy Department, National Center for Cancer Care and Research, Hamad Medical Corporation, Doha, Qatar
• ²Clinical and Population Health Research Program, College of Pharmacy, QU Health, Qatar University, Doha, Qatar
• ³College of Pharmacy, QU Health, Qatar University, Doha, Qatar
• ⁴Pharmacy Department, Al Wakra Hospital, Hamad Medical Corporation, Doha, Qatar
• ⁵Medical Oncology Department, National Center for Cancer Care and Research, Hamad Medical Corporation, Doha, Qatar

Introduction Immune checkpoint inhibitors (ICIs) have transformed the management of multiple malignancies. However, immune-related adverse events (irAEs) remain a major limitation, and their incidence, spectrum, and prognostic impact in real-world populations require clarification. Methods This retrospective study included adults who received ≥1 dose of an ICI between January 2015 and January 2020. Data were collected from electronic health records and institutional adverse drug reaction reporting systems. irAEs were graded per CTCAE v5. Logistic regression assessed predictors of irAEs, while Kaplan–Meier, landmark, and time-dependent Cox regression evaluated associations with progression-free survival (PFS) and overall survival (OS). Approvals were obtained from HMC IRB (MRC-01-20-251) and Qatar University IRB (QU-IRB 073/2025-EM). Results Among 236 patients (median age 57 years; 72% male), most had advanced solid tumors, predominantly thoracic malignancies, and pembrolizumab was the most common agent. irAEs occurred in 55.9% of patients, most frequently endocrine (26.4%), dermatologic (13.5%), and hepatic (12.4%). Sixteen patients (6.8%) developed fatal irAEs, mainly pneumonitis. Median time to onset was 55 days (IQR 16–129.5), with most events between 21–180 days. Resolution varied: gastrointestinal irAEs resolved in 92%, compared with 40% for hematologic events. Pulmonary irAEs caused the highest treatment discontinuation. Risk factors included higher ICI cycles (p=0.019), lower baseline and six-week platelet counts (p=0.015, p=0.012), and elevated baseline TSH (p=0.048); only treatment cycles remained significant in multivariable analysis (p=0.004). Dermatologic irAEs were more common in patients ≥65 years (17.9% vs. 7.1%, p=0.018), while poor performance status (≥2) predicted more cardiac irAEs (10.9% vs. 1.7%, p=0.036). At the 30-day landmark, irAEs were associated with worse PFS (HR 1.88, 95% CI 1.22–2.87, p=0.004) and OS (HR 2.13, 95% CI 1.34–3.30, p=0.001), findings confirmed by time-dependent Cox regression. Conclusion In this real-world cohort, irAEs were frequent, diverse, and associated with inferior survival when early. Baseline factors such as poor performance status, older age, thrombocytopenia, and elevated TSH may inform risk stratification. Timely recognition and multidisciplinary management remain essential to optimize ICI safety and outcomes.