Impact of Frequent Immune‐Mediated Adverse Events on Treatment Continuity and Outcomes During Durvalumab Plus Tremelimumab Therapy for Unresectable Hepatocellular Carcinoma

ABSTRACT Durvalumab plus tremelimumab (Dur/Tre) is the first‐line treatment for unresectable hepatocellular carcinoma (uHCC). Immune‐mediated adverse events (imAEs) are common; however, the impact of specific imAE types on treatment persistence and outcomes remains unclear. This study evaluated the clinical features and prognostic implications of common imAEs during Dur/Tre therapy. This multicenter retrospective analysis included 351 patients with uHCC treated with Dur/Tre (January 2023 and February 2025), of whom 69 developed imAEs and had a follow up period of > 1 month. Baseline characteristics, period to onset and severity of imAEs, corticosteroid use, treatment continuation and subsequent therapies, progression‐free survival (PFS) and overall survival (OS) were analyzed according to imAE types. Among 69 patients, 34 developed colitis, 19 developed hepatitis and 16 developed endocrine disorders. The median age was 72 years, with 13% classified as Child‐Pugh B. The median period to imAE onset was 0.75 months (interquartile range, 0.38–1.25). Steroids at a dose equivalent to > 20 mg of prednisolone were administered to 46 patients (66.7%). Two‐thirds of the patients continued Dur/Tre despite imAE onset. Colitis occurred the earliest (median 0.54 months) and had the highest steroid requirement (82.4%), frequently resulting in treatment interruption. Endocrine disorders showed the highest continuation rate (75%). Although not statistically significant in PFS (median 11.2 months: 95% CI, 1.96–not achieved (NA), p = 0.450) and OS (95% CI, NA–NA, p = 0.134), compared with colitis (PFS; 4.3 months, OS; not reached) and hepatitis (PFS; 3.4 months, OS: 14.6 months). These findings should be interpreted cautiously given the small sample size. Subsequent systemic or locoregional therapies, including tyrosine kinase inhibitors, atezolizumab plus bevacizumab and interventional therapies, were administered to more than 65% of the patients. In Dur/Tre therapy, imAE impact varied by type; endocrine disorders are linked to better treatment continuation and prognosis, whereas colitis and hepatitis often lead to treatment interruption. Trial Registration: Takasaki General Medical Center (IRB No. TGMC2024–03)