Pembrolizumab Monotherapy in Sorafenib-Treated and Treatment-Naïve Advanced Hepatocellular Carcinoma: Long-Term Follow-up of the Open-Label, Phase II KEYNOTE-224 Study

PURPOSE: In the phase II KEYNOTE-224 study, pembrolizumab showed durable antitumor activity and manageable safety in participants with sorafenib-treated (cohort 1) or treatment-naïve (cohort 2) advanced hepatocellular carcinoma (HCC). We present data after a median follow-up of ∼7 years for cohort 1 and ∼5 years for cohort 2. PATIENTS AND METHODS: Adults with advanced HCC received pembrolizumab 200 mg intravenously every 3 weeks until disease progression or unacceptable toxicity for ≤35 cycles. The primary endpoint was objective response rate per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1) by blinded independent central review. Secondary endpoints included overall survival (OS), progression-free survival (PFS), and safety. RESULTS: Overall, 155 participants received ≥1 dose of pembrolizumab (cohort 1, n = 104; cohort 2, n = 51). The median follow-up was 83 months (range, 79.3-87.3) for cohort 1 and 58.8 months (range, 55.3-60.8) for cohort 2. The median OS was 13.2 months [95% confidence interval (CI), 9.7-15.3] and 16.9 months (95% CI, 8.3-23.1), respectively; 24- and 48-month OS rates were 31%/17% and 34%/20%, respectively. The median PFS was 4.9 months (95% CI, 3.5-7) and 4.3 months (95% CI, 2.1-7.8), respectively. Treatment-related adverse events occurred in 76 participants [73.1%; grade 3-5, 27 (26%)] in cohort 1 and 28 participants [54.9%; grade 3-5, 8 (15.7%)] in cohort 2. CONCLUSIONS: Pembrolizumab continued to show durable response and manageable safety in participants with advanced HCC with or without prior systemic therapy, with long-term effects on OS lasting beyond 48 months in some participants despite receiving study treatment for ≤2 years.