PETAL protocol: a phase Ib study of pembrolizumab after transarterial chemoembolization in hepatocellular carcinoma.

Transarterial chemoembolization (TACE) is the treatment of choice for intermediate-stage hepatocellular carcinoma (HCC). Recent data suggest that TACE may boost the efficacy of anti-PD-1 immunotherapy. The authors present the trial protocol for PETAL, a phase Ib study, which will assess the safety and bioactivity of pembrolizumab, an anti-PD-1 antibody, following TACE in HCC. After a run-in phase evaluating six patients to establish preliminary safety, up to 26 additional participants will be enrolled. Pembrolizumab will be administered three-times weekly for 1 year or until progression, starting 30-45 days after TACE. The primary objective is to determine safety and the secondary objective is to preliminarily evaluate efficacy. Radiological responses will be evaluated every four cycles. Clinical Trial Registration: NCT03397654 (ClinicalTrials.gov).