Tremelimumab

Tremelimumab plus durvalumab (STRIDE regimen) is an approved first-line therapy for unresectable hepatocellular carcinoma (HCC), yet it shows limited efficacy with an ORR of only 20.1%. Proton radiotherapy (RT), known for its precision and tissue-sparing advantages, has demonstrated improved survival outcomes and reduced toxicity compared to X-ray RT. Retrospective data suggest that combining proton RT with immune checkpoint inhibitors yields a promising ORR of 61.5%. Preclinical studies further support enhanced antitumor immunity when RT is combined with PD-L1 and CTLA-4 blockade. This phase II, single-arm clinical trial aims to evaluate the safety, efficacy, and immunologic effects of combining proton RT with tremelimumab and durvalumab in patients with unresectable HCC.

Tremelimumab plus durvalumab (the STRIDE regimen) is an approved first-line therapy for unresectable hepatocellular carcinoma (HCC); however, it demonstrates limited efficacy, with an objective response rate (ORR) of only 20.1%. Radiation therapy (RT) is highly effective in controlling localized solid tumors and has become an integral component of the treatment algorithm for unresectable HCC. Preclinical studies have shown that combining RT with PD-L1/PD-1 blockade promotes immunogenic cell death and enhances antigen presentation by dendritic cells, thereby boosting systemic T cell-mediated antitumor responses in mouse models. The addition of CTLA-4 inhibition further enhances antigen cross-priming following RT. Recent retrospective data also indicate that combining RT with immune-oncology agents is associated with improved overall survival and prolonged time to progression compared to RT or immunotherapy alone. However, the clinical benefit and immunologic impact of combining RT with tremelimumab and durvalumab have not yet been evaluated in prospective clinical trials for unresectable HCC. This phase II, single-arm clinical trial aims to assess the safety, efficacy, and immunologic effects of combining proton RT with tremelimumab and durvalumab in patients with unresectable HCC.