Positive high-level results from the Himalaya phase 3 trial showed a single, high priming dose of tremelimumab added to Imfinzi (durvalumab) demonstrated a statistically significant and clinically meaningful overall survival (OS) benefit versus sorafenib as a 1st-line treatment for patients with unresectable hepatocellular carcinoma (HCC) who had not received prior systemic therapy and were not eligible for localised treatment. This novel dose and schedule of tremelimumab, an anti-CTLA4 antibody, and Imfinzi are called the STRIDE regimen (Single Tremelimumab Regular Interval Durvalumab). The combination demonstrated a favourable safety profile, and the addition of tremelimumab to Imfinzi did not increase severe hepatic toxicity.

Imfinzi alone demonstrated non-inferior OS to sorafenib with a numerical trend in favour of Imfinzi and an improved tolerability profile compared to sorafenib.

Liver cancer, of which HCC is the most common type, is the third leading cause of cancer death and the sixth most commonly diagnosed cancer worldwide with approximately 900,000 people diagnosed each year. Only 7% of patients with the advanced disease survive five years.

Susan Galbraith, Executive Vice President, Oncology R&D, AstraZeneca, said: “Inhibition of CTLA-4 has shown the ability to drive benefit particularly in the tail of the survival curve in several settings. This is the first time a dual immunotherapy regimen has improved overall survival as a 1st-line treatment for patients with unresectable liver cancer for whom treatment options are limited and long-term outcomes are poor.”

Imfinzi and tremelimumab were granted Orphan Drug Designations in the US for the treatment of HCC in 2020. Tremelimumab was also granted orphan designation in the EU in HCC in 2020.