AstraZeneca announced Phase III results Friday showing that adding a single, high-priming dose of its experimental anti-CTLA4 antibody tremelimumab to the PD-L1 blocker Imfinzi (durvalumab) led to a "significant and clinically meaningful" overall survival (OS) benefit, compared to Bayer's Nexavar (sorafenib), in patients with hepatocellular carcinoma (HCC).
"This is the first time a dual immunotherapy regimen has improved OS as a first-line treatment for patients with unresectable liver cancer for whom treatment options are limited and long-term outcomes are poor," remarked Susan Galbraith, executive vice president of oncology R&D at AstraZeneca.
The randomised HIMALAYA trial evaluated Imfinzi monotherapy and the so-called STRIDE regimen, which consists of a single priming dose of tremelimumab added to Imfinzi, followed by Imfinzi every four weeks, versus standard-of-care Nexavar. The study included 1324 patients with unresectable, advanced HCC who had not been treated with prior systemic therapy and were not eligible for treatment localised to the liver and surrounding tissue.
AstraZeneca said the combination had a favourable safety profile, and the addition of tremelimumab to Imfinzi did not increase severe hepatic toxicity. Results from the HIMALAYA trial will be presented at an upcoming conference.
Following a series of clinical failures for tremelimumab, AstraZeneca earlier this year said the anti-CTLA4 antibody demonstrated an OS benefit in the Phase III POSEIDON study when used together with Imfinzi and chemotherapy in first-line patients with metastatic non-small-cell lung cancer (NSCLC), compared to chemotherapy alone. POSEIDON data detailed at the World Conference on Lung Cancer (WCLC) last month showed the combination improved OS by 23% and progression-free survival by 28%.
The combination of Imfinzi and tremelimumab is being tested in various tumour types, although the regimen has failed in a number of Phase III studies, including KESTREL in head and neck squamous cell carcinoma, CASPIAN in small-cell lung cancer and DANUBE in bladder cancer.
For more on the impact of today's HIMALAYA trial news, see ViewPoints: An important stride forward for AstraZeneca's tremelimumab.
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