AstraZeneca has announced positive results from the Phase 3 HIMALAYA trial, which evaluated tremelimumab plus Imfinzi (durvalumab) in treating a type of liver cancer.

The combination showed clinically meaningful improvement in overall survival (OS) in treating unresectable hepatocellular carcinoma (HCC), compared to sorafenib.

Imfinzi is a human monoclonal antibody that works by binding to the PD-L1 protein to counter the tumour’s immune-evading tactics and release the immune responses.

The novel dose and schedule of Imfinzi plus tremelimumab is called single tremelimumab regular interval durvalumab (STRIDE) regimen.

AstraZeneca Oncology R&D executive vice president Susan Galbraith said: “The HIMALAYA trial reinforces our scientific approach for tremelimumab, tapping into the potential of CTLA-4 inhibition and a unique dosing regimen to prime the immune system to help patients live longer and with minimal side effects.

“We look forward to bringing potential new treatment options to patients with unresectable liver cancer, an area of high unmet need, as quickly as possible.”

In the Phase 3 HIMALAYA trial, STRIDE regimen showed 22% reduction in the risk of death versus sorafenib, with a median OS of 16.4 months compared to 13.8 for sorafenib.

The regimen also showed increase in objective response rate (ORR) compared to sorafenib, with median duration of response (DoR) of 22.3 months versus 18.4 for sorafenib.

HIMALAYA also studied Imfinzi as a monotherapy, with a non-inferior OS of 16.6 months compared to 13.8 for sorafenib, along with an improved tolerability profile than sorafenib.

The safety profiles of the STRIDE regimen and for Imfinzi alone were consistent with the known profiles of each medicine, and no new safety signals were identified, the company said.

Phase 3 HIMALAYA trial principal investigator Ghassan Abou-Alfa said: “Patients with unresectable liver cancer face a dismal prognosis, and new treatment options are critical to improving long-term survival.

“The three-year overall survival rate and favourable safety profile seen with the STRIDE regimen set a new benchmark in this setting and underscore the potential of this innovative treatment approach.”

In a separate development, AstraZeneca has also announced positive results from the Phase 3 TOPAZ-1 trial of Imfinzi plus standard-of-care chemotherapy.

The combination showed improvement in overall survival (OS) and progression-free survival (PFS) versus chemotherapy, as a first-line treatment for advanced biliary tract cancer (BTC).

BTC is a group of rare and aggressive cancers formed in the bile ducts and gallbladder.