UNITED KINGDOM – AstraZeneca PLC has reported its trial of the cancer drug Imfinzi (Durvalumab) showed a “statistically significant and clinically meaningful overall survival benefit” when compared to chemotherapy alone.

The positive results of the Topaz-1 Phase III trial demonstrated that Imfinzi was effective as a treatment for patients with advanced biliary tract cancer when combined with standard-of-care chemotherapy.

According to Astra, the trial met the primary endpoint by demonstrating an improvement in overall survival as well as improvements in progression-free survival and overall response rate, which are key secondary endpoints.

Imfinzi is the first immunotherapy combination to show superior clinical outcomes in a global, randomized trial in this setting.

Imfinzi is a human monoclonal antibody that binds to the PD-L1 protein and inhibits its interaction with the Programmed Death-1 (PD-1) and CD80 proteins, thus counteracting the tumor’s immune-evasion tactics and releasing immune response inhibition.

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,” said Susan Galbraith, executive vice president, Oncology R&D at AstraZeneca, said in a statement.

Imfinzi and tremelimumab were granted Orphan Drug Designations in the United States in 2020 for the treatment of unresectable hepatocellular carcinoma (HCC). Tremelimumab was also designated as an orphan drug in the European Union in 2020.

Astra stated that the Imfinzi and chemotherapy combination was well tolerated and had a “similar safety profile” to chemotherapy alone.

We are delighted Topaz-1 has been unblinded early due to clear evidence of efficacy for Imfinzi plus chemotherapy, which has also demonstrated a strong safety profile,” said Susan Galbraith, executive vice president of Oncology Research & Development at AstraZeneca.

The findings are Imfinzi’s second positive gastrointestinal cancer trial finding in a row, following the Himalaya Phase 3 trial, which demonstrated Imfinzi monotherapy improved overall survival in first-line unresectable liver cancer.

Biliary tract cancer is a rare and aggressive cancer that affects the bile ducts and gallbladder, affecting approximately 210,000 people worldwide each year.

Imfinzi from AstraZeneca is one of seven approved immunotherapies that work by blocking proteins known as Programmed death-1 (PD-1) or Programmed Death-Ligand 1 (PD-L1).

While Merck & Co.’s Keytruda, Bristol-Myers Squibb’s Opdivo, and Roche’s Tecentriq dominate the immunotherapy market, AstraZeneca’s drug has seen some success as a treatment for early-stage non-small cell lung cancer.

Tremelimumab, which works similarly to Imfinzi by directing the immune system against tumors but in a different way, was intended to supplement Imfinzi, much like Bristol Myers used its drug Yervoy in combination with Opdivo.

Roche’s Tecentriq is currently approved to treat advanced liver cancer in the first-line setting, though other immunotherapies such as Keytruda and Opdivo are still in development.

The FDA rejected Merck and Eisai’s combination of Keytruda and Lenvima for that use last year, as Roche’s approval closed the regulatory path for an accelerated approval.

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