AstraZeneca’s human monoclonal antibody Imfinzi (durvalumab), when combined with standard-of-care Bacillus Calmette-Guérin (BCG) induction and maintenance therapy, showed disease-free survival (DFS) improvement in individuals with high-risk non-muscle-invasive bladder cancer (NMIBC) in the POTOMAC Phase III trial.

The multi-centre, open-label, global study is assessing the combo in 1,018 BCG-naïve NMIBC subjects after undergoing transurethral resection of bladder tumour (TURBT).

The trial was conducted across over 120 centres in 12 nations, including Canada, and regions across Asia and Europe.

The primary goal was to measure DFS, which is time from randomisation till the date of initial recurrence of high-risk disease or mortality due to any cause, for the combination therapy compared to only BCG induction and maintenance therapy.

While the trial was not designed to formally evaluate overall survival (OS), descriptive analysis did not show any detriment.

Furthermore, the tolerability and safety profile of the combination therapy was found to be consistent with the known safety profiles of each medicine, without any safety issues observed.

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However, the secondary experimental arm of the trial, which tested Imfinzi with only BCG induction therapy, did not achieve the DFS endpoint.

AstraZeneca oncology chief development officer and chief medical officer Cristian Massacesi said: “The positive results for Imfinzi in the POTOMAC trial represent a significant advance that will potentially allow more patients with early-stage bladder cancer to benefit from this important immunotherapy.”

Imfinzi is part of a comprehensive development programme, being evaluated both as a standalone therapy and in conjunction with other therapies for various cancers, including NSCLC, ovarian, breast, and gastrointestinal cancers.

The antibody has been approved for muscle-invasive bladder cancer (MIBC) in the US and other nations, based on the outcomes from the NIAGARA Phase III trial.

In March 2025, the company reported outcomes from the Phase III MATTERHORN trial of Imfinzi with standard-of-care fluorouracil, leucovorin, oxaliplatin, and docetaxel (FLOT) chemotherapy in people with resectable, early-stage, and locally advanced (Stages II, III, IVA) gastric and gastroesophageal junction (GEJ) cancers.

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