Imfinzi Regimen Shows Significant Disease-Free Survival Improvement in Phase III Bladder Cancer Trial

Positive high-level results from the POTOMAC Phase III trial indicate that a year-long treatment combining AstraZeneca’s Imfinzi (durvalumab) with standard BCG induction and maintenance therapy leads to a significant improvement in disease-free survival (DFS) for patients dealing with high-risk non-muscle-invasive bladder cancer (NMIBC). This combination is more effective compared to just BCG induction and maintenance therapy on its own.

NMIBC is an early-stage cancer affecting over 70% of bladder cancer patients. In this stage, the tumor is located in the tissue lining the bladder's inner surface but hasn't penetrated the muscle wall. Approximately half of NMIBC patients are at high risk of disease progression or recurrence, due to specific attributes like tumor grade and stage. Dr. Maria De Santis, overseeing the Interdisciplinary Uro-Oncology Section at Charité Universitätsmedizin Berlin and a principal investigator in the trial, emphasized the significance of the results. She noted that while the majority of NMIBC patients are treated with the goal of cure, an alarming 80% experience recurrence, with many possibly needing significant surgery to remove the bladder. This highlights a critical need for enhanced treatment strategies.

AstraZeneca's Chief Medical Officer, Cristian Massacesi, hailed the trial findings as a crucial advancement, offering hope that more early-stage bladder cancer patients might benefit from this important immunotherapy. This success builds on earlier data from the NIAGARA trial, underscoring AstraZeneca’s approach to introducing innovative therapies for early-stage diseases where long-term benefits are most achievable.

The study also evaluated the safety and tolerability of combining Imfinzi with BCG induction and maintenance therapy, finding that the safety profiles remained consistent with known data, and no new safety concerns were noted. Importantly, adding Imfinzi didn't interfere with patients' ability to complete the BCG therapy regimen.

Another experimental arm in the study tested Imfinzi with only BCG induction therapy, but this approach did not achieve a significant DFS improvement compared to BCG therapy alone. Upcoming medical conferences will feature these findings, and discussions with global regulatory bodies are planned.

Imfinzi is already approved in the US and other nations for muscle-invasive bladder cancer (MIBC), based on outcomes from the NIAGARA Phase III trial. It continues to be evaluated in various treatment combinations across different stages of bladder cancer, including for patients who cannot or choose not to undergo cisplatin treatment, and in advanced metastatic scenarios.

Bladder cancer ranks as the ninth most common cancer globally, with over 614,000 diagnoses each year. Urothelial carcinoma is the most prevalent type, originating in the urinary tract’s urothelial cells. In 2024, approximately 125,000 patients received treatment for high-risk NMIBC, typically involving transurethral resection of bladder tumors (TURBT) followed by intravesical BCG therapy. Despite treatment, up to 80% of these patients experience recurrence within five years, with high-risk cases facing a 45% progression rate, underscoring the urgent call for effective treatment options in this curative-intent setting.

The POTOMAC trial, a global Phase III study, assessed Imfinzi's efficacy combined with BCG therapy in 1,018 patients with high-risk, BCG-naïve NMIBC post-TURBT. Conducted across more than 120 centers in 12 countries, the trial primarily measured DFS, with secondary endpoints including safety and overall survival at five years. The results signify a step forward in the treatment of bladder cancer, offering new hope for patients facing this challenging disease.