FDA endorses durvalumab for muscle-invasive bladder cancer

On March 28, 2025, the U.S. Food and Drug Administration (FDA) made a landmark decision by approving the use of durvalumab, also known as Imfinzi, in combination with the chemotherapy agents gemcitabine and cisplatin. This regimen is designated as a neoadjuvant treatment, meaning it is administered before the main treatment, which in this case is surgery. Subsequently, durvalumab is to be used as an adjuvant treatment, a post-surgery therapy, following a radical cystectomy. This approval is specifically for adults diagnosed with muscle invasive bladder cancer (MIBC), a condition where the cancer has penetrated the muscular wall of the bladder. Complete prescribing details for Imfinzi are expected to be available on Drugs@FDA.

The approval was largely based on the outcomes from the NIAGARA trial (NCT03732677), a Phase III, randomized, open-label, multicenter study that included 1,063 participants. These individuals were candidates for radical cystectomy and had not undergone any prior systemic therapy for their bladder cancer. Participants were divided into two groups: one received durvalumab with chemotherapy before the surgery and durvalumab alone afterward, while the other group received chemotherapy before surgery and no treatment afterward.

The primary measure of effectiveness in this trial was event-free survival (EFS), assessed by a blinded independent central review. Overall survival (OS) was also evaluated as a secondary measure. The interim analysis of the trial indicated statistically significant results in favor of the treatment regimen including durvalumab. Specifically, the median event-free survival was not reached in the durvalumab plus chemotherapy group, contrasting with 46.1 months in the chemotherapy-only group. The hazard ratio for EFS stood at 0.68, with a two-sided p-value of less than 0.0001, highlighting a significant improvement. In terms of overall survival, the median was not reached in either treatment arm, but the hazard ratio was 0.75, with a p-value of 0.0106, indicating a favorable result for the durvalumab-treated patients.

Regarding safety, adverse reactions observed were consistent with prior experiences involving durvalumab when used alongside platinum-based chemotherapy. The dosing recommendations for durvalumab post-approval stipulate 1,500 mg every three weeks alongside chemotherapy for patients weighing 30 kg or more in the neoadjuvant setting, and 1,500 mg every four weeks as a solo agent in the adjuvant setting. For patients under 30 kg, the dose is 20 mg per kg with chemotherapy every three weeks and as a single agent every four weeks after surgery. The treatment is advised to continue until the disease progresses to a state where definitive surgery is not viable, there is a recurrence, unacceptable toxicity occurs, or a maximum of eight cycles post-surgery is completed.

This FDA decision was expedited by a priority review, a part of the agency's expedited programs aimed at fast-tracking treatments for serious conditions. The application process was supported by the Assessment Aid, a voluntary submission designed to facilitate the FDA's review process.