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Thomas Flaig, MD


ASCO GU 2024: Phase III Trial of Pembrolizumab in Advanced Urothelial Cancer

By: Joshua D. Madera, MD
Posted: Tuesday, January 30, 2024

For patients with muscle-invasive and locally advanced urothelial cancer who are at high risk for recurrence, adjuvant treatment with the PD-1 inhibitor pembrolizumab may be a therapeutic alternative, according to the results of the phase III AMBASSADOR Alliance A031501 trial, presented at the 2024 American Society of Clinical Oncology (ASCO) Genitourinary (GU) Cancers Symposium (Abstract LBA531). Adjuvant pembrolizumab therapy may improve disease-free survival and has a favorable safety profile, suggesting its clinical benefit in this patient population, according to Andrea B. Apolo, MD, of the National Cancer Institute, National Institutes of Health, Bethesda, Maryland, and colleagues.

“Additional follow-up is ongoing for the final disease-free survival/overall survival, PD-L1 subgroups, and circulating tumor DNA analyses,” the investigators commented.

From 2017 to 2021, a total of 702 patients with muscle-invasive urothelial carcinoma were recruited for the study. All patients were required to have histologically confirmed disease located in the upper tract, urethra, or bladder. Patients were initially stratified by centrally tested PD-L1 status, history of treatment with neoadjuvant chemotherapy, and pathologic stage before randomization. They were then randomly assigned to receive pembrolizumab after surgical intervention (n = 354) or observation alone (n = 348).

The study findings revealed an increased rate of disease-free survival (hazard ratio [HR] = 0.69) for patients who received treatment with pembrolizumab (29 months) compared with those who underwent observation postoperatively (14 months). In contrast, at the interim analysis, median overall survival was 50.9 months vs 55.8 months with observation. However, the study authors noted, the overall survival endpoint may have been impacted by patients on the observation arm receiving a checkpoint inhibitor. Furthermore, treatment-related adverse events were reported in 48.4% and 31.8% of patients, respectively.

Disclosure: Dr. Apolo reported no conflicts of interest. For full disclosures of the other study authors, visit

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