AMBASSADOR: Pembrolizumab More Beneficial Than Observation in MIUC

The open-label, randomized, phase 3 AMBASSADOR study led by Andrea B. Apolo, MD, and presented at the European Society for Medical Oncology Congress 2024 demonstrated a significant improvement in disease-free survival (DFS) for adjuvant pembrolizumab versus observation in patients with high-risk muscle-invasive urothelial carcinoma (MIUC) after radical surgery.

Seven-hundred-and-two patients who had MIUC of the bladder, upper tract, or urethra were randomly assigned 1:1 to receive pembrolizumab 200 mg every three weeks for one year or to observation. The dual primary endpoints were DFS and overall survival (OS). Median DFS follow-up was 41.3 months; final OS analysis requires additional events. DFS benefit (19 additional median months) was seen in most of the subgroups analyzed, including pathologic state, programmed death-ligand 1 status, and age.

The researchers concluded that pembrolizumab shows DFS benefit versus observation in all patients as well as DFS benefit regardless of lymph node status, and metastatic recurrences were more common with observation than with pembrolizumab.