Dr Galsky on Atezolizumab Plus Chemotherapy in Metastatic Urothelial Carcinoma

Matthew Galsky, MD, professor, medicine, director, genitourinary medical oncology, co-director, the Center of Excellence for Bladder Cancer, associate director for translational research, the Tisch Cancer Institute, Mount Sinai, discusses final results from the phase 3 IMvigor130 trial (NCT02807636) in patients with metastatic urothelial cancer.

IMvigor130 randomly assigned patients with treatment-naïve locally advanced or metastatic urothelial cancer to receive the immunotherapy atezolizumab (Tecentriq) plus chemotherapy (arm A), atezolizumab monotherapy (arm B), or chemotherapy plus placebo (arm C). The coprimary end points of this trial were progression-free survival (PFS) and overall survival (OS), and key secondary end points included duration of response and overall response rate.

The final PFS analysis of arms A and C of this trial showed the PFS improvement in the atezolizumab arm to be statistically significant, Galsky explains. The median PFS was 8.2 months (95% CI, 6.5-8.3) with atezolizumab plus chemotherapy vs 6.3 months (95% CI, 6.2-7.0) with chemotherapy plus placebo (HR, 0.82-95% CI, 0.70-0.96; 1-sided P = .007).

At the time of the interim OS analysis for arms A and C, with a median follow-up of 11.8 months, the median OS was 16.0 months (95% CI, 13.9-18.9) with atezolizumab plus chemotherapy vs 13.4 months (95% CI, 12.0-15.2) with chemotherapy plus placebo (HR, 0.83; 95% CI, 0.69-1.00; 1-sided P = .027). The P value for OS was slightly above the threshold for statistical significance, Galsky notes.

Results from the final OS analysis, which were presented at the 2023 Genitourinary Cancers Symposium, demonstrated a median OS of 15.2 months (95% CI, 13.1-17.7) in patients who received atezolizumab monotherapy vs 13.3 months (95% CI, 11.9-15.6) in those who received chemotherapy plus placebo (HR, 0.98; 95% CI, 0.82-1.16).

The phase 3 KEYNOTE-361 trial (NCT02853305) investigated the efficacy and safety of platinum-based chemotherapy with or without another immune checkpoint inhibitor, pembrolizumab (Keytruda), in patients with previously untreated advanced urothelial carcinoma. Neither KEYNOTE-361 nor IMvigor130 demonstrated OS improvements with immune checkpoint blockade plus chemotherapy in the advanced urothelial carcinoma population, Galsky concludes.