Phase 3 KEYNOTE-361 trial: Pembrolizumab (pembro) with or without chemotherapy versus chemotherapy alone in advanced urothelial cancer.

TPS4590 Background: Only 5%-15% of patients (pts) with advanced bladder cancer attain long-term survival with standard first-line cisplatin-based chemotherapy. Programmed death 1 (PD-1)/PD-L1 inhibitors have proven effective in recurrent, advanced urothelial cancer. Emerging data suggest these agents may also be useful in the first-line setting. In KEYNOTE-052, first-line pembro, an anti–PD-1 antibody, demonstrated antitumor activity and acceptable safety in cisplatin-ineligible pts with advanced urothelial cancer. KEYNOTE-361 (NCT02853305) is a randomized, open-label, phase 3 study of pembro with or without chemotherapy versus chemotherapy alone in pts with advanced urothelial carcinoma. Methods: Key eligibility criteria include age ≥18 years; histologically or cytologically confirmed unresectable/metastatic urothelial carcinoma of the renal pelvis, ureter, bladder, or urethra; measurable disease (RECIST v1.1, investigator review); no prior systemic chemotherapy ([neo]adjuvant platinum-based chemotherapy with recurrence > 12 months after completion is allowed); ECOG PS 0-2; and provision of a tumor sample for biomarker analyses. Pts will be randomly assigned 1:1:1 to receive pembro 200 mg every 3 weeks (Q3W), pembro + investigator’s choice of chemotherapy (gemcitabine [1000 mg/m 2 on day 1 and 8 Q3W] + cisplatin [70 mg/m 2 Q3W]), or chemotherapy alone. Cisplatin-ineligible pts randomly assigned to chemotherapy will receive gemcitabine + carboplatin [AUC 5 Q3W]. Chemotherapy choice must be selected before randomization. Treatment will continue until progressive disease, unacceptable adverse events (AEs), or 35 cycles of pembro (pembro arms only). Response will be assessed Q9W for the first year and Q12W thereafter. AEs will be evaluated throughout and graded per NCI CTCAE v4.0. Primary end points are progression-free survival (RECIST v1.1 per central review) and overall survival; secondary end points include objective response rate and safety and tolerability. Efficacy outcomes will be compared for pembro vs chemotherapy and pembro + chemotherapy vs chemotherapy. Enrollment is ongoing; ~990 pts will be enrolled. Clinical trial information: NCT02853305.