Background: Cisplatin-based combination chemotherapy is standard first-line treatment for patients with advanced urothelial carcinoma (UC). Molecular profiling studies reveal that the PI3K/AKT/mTOR pathway is altered in a significant percentage of UCs.
Objective: We conducted a phase I trial to evaluate the feasibility of combining the mTOR inhibitor everolimus with gemcitabine and split-dose cisplatin (GC) in advanced UC in the first-line setting.
Methods: Patients received gemcitabine 800 mg/m2 and cisplatin 35 mg/m2 on days 1 and 8 of 21-day cycles for a total of 6 cycles in combination with everolimus at increasing dose levels (DL1:5 mg QOD, DL2:5 mg daily, DL3:10 mg daily) following a standard 3+3 design. Responses were assessed every 2 cycles. Patients with at least stable disease (SD) continued everolimus until progression. Goals were to establish dose-limiting toxicities (DLTs) and maximum tolerated dose (MTD) for the combination.
Results: 12 patients were enrolled, 3 at DL1, 3 at DL2, and an additional 6 at DL1 *(DL1 following de-escalation). 3/3 patients at DL2 had DLTs during cycle 1. 2/8 evaluable patients at DL1/DL1 * had DLTs during cycle 1. DLTs were primarily hematologic. Further toxicities, also primarily hematologic, were observed during later treatment cycles, leading to 8 chemotherapy dose reductions overall. Partial responses were observed in 4/10 evaluable patients, and SD in 5/10. Median overall survival was 10.8 months (95% CI 6.9, not reached).
Conclusions: The maximum tolerated dose was reached at the lowest dose level, 5 mg QOD, for everolimus in combination with gemcitabine and split-dose cisplatin in advanced UC. The regimen was limited by hematologic toxicity.
Keywords: Everolimus; Urothelial carcinoma; cisplatin; gemcitabine; mTOR inhibitor.