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Switch Maintenance Pembrolizumab Improves Response, PFS in Metastatic Urothelial Cancer

Switch maintenance pembrolizumab led to improved progression-free survival (PFS) and overall response rates in patients with metastatic urothelial cancer, according to results from a double-blind phase 2 clinical trial (J Clin Oncol. 2020 Apr 9. Epub ahead of print).

“Platinum-based chemotherapy for first-line treatment of metastatic urothelial cancer is typically administered for a fixed duration followed by observation until progression,” stated Matthew D. Galsky, MD, Division of Hematology and Medical Oncology, The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, and colleagues.

Dr Galsky et al posited that “switch maintenance” therapy with PD-1 blockade at chemotherapy cessation may provide a survival benefit in this patient population.

Therefore, 108 patients with metastatic urothelial cancer who achieved stable disease with first-line platinum-based chemotherapy were randomly assigned between December 2015 and November 2018 to receive switch maintenance pembrolizumab 200 mg once every 3 weeks (n = 55) or placebo for up to 24 months (n = 53).

The primary end point was PFS, and secondary end points included overall survival (OS) and treatment outcomes according to PD-L1 combined positive score (CPS).

Ultimately, the PFS was significantly longer in the pembrolizumab arm (5.4 months) versus the placebo arm (3.0 months), and the ORR was 23% versus 10%, respectively.

In addition, the OS was 22 months versus 18.7 months in the pembrolizumab and placebo arms, respectively.

Of note, there was no significant interaction between PD-L1 CPS ≥10 and treatment with regard to PFS or OS.

“Switch maintenance pembrolizumab leads to additional objective responses in patients achieving at least stable disease with first-line platinum-based chemotherapy and prolongs [PFS] in patients with metastatic urothelial cancer,” Dr Galsky and colleagues concluded.—Kaitlyn Manasterski

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