Pembrolizumab plus trimodality therapy ‘promising’ for muscle-invasive urothelial cancer
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Pembrolizumab added to twice weekly gemcitabine plus transurethral muscle-invasive urothelial cancer resection of a bladder tumor and hypofractionated radiation therapy appeared safe for patients with muscle-invasive urothelial cancer.
Data from ahe multicenter phase 2 trial presented at ASCO Annual Meeting included patients from five institutions with clinical T2-T4aN0M0 muscle-invasive urothelial cancer who were ineligible for or declined radical cystectomy, had ECOG PS 0/1 and eGFR 30 cc/min.
Patients received 200 mg IV pembrolizumab (Keytruda, Merck) followed by maximal transurethral resection of bladder tumor and then whole bladder radiation therapy (52 Gy/20 fx) with 27 mg/m2 gemcitabine twice weekly,plus pembrolizumab every 3 weeks for three treatments. The primary endpoint was 2-year bladder-intact DFS.
In a previous trial, Minas P. Economides, MD, oncologist at NYU Langone’s Perlmutter Cancer Center, and colleagues reported an early analysis of a phase 2 study but noted this study showed updated follow-up safety and efficacy results.
Researchers assessed response every 12 weeks after radiation therapy with CT/MRI, tumor bed biopsy and cytology. They found 85% power to detect a 20% absolute improvement in 2-year bladder-intact DFS rate over 60% historical rate. Secondary endpoints included safety, 12-week pathologic complete response, metastases-free survival and OS.
PD-L1 status was available in 43 patients, while 21 patients had modified proportion scores of 10 or greater. Most patients (88%) completed all therapy. Discontinuation most commonly occurred due to toxicity; 11% of patients underwent salvage cystectomies.
Since June 2022 researchers noted 12 (22%) tumor recurrences and 7% of patients had non-muscle invasive only recurrences. Ten patients died during the study period (18%; three from disease progression, one from treatment toxicity and six from unrelated/unknown causes). Researchers noted no new safety signals.
Trimodality therapy combined with pembrolizumab “was well tolerated and continues to show promising early outcomes data. A large phase 3 trial is underway to further explore this treatment,” Economides and colleagues wrote.
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Economides MP, et al. Abstract 4509. Presented at: ASCO Annual Meeting; June 2-6, 2023; Chicago.
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