Phase 2 pilot trial of tislelizumab plus low-dose nab-paclitaxel for extensive very high-risk non-muscle-invasive bladder cancer

Abstract Purpose: Combinations of immune checkpoint inhibitors and nab-paclitaxel have improved outcomes in advanced urothelial carcinoma and muscle-invasive bladder cancer. This study evaluates the safety and efficacy of tislelizumab combined with low-dose nab-paclitaxel in extensive very high-risk (VHR) non-muscle-invasive bladder cancer (NMIBC). Patients and Methods: TRUCE-02 was a single-arm phase 2 trial that included 63 patients with visually incomplete resection and/or high-volume high-grade T1 tumors (with or without carcinoma in situ), who were ineligible for or declined radical cystectomy. Patients received intravenous tislelizumab (200 mg on day 1) and nab-paclitaxel (200 mg on day 2) every 3 weeks, with assessment approximately 3 months after initial administration. The primary endpoint was the complete response rate of high-risk disease. Main secondary endpoints included safety and duration of complete response. Results: The safety analysis included all 63 patients and the efficacy analysis included 59 patients. Thirty-seven patients [62.7%; 95% confidence interval (CI), 49.1-75.0%] achieved a complete response of high-risk disease, with a 24-month sustained response rate of 96.3% (95% CI, 89.4-100.0%). Grade 3-4 treatment-related adverse events occurred in nine patients (14%), with no fatal events reported. Conclusions: Tislelizumab plus low-dose nab-paclitaxel was well-tolerated and showed promising antitumor activity, making it a potential alternative for extensive VHR NMIBC patients who are ineligible for or decline radical cystectomy.