(UroToday.com) The 2026 American Society of Clinical Oncology Genitourinary (ASCO) Annual Meeting held in Chicago, IL, will host the Kidney and Bladder Cancer - Posters. Dr. Zhiyong Li will be presenting Abstract 4599: Final results from a phase II study of tislelizumab combined with RT as bladder preserving treatment for high-risk non-muscle invasive bladder cancer (NMIBC) patients with unresponsive BCG.
Radical cystectomy (RC) remains the standard of care for patients with BCG-unresponsive high-risk NMIBC with papillary tumors. However, there is a significant unmet need for effective non-surgical treatment options for patients who are either ineligible for or decline RC. In this context, they evaluated the efficacy and safety of tislelizumab combined with radiotherapy as a bladder-preserving strategy in patients with BCG-unresponsive HR NMIBC.
This open-label, single-arm phase II study enrolled patients with BCG-unresponsive high-grade Ta or T1 papillary tumors without concomitant CIS following complete trans urethral resection of bladder tumor (TURBT). Within two weeks after TURBT, eligible patients received tislelizumab 200 mg every 21 days for eight cycles in combination with radiotherapy delivered to a total dose of 60–66 Gy in 30–33 fractions over seven weeks. The primary endpoint was 12-month disease-free survival (DFS), defined as the absence of recurrent high-grade or T1 disease or clinical stage progression following treatment. Secondary endpoints included bladder-preservation rate, OS, and safety.
Between September 2020 and December 2024, 32 patients were enrolled, including 26 men and 6 women, with patients having received a median of 11 prior BCG instillations (IQR: 7–22). Median follow-up was 28.8 months (range: 19.7–43.8). Patients completed a median of 8 cycles of tislelizumab and received a median radiotherapy dose of 62.0 Gy.
The study met its primary endpoint, demonstrating a 12-month DFS rate of 90.6% (95% CI: 79.8%–99.6%). DFS at 24 months was 70.2% (95% CI: 50.1%–83.4%). The bladder-preservation rate at 24 months was 93.2% (95% CI: 75.4%–98.3%). Overall survival outcomes were also encouraging, with a 24-month OS rate of 100% and a 36-month OS rate of 90.5%.
Treatment-related adverse events occurred in 84.4% of patients, with grade 3 toxicities observed in 21.9%. The most common grade 3 adverse events included diarrhea (9.4%), radiocystitis (3.1%), leukopenia (3.1%), and liver function abnormalities (3.1%). Importantly, no grade 4 or 5 treatment-related adverse events were reported.
Key Points:
- Tislelizumab combined with radiotherapy demonstrated promising long-term efficacy as a bladder-preserving strategy in BCG-unresponsive HR NMIBC
- The regimen achieved high disease-free survival and bladder-preservation rates with durable follow-up
- Overall survival outcomes remained favorable, with 100% OS observed at 24 months
- Treatment-related toxicities were manageable, with no grade 4 or 5 adverse events reported
- These findings support further investigation of combined immunotherapy and radiotherapy approaches as alternatives to radical cystectomy in selected patients with BCG-unresponsive disease
Presented by: Zhiyong Li, MD, Department of Urology, Sun Yat-Sen University Cancer Center, Guangzhou, China
Written by: Julian Chavarriaga, MD, Clinical Assistant Professor, Urologic Oncologist, Department of Urology at Penn State Health @chavarriagaj on X during the American Society of Clinical Oncology Genitourinary (ASCO) Annual Meeting held in Chicago, IL between May 29th and June 1st, 2026