ESTRO 2025 - Abstract Book

S2142

Clinical - Urology

ESTRO 2025

4554

Proffered Paper Nivolumab plus chemoradiotherapy in patients with muscle-invasive bladder: final results of a phase II, randomized study by the HGUCG (NCT03993249). Andromachi Kougioumtzopoulou 1 , Konstantinos Koutsoukos 2 , Roubini Zakopoulou 3 , Kimon Tzannis 4 , Anastasios Kyriazoglou 3 , Athanasia Damatopoulou 5 , Michalis Liontos 6 , Konstantinos Ntoumas 7 , Konstantinos Stravodimos 8 , Dionisios Mitropoulos 8 , Athanasios Dellis 9 , Athanasios Papatsoris 10 , Michalis Chrisofos 11 , Dimitrios Kardamakis 12 , Anna Zygogianni 13 , Zoi Liakouli 13 , George Pissakas 14 , Aristotelis Bamias 15 , Vassilis Kouloulias 1 1 Clinical Radiation Oncology, Attikon Univestity hospital, Athens, Greece. 2 2nd Oncology Clinic, Metropolitan Hospital, Athens, Greece. 3 Oncology unit, Attikon Univestity hospital, Athens, Greece. 4 2nd Propaedeutic Department of Internal Medicine, National and Kapodistrian University of Athens, Attikon Univestity hospital, Athens, Greece. 5 Radiotherapy Department, General Hospital of Athens Alexandra, Athens, Greece. 6 Oncology Unit, Department of Clinical Therapeutics, Alexandra Hospital, Athens, Greece. 7 Department of Urology, General Hospital of Athens G.N.A. G. Gennimatas,, Athens, Greece. 8 1st Department of Urology, National & Kapodistrian University of Athens, Laiko Hospital, Athens, Greece. 9 Department of Surgery,National and Kapodistrian University of Athens, Aretaieion Hospital, Athens, Greece. 10 2nd Department of Urology, National and Kapodistrian University of Athens, Sismanoglio Hospital, Athens, Greece. 11 133rd Department of Urology,National and Kapodistrian University of Athens, Attikon Univestity hospital, Athens, Greece. 12 Department of Radiation Oncology, University Hospital Patras, Patras, Greece. 13 Radiation Oncology Unit, Aretaieion Hospital, Athens, Greece. 14 Radiotherapy Department, Alexandra Hospital, Athens, Greece. 15 2nd Propaedeutic Department of Internal Medicine, National & Kapodistrian University of Athens, Attikon Univestity hospital, Athens, Greece Purpose/Objective: Bladder preservation consisting of maximal transurethral resection (TURBT) followed by chemoradiotherapy serves as an alternative to radical cystectomy (RC) in selected patients. This study aims to evaluate the efficacy of concurrently administering Nivolumab with chemoradiotherapy (CRT) in patients with nonmetastatic muscle invasive bladder cancer (MIBC) not undergoing RC. Material/Methods: Eligibility criteria encompass patients with MIBC stage T2-4N0M0 disease who had prior undergone an optimal TURBT and were randomized to receive either CRT (cisplatin concurrently with radical radiotherapy) alone or CRT plus Nivolumab. The administration of Nivolumab started 2 weeks prior to the CRT, continued concurrently, and persisted for 6 months after the end of treatment (6 cycles of nivolumab at 480mg every 4 weeks). Both arms received dose escalated RT with conventional fractionation, 60 Gy were prescribed to the whole bladder and a boost of 10 Gy to the tumor site with conventional fractionation. The primary endpoint was locoregional failure free rate (LRFR) at 2 years, and the secondary endpoints were bladder cancer failure free survival (BCFFS), OS and toxicity. Results: Seventy-seven patients were randomized, with 39 patients assigned to CRT alone (arm A) and 38 in CRT plus Nivolumab (arm B). In arm A, 90% of the patients complied to the study protocol in arm A, compared to 66% in arm B. At the time of the analysis, 69 patients had finalized the 2-year follow-up. The 2-year LRFR was 59.2% (95% CI 37.7-75.5) in arm A versus 72.2% (95% CI 53.3-84.5) in arm B (p=.22). The 2-year BCFFS and OS showed a significant difference, favoring arm B (p = .005 and .008, respectively). Grade ≥3 adverse events presented in 25.6% patients in arm A and 36.8% in arm B, not significant different with exception thyroid immune-related dysfunction in the arm B. No treatment related deaths occurred. Conclusion: The addition of Nivolumab into trimodality therapy marked a significant improvement in OS and BDFFS. Furthermore, the benefit of local control did not reach a statistically significant difference. The outcomes support the necessity for a randomized phase III trial to determine Nivolumab in combination with CRT as the standard treatment for bladder preservation.