Breakthrough Phase II Clinical Trial Results for Bladder Cancer Treatment at ASCO GU 2025

Exciting Advances in Bladder Cancer Treatment



On February 14, 2025, at the American Society of Clinical Oncology's Genitourinary Cancers Symposium (ASCO GU) in San Francisco, groundbreaking findings were revealed regarding the treatment of muscle-invasive bladder cancer (MIBC). Professor Xinan Sheng, affiliated with the Peking University Cancer Hospital, presented the results from a Phase II clinical trial that explored the combination of Disitamab Vedotin (DV) and Toripalimab as a neoadjuvant therapy for patients with HER2-expressing MIBC.

This clinical trial, designated NCT05297552, marked a significant milestone as it is the first prospective study to examine an antibody-drug conjugate (ADC) in conjunction with immunotherapy for MIBC. The trial's outcomes were impressive, showcasing a remarkable pathological complete response (pCR) rate of 63.6%. This result stands in stark contrast to traditional neoadjuvant chemotherapy options, which generally yield pCR rates between 36% to 42%.

Significance of Findings



The study evaluated the synergy of combining targeted therapy with immunotherapy in the perioperative context for MIBC. DV, an ADC specifically targeting HER2, was developed by RemeGen Co., Ltd., while Toripalimab functions as a PD-1 inhibitor. A noteworthy development occurred in May 2024, when the Center for Drug Evaluation (CDE) of China's National Medical Products Administration (NMPA) awarded breakthrough therapy designation to DV based on preliminary findings from this study. The initial results garnered considerable attention during the 2024 ASCO Annual Meeting, prompting ongoing discussions among experts globally.

During the NCT05297552 trial, a total of 47 patients were eligible, with various HER2 expression levels reported: 10.6% had IHC 1+, 57.4% had IHC 2+, and 31.9% had IHC 3+. Out of these, 33 patients proceeded with radical cystectomy and pelvic lymph node dissection (RC + PLND). As of the data cutoff on December 3, 2024, the study highlighted significant efficacy and a manageable safety profile.

Efficacy Breakdown



The results indicated a pCR rate of 63.6%, with a confidence interval of 45.1% to 79.6%. The overall pathological response rate reached 75.8%, with a postoperative pCR rate of 85.7% in patients presenting with a baseline clinical stage of T2N0. Furthermore, a pCR rate of 55.6% was observed in patients with different pathological subtypes of urothelial carcinoma at the beginning of the trial. Importantly, efficacy was noted across different groups, regardless of PD-L1 expression or HER2 status; in HER2 IHC 3+ patients, the pCR stood at an impressive 84.6%.

Event-free survival (EFS) rates were equally promising, with a 12-month EFS of 92.5% and an 18-month EFS of 85.9% for those who underwent radical cystectomy, demonstrating the treatment's sustained effectiveness over time.

Safety Profile



As for safety, the combination therapy exhibited a manageable profile with only a 27.7% occurrence of grade 3 or higher treatment-emergent adverse events, which is notably lower than rates typically seen with conventional chemotherapy, estimated at 40%-50%. This suggests a favorable tolerability for patients, thereby enhancing the attractiveness of this new regimen.

Moving Forward



RemeGen continues to advance research efforts aimed at widening the application of DV for bladder cancer through innovation and indication expansion. Ongoing studies are examining the potential for DV-based therapies to transition from later-stage treatment options to front-line therapies for locally advanced or metastatic urothelial cancers. Additionally, investigations are underway to extend the application of DV as a neoadjuvant treatment over the entire perioperative timeframe, alongside exploring its synergy with chemotherapy or additional immunotherapy treatments.

The encouraging results from this trial not only signify potential new avenues for bladder cancer treatment but also illuminate a promising future for patients striving for effective therapeutic options. The landscape of bladder cancer treatment continues to evolve, and with ongoing research, there is hope that breakthroughs like these will translate into significant advancements in patient care.

Topics Health)

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