Efficacy and safety of disitamab vedotin combined with toripalimab as neoadjuvant treatment in patients with HER2 positive locally advanced muscle-invasive urothelial bladder cancer.

Abstract

631 Background: For HER2 positive muscle-invasive bladder cancer (MIBC), the efficacy of cisplatin-based NAC is unsatisfied, and adverse reactions are inevitable or even intolerable. Disitamab vedotin is an antibody-drug conjugate composed of an anti-HER2 antibody disitamab and MMAE payload. Multiple clinical studies have confirmed that promising activity in HER2-positive locally advanced or mUC patients。This study aims to evaluate the safety and efficacy of disitamab vedotin, and toripalimab as a novel neoadjuvant treatment combination in patients with HER2 positive locally advanced MIBC. Methods: In this Study, Platinum intolerance and pathological andimaging diagnosed cT2-4bN0M0 MIBC patients with HER2 positive (HER2 IHC2+ or HER2 IHC3+) received 3 cycles toripalimab (200mg, iv, D1, Q2W) combined with disitamab vedotin (2mg/kg, iv, D1, Q2W). The primary endpoint was pCR, and the secondary endpoints included PFS, OS, and safety. Results: From July 2023 to Sep 2023, 12 patients were enrolled. The median age was 68 (55-82) years . By the data cut off in August 2023, the primary end point pCR was 80% (8/10). Median follow-up time was 4.2 (2.2-8.45) month. The median overall survival (OS) was not reached，ORR was100%. In terms of safety, the treatment-related adverse events (TRAEs) of any grade occurred in ten patients (83.3%), and the most common TRAEs were nausea (58.3%), followed by alopecia (33.3%), diarrhea (16.7%) and Cardiac tachycardia (8.3%). most of which are grade 1-2. Grade 3 TRAE is Cardiac tachycardia and occurred in one patient. No grade 4 and 5 TRAEs were observed. Conclusions: From July 2023 to Sep 2023, 12 patients were enrolled. The median age was 68 (55-82) years . By the data cut off in August 2023, the primary end point pCR was 80% (8/10). Median follow-up time was 4.2 (2.2-8.45) month. The median overall survival (OS) was not reached, ORR was100%. In terms of safety, the treatment-related adverse events (TRAEs) of any grade occurred in ten patients (83.3%), and the most common TRAEs were nausea (58.3%), followed by alopecia (33.3%), diarrhea (16.7%) and Cardiac tachycardia (8.3%). most of which are grade 1-2. Grade 3 TRAE is cardiac tachycardia and occurred in one patient. No grade 4 and 5 TRAEs were observed.