A phase II study investigating the safety and efficacy of neoadjuvant atezolizumab in muscle invasive bladder cancer (ABACUS).

Abstract

4506Background: Atezolizumab is a PD-L1 inhibitor which is licenced in metastatic urothelial cancer. This study investigates the efficacy and safety of neoadjuvant atezolizumab given prior to cystectomy in operable muscle invasive transitional cell carcinoma bladder cancer. Methods: This single arm phase 2 study investigated 2 cycles of atezolizumab (1200mg Q3) prior to cystectomy in muscle invasive transitional cell cancer (T2-4N0M0). Pathological complete response (pCR) occurring in ≥20% of patients was the primary endpoint. Biomarker analysis on sequential tissue was a co-primary endpoint. Cross sectional imaging was performed at baseline and prior to cystectomy which occurred 4 - 8 weeks after starting atezolizumab. Radiological response was assessed. Adverse events (AEs) and surgical complications were assessed using CTCAE v4.03 and the Clavien-Dindo classification. The IDMC reviewed the first 69 patients (of 85) and supported this interim presentation. Results: The median age of the 69 patients was ...