Efficacy of neoadjuvant atezolizumab treatment in patients with advanced urothelial bladder cancer according to the BASQ classification: a study protocol for an open-label, two-cohort, phase II trial

INTRODUCTION: Atezolizumab is a programmed death ligand-1 inhibitor for urothelial bladder cancer treatment. Atezolizumab has become the standard therapy for patients with urothelial bladder cancer who are not responding to cisplatin-based chemotherapy and is also used as a first-line treatment in cisplatin-ineligible patients. However, the efficacy of atezolizumab as a neoadjuvant chemotherapy for radical cystectomy has not yet been published and is still under study. This trial investigates the effectiveness of basal/squamous-like (BASQ) classification in the selection of an effective target group of patients with muscle-invasive bladder cancer (MIBC) for neoadjuvant atezolizumab treatment. METHODS AND ANALYSIS: This study is an open-label, two-cohort, phase II trial. It was designed to evaluate the efficacy of neoadjuvant atezolizumab treatment in patients with MIBC (T2–4N0M0) pathological responses after neoadjuvant chemotherapy and radical cystectomy. According to the molecular subtype characteristics of previous transurethral resection of the bladder specimens, patients are divided into two groups: luminal type (KRT5/6−KRT14−FOXA1+GATA3+) and basal type (KRT5/6+KRT14+FOXA1−GATA3−). Every 3 weeks, atezolizumab is administered at a dose of 1200 mg for three cycles prior to radical cystectomy in patients with MIBC. The primary end point is objective pathological responses in the intention-to-treat patients. The secondary end point is a 1-year progression-free survival difference according to the BASQ classification in patients who underwent neoadjuvant atezolizumab treatment. ETHICS AND DISSEMINATION: The study protocol was approved by the Institutional Review Board of Seoul National University Hospital, Seoul, Republic of Korea (H 1806-051-950). The trial is registered at ClinicalTrials.gov. The trial results will be published in peer-reviewed journals and at conferences. TRIAL REGISTRATION NUMBER: NCT03577132.