ASCO GU 2017: Muscle-invasive bladder cancer: Molecular subtypes and response to neoadjuvant chemotherapy. - Session Highlights
Orlando, Florida USA (UroToday.com) There was much discussion and excitement at this year’s genitourinary cancer symposium regarding the ability of genomic classifiers to predict response to neoadjuvant chemotherapy. Through a fantastic demonstration of collaboration, molecular subtypes in bladder cancer based on gene expression have been widely accepted. Dr. Peter Black and Dr. Roland Seiler from Vancouver, BC demonstrated the benefit of molecular subtypes in its potential to predict response to neoadjuvant chemotherapy. Transcriptome-wide microarray analysis was performed on pre-neoadjuvant chemotherapy bladder tumor transurethral resection specimens. 223 patients with muscle invasive bladder cancer from 5 centers were used for the analysis. The specimens were classified according to four published methods for molecular subtype (UNC, MDA, TCGA, Lund). They trained a genomic classifier (GSC) to predict subtype in a single sample model and validated in 2 separate cohorts. Their model-generated subtype calls similar to previously published classifiers.
Interestingly, patients with tumors classified as basal or cluster III had poor overall survival in the absence of neoadjuvant chemotherapy (NAC). Basal, however, experienced the greatest improvement in overall survival after NAC. The good prognosis of luminal/cluster I tumors could not be improved with NAC, which suggests these patients may be managed best with surgery alone. Poor overall survival of claudin-low tumors persisted after NAC implying that these tumors are resistant to cisplatin-based chemotherapy. Genomic subtyping appears to provide predictive ability for response to NAC. Further validation is required.
First Author: Roland Seiler
Written By: Michael J Metcalfe, MD, Fellow of Urologic Oncology Urology, MD Anderson Cancer Center, Houston TX Ashish M. Kamat, MD, MBBS, FACS, President, International Bladder Cancer Network Chair, Society of Immunotherapy for Cancer (SITC), BCTF, Director of Urologic Oncology Fellowship, Professor of Urology, Attending Surgeon, Division of Surgery, The University of Texas, MD Anderson Cancer Center, Houston TX