Prognostic value of genomic alterations in DNA damage response (DDR) genes in relapsed/advanced bladder cancer (BCa).

Abstract

427 Background: DDR defects play an important role in tumorigenesis, progression, treatment response and outcomes of BCa. We previously showed DDR mutations were associated with better prognosis in relapsed/advanced (TxN2-3M0-1) BCa. In this study, we aimed to update and validate our findings in 3 independent datasets. Methods: 81 BCa patients (pts) who had FoundationOne tumor tissue genomic sequencing (315 cancer-related genes) were used as discovery dataset. Validation dataset 1 consisted of additional 91 pts with FoundationOne test. Validation dataset 2 consisted of 129 relapsed/advanced pts from TCGA BCa cohort. Overall survival (OS) was measured from time of initial BCa diagnosis to death or last follow-up. Cox proportional hazard regression analysis was performed to calculate the hazard ratio (HR) and 95% confidence interval (CI). Logistic regression analysis was performed to calculate odds ratio (OR) and 95% CI. A panel of 32 DDR genes (excluding ATM) were used for analyses because ATM mutation was a negative prognostic factor in our prior study. Results: DDR mutations were present in 76.5% (62/81), 40.7% (37/91) and 51.2% (66/129) pts of the 3 datasets. They were associated with longer OS (adjHR = 0.39, 95% CI 0.21–0.73, p = 0.003) in the discovery dataset, which were confirmed in two validation datasets (Validation 1: adjHR = 0.51, 95% CI 0.26–1.03, p = 0.059; Validation 2: adjHR = 0.62, 95% CI 0.39–0.97, p = 0.038). There was a trend for longer OS with increased number of DDR mutations in individual pts. Pts carrying ≥3 DDR mutations had the best prognosis (data not shown). In 144 cisplatin or carboplatin-treated pts pooled from the 3 cohorts, pts with DDR mutations were more likely to have objective response (OR = 1.81, 95% CI 0.85–3.92 for any DDR mutations; OR = 3.65, 95% CI 0.91–14.7 for ≥3 DDR mutations) and longer overall survival (HR = 0.61, 95% CI 0.38–0.98 for any DDR mutations; HR = 0.49, 95% CI 0.19–1.27 for ≥3 DDR mutations). Conclusions: DDR mutations (excluding ATM gene and especially ≥3) correlated with better outcomes in relapsed/advanced BCa. Further exploration of the deleterious nature and functional impact of alterations is critical along with prospective validation in ongoing trials.