Alterations of DNA damage response (DDR) genes correlate with favorable response and overall survival (OS) in anti-PD-1/PD-L1-treated advanced urothelial cancer (UC).

Abstract

438 Background: DDR gene alterations may contribute to higher tumor mutational burden (TMB) via genomic instability in addition to APOBEC mutagenesis. We previously showed that ATM mutations correlated with shorter OS in UC, while Teo et al. showed patients (pts) with DDR alterations benefited from PD-1/PD-L1 blockade in advanced UC. Here, we aimed to validate those findings and further explore the prognostic role of ATM mutations in advanced UC treated with anti-PD-1/PD-L1 agents. Methods: The study included 53 pts who had FoundationOne tumor tissue genomic sequencing and anti-PD-1/PD-L1 therapy. Fisher exact test was used to test difference in objective response rate (ORR). OS was measured from time of initial UC diagnosis and Cox proportional hazard regression analysis was performed to calculate the hazard ratio (HR) and 95% confidence interval (CI). Results: The cohort had a median age of 66 (range 21–81) with 34% females and 64.2% platinum-based chemotherapy. DDR alterations (including ATM) were present in 49.1% pts (26/53) and favored a higher ORR (37.5% vs. 23.1%, p = 0.26). Compared with those without DDR alterations, pts with DDR alterations (excluding ATM) seemed to have longer OS, although significance was not reached likely due to a short follow-up time (HR = 0.53, 95% CI 0.20–1.38, p = 0.19). ATM alterations seemed to favor higher response rate to PD-1/PD-L1 blockade (ORR, 40% vs. 28.9%, p = 0.6), but was associated with significantly shorter OS (HR = 5.7, 95% CI 1.65–19.74, p = 0.006) in overall pts and in subgroups with/without platinum-based chemotherapy (data not shown). Pts with ≥ 3 DDR alterations (including ATM) had substantial higher TMB (13.9–72.2 perMb, median 22.6) and benefited the most from PD-1/PD-L1 blockade with 80% ORR vs. 24.4% ORR in pts with < 3 DDR alterations. Conclusions: Our study supported that DDR alterations are associated with higher response rate and prolonged OS in advanced UC pts receiving anti-PD-1/PD-L1 agents, likely from impact on TMB. However, ATM alterations correlated with poor prognosis also in those pts. Further studies are needed to assess the clinical utility of DDR alterations in directing therapies in UC.