Impact of Molecular Subtyping and Immune Infiltration on Pathological Response and Outcome Following Neoadjuvant Pembrolizumab in Muscle-invasive Bladder Cancer.

BACKGROUND: The PURE-01 study (NCT02736266) evaluated the use of pembrolizumab before radical cystectomy (RC) in muscle-invasive bladder cancer (MIBC). OBJECTIVE: To evaluate the ability of molecular signatures to predict the pathological complete response (CR: ypT0N0) and progression-free survival (PFS) after pembrolizumab and RC. DESIGN, SETTING, AND PARTICIPANTS: We analyzed the expression data from patients with T2-4aN0M0 MIBC enrolled in the PURE-01 study (N=84) and from patients of a retrospective multicenter cohort treated with cisplatin-based neoadjuvant chemotherapy (NAC; N=140). INTERVENTION: Neoadjuvant pembrolizumab or NAC and RC. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Immune signatures and molecular subtyping (The Cancer Genome Atlas, consensus model, and genomic subtyping classifier [GSC]) were evaluated in relation to CR and PFS. Multivariable logistic regression analyses for CR were used, adjusting for gender and clinical T stage. RESULTS AND LIMITATIONS: The Immune190 signature was significant for CR on multivariable logistic regression analyses (p= 0.02) in PURE-01, but not in the NAC cohort (p= 0.7). Hallmark signatures for interferon gamma (IFNγ; p= 0.004) and IFNα response (p= 0.006) were also associated with CR for PURE-01, but not for NAC (IFNγ: p= 0.9 and IFNα: p= 0.8). In PURE-01, 93% of patients with the highest Immune190 scores (>1st quartile) had 2-yr PFS versus 79% of those with lower scores; no difference was observed in NAC patients, as well as for the other hallmarks in both groups. The neuroendocrine-like subtype had the worst 2-yr PFS in all three subtyping models (33%) and the GSC claudin-low subtype had the best, with no recurrences in 2 yr. Basal subtypes (across classifications) with higher Immune190 scores showed 100% 2-yr PFS after pembrolizumab therapy (p = 0.04, compared with basal-Immune190 low). Statistical analyses are limited by the small number of events and short follow-up. CONCLUSIONS: Higher RNA-based immune signature scores were significantly associated with CR and numerically improved PFS outcomes after pembrolizumab, but not after NAC. These data emphasize that RNA profiling is a potential tool for personalizing neoadjuvant therapy selection. PATIENT SUMMARY: We used gene expression profiling to evaluate the association between immune gene expression and response to neoadjuvant immunotherapy, compared with standard chemotherapy, in patients with muscle-invasive bladder cancer (MIBC). We found a significant association between immune gene expression and response to pembrolizumab, but not chemotherapy. We conclude that gene expression profiling has the potential to guide personalized neoadjuvant therapy in MIBC.