Immune-related biomarkers associated with pathologic complete response (pCR) to neoadjuvant cisplatin-based chemotherapy in patients with muscle-invasive bladder cancer undergoing cystectomy

Abstract Background: NeoAdjuvant cisplatin-based Chemotherapy (NAC) followed by cystectomy is the standard of care for patients with muscle-invasive bladder cancer (MIBC). Pathologic complete response (pCR) at the time of cystectomy predicts better survival. Unfortunately, only approximately a third of patients achieve such a response. The aim of this study is to explore in the tumor microenvironment and in the peripheral blood, biomarkers associated with pCR following NAC and to further evaluate the pharmacodynamic modifications induced by NAC on immune cells detected in the peripheral blood. Methods: N= 13 patients with MIBC received NAC and were classified as pCR (n=8) or no-pCR (n=5). Bulk RNA-seq was performed on the 13-patients formalin-fixed paraffin-embedded (FFPE) tumor biopsies collected prior to NAC treatment (baseline). Lymphocytes and neutrophils counts were assessed in the peripheral blood at baseline and following treatment with NAC. Kaplan-Meier analyses and Cox PH regression models were used for survival analyses (OS). Inter- and intra-tumor immune heterogeneity of n=59 selected immune protein was determined using GeoMx DigitalSpatial Profiling (DSP) technology. Results: Bulk RNAseq revealed 1119 transcripts differentially expressed between pCR and no-pCR (p ≤ 0.01; Abs linear Fold Change >2). Particularly, we observed an increased expression of genes involved in B cell function (CD19, CLEC4D, CXCR5), dendritic cell activation (XCR1, CCL5) and formation of tertiary lymphoid structure in the TME of pCR vs. no-pCR. On the contrary, an increased expression of IL8, DNA repair genes (POLB, DMC1, RPA4, HFM1, RAD54B) and genes involved in cell adhesion was observed at baseline in the TME of no-pCR. Interestingly, patients with higher expression of CXCR5 and XCR1 and lower expression of POLB at baseline (medium expression as cut off) were also characterized by longer overall survival following cystectomy. DSP confirmed a TLS enrichment (CD20+, HLA-DR+) in the TME of pCR prior treatment initiation. On the contrary, an increased infiltration of Tregs (CD25+, CD127+) and immunosuppressive cells (CD45+, ARG+) was detected at baseline in no-pCR. Interestingly, also an increased expression of immune checkpoints such as PD-L1, VISTA, ICOS and LAG3, was observed at baseline in the TME of no-pCR. While no clear association with NAC response was seen for lymphocytes and neutrophils counts when evaluated in baseline peripheral blood, a significant increase of lymphocytes and decrease of neutrophils counts, respectively, was observed in pCR vs no-pCR following NAC. Conclusions: When confirmed on a larger cohort, our results will lead to novel therapeutic strategies and to novel biomarkers predicting patients likely to respond to NAC. Citation Format: Maria L. Ascierto, Alberto Mendoza-Valderrey, Jane Choe, Daria M. Kessler, Xinmin Li, Jennifer A. Linehan, Przemyslaw W. Twardowski. Immune-related biomarkers associated with pathologic complete response (pCR) to neoadjuvant cisplatin-based chemotherapy in patients with muscle-invasive bladder cancer undergoing cystectomy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2167.