Molecular basis of lineage plasticity in neuroendocrine bladder cancer: implications for therapeutic response

The National Cancer Institute awarded Health Research, Inc. (Roswell Park Division), doing business as Health Research At Roswell Park, $655,846 on August 24, 2026, under the Cancer Biology Research program (CFDA 93.396) to investigate the molecular basis of lineage plasticity in neuroendocrine bladder cancer and its implications for therapeutic response.

The funded research develops genetically engineered mouse models and conducts mechanistic studies to understand neuroendocrine bladder cancer tumorigenesis, a highly aggressive variant that accounts for significant mortality and typically relapses after standard chemotherapy. The project generates bladder-specific triple-knockout mouse models with inactivated TP53, PTEN, and RB1 genes using uroplakin 2-cre recombination to induce mutations in urothelial tissue, enabling investigation of cell-of-origin, lineage transitions, and therapeutic responses within an intact immune microenvironment—processes that cannot be adequately studied in vitro. The research addresses a major knowledge gap in understanding tumor heterogeneity, which manifests as histological variants and molecular subtypes that directly impact treatment response to chemotherapy and immune checkpoint immunotherapy in bladder cancer patients.

The award has a period of performance through July 31, 2031, with place of performance in Buffalo, New York. Health Research At Roswell Park is a tax-exempt not-for-profit child organization affiliated with Roswell Park Comprehensive Cancer Center and serves as a prime recipient of National Cancer Institute grants specializing in hypothesis-driven cancer research, clinical trials, biostatistics, and biorepository services.

Abstract

A major knowledge GAP in bladder cancer biology is to understand the biological nature of tumor heterogeneity, manifested by "histology variants" at the morphological level, or "molecular subtypes" at the transcriptional level. Most BCS are conventional urothelial carcinomas (UC) that originate from urothelial cells, the lining of the renal pelvis, the ureter, the bladder, and the proximal urethra. Histology variants can be found in up to 30% of bladder cancer patients and often CO-exist with UC tumors. Among these variants, neuroendocrine bladder cancer (NEBC) is the most aggressive variant. NEBC significantly contributes to BC death because NEBC is incurable and often relapses after etoposide and cisplatin (EP) chemotherapy. Further, BC subtype categorization is important clinically because molecular subtypes have direct impact on the treatment responses to standard care for BC patients: chemotherapy and immune checkpoint immunotherapy. A clear unmet need is to understand the different pathogenesis of NEBC tumors and its relationship to conventional UC. However, no studies have systemically investigated NEBC tumorigenesis, due to a lack of relevant genetically engineered mouse models (GEMMS) and/or patient derived organoid/xenograft (PDO/PDX). Inactivating mutations of TP53/RB1 are more enriched in NEBC patients than in UC patients and pten mutations are found in 13% of NEBC patients. Therefore, we generated bladder specific triple knockout (TKO) (TRP53-/-:pten-/-:RB1-/-) GEMMS using uroplakin 2-CRE (UP2-CRE; urothelium specific) to induce CRE recombination in the urothelium. Our UP2-CRE; TKO GEMMS demonstrated 100% mouse NEBC (MNEBC) tumors. These animal models are essential for defining the cell of origin, lineage transitions, and responses to standard therapies within an intact immune microenvironment- processes that cannot be studied using in vitro systems alone. Pathological and molecular analyses confirmed that MNEBC tumors express key transcription factors (TFS) of ASCL1 and FOXA2, consistent with the ASCL1 human NEBC (HNEBC) tumors. Moreover, we developed five pdxs derived from five NEBC patients, with either NEBC morphology or UC morphology. Building on novel NEBC GEMMS and PDO/PDX models, we are uniquely positioned to test the hypothesis that FOXA2 is an essential TF that regulates NE transcriptional program, NEBC histology state, or treatment responses to standard chemotherapy or chemo-immunotherapy. Aim 1 will define the cell-of-origin and lineage transition in MNEBC GEMMS. Aim 2: determine the impact of FOXA2 perturbation on tumor histology (NEBC VS UC), transcriptional program (NE VS luminal VS basal), tumor microenvironment, and treatment responses to chemo-immunotherapy. Impact: the proposed study integrates our novel gemm and PDX platforms to address a significant fundamental knowledge GAP in NE subtypes/NEBC: how cell-of-origin and cellular plasticity state shape tumor subtype identity and influence treatment response. This complementary approach will enable rigorous mechanistic investigation while establishing direct translational relevance.