Deciphering tumor heterogeneity, metastatic spread, and treatment resistance in advanced bladder cancer

About This Grant

PROJECT SUMMARY/ABSTRACT Metastatic bladder cancer (mBLCA) is a highly lethal disease characterized by extensive histological and molecular heterogeneity. Histological variants such as plasmacytoid, squamous, neuroendocrine, and sarcomatoid subtypes are associated with aggressive clinical behavior and poor outcomes. Despite recent therapeutic advances—including cisplatin-based chemotherapy, immune checkpoint inhibitors, and antibody- drug conjugates—the mechanisms driving treatment resistance and metastatic progression remain poorly understood. A major barrier to progress is the lack of comprehensive resources to study tumor evolution across multiple metastatic sites and histological subtypes. To address this gap, we established the Fred Hutch/UW Bladder Cancer Rapid Autopsy Program, a one- of-a-kind resource designed to study tumor evolution and heterogeneity in mBLCA. Since 2015, we have collected tumors and matched benign tissues from 34 patients within hours of death, with cohort enrichment for histological variants. Multi-omic profiling of 20 patients—including whole genome sequencing, RNA-seq, and post-mortem circulating tumor DNA (ctDNA)—has revealed that metastasis-to-metastasis seeding and polyclonal dissemination are dominant modes of spread, particularly from early oligometastatic disease. These findings suggest that clonal diversity and early dissemination are key drivers of poor prognosis and may be targetable through localized therapies such as radiation. We hypothesize that genomic heterogeneity underlies the aggressive nature of mBLCA and significantly influences treatment response. To test this, we propose three integrated aims: (1) delineate the role of polyclonal seeding from oligometastatic disease in driving aggressive, treatment-resistant mBLCA; (2) elucidate the role of the Fanconi anemia (FANC) pathway in modulating cisplatin sensitivity and genomic scarring, using mechanistic and therapeutic perturbation studies; and (3) characterize tumor evolution and resistance mechanisms in patients treated with enfortumab vedotin and pembrolizumab, leveraging rapid autopsy specimens and serial ctDNA profiling. This proposal is conceptually and technically innovative. It leverages rare multi-organ sampling, histological variant patient-derived xenograft models, and a novel multi-clone dosing strategy to study clonal dynamics. It includes the first in-depth multi-omic characterization of cfDNA heterogeneity and proposes a therapeutic rationale for targeting clonality through radiation in oligometastatic disease. Completion of this work will provide a deep biological understanding of mBLCA progression, uncover new paradigms of treatment resistance, and inform precision medicine strategies to improve patient survival.