Project 1: Tumor Microenvironment Initiators of the Metastatic Cascade in High-Risk Prostate Cancer

Project Summary

There is an increasing incidence of men with newly diagnosed prostate cancer (PC) presenting with locally advanced or metastatic disease, a population that comprises >60% of the men who die from the disease. The failure of early detection has led to the initiation of multiple clinical trials testing neoadjuvant therapies in an attempt to cure these patients. Analysis of pre-treatment samples from neoadjuvant trials have identified genomic alterations that associate with a treatment resistance. More recent studies indicate the tumor microenvironment (TME) can initiate the metastatic cascade. However, it remains unclear how and when genomic alterations co-opt different cell types in a complex 3-dimensional TME to initiate the metastatic cascade. We have recently found that activated fibroblasts and macrophage sub-populations induce lymphovascular sprouting and permeability. Based on these data sets, we hypothesize that somatic alterations in tumor DNA co-opt stromal and immune cells in the TME to promote invasion and intravasation of lympho-vascular channels. To test this hypothesis, we have three cohorts of patients with high-risk prostate cancer (surgery alone, neoadjuvant Abiraterone, and neoadjuvant chemohormonal therapy) that undergo PSMA PET/MRI scans prior to surgery. This scan is used to develop 3D mold of the prostate to perform whole mount sectioning and dissection of multi-focal PC for multi-plex molecular analysis. Samples from these specimens are used to create patient-specific “TMEs on a Chip” using a humanized Micro-Physiologic System (MPS) of the prostate with surrounding lympho-vasculature. This novel model system allows culture of patient tumor cells and stromal cells to identify the factors that induce lymphatic permeability and culminate in tumor invasion and intravasation.
Success in these studies will identify the biologic interactions in the TME that can initiate the metastatic cascade as potential biomarkers and therapeutic targets for men with high-risk, locally advanced PC. In Aim 1 we will perform whole exome and transcriptome sequencing, across 3D whole mount sections identified by PSMA PET/MRI, in untreated patients to evaluate heterogeneity and determine the impact of neoadjuvant ARSIs and docetaxel across 3D multifocal PC. In Aim 2, we extend spatial mapping with PSMA PET/MRI and IHC data to perform transcriptional Digital Spatial Profiling (DSP) on whole-mount sections collected in Aim 1. This integration will test whether distinct CAF and immune cell infiltrates associate with genomic alterations in a spatial configuration of cells invading regional lymphovascular channels. In Aim 3, we use LumeNEXT MPS technology to create humanized lymphatic vessels cultured in patient-specific humanized prostate TMEs, with genomically engineered PC cells, that reflect the molecular and cellular signatures identified in Aims 1 and 2. When completed, the outcome of this work will advance the field by helping us to understand how prostate cancer metastasizes for both biomarker and drug development.

Specific Aims:

Aim 1 – To evaluate molecular features across multi-focal lesions associated with recurrence and
metastatic disease in high-risk prostate cancer.

Aim 2 – To identify the underlying molecular mechanisms in the prostate TME that initiate invasion and
metastatic disease.

Aim 3 – To examine functional alterations induced by cellular components and interactions in the
prostate TME that initiate the metastatic cascade.