Work in the Cynthia Sears Laboratory focuses on the bacterial contributions to the development of human colon cancer and the impact of the microbiome on other cancers and the therapy of cancer. The current work involves mouse and human studies to define how enterotoxigenic Bacteroides fragilis, pks+ Escherichia coli, Fusobacterium nucleatum, biofilms and the colonic microbiota induce chronic colonic inflammation and colon cancer. Prospective human studies of the microbiome and biofilms in screening colonoscopy are in progress as are studies to determine if and how the microbiome impacts the response of individuals with cancer to immunotherapy and other cancer therapies.

The Brennen laboratory takes a rigorous, multi-disciplinary, team-based approach towards developing innovative therapeutic and prognostic strategies for prostate cancer with an emphasis on exploiting vulnerabilities within the tumor microenvironment towards this goal. To accomplish this goal, we are strategically pursuing novel therapeutic platforms, including stromal-targeted prodrugs, protoxins, and radiolabeled antibodies, in addition to cell-based therapy and drug delivery; all of which are designed to reduce toxicity to peripheral non-target tissue (i.e. side effects) while maximizing anti-tumor efficacy (i.e. therapeutic benefit). Currently, many of these strategies are focused on overcoming stromal barriers to anti-tumor immune responses such that men suffering from prostate cancer can share in the immense, revolutionary power of immunotherapy that is transforming care for many with advanced disease in other tumor types previously thought to be unmanageable using conventional approaches. Unfortunately, prostate cancer has largely proven refractory to these powerful approaches thus far and requires novel mono- or combinatorial treatment strategies to unleash the full potential of the immune system and generate personalized anti-tumor responses with the capability of producing long-term durable responses or even cures in these men.

Our Molecular Oncology lab seeks to understand the genomic wiring of response and resistance to immunotherapy through integrative genomic, transcriptomic, single-cell and liquid biopsy analyses of tumor and immune evolution. Through comprehensive exome-wide sequence and genome-wide structural genomic analyses we have discovered that tumor cells evade immune surveillance by elimination of immunogenic mutations and associated neoantigens through chromosomal deletions. Additionally, we have developed non-invasive molecular platforms that incorporate ultra-sensitive measurements of circulating cell-free tumor DNA (ctDNA) to assess clonal dynamics during immunotherapy. These approaches have revealed distinct dynamic ctDNA and T cell repertoire patterns of clinical response and resistance that are superior to radiographic response assessments. Our work has provided the foundation for a molecular response-adaptive clinical trial, where therapeutic decisions are made not based on imaging but based on molecular responses derived from liquid biopsies. Overall, our group focuses on studying the temporal and spatial order of the metastatic and immune cascade under the selective pressure of immune checkpoint blockade with the ultimate goal to translate this knowledge into “next-generation” clinical trials and change the way oncologists select patients for immunotherapy.