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2020 Larry Ruvo-PCF Young Investigator Award

Validating a PET Imaging Biomarker for Targeting Fibroblast Activation Protein in Prostate Cancer Stroma

Jeremie Calais, MD

University of California, Los Angeles

Mentors: Johannes Czernin, MD; Matt Rettig, MD; Robert Reiter, MD

Description:

  • Tumors are composed of cancer cells and surrounded by the “stroma”. The stroma essentially consists of cancer supportive structures. Stromal cells are not cancer cells but are primarily fibroblasts, immune cells, and blood vessels. Cancer associated fibroblasts are an essential component of the tumor stroma as they support tumor growth and invasiveness, can help cancer cells evade immune responses, and aid in therapy resistance by acting as a physical barrier to prevent drug access.
  • Dr. Jeremie Calais is studying the potential for the cancer associated fibroblast protein FAP as a new target for treatments and cancer imaging agents in prostate cancer.
  • In this project, Dr. Calais will study a new FAP-targeting tracer,68Ga-FAPi-46, as a PET imaging agent for prostate cancer.
  • To validate FAP as a biomarker in prostate cancer, the incidence, extent and degree of FAP protein levels will be evaluated in early vs. advanced stage prostate cancer samples.
  • A clinical trial will be conducted to determine the potential for68Ga-FAPi-46 as a FAP-targeted PET imaging agent. Patients scheduled for a surgical excision or biopsy of a primary or metastatic lesion will first undergo FAPi PET imaging and PSMA-PET imaging. Results from FAPi-PET will be compared with PSMA-PET to determine the performance of FAPi-PET for detecting prostate cancer.
  • FAPi-PET results will also be compared with direct FAP protein level measurements in biopsy and surgical samples from the same patients, to determine how well FAPi-PET corresponds with FAP protein levels in tumors.
  • Whether FAPi-PET imaging correlates with prostate cancer clinical indicators such as PSA levels and Gleason grade will also be determined.
  • If successful, this project will validate the potential for FAPi-PET as a new prostate cancer imaging agent and be used to identify patients who may benefit from FAP-targeted treatments.

What this means to patients: Dr. Calais is developing a novel prostate cancer imaging agent, FAPi-PET, which looks at tumor stroma instead of the tumor cells themselves.This project will determine the performance of FAPi-PET for prostate cancer detection and prognosis, and will be used to launch the development of new FAP-targeting precision medicines.