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2023 Regeneron – PCF Special Challenge Award

A Pilot Presurgical Trial of REGN5678 (Anti-PSMAxCD28) In Patients with High-Risk, Localized Prostate Cancer Followed by Radical Prostatectomy

Principal Investigators: Padmanee Sharma, MD, PhD (The University of Texas MD Anderson Cancer Center), Sumit Subudhi, MD, PhD (The University of Texas MD Anderson Cancer Center), Brian Chapin, MD (The University of Texas MD Anderson Cancer Center), Bilal Siddiqui, MD (The University of Texas MD Anderson Cancer Center)

Description:

  • PSMA is a protein that is highly expressed on prostate cancer cells and is a promising therapeutic and imaging target.
  • Prostate cancer is typically “immunologically cold,” meaning the immune system does not effectively recognize prostate cancer and immunotherapies are rarely effective. New approaches are needed to harness the immune system to recognize and target prostate cancer.
  • Anti-PSMAxCD28 (REGN5678) is a new experimental immunotherapy treatment that simultaneously targets PSMA on prostate cancer cells and CD28 on T cells. This treatment brings T cells into direct contact with tumor cells, activating the T cells to kill tumor cells.
  • Drs. Sumit Subudhi, Bilal Siddiqui, Brian Chapin and team are conducting a phase 1/2 clinical trial testing the safety and tolerability of REGN5678 in patients with high-risk localized prostate cancer who are scheduled for radical prostatectomy.
  • In this project, Dr. Padmanee Sharma and her team will use samples from this trial to identify biomarkers of response and mechanisms of treatment resistance to REGN5678.
  • Mechanisms of action and how the treatment impacts immune responses in the prostate tumor microenvironment and peripheral blood will be investigated.
  • The potential for PSMA PET/CT and FDG PET/CT as molecular imaging biomarkers to identify patients who are more or less likely to benefit from the treatment will be explored.
  • If successful, this project will establish the safety and preliminary efficacy of REGN5678 in patients with high-risk localized prostate cancer and identify biomarkers for selecting patients for this treatment and mechanisms of treatment response or resistance.

What this means to patients: Dr. Sharma and team are studying the efficacy of a new immunotherapy treatment, anti-PSMAxCD28 (REGN5678), that enables T cells to directly bind and kill prostate cancer cells. The team is conducting a clinical trial testing REGN5678 and in this project, will perform correlative studies to understand mechanisms of action or resistance and identify biomarkers for identifying patients who may benefit from REGN5678. This may result in a new curative treatment approach for patients with high-risk localized prostate cancer.