A Phase 2 Trial of Darolutamide as a Prostate-Specific Membrane Antigen (PSMA) Expression Enhancer in Patients With Localized Prostate Cancer

Prostate cancer is the second leading cause of cancer death in men. According to estimates by the American Cancer Society Prostate for 2022, about 268,490 men would be diagnosed with prostate cancer and 34,500 would die from the disease. Clinical evolution follows the clinical stages are: localized disease, biochemical recurrence after surgery or radiotherapy, and castration-sensitive or castration-resistant metastatic disease. Localized disease is often classified according to a risk stratification system, which includes assessment of the Gleason score, prostate-specific antigen (PSA) at diagnosis, number of involved fragments per disease at biopsy, and clinical T-staging. Gleason score greater than or equal to 8, PSA greater than or equal to 20 ng/dL at diagnosis, and/or involvement of the prostatic capsule or seminal vesicle are high-risk criteria for biochemical recurrence and later development of metastases, for which the standard treatment is radical prostatectomy or radiotherapy plus androgen deprivation therapy. Prostate-specific membrane antigen (PSMA) is highly expressed on the surface of prostate cancer cells, with relatively low expression in normal tissue. PSMA has been explored as a target in imaging studies using positron emission tomography (PSMA-PET) to reveal occult metastatic disease, as well as a target in the development of PSMA-based treatments with radioligands. According to Hoffman et al., performing PSMA-PET demonstrated greater sensitivity (85% vs. 38%) and specificity (98% vs. 91%), and determined more changes in patient management (28% vs. 15% ) compared to conventional images. Other studies have also demonstrated the greater accuracy of PSMA-based radiotracers compared to conventional images. Finding strategies that increase PSMA expression is a necessity for patients with prostate cancer. According to researchers, high SUVmax values are associated with better outcomes in patients treated with 177-lutetium-PSMA-617. PSMA expression can be rapidly modulated by androgen suppression. The investigators understand that there is great potential to evaluate darolutamide as a PSMA expression enhancer. However, to date there are no prospective data evaluating the effect of ARSI in increasing PSMA expression in localized disease. Here the investigators propose a phase 2 study to investigate the efficacy of a limited course of darolutamide as a PSMA expression enhancer in men with localized prostate cancer according to conventional imaging. PSMA-PET/CT scans will be acquired before and after treatment with darolutamide, as detailed in the protocol. Slides of prostate biopsies and prostatectomies stained with hematoxylin and eosin (H&E) will be reviewed by two pathologists to select the most representative tumor block. Immunohistochemical (IHC) reaction using standard protocols will be performed using an anti-PSMA antibody and intraprostatic anti-androgens. Gene expression analysis will be performed using RNA extracted from biopsies and prostatectomies and evaluated by a panel of over 300 transcripts. For methylation patterns, hematoxylin and eosin (H&E) slides from prostate biopsies and prostatectomies will undergo DNA extraction and evaluation of the methylation profile performed using a kit. It is expected to identify that treatment with darolutamide increases PSMA expression and that the biochemical mechanisms involved can be better evidenced.