PRIMARY OBJECTIVE:
I. Recurrence-free survival (RFS).
SECONDARY OBJECTIVES:
I. Time to prostate-specific antigen (PSA) recurrence.
II. Change of PSA levels from baseline to the date of prostatectomy.
III. Overall survival.
IV. Metastasis-free survival.
V. PSA response.
VI. RFS at 36 months since randomization.
VII. Incidence of adverse events.
VIII. To quantify an anti-tumor response to enoblituzumab versus standard of care (SOC).
IX. To assess the immune response to enoblituzumab versus SOC.
X. To assess Gleason grade group before and after neoadjuvant enoblituzumab treatment versus SOC, by comparing prostatectomy Gleason sum to pre-treatment biopsy Gleason sum based on central review.
XI. To evaluate the proportion of pathological complete responses (pCR) in prostate tumor specimens of treated patients.
EXPLORATORY OBJECTIVES:
I. Quality of life: Functional Assessment of Cancer Therapy (FACT).
II. To quantify B7-H3 immunohistochemistry (IHC) expression in pre-treatment and post-treatment tumor tissue and correlate with tumor cell apoptosis and time to recurrence.
III. To quantify checkpoint IHC expression (e.g., PD-1, PD-L1, LAG3 and TIM3) in intrapatient pre and post treatment tumor tissue, and interpatient prostates from harvested prostate glands of enoblituzumab versus SOC patients.
IV. Determination of the prevalence of tumor cell free deoxyribonucleic acid (cfDNA), circulating tumor DNA (ctDNA), and tumor vesicle associated DNA/ribonucleic acid (RNA) in this patient population as a biomarker of longitudinal response or resistance when compared to progression-free survival (PFS), metastases-free survival (MFS), and overall survival (OS).
V. IHC analyses of CD137, CD16 and/or CD107A across potential immune infiltrate following enoblituzumab (based on proposed mechanism of action [MoA]).
VI. Global expression profiling of pre and post treatment tumor tissue in treated and untreated prostatectomies using spatial transcriptomics and proteomics.
VII. Global metabolomic profiling of tumor tissue in treated and untreated prostatectomies.
VIII. T-cell receptor (TCR) deep sequencing (Adaptive Biotech) testing hypothesis that successful anti-tumor response modulates TCR repertoire in peripheral and tumor infiltrating lymphocytes.
IX. Whole genome sequencing of tumor tissue in treated and untreated prostatectomies.
X. Long-read whole-genome sequencing analysis of DNA methylation of tumor tissue in treated and untreated prostatectomies.
XI. Single cell RNA sequencing of tumor tissue in treated and untreated prostatectomies.
XII. Flow cytometric analysis of peripheral blood cell population compositions pre-treatment, on-treatment, and post-treatment.
XIII. Quantification of baseline and pre-prostatectomy blood cytokines and chemokines.
XIV. Assessment of congruence between conventional (computed tomography [CT] and bone scans) imaging and prostate-specific membrane antigen (PSMA) imaging.
OUTLINE: Patients are randomized to 1 of 2 arms.
ARM I: Patients receive enoblituzumab intravenously (IV) over 120 minutes on days 1, 15, 29, 43, 57 and 71 in the absence of disease progression or unacceptable toxicity. Patients undergo radical prostatectomy on day 84. Patients undergo urine, stool, and blood sample collection, CT or magnetic resonance imaging (MRI) and bone scan. Patients also undergo prostatic MRI and optional digital rectal examination at screening and PSMA positron emission tomography (PET) scan at screening and optionally throughout the study. Additionally, patients may optionally undergo bone marrow aspiration on study.
ARM II: Patients undergo radical prostatectomy 4-8 weeks after day 1. Patients undergo urine, stool, and blood sample collection, CT or MRI and bone scan. Patients also undergo prostatic MRI and optional digital rectal examination at screening and PSMA PET scan at screening and optionally throughout the study. Additionally, patients may optionally undergo bone marrow aspiration on study.
After completion of surgery, patients are followed up at 30 and 90 days, then every 3 months during year 1 followed by every 6 months during years 2-5.