Hormone Therapy (Apalutamide) and Image-guided Stereotactic Body Radiation Therapy for the Treatment of Patients With Prostate Cancer, HEATWAVE Trial

PRIMARY OBJECTIVE: I. To assess prostate specific antigen (PSA) complete response rates in patients with unfavorable intermediate risk prostate cancer who are receiving apalutamide monotherapy in conjunction with magnetic resonance imaging stereotactic body radiotherapy with precision dose-escalation and de-escalation to involved and uninvolved areas of the prostate, respectively. SECONDARY OBJECTIVES: I. Assessing time to biochemical recurrence (BCR; PSA ≥ nadir PSA + 2 ng/mL) among patients initially meeting primary endpoint. II. Assessing patient-reported genitourinary quality of life, as assessed by the Expanded Prostate Cancer Index Composite-26 (EPIC-26) survey instrument 24 months after radiotherapy completion. III. Assessing patient-reported bowel quality of life, as assessed by the EPIC-26 survey instrument 24 months after radiotherapy completion. IV. Assessing radiographic persistence of disease on a prostate specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) six months following hormonal therapy completion. V. Assessing radiographic persistence of disease on a multiparametric MRI at fixed intervals (i.e., 6, 12, 18, 24, 30) months after radiotherapy completion. VI. Assessment of longitudinal changes in patient-reported quality of life metrics on the EPIC-26 survey instrument. VII. Physician-reported acute and late toxicities as per the Common Terminology Criteria for Adverse Events (CTCAE) scale version (v)5.0. OUTLINE: Patients receive apalutamide orally (PO) once daily (QD) on days 1-28 of each cycle. Cycles repeat every 28 days for up to 6 or 12 months in the absence of disease progression or unacceptable toxicity. Patients undergo SBRT for 5 fractions over 1-2 weeks beginning on day 1 of cycle 1. Patients also undergo multiparametric MRI and collection of blood samples throughout the trial. Patients undergo PSMA-PET/CT scans during screening and follow up. After completion of study treatment, patients are followed up every 3 months for up to 24 months after SBRT and then up to 60 months after SBRT.