Pertuzumab, Trastuzumab, Hyaluronidase-zzxf and Enzalutamide for Treatment of Metastatic Castration-Resistant Prostate Cancer

This phase II trial tests how well pertuzumab, trastuzumab, hyaluronidase-zzxf and enzalutamide works in treating patients with castration-resistant prostate cancer that has spread from where it first started to other places in the body (metastatic). Pertuzumab and trastuzumab are monoclonal antibodies and forms of targeted therapy that attach to a receptor protein called human epidermal growth factor receptor-2 (HER2). HER2 is found on some cancer cells. When pertuzumab or trastuzumab attach to HER2, the signals that tell the cells to grow are blocked and the tumor cell may be marked for destruction by the body's immune system. Hyaluronidase is an endoglycosidase. It helps to keep pertuzumab and trastuzumab in the body longer, so that these medications will have a greater effect. Hyaluronidase also allows pertuzumab and trastuzumab to be given by injection under the skin and shortens their administration time compared to pertuzumab or trastuzumab alone. Chemotherapy drugs, such as enzalutamide, work in different ways to stop the growth of cancer cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Giving pertuzumab, trastuzumab, hyaluronidase-zzxf and enzalutamide may kill more cancer cells.

PRIMARY OBJECTIVE: I. Evaluate the preliminary efficacy of the combination of pertuzumab, trastuzumab, and hyaluronidase-zzxf plus enzalutamide with regard to objective response rate (Prostate Cancer Clinical Trials Working Group 3 \[PCWG 3.0\]) in enzalutamide-refractory metastatic castration-resistant prostate cancer. SECONDARY OBJECTIVES: I. Estimate the radiographic progression-free survival for this combination. II. Estimate the overall survival for this combination. EXPLORATORY OBJECTIVES: I. Assessment of this combination for adverse events according to clinical judgment and patient-reported outcomes (Patient Reported Outcomes-Common Terminology Criteria for Adverse Events \[PRO-CTCAE\] - Prostate Cancer). II. Assessment of patient quality of life using Functional Assessment of Cancer Therapy- Prostate (FACT-P) questionnaire. CORRELATIVE OBJECTIVES: I. Determine the correlation between outcomes as above and systemic NRG-1 levels at baseline and over time. II. Determine the correlation between outcomes as above and change in HER2/HER3/androgen receptor (AR) gene signatures. OUTLINE: Patients receive pertuzumab, trastuzumab, and hyaluronidase-zzxf subcutaneously (SC) on day 1 of each cycle and enzalutamide orally (PO) once daily (QD) on days 1-21 of each cycle. Cycles repeat every 21 days in the absence of disease progression or unacceptable toxicity. Patients undergo echocardiography (ECHO), biopsy, computed tomography (CT), and magnetic resonance imaging (MRI) scans and collection of blood samples throughout the study. After completion of study treatment, patients are followed up every 3 months until progressive disease then every 6 months thereafter.