This phase Ib/II trial studies the side effects and best dose of venetoclax when given together with enzalutamide and to see how well they work in treating patients with castration resistant prostate cancer that has spread to other places in the body. Androgens can cause the growth of prostate cancer cells. Drugs, such as enzalutamide, may lessen the amount of androgens made by the body. Venetoclax may target a special group of prostate cancer cells that is known to lead to resistance to treatment. Giving enzalutamide and venetoclax may work better in treating patients with castration resistant prostate cancer.
PRIMARY OBJECTIVES: * To determine the dose-limiting toxicity (DLT), maximum tolerated dose (MTD), and recommended phase II dose (RP2D) of enzalutamide in combination with venetoclax in patients with metastatic castrate resistant prostate cancer (mCRPC). (Phase Ib) * To characterize the safety and tolerability profile of enzalutamide in combination with venetoclax in patients with metastatic castrate resistant prostate cancer (mCRPC). (Phase Ib) * To evaluate the efficacy of venetoclax in combination with enzalutamide in patients with metastatic castrate resistant prostate cancer (mCRPC) that are enzalutamide-naive, as measured by 12-month progression free survival rate. (Phase II) SECONDARY OBJECTIVES: * To assess PSA50 response as well as circulating tumor cell (CTC) response in patients who received venetoclax + enzalutamide. (Phase II) -To estimate the proportion of patients who received venetoclax + enzalutamide and remain radiographic progression free at 6 months. (Phase II) * To estimate the time to first skeletal-related event (SRE) and the time to first symptomatic skeletal event (SSE). (Phase II) \- To estimate the time to clinical progression. (Phase II) * To estimate the time to initiation of new systemic treatment for prostate cancer. (Phase II) * Assess the effect of venetoclax + enzalutamide on overall survival. (Phase II) PHARMACOKINETIC OBJECTIVES: I. To characterize the pharmacokinetic (PK) profiles of enzalutamide and venetoclax when given in combination to patients with metastatic castrate resistant prostate cancer (mCRPC). II. Comprehensive analyses of venetoclax levels to assure that they are in the therapeutic range. EXPLORATORY BIOMARKER OBJECTIVES: I. To identify non-inherited biomarkers that are predictive of response to study treatment (i.e., predictive biomarkers), are associated with progression to a more severe disease state (i.e., prognostic biomarkers), are associated with acquired resistance to study treatment, are associated with susceptibility to developing adverse events, can provide evidence of study treatment activity, can increase the knowledge and understanding of prostate cancer biology or study treatment mechanism of action, or can contribute to improvement of diagnostic assays. OUTLINE: This is a phase Ib, dose-escalation study of venetoclax followed by a phase II study. Patients receive venetoclax orally (PO) once daily (QD) and enzalutamide PO QD on days 1-28. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up for 1 year and then every 3 months.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
TREATMENT
Masking
NONE
Enrollment
10
Given PO
Given PO
Roswell Park Cancer Institute
Buffalo, New York, United States
Maximum tolerated dose (MTD) (Phase Ib)
The MTD will be determined based on the rate of dose-limiting toxicities (DLTs). Adverse events will be categorized and graded according to National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) version 5.0.
Time frame: Up to 28 days
Recommended phase 2 dose (RP2D) (Phase Ib)
Will be selected based on the overall tolerability of the regimen, but will not exceed the MTD.
Time frame: Up to 28 days
Progression free survival (Phase II)
Prostate Cancer Working Group (PCWG)3 will be used to evaluate PSA response and progression as well as progression on bone scans. Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 will be used to assess response and progression for nodal and visceral metastasis. The Kaplan-Meier product-limit estimator will be used.
Time frame: Time from start of treatment combination therapy to disease progression, assessed at 12 months
PSA50 (Phase II)
Will be defined as the proportion of patients with a \>= 50% reduction in PSA from baseline.
Time frame: Up to 3 years
Circulating tumor cell (CTC) conversion in patients who enter the trial with unfavorable CTCs (five or more cells per 7.5 mL of blood) (Phase II)
Conversion to favorable status is defined as four or fewer cells per 7. mL of blood.
Time frame: Up to 3 years
Radiographic (r)PFS (Phase II)
Will be defined per PCWG3.
Time frame: Time from day (D) 1 of treatment to the date when the first site of disease is found to progress (using a manifestation-specific definition off progression), or death, whichever occurs first, assessed up to 3 years
Proportion of patients who remain radiographic progression free defined per PCWG3 (Phase II)
Time frame: Tt 6 months
Overall response rate (ORR) (Phase II)
For patients with measurable soft tissue disease, ORR will be defined as the proportion of patients with a complete response (CR) or partial response (PR) per PCWG3.
Time frame: Up to 3 years
Duration of response (DOR) (Phase II)
Time frame: From the time measurement criteria are met for CR or PR (whichever status is recorded first) until the first date that radiographic progression is documented per PCWG3, assessed up to 3 years
Time to first skeletal-related event (SRE) (Phase II)
Time frame: Time from D1 of treatment to the date of first SRE, assessed up to 3 years
Time to clinical progression (Phase II)
Time frame: Time from D1 of treatment to the date of clinical progression, assessed up to 3 years
Time to initiation of new systemic treatment for prostate cancer (Phase II)
Time frame: Time from D1 of treatment to the date any new systemic treatment for prostate cancer is initiated, assessed up to 3 years
Overall survival (Phase II)
The Kaplan-Meier product-limit estimator will be used.
Time frame: From the time of initiation of the combination therapy until death from any cause, assessed up to 3 years
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