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Pembrolizumab in Treating Patients With Metastatic Castration Resistant Prostate Cancer Previously Treated With Enzalutamide

Addition of Pembrolizumab Upon Progression on Enzalutamide in Men With mCRPC

Status
Active, not recruiting
Phases
Phase 2
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT02312557
Enrollment
58
Registered
2014-12-09
Start date
2014-11-18
Completion date
2026-10-31
Last updated
2026-05-14

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Castration-Resistant Prostate Carcinoma, Hormone-Resistant Prostate Cancer, PSA Progression, Recurrent Prostate Carcinoma, Stage IV Prostate Adenocarcinoma Cancer AJCC v8

Brief summary

This phase II trial studies how well pembrolizumab works in treating patients with prostate cancer that has spread to other places in the body and keeps growing even when the amount of testosterone in the body is reduced to very low levels despite previous treatment with enzalutamide. Monoclonal antibodies, such as pembrolizumab, may block tumor growth in different ways by targeting certain cells.

Detailed description

PRIMARY OBJECTIVES: I. Measure the anti-cancer activity of pembrolizumab in men with metastatic, castration resistant prostate cancer. SECONDARY OBJECTIVES: I. To investigate immunological and genetic parameters to evaluate for possible markers and functional changes that are predictive of a clinical response or linked to response or resistance to PD-1 inhibition. II. To collect circulating tumor cells (CTCs) and determine the degree to which tumor characteristics are shared by the CTCs. III. Changes in T cell numbers, activation, and phenotype as measured in whole blood at diagnosis and throughout therapy. IV. Systemic inflammatory markers: serum interleukin (IL)-8, IL-6, IL-1, tumor necrosis factor (TNF) and transforming growth factor (TGF)-beta. V. Objective disease response by radiographs. VI. Prostate-specific antigen (PSA) progression free survival. VII. Overall survival. VIII. Microbiome and correlation with response. TERTIARY OBJECTIVES: I. Additional genetic (deoxyribonucleic acid \[DNA\], ribonucleic acid \[RNA\]) and protein analyses will be conducted to further evaluate immunotherapy and profile/characterize disease. OUTLINE: INITIAL TREATMENT PHASE: Patients who are progressing on enzalutamide will receive pembrolizumab intravenously (IV) over 30 minutes on day 1. Treatment repeats every 3 weeks for 4 courses in the absence of disease progression or unacceptable toxicity. Patients continue to receive standard of care enzalutamide orally (PO) daily. MONITORING PHASE: After completion of the initial treatment phase, patients continue to receive standard of care enzalutamide PO daily for the duration of the trial. RETREATMENT PHASE: Patients with disease response or stability after the initial treatment phase will receive pembrolizumab IV over 30 minutes on day 1. Treatment repeats every 3 weeks for an additional 4 courses in the absence of disease progression or unacceptable toxicity. Patients continue to receive standard of care enzalutamide PO daily for the duration of the trial. After completion of study treatment, patients are followed up at 30 days, and then every 12 weeks for 2.5 years.

Interventions

DRUGEnzalutamide

Given PO

OTHERLaboratory Biomarker Analysis

Correlative studies

BIOLOGICALPembrolizumab

Given IV

Sponsors

OHSU Knight Cancer Institute
Lead SponsorOTHER
Merck Sharp & Dohme LLC
CollaboratorINDUSTRY
Collins Medical Trust
CollaboratorOTHER
Oregon Health and Science University
CollaboratorOTHER

Study design

Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
NONE

Eligibility

Sex/Gender
MALE
Age
18 Years to No maximum
Healthy volunteers
No

Inclusion criteria

* ENTRY CRITERIA: Metastatic, castration resistant prostate cancer progressing on enzalutamide after initial response to enzalutamide * Histologically or cytologically confirmed adenocarcinoma of the prostate without pure small cell carcinoma; patients without histologically confirmed adenocarcinoma may be eligible if both the treating physician and the study principal investigator (PI) agree that the patient?s history is unambiguously indicative of advanced adenocarcinoma * Be willing and able to provide written informed consent/assent for the trial * Be \>= 18 years of age on day of signing informed consent * Have metastatic disease * Have permission to access tissue from an archival tissue sample; (absence of archival tissue will not preclude trial participation) * Has a metastatic deposit that can be biopsied * Have a performance status of 0 or 1 on the Eastern Cooperative Oncology Group (ECOG) performance scale * Absolute neutrophil count (ANC) \>= 1,500/mcL, performed within 28 days of treatment initiation * Platelets \>= 100,000/mcL, performed within 28 days of treatment initiation * Hemoglobin \>= 9 g/dL or \>= 5.6 mmol/L, performed within 28 days of treatment initiation * Serum creatinine =\< 1.5 X upper limit of normal (ULN) OR measured or calculated creatinine clearance \>= 60 mL/min for subject with creatinine levels \> 1.5 X institutional ULN (glomerular filtration rate \[GFR\] can also be used in place of creatinine or creatinine clearance \[CrCl\]); creatinine clearance should be calculated per institutional standard, performed within 28 days of treatment initiation * Serum total bilirubin =\< 1.5 X ULN OR direct bilirubin =\< ULN for subjects with total bilirubin levels \> 1.5 ULN, performed within 28 days of treatment initiation * Aspartate aminotransferase (AST) (serum glutamic oxaloacetic transaminase \[SGOT\]) and alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase \[SGPT\]) =\< 2.5 X ULN OR =\< 5 X ULN for subjects with liver metastases, performed within 28 days of treatment initiation * International normalized ratio (INR) or prothrombin time (PT) =\< 1.5 X ULN unless subject is receiving anticoagulant therapy as long as PT or partial thromboplastin time (PTT) is within therapeutic range of intended use of anticoagulants (only if submitting to a biopsy), performed within 28 days of treatment initiation * Activated partial thromboplastin time (aPTT) =\< 1.5 X ULN unless subject is receiving anticoagulant therapy as long as PT or PTT is within therapeutic range of intended use of anticoagulants (only if submitting to a biopsy), performed within 28 days of treatment initiation * Male subjects should agree to use an adequate method of contraception starting with the first dose of study therapy through 120 days after the last dose of study therapy * Have a PSA or radiographic progression on enzalutamide; PSA progression is defined as two consecutive increases in PSA with the second level obtained at least 3 weeks after the first, and the second level of at least 0.5 ng/mL; soft tissue disease progression defined by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 criteria or \>= 2 new lesions on bone scan * Have had either surgical castration OR be on luteinizing hormone-releasing hormone (LHRH) agonist or antagonist therapy with serum testosterone \< 50 ng/dl AND agree to stay on LHRH agonist or antagonist therapy during the study

Exclusion criteria

* Is currently participating in or has participated in a study of an investigational agent or using an investigational device within 4 weeks of the first dose of treatment * Has a diagnosis of immunodeficiency or is receiving systemic steroid therapy or any other form of immunosuppressive therapy within 7 days prior to the first dose of trial treatment; the use of physiologic doses of corticosteroids may be approved after consultation with the sponsor * Has had a prior monoclonal antibody within 4 weeks prior to study day 1 or who has not recovered (i.e., =\< grade 1 or at baseline) from adverse events due to agents administered more than 4 weeks earlier; denosumab is a prohibited medication on study and for 4 weeks prior to day 1 * Has had chemotherapy for castration-resistant disease; chemotherapy for castration-sensitive disease is permitted * Has had prior chemotherapy, targeted small molecule therapy, or radiation therapy within 2 weeks prior to study day 1 or who has not recovered (i.e., =\< grade 1 or at baseline) from adverse events due to a previously administered agent * Note: subjects with =\< grade 2 neuropathy are an exception to this criterion and may qualify for the study * Note: if subject received major surgery, they must have recovered adequately from the toxicity and/or complications from the intervention prior to starting therapy * Has a known additional malignancy that is progressing or requires active treatment; exceptions include basal cell carcinoma of the skin, squamous cell carcinoma of the skin, or in situ bladder cancer that has undergone potentially curative therapy * Has known brain metastases and/or carcinomatous meningitis * Has a history of seizure * Has allergy to enzalutamide * Has an active autoimmune disease requiring systemic treatment within the past 3 months or a documented history of clinically severe autoimmune disease, or a syndrome that requires systemic steroids or immunosuppressive agents; a severe autoimmune disease is one that requires a significant medical intervention such as hospitalization; subjects with vitiligo or resolved childhood asthma/atopy would be an exception to this rule; subjects that require intermittent use of bronchodilators or local steroid injections would not be excluded from the study; subjects with hypothyroidism stable on hormone replacement or Sjogren?s syndrome will not be excluded from the study * Has a history of (non-infectious) pneumonitis that required steroids or current pneumonitis * Has an active infection requiring systemic therapy * Has a history or current evidence of any condition, therapy, or laboratory abnormality that might confound the results of the trial, interfere with the subject?s participation for the full duration of the trial, or is not in the best interest of the subject to participate, in the opinion of the treating investigator * Has known psychiatric or substance abuse disorders that would interfere with cooperation with the requirements of the trial * Has received prior therapy with an anti-programmed cell death (PD)-1, anti-PD-ligand (L)1, anti-PD-L2, anti-cluster of differentiation (CD)137, or anti-cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) antibody (including ipilimumab or any other antibody or drug specifically targeting T-cell co-stimulation or checkpoint pathways); previous treatment with sipuleucel-T is permitted * Has plans to receive cytotoxic chemotherapy, immune checkpoint inhibitors (eg CTLA-4 blockade), sipuleucel-T, radiopharmaceuticals, abiraterone or other experimental therapy during this study period * Has a known history of human immunodeficiency virus (HIV) (HIV 1/2 antibodies) * Has known active hepatitis B (e.g., hepatitis B virus surface antigen \[HBsAg\] reactive) or hepatitis C (e.g., hepatitis C virus \[HCV\] ribonucleic acid \[RNA\] \[qualitative\] is detected) * Has received a live vaccine within 30 days prior to the first dose of trial treatment * Has rapid progression of visceral disease and, thus is a candidate for docetaxel; this determination will be at the discretion of the treating physician

Design outcomes

Primary

MeasureTime frameDescription
PSA Response, Defined by a PSA Decrease of at Least 50% Confirmed by a Second Measurement at Least 3 Weeks LaterUp to 30 days after completion of study treatment, up to approximately 2.5 years total.One-sample binomial test will be used to assess whether the proportion of PSA response (PSA decrease of at least 50%) is significantly greater than 0.05. Univariable logistic regression analysis will be conducted to assess the association between immunological parameters and PSA response responses. Scale in logit will be assessed for all continuous parameters that are identified to be significantly associated with PSA response. Descriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval.

Secondary

MeasureTime frameDescription
Changes in T Cell Activation as Measured in Whole BloodBaseline to up to 4 weeksDescriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval, and the continuous variables will be summarized using nmissing, mean, std, median, min, and max.
Changes in T Cell Numbers as Measured in Whole BloodBaseline to up to 4 weeksDescriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval, and the continuous variables will be summarized using nmissing, mean, std, median, min, and max.
Changes in T Cell Phenotype as Measured in Whole BloodBaseline to up to 4 weeksDescriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval, and the continuous variables will be summarized using nmissing, mean, std, median, min, and max.
Circulating Tumor CellsUp to 4 weeksDescriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval, and the continuous variables will be summarized using nmissing, mean, std, median, min, and max.
Deoxyribonucleic Acid MutationUp to 2.5 years
Immunohistochemistry for PD-1, PD-L1 and PD-L2 in Prostate TissueBaselineDescriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval, and the continuous variables will be summarized using nmissing, mean, std, median, min, and max.
Immunological Parameters, Including Leukocytes, Lymphocytes, and Macrophages in Prostate TissueBaselineDescriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval, and the continuous variables will be summarized using nmissing, mean, std, median, min, and max.
Objective Disease Response by RadiographsUp to 2.5 yearsDescriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval.
Overall SurvivalUp to 2.5 years
Percent Change in PSABaseline to up to 30 days after completion of study treatmentDescriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval, and the continuous variables will be summarized using number (n)missing, mean, standard deviation (std), median, minimum (min), and maximum (max).
PSA Progression Free Survival, Where the Definition of Progression Will be PSA Progression Per Prostate Cancer Working Group 2 CriteriaUp to 2.5 yearsIf there is a decline from baseline, progression is an increase in PSA that is 25% and 2 ng/ml above the nadir, which is confirmed by a second value 3 or more weeks later (i.e., a confirmed rising trend). Kaplan-Meier curve will be plotted to illustrate the PSA progression free survival for all, and for subgroups (abiraterone versus no prior abiraterone and sipuleucel-T versus no prior sipuleucel-T).
Systemic Inflammatory Markers (Serum IL-8, IL-6, IL-1, TNF and TGF-beta)Up to 4 weeksDescriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval, and the continuous variables will be summarized using nmissing, mean, std, median, min, and max.

Countries

United States

Contacts

PRINCIPAL_INVESTIGATORJulie Graff, M.D.

OHSU Knight Cancer Institute

Participant flow

Participants by arm

ArmCount
Treatment (Pembrolizumab)
INITIAL TREATMENT PHASE: Patients who are progressing on enzalutamide will receive pembrolizumab IV over 30 minutes on day 1. Treatment repeats every 3 weeks for 4 courses in the absence of disease progression or unacceptable toxicity. Patients continue to receive standard of care enzalutamide PO daily. MONITORING PHASE: After completion of the initial treatment phase, patients continue to receive standard of care enzalutamide PO daily for the duration of the trial. RETREATMENT PHASE: Patients with disease response or stability after the initial treatment phase will receive pembrolizumab IV over 30 minutes on day 1. Treatment repeats every 3 weeks for an additional 4 courses in the absence of disease progression or unacceptable toxicity. Patients continue to receive standard of care enzalutamide PO daily for the duration of the trial. Enzalutamide: Given PO Laboratory Biomarker Analysis: Correlative studies Pembrolizumab: Given IV
58
Total58

Baseline characteristics

CharacteristicTreatment (Pembrolizumab)
Age, Categorical
<=18 years
0 Participants
Age, Categorical
>=65 years
46 Participants
Age, Categorical
Between 18 and 65 years
12 Participants
Ethnicity (NIH/OMB)
Hispanic or Latino
1 Participants
Ethnicity (NIH/OMB)
Not Hispanic or Latino
51 Participants
Ethnicity (NIH/OMB)
Unknown or Not Reported
6 Participants
Race (NIH/OMB)
American Indian or Alaska Native
0 Participants
Race (NIH/OMB)
Asian
1 Participants
Race (NIH/OMB)
Black or African American
0 Participants
Race (NIH/OMB)
More than one race
0 Participants
Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
0 Participants
Race (NIH/OMB)
Unknown or Not Reported
7 Participants
Race (NIH/OMB)
White
50 Participants
Region of Enrollment
Canada
1 participants
Region of Enrollment
United States
57 participants
Sex: Female, Male
Female
0 Participants
Sex: Female, Male
Male
58 Participants

Adverse events

Event typeEG000
affected / at risk
deaths
Total, all-cause mortality
3 / 58
other
Total, other adverse events
55 / 58
serious
Total, serious adverse events
27 / 58

Outcome results

Primary

PSA Response, Defined by a PSA Decrease of at Least 50% Confirmed by a Second Measurement at Least 3 Weeks Later

One-sample binomial test will be used to assess whether the proportion of PSA response (PSA decrease of at least 50%) is significantly greater than 0.05. Univariable logistic regression analysis will be conducted to assess the association between immunological parameters and PSA response responses. Scale in logit will be assessed for all continuous parameters that are identified to be significantly associated with PSA response. Descriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval.

Time frame: Up to 30 days after completion of study treatment, up to approximately 2.5 years total.

ArmMeasureValue (COUNT_OF_PARTICIPANTS)
Treatment (Pembrolizumab)PSA Response, Defined by a PSA Decrease of at Least 50% Confirmed by a Second Measurement at Least 3 Weeks Later11 Participants
p-value: <0.0195% CI: [0.09, 0.29]One-sample binomial test of proportion
Secondary

Changes in T Cell Activation as Measured in Whole Blood

Descriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval, and the continuous variables will be summarized using nmissing, mean, std, median, min, and max.

Time frame: Baseline to up to 4 weeks

Secondary

Changes in T Cell Numbers as Measured in Whole Blood

Descriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval, and the continuous variables will be summarized using nmissing, mean, std, median, min, and max.

Time frame: Baseline to up to 4 weeks

Secondary

Changes in T Cell Phenotype as Measured in Whole Blood

Descriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval, and the continuous variables will be summarized using nmissing, mean, std, median, min, and max.

Time frame: Baseline to up to 4 weeks

Secondary

Circulating Tumor Cells

Descriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval, and the continuous variables will be summarized using nmissing, mean, std, median, min, and max.

Time frame: Up to 4 weeks

Secondary

Deoxyribonucleic Acid Mutation

Time frame: Up to 2.5 years

Secondary

Immunohistochemistry for PD-1, PD-L1 and PD-L2 in Prostate Tissue

Descriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval, and the continuous variables will be summarized using nmissing, mean, std, median, min, and max.

Time frame: Baseline

Secondary

Immunological Parameters, Including Leukocytes, Lymphocytes, and Macrophages in Prostate Tissue

Descriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval, and the continuous variables will be summarized using nmissing, mean, std, median, min, and max.

Time frame: Baseline

Secondary

Objective Disease Response by Radiographs

Descriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval.

Time frame: Up to 2.5 years

Secondary

Overall Survival

Time frame: Up to 2.5 years

ArmMeasureValue (MEDIAN)
Treatment (Pembrolizumab)Overall Survival17.6 months
Secondary

Percent Change in PSA

Descriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval, and the continuous variables will be summarized using number (n)missing, mean, standard deviation (std), median, minimum (min), and maximum (max).

Time frame: Baseline to up to 30 days after completion of study treatment

Secondary

PSA Progression Free Survival, Where the Definition of Progression Will be PSA Progression Per Prostate Cancer Working Group 2 Criteria

If there is a decline from baseline, progression is an increase in PSA that is 25% and 2 ng/ml above the nadir, which is confirmed by a second value 3 or more weeks later (i.e., a confirmed rising trend). Kaplan-Meier curve will be plotted to illustrate the PSA progression free survival for all, and for subgroups (abiraterone versus no prior abiraterone and sipuleucel-T versus no prior sipuleucel-T).

Time frame: Up to 2.5 years

ArmMeasureValue (MEDIAN)
Treatment (Pembrolizumab)PSA Progression Free Survival, Where the Definition of Progression Will be PSA Progression Per Prostate Cancer Working Group 2 Criteria4.3 months
Secondary

Systemic Inflammatory Markers (Serum IL-8, IL-6, IL-1, TNF and TGF-beta)

Descriptive statistical analysis will be conducted. The proportion estimate will be reported with 95% confidence interval, and the continuous variables will be summarized using nmissing, mean, std, median, min, and max.

Time frame: Up to 4 weeks

Source: ClinicalTrials.gov · Data processed: May 15, 2026