A Phase 3, Randomized, Double-blind Trial of Pembrolizumab (MK-3475) Plus Enzalutamide Versus Placebo Plus Enzalutamide in Participants With Metastatic Castration-Resistant Prostate Cancer (mCRPC) (KEYNOTE-641)


Condition: Prostatic Neoplasms

Study Type: Interventional

Clinical Trials Identifier NCT 8-digits: NCT03834493

Sponsor: Merck Sharp & Dohme Corp.

Phase: Phase 3

Eligibility:

  • Age: minimum 18 Years maximum N/A
  • Gender: Male

Inclusion Criteria:

  • Has histologically- or cytologically-confirmed adenocarcinoma of the prostate without small cell histology
  • Has prostate cancer progression while on androgen deprivation therapy (or post bilateral orchiectomy) within 6 months prior to randomization
  • Has current evidence of metastatic disease documented by either bone lesions on bone scan and/or soft tissue disease by computed tomography/magnetic resonance imaging (CT/MRI)
  • Has met one of the following criteria with regard to abiraterone acetate exposure: (1) is abiraterone-naïve; (2) received prior abiraterone acetate for the treatment of mHSPC or mCRPC, for a minimum of 4 weeks and not progressed while on treatment; or (3) received prior abiraterone acetate for the treatment of mHSPC or mCRPC and progressed on treatment after a minimum of 8 weeks treatment (minimum 14 weeks for those with bone progression)
  • Has ongoing androgen deprivation with serum testosterone <50 ng/dL (<2.0 nM)
  • Participants receiving bone resorptive therapy (including, but not limited to, bisphosphonate or denosumab) must have been on stable doses prior to randomization
  • Participants must agree to the following during the study treatment period and for ≥90 days after the last dose of enzalutamide: Refrain from donating sperm PLUS Use contraception unless confirmed to be azoospermic (vasectomized or secondary to medical cause)
  • Participants must agree to use male condom when engaging in any activity that allows for passage of ejaculate to another person of any sex
  • Has provided newly obtained core or excisional biopsy (obtained within 12 months of screening) from soft tissue not previously irradiated (samples from tumors progressing in a prior site of radiation are allowed). Participants with bone only or bone predominant disease may provide a bone biopsy sample
  • Has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 assessed within 7 days of randomization.

Exclusion Criteria:

  • Has a known additional malignancy that is progressing or has required active treatment in the last 3 years
  • Has an active autoimmune disease that has required systemic treatment in past 2 years
  • Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy
  • Has undergone major surgery including local prostate intervention (excluding prostate biopsy) within 28 days prior to randomization and not recovered adequately from the toxicities and/or complications
  • Has a gastrointestinal disorder affecting absorption or is unable to swallow tablets/capsules
  • Has an active infection (including tuberculosis) requiring systemic therapy
  • Has a history of (non-infectious) pneumonitis that required steroids or current pneumonitis
  • Has known active human immunodeficiency virus (HIV), concurrent active hepatitis B virus (HBV) or known active hepatitis C virus (HCV) infection
  • Has known active central nervous system (CNS) metastases and/or carcinomatous meningitis
  • Has hypersensitivity to pembrolizumab and/or enzalutamide and/or any of their excipients
  • Has a history of seizure or any condition that may predispose to seizure
  • Has a history of loss of consciousness within 12 months of screening
  • Has hypotension (systolic blood pressure <86 millimeters of mercury [mmHg]) or uncontrolled hypertension (systolic blood pressure >170 mmHg or diastolic blood pressure >105 mmHg) at the screening visit
  • Has bradycardia (heart rate of <50 beats per minute) on the screening electrocardiogram (ECG)
  • Has history of prostate cancer progression on ketoconazole
  • Has had prior treatment with enzalutamide, apalutamide, darolutamide or cytochrome P450 (CYP) 17 inhibitor other than abiraterone acetate
  • Has received prior therapy with an anti-programmed cell death-1 (anti-PD-1), anti-programmed cell death-ligand 1 (anti-PD-L1), or anti PD-L2 agent or with an agent directed to another stimulatory or coinhibitory T-cell receptor
  • Has received prior treatment with radium or other therapeutic radiopharmaceuticals for prostate cancer
  • Has received prior treatment with docetaxel or another chemotherapy agent for mCRPC
  • Has had a prior anti-cancer monoclonal antibody (mAb) prior to randomization
  • Has used herbal products that may have hormonal anti-prostate cancer activity and/or are known to decrease PSA levels (eg, saw palmetto) prior to randomization
  • Has received a live vaccine within 30 days prior to randomization
  • Is currently participating in or has participated in a study of an investigational agent or has used an investigational device within 4 weeks prior to the first dose of study treatment
  • Has a "superscan" bone scan
  • Is expecting to conceive or father children within the projected duration of the study, starting with the screening visit through 90 days after the last dose of enzalutamide
  • Has had an allogenic tissue/solid organ transplant

View trial on ClinicalTrials.gov