Efficacy and Safety of Pembrolizumab (MK-3475) Plus Enzalutamide Plus Androgen Deprivation Therapy (ADT) Versus Placebo Plus Enzalutamide Plus ADT in Participants With Metastatic Hormone-Sensitive Prostate Cancer (mHSPC) (MK-3475-991/KEYNOTE-991)-China Extension
Study Details
Study Description
Brief Summary
This study will assess the efficacy and safety of pembrolizumab plus enzalutamide plus ADT versus placebo plus enzalutamide plus ADT in Chinese participants with mHSPC. The primary hypothesis is that in participants with mHSPC, the combination of pembrolizumab plus enzalutamide plus ADT is superior to placebo plus enzalutamide plus ADT with respect to 1) radiographic progression-free survival (rPFS) per Prostate Cancer Working Group (PCWG)-modified Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 as assessed by blinded independent central review (BICR) and 2) overall survival (OS).
| Condition or Disease | Intervention/Treatment | Phase |
|---|---|---|
|
Phase 3 |
Detailed Description
The China extension study will include participants previously enrolled in China in the global study for MK-3475-991 (NCT04191096) plus those enrolled during the China extension enrollment period. A total of approximately 186 Chinese participants will be enrolled.
Study Design
Arms and Interventions
| Arm | Intervention/Treatment |
|---|---|
| Experimental: Pembrolizumab + Enzalutamide + ADT Starting on Day 1 of each 21-day cycle, participants receive 200 mg pembrolizumab intravenously (IV) every 3 weeks (Q3W) for up to 35 cycles (approximately 2 years), plus 160 mg enzalutamide taken orally once daily, while maintaining continuous ADT with a luteinizing-hormone releasing hormone (LHRH) agonist or antagonist during study treatment. Participants will continue to receive enzalutamide and ADT until criteria for discontinuation are met. |
Biological: Pembrolizumab
Pembrolizumab is administered as an IV infusion at 200 mg on Day 1 of each 21-day cycle for up to 35 cycles.
Other Names:
Drug: Enzalutamide
Enzalutamide is administered orally as capsules/tablets at a dosage of 160 mg daily. Enzalutamide is administered continuously until criteria for discontinuation are met.
Other Names:
Procedure: Androgen Deprivation Therapy (ADT)
Stable regimen of ADT (LHRH agonist or antagonist) at a dose and frequency of administration that is consistent with the local product label.
|
| Placebo Comparator: Placebo + Enzalutamide + ADT Starting on Day 1 of each 21-day cycle, participants receive placebo IV Q3W for up to 35 cycles (approximately 2 years), plus 160 mg enzalutamide taken orally once daily, while maintaining continuous ADT with a LHRH agonist or antagonist during study treatment. Participants will continue to receive enzalutamide and ADT until criteria for discontinuation are met. |
Drug: Enzalutamide
Enzalutamide is administered orally as capsules/tablets at a dosage of 160 mg daily. Enzalutamide is administered continuously until criteria for discontinuation are met.
Other Names:
Procedure: Androgen Deprivation Therapy (ADT)
Stable regimen of ADT (LHRH agonist or antagonist) at a dose and frequency of administration that is consistent with the local product label.
Other: Placebo
Placebo infusion solution is administered as an IV infusion on Day 1 of each 21-day cycle for up to 35 cycles.
|
Outcome Measures
Primary Outcome Measures
- Radiographic Progression-free Survival (rPFS) Per Prostate Cancer Working Group (PCWG)-modified Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) as Assessed by Blinded Independent Central Review [Up to approximately 77 months]
rPFS is defined as the time from randomization to radiographic progression, or death due to any cause, whichever occurs first. rPFS according to PCWG-modified RECIST 1.1 as assessed by Blinded Independent Central Review will be reported for each study arm.
- Overall Survival (OS) [Up to approximately 77 months]
OS is defined as the time from randomization to death due to any cause. OS will be reported for each study arm.
Secondary Outcome Measures
- Time to Initiation of the First Subsequent Anti-cancer Therapy or Death (TFST) [Up to approximately 77 months]
TFST is defined as the time from randomization to initiation of the first subsequent anti-cancer therapy or death, whichever comes first. TFST will be reported for each study arm.
- Time to Symptomatic Skeletal-Related Event (TTSSRE) [Up to approximately 77 months]
TTSSRE is defined as the time from randomization to the first Symptomatic Skeletal-Related Event (SSRE), defined as use of external-beam radiation therapy (EBRT) to prevent or relieve skeletal symptoms, occurrence of new symptomatic pathologic bone fracture (vertebral or nonvertebral), occurrence of spinal cord compression, or tumor-related orthopedic surgical intervention, whichever occurs first. TTSSRE will be reported for each study arm.
- Time to Prostate-specific Antigen (PSA) Progression [Up to approximately 77 months]
Time to PSA progression is defined as the time from randomization to PSA progression. The PSA progression date is defined as the date of 1) ≥25% increase and ≥2 ng/mL above the nadir, confirmed by a second value ≥3 weeks later if there is PSA decline from baseline, or 2) ≥25% increase and ≥2 ng/mL increase from baseline beyond 12 weeks if there is no PSA decline from baseline. Time to PSA progression will be reported for each study arm.
- Time to Radiographic Soft Tissue Progression Per Soft Tissue Rules of Prostate Cancer Working Group (PCWG)-modified Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) as Assessed by Blinded Independent Central Review [Up to approximately 77 months]
Time to radiographic soft tissue progression is defined as the time from randomization to radiographic soft tissue progression, and will be reported for each study arm.
- Time to Pain Progression (TTPP) as Assessed by Brief Pain Inventory-Short Form (BPI-SF) Item 3 ("Worst Pain in 24 Hours") and Opiate Use [Up to approximately 77 months]
TTPP is defined as the time from randomization to pain progression. In this study, pain progression will be assessed by participant responses to Item 3 of the BPI-SF ("worst pain in 24 hours") and by participant opiate use, and will be reported for each study arm.
- Time from Randomization to Disease Progression as Determined by Investigator Assessment after Next-line of Therapy or Death from Any Cause, Whichever Occurs First (PFS2) [Up to approximately 77 months]
PFS2 is defined as the time from randomization to disease progression as determined by investigator assessment of radiological or clinical progression after next-line of therapy or death from any cause, whichever occurs first. PFS2 will be reported for each study arm.
- Prostate-specific Antigen (PSA) Response Rate [Up to approximately 77 months]
PSA response rate is defined as the percentage of participants in the analysis population with PSA decline of ≥50% from baseline measured twice at least 3 weeks apart, and will be reported for each study arm.
- Prostate-specific antigen (PSA) Undetectable Rate [Up to approximately 77 months]
PSA undetectable rate is defined as the percentage of participants in the analysis population with PSA < 0.2 ng/mL during study intervention, and will be reported for each study arm.
- Objective Response Rate (ORR) Per Prostate Cancer Working Group (PCWG)-modified Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) as Assessed by Blinded Independent Central Review [Up to approximately 77 months]
ORR is defined as the percentage of participants in the analysis population who have a best overall response of either confirmed CR or PR. ORR per PCWG-modified RECIST 1.1 as assessed by Blinded Independent Central Review will be reported for each study arm.
- Duration of Response (DOR) Per Prostate Cancer Working Group (PCWG)-modified Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) as Assessed by Blinded Independent Central Review [Up to approximately 77 months]
DOR is defined as the time from the earliest date of first documented evidence of confirmed CR or PR until the earliest date of disease progression or death from any cause, whichever occurs first. DOR per PCWG-modified RECIST 1.1 as assessed by Blinded Independent Central Review will be reported for each study arm.
- Number of Participants Who Experience an Adverse Event (AE) [Up to approximately 77 months]
An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a study intervention. The number of participants who experience an AE will be reported for each arm.
- Number of Participants Who Discontinue Study Treatment Due to an Adverse Event (AE) [Up to approximately 77 months]
An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a study intervention. The number of participants who discontinue study treatment due to an AE will be reported for each arm.
Eligibility Criteria
Criteria
Inclusion Criteria:
-
Male participants with histologically- or cytologically-confirmed adenocarcinoma of the prostate without small cell histology
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Has metastatic disease assessed by investigator and verified by BICR by either ≥2 bone lesions on bone scan and/or visceral disease by computed tomography/magnetic resonance imaging (CT/MRI)
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Willing to maintain continuous ADT with a LHRH agonists or antagonists during study treatment or have a history of bilateral orchiectomy
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Has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 assessed within 10 days of randomization
-
Participants receiving bone resorptive therapy (including, but not limited to, bisphosphonate or denosumab) must have been on stable doses prior to randomization
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Has adequate organ function
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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
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Male participants must agree to the following during the intervention period and for at least 120 days after the last dose of study intervention: Refrain from donating sperm PLUS either be abstinent from heterosexual intercourse and agree to remain abstinent OR agree to use contraception, unless confirmed to be azoospermic
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Male participants must agree to use male condom when engaging in any activity that allows for passage of ejaculate to another person of any sex
Exclusion Criteria:
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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
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Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy
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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 has current pneumonitis
-
Has known active human immunodeficiency virus (HIV), hepatitis B virus (HBV) or hepatitis C virus (HCV) infection
-
Has known or suspected central nervous system (CNS) metastases and/or carcinomatous meningitis
-
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
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Has had myocardial infarction or uncontrolled angina within 6 months prior to randomization, or has New York Heart Association class III or IV congestive heart failure or a history of New York Heart Association class III or IV congestive heart failure
-
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
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Has a history of clinically significant ventricular arrhythmias
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Has hypersensitivity to pembrolizumab and/or enzalutamide and/or any of their excipients
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Has received prior ADT as neoadjuvant/adjuvant therapy for non-metastatic prostate cancer for >39 months in duration or within 9 months prior to randomization or with evidence of disease progression while receiving ADT
-
Has had prior treatment with a next generation hormonal agent (eg, abiraterone, enzalutamide, apalutamide, darolutamide)
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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
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Has received a live vaccine within 30 days prior to randomization
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Has a "superscan" bone scan
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Has had an allogenic tissue/solid organ transplant
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Is expecting to conceive or father children within the projected duration of the study, starting with the screening visit through 120 days after the last dose of study treatment
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Has received any prior pharmacotherapy, radiation therapy or surgery for metastatic prostate cancer with the following exceptions:
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Up to 3 months of ADT or orchiectomy with or without concurrent first-generation antiandrogens, if patient was not treated with docetaxel
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May have 1 course of palliative radiation or surgical therapy to treat symptoms resulting from metastatic disease if it was administered at least 4 weeks prior to randomization
-
For participants with low volume metastatic disease, may have 1 course of definitive radiotherapy if it was administered at least 4 weeks prior to randomization
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Up to 6 cycles of docetaxel therapy with final treatment administration completed within 2 months of randomization and no evidence of disease progression. In these participants up to 6 months of ADT permitted
Contacts and Locations
Locations
| Site | City | State | Country | Postal Code | |
|---|---|---|---|---|---|
| 1 | Peking University First Hospital ( Site 0800) | Beijing | Beijing | China | 100034 |
| 2 | Beijing Cancer Hospital ( Site 0802) | Beijing | Beijing | China | 100142 |
| 3 | Chongqing Cancer Hospital ( Site 0815) | Chongqing | Chongqing | China | 400030 |
| 4 | The First Affiliated Hospital of Xiamen University (Site 0816) | Xiamen | Fujian | China | 361000 |
| 5 | Sun Yat-Sen University Cancer Center ( Site 0825) | Guangzhou | Guangdong | China | 510060 |
| 6 | The First Affiliated Hospital of Guangzhou Medical University-Urology ( Site 0638) | Guangzhou | Guangdong | China | 510120 |
| 7 | Sun Yat Sen Memorial Hospital (Site # 0819) | Guangzhou | Guangdong | China | 510220 |
| 8 | Southern Medical University Nanfang Hospital ( Site 0838) | Guangzhou | Guangdong | China | 510515 |
| 9 | Harbin Medical University Cancer Hospital ( Site 0822) | Harbin | Heilongjiang | China | 150081 |
| 10 | Henan Cancer Hospital ( Site 0818) | Zhengzhou | Henan | China | 450008 |
| 11 | Union Hospital Tongji Medical College Huazhong University of Science and Technology ( Site 0829) | Wuhan | Hubei | China | 430000 |
| 12 | Hubei Cancer Hospital ( Site 0833) | Wuhan | Hubei | China | 430079 |
| 13 | Hunan Cancer Hospital ( Site 0817) | Changsha | Hunan | China | 410013 |
| 14 | Nanjing Drum Tower Hospital ( Site 0811) | Nanjing | Jiangsu | China | 210008 |
| 15 | The First Affiliated Hospital of Nanchang University ( Site 0821) | Nanchang | Jiangxi | China | 330006 |
| 16 | The Second Affiliated Hosp of Xi'an Jiaotong Univ College of Medicine ( Site 0831) | XI An | Shaanxi | China | 710004 |
| 17 | Renji Hospital Shanghai Jiaotong University School of Medicine ( Site 0807 ) | Shanghai | Shanghai | China | 200127 |
| 18 | The first affiliated Hospital of Xi an Jiaotong University ( Site # 0812) | XI An | Shanxi | China | 710061 |
| 19 | Tianjin Medical University Cancer Institute & Hospital ( Site 0804 ) | Tianjin | Tianjin | China | 300000 |
| 20 | 2nd Affil Hosp of Zhejiang University College of Medicine ( Site 0808) | Hangzhou | Zhejiang | China | 310009 |
| 21 | The 1st Affil Hosp of College of Medicine, Zhejiang Univ ( Site 0830) | Hangzhou | Zhejiang | China | 310009 |
| 22 | Zhejiang Provincial People's Hospital ( Site 0809) | Hangzhou | Zhejiang | China | 310014 |
| 23 | Ningbo First Hospital-Urology (0835) | Ningbo | Zhejiang | China | 315010 |
| 24 | The First Affiliated Hospital of Wenzhou Medical University ( Site 0834) | Wenzhou | Zhejiang | China | 325000 |
Sponsors and Collaborators
- Merck Sharp & Dohme LLC
Investigators
- Study Director: Medical Director, Merck Sharp & Dohme LLC
Study Documents (Full-Text)
None provided.More Information
Additional Information:
Publications
None provided.- 3475-991 China Extension
- MK-3475-991 China Extension
- KEYNOTE-991
- 205267