This study is testing MK-5684 in men who have prostate cancer that has gotten worse and spread beyond the prostate after drug therapy or surgery to block the testes from producing hormones. This is called metastatic castration-resistant prostate cancer (mCRPC). MK-5684 is experimental. It has not been approved for any disease or condition by the Pharmacy and Poisons Board (PPB) or other Regulatory Authorities. This study will compare MK-5684 to abiraterone acetate and enzalutamide. Abiraterone acetate and enzalutamide are standard treatments for mCRPC.

This study is being done to: 

Test the safety of MK-5684

See how well MK-5684 works, compared to abiraterone acetate or enzalutamide 

See if participants who get MK-5684 live longer compared to those who get abiraterone acetate or enzalutamide

See if participants who get MK-5684 live longer before their disease worsens, compared to those who get abiraterone acetate or enzalutamide

Who can be in this study? Patient  at least 18 years old

Patient who have advanced mCRPC (Stage 4 metastatic prostate cancer)

ï‚· Patient who mCRPC that has become worse within 6 months before starting the study and: 

After being treated with drugs or surgery to block the testes from making hormones

AND 

After treatment with other drugs for prostate cancer

Protocol Title: A Phase 3, Randomized, Open-label Study of MK-5684 Versus Alternative Abiraterone Acetate or Enzalutamide in Participants with Metastatic Castration-resistant Prostate Cancer (mCRPC) That Progressed On or After Prior Treatment with One Nextgeneration Hormonal Agent (NHA)

Short Title: Phase 3 study of MK-5684 versus alternative NHA in mCRPC post one NHA

Primary Objectives

To compare MK-5684 to alternative abiraterone acetate or enzalutamide with respect to rPFS per PCWG Modified RECIST 1.1, as assessed by BICR in participants with mCRPC

To compare MK-5684 to alternative abiraterone acetate or enzalutamide with respect to overall survival in participants with mCRPC. 

Secondary Objectives 

To evaluate the TFST of participants treated with MK-5684 compared with participants treated with alternative abiraterone acetate or enzalutamide

To evaluate the OR and DOR per PCWG Modified RECIST 1.1 as assessed by BICR of participants treated with MK-5684 compared with participants treated with alternative abiraterone acetate or enzalutamide.

To evaluate the TTPP of participants treated with MK-5684 compared with participants treated with alternative abiraterone acetate or enzalutamide

To evaluate MK-5684 and abiraterone acetate or enzalutamide with respect to HRQoL using the FACT-P questionnaire. 

To evaluate the time to PSA progression of participants treated with MK-5684 compared with participants treated with alternative abiraterone acetate or enzalutamide.

To evaluate the PSA response rate of participants treated with MK-5684 compared with participants treated with alternative abiraterone acetate or enzalutamide.

To evaluate the time to first SSRE of participants treated with MK-5684 compared with participants treated with alternative abiraterone acetate or enzalutamide

To evaluate the safety and tolerability of MK-5684

Study Phase Phase 3 

Indication Prostate cancer metastatic

Population Participants ≥18 years of age with metastatic castration-resistant-prostate cancer

Study Type Interventional

Intervention Model Parallel This is a multi site study.

Type of Control Active Control Without Placebo

Study Blinding Unblinded open-label Blinding Roles No blinding Estimated

Duration of Study The Sponsor estimates that the study will require approximately 7 years from the time the first participant (or their legally acceptable representative) provides documented informed consent until the last participant’s last study-related contact.