NCT06353386 · Merck Sharp & Dohme LLC
Substudy 01A: Safety and Efficacy of Opevesostat (MK-5684)-Based Treatment Combinations or Opevesostat Alone in Participants With Metastatic Castration-resistant Prostate Cancer (mCRPC) (MK-5684-01A)
What this study is about
Substudy 01A is part of a larger research study that is testing experimental treatments for metastatic castration-resistant prostate cancer (mCRPC). The larger study is the umbrella study (U01). The goal of substudy 01A is to evaluate the safety and effectiveness of opevesostat-based treatment combinations, or as a single agent, in participants with mCRPC.
View original scientific description
Substudy 01A is part of a larger research study that is testing experimental treatments for metastatic castration-resistant prostate cancer (mCRPC). The larger study is the umbrella study (U01). The goal of substudy 01A is to evaluate the safety and efficacy of opevesostat-based treatment combinations, or as a single agent, in participants with mCRPC. This substudy will have two phases: a safety lead-in phase and an efficacy phase.
Interventions
DRUG
Opevesostat
Oral Tablet
DRUG
Olaparib
Oral Tablet
DRUG
Docetaxel
IV Infusion
DRUG
Cabazitaxel
IV Infusion
DRUG
Fludrocortisone acetate
Oral Tablet
DRUG
Dexamethasone
Oral Tablet
DRUG
Prednisone
Oral Tablet
Primary outcome measures
Number of participants who experience one or more dose-limiting toxicities (DLTs)
Time frame: Up to approximately 28 days
The following events, if considered drug related by the investigator, will be considered a DLT: Grade 4 nonhematologic toxicity (not laboratory value); Grade 4 hematologic toxicity lasting \>7 days, except thrombocytopenia (Grade 4 thrombocytopenia of any duration, Grade 3 thrombocytopenia associated with clinically significant bleeding); Any nonhematologic adverse event (AE) \>Grade 3 in severity should be considered a DLT (with exceptions); Any Grade 3 or Grade 4 nonhematologic laboratory value (if certain criteria are met); Febrile neutropenia Grade 3 or Grade 4; Prolonged delay (\>2 weeks) in initiating treatment after the first 28 days due to study intervention-related toxicity; Missing \>25% of study intervention doses as a result of drug-related AE(s) during the first 28 days; Grade 5 toxicity.
Number of participants who experience one or more adverse events (AEs)
Time frame: Up to approximately 46 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.
Number of participants who discontinue study intervention due to an AE
Time frame: Up to approximately 46 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.
Prostate-specific antigen (PSA) response rate
Time frame: Up to approximately 46 months
The Prostate-specific Antigen (PSA) response rate is the percentage of participants who had PSA response defined as a reduction in the PSA level from baseline by ≥50%. The reduction in PSA level will be confirmed by an additional PSA evaluation performed ≥3 weeks from the original response per Prostate Cancer Working Group (PCWG) criteria.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- The main inclusion criteria include but are not limited to the following:
- Histologically or cytologically confirmed diagnosis of adenocarcinoma of the prostate without small cell histology.
- Prostate cancer progression and received androgen deprivation therapy (ADT) or post bilateral orchiectomy within 6 months before screening.
- Evidence of disease progression from either, \>4 weeks from last flutamide treatment, or \>6 weeks from last bicalutamide or nilutamide treatment, if receiving first generation anti-androgen therapy as last treatment therapy.
- Current evidence of metastatic disease.
- Prior treatment with 1 to 2 novel hormonal agent(s) (NHA) for non-metastatic, or metastatic, hormone-sensitive prostate cancer or castration-resistant prostate cancer and have disease progression during or after treatment.
- Treatment with bone resorptive therapy (including, but not limited to, bisphosphonate or denosumab) must have been on stable doses for \>4 weeks be
Where
- La Jolla, California
- Los Angeles, California
- Miami, Florida
- Baltimore, Maryland
- New Brunswick, New Jersey
- Cleveland, Ohio
- Milwaukee, Wisconsin
Collaborators
Orion Corporation, Orion Pharma
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced May 26, 2026 · Source of record for eligibility and locations