A Phase 1/2 interventional study of Opevesostat and Olaparib in Prostatic Neoplasms, Castration-Resistant, sponsored by Merck Sharp & Dohme LLC. Active, not recruiting at 77 sites in 20 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-10.
Sponsored by Merck Sharp & Dohme LLC (part of Merck & Co., Inc) · Phase 1/2, Interventional, and Treatment
Among 50 studies in Prostatic Neoplasms, Castration-Resistant with a site in United States — 17 open to participants now, 23 under way, 3 of them phase 3. Prostatic Neoplasms, Castration-Resistant · United States.
Among the 50 studies in Prostatic Neoplasms, Castration-Resistant with a site in United States, this one is the 10th largest by planned enrollment of the 42 interventional ones, is one of 4 that started in 2024, is one of 8 in phase 1/2, reaches primary completion later than 19 of the 22 other live ones, and was the 40th registered.
85 studies on the registry are indexed under Prostatic Neoplasms, Castration-Resistant; 28 are open to participants now.
This study's planned enrollment of 220 is above the median of 82 across 62 interventional studies indexed under Prostatic Neoplasms, Castration-Resistant.
Browse Prostatic Neoplasms, Castration-Resistant studies →17 of the 50 studies in Prostatic Neoplasms, Castration-Resistant with a site in United States are open now, in 12 countries. Each count lists the studies.
Of the 25 Prostatic Neoplasms, Castration-Resistant studies recruiting now, 22 (88%) set no upper age limit and 0 (0%) stop at 75 or younger; 1 take children under 18; 0 take healthy volunteers.
This study: 18 Years and older · all sexes · no healthy volunteers.
The full table on the hub →50 studies; the count open now beside each. This study's row is marked.
First in 2014; this study’s year is marked. 4 started in 2024.
Median enrollment 91 across the 42 interventional studies, 1,908 across the 6 observational. Of the 23 that completed or were terminated, 11 (48%) have results posted.
41 of 50 have an industry lead sponsor. The 10 most frequent:
Merck Sharp & Dohme LLC is the lead sponsor of 2,166 studies on the registry; 132 are open to participants now.
Of its 501 completed or terminated interventional studies of FDA-regulated products, 370 (74%) have results posted.
Merck Sharp & Dohme LLC has 2 studies filed under Prostatic Neoplasms, Castration-Resistant — fewer than ten, so there is no comparison to draw.
8 of the studies in Prostatic Neoplasms, Castration-Resistant with a site in United States that are under way reach primary completion within a year, 1 of them phase 3. Phase 3 first, then by date:
| Study | Primary completion |
|---|---|
| NCT07225946Phase 3Janssen Research & Development, LLCA Study of Pasritamig With Docetaxel Versus Docetaxel in Participants With Metastatic Castration-Resistant Prostate Cancer | 2027-11-19 |
| NCT07697989Novartis PharmaceuticalsPluvicto Real-world Investigation in Survival in Metastatic CRPC | 2027-01-31 |
| NCT07677254Novartis PharmaceuticalsA Study of Real-World Characteristics, Treatment Patterns, and Clinical Outcomes in Patients With Metastatic Castration-Resistant Prostate Cancer | 2027-05-31 |
| NCT07677267Novartis PharmaceuticalsA Study of Real-World Characteristics, Treatment Patterns, and Outcomes Among mCRPC Patients Previously Treated With an Androgen Receptor Pathway Inhibitor, Taxane-Based Chemotherapy, and Lutetium-177 Vipivotide Tetraxetan | 2027-05-31 |
| NCT05519449Janux TherapeuticsStudy of JANX007 in Subjects With Metastatic Castration-Resistant Prostate Cancer (ENGAGER-PSMA-01) | 2027-07 |
Among the 50 studies in Prostatic Neoplasms, Castration-Resistant with a site in United States, from their registry updates:
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. The safety lead-in phase will be used to evaluate the safety and tolerability, and to establish a recommended Phase 2 dose (RP2D) for the opevesostat-based treatment combinations. There will be no hypothesis testing in this study.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
The main inclusion criteria include but are not limited to the following:
Exclusion Criteria:
The main exclusion criteria include but are not limited to the following:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Vaccines made with a weakened form of the germ, such as measles–mumps–rubella (MMR), chickenpox and yellow fever. They can be risky when the immune system is weakened. Flu injections are not live; the nasal flu spray is.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.
Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.
Histologically or cytologically confirmed
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Metastases
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
TIA (transient ischaemic attack)
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
NYHA class (heart failure)
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
QT and QTc
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Biopsy and archival tissue
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Platelets
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Live vaccines
Vaccines made with a weakened form of the germ, such as measles–mumps–rubella (MMR), chickenpox and yellow fever. They can be risky when the immune system is weakened. Flu injections are not live; the nasal flu spray is.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Autoimmune disease
A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.
Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants receive 5 mg of opevesostat twice daily (BID) via oral tablet plus dexamethasone 1.5 mg by oral tablets once daily (QD) and 0.1 mg fludrocortisone acetate by oral tablet QD until progression or discontinuation.
Drug: Opevesostat · Drug: Fludrocortisone acetate · Drug: Dexamethasone
Participants receive 5 mg of opevesostat BID via oral tablet plus dexamethasone 1.5 mg by oral tablets QD and 0.1 mg fludrocortisone acetate by oral tablet QD, PLUS 300 mg of olaparib BID via oral tablet until progressive disease or discontinuation.
Drug: Opevesostat · Drug: Olaparib · Drug: Fludrocortisone acetate · Drug: Dexamethasone
Participants receive 5 mg of opevesostat BID via oral tablet plus dexamethasone 1.5 mg by oral tablets QD and 0.1 mg fludrocortisone acetate by oral tablet QD, PLUS 75 mg/m\^2 of docetaxel once every 3 weeks (Q3W) via IV infusion, plus prednisone per approved product label BID by oral tablets until progressive disease or discontinuation.
Drug: Opevesostat · Drug: Docetaxel · Drug: Fludrocortisone acetate · Drug: Dexamethasone · Drug: Prednisone
Participants receive 5 mg of opevesostat BID via oral tablet plus dexamethasone 1.5 mg by oral tablets QD and 0.1 mg fludrocortisone acetate by oral tablet QD, PLUS 20 mg/m\^2 of cabazitaxel Q3W via IV infusion, plus prednisone per approved product label BID by oral tablets until progressive disease or discontinuation.
Drug: Opevesostat · Drug: Cabazitaxel · Drug: Fludrocortisone acetate · Drug: Dexamethasone · Drug: Prednisone
Oral Tablet
Also known as: MK-5684
Oral Tablet
Also known as: LYNPARZA®
IV Infusion
Also known as: TAXOTERE®
IV Infusion
Also known as: JEVTANA®
Oral Tablet
Oral Tablet
Oral Tablet
Number of participants who experience one or more dose-limiting toxicities (DLTs)
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.
Time frame: Up to approximately 28 days
Number of participants who experience one or more adverse events (AEs)
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.
Time frame: Up to approximately 46 months
Number of participants who discontinue study intervention due to an AE
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.
Time frame: Up to approximately 46 months
Prostate-specific antigen (PSA) response rate
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.
Time frame: Up to approximately 46 months
Objective response rate (ORR)
The ORR is defined as the percentage of participants with complete response (CR: disappearance of all target lesions per Response Criteria in Solid Tumors version 1.1 (RECIST 1.1); and no evidence of disease (NED) on base scan per Prostate Cancer Working Group (PCWG) or partial response (PR: at least a 30% decrease in the sum of diameters of target lesions per RECIST 1.1; and non-progressive disease, non-evaluable \[NE\], or NED on bone scan or CR with non-progressive disease or NE bone scan per PCWG). ORR will be assessed by Blinded Independent Central Review (BICR).
Time frame: Up to approximately 46 months
Radiographic progression-free survival (rPFS)
rPFS is defined as the time from randomization to occurrence of: radiological tumor progression using RECIST 1.1 as assessed by BICR; progression of bone lesions using PCWG criteria; or death due to any cause. Progression as per modified RECIST 1.1 is ≥20% increase in the sum of diameters of target lesions and progression of existing non-target lesions. Progression of bone lesions by PCWG criteria is the appearance of ≥2 new bone lesions on bone scan, that have been confirmed to not represent tumor flare, and are persistent for ≥6 weeks. rPFS will be assessed by BICR.
Time frame: Up to approximately 46 months
Overall survival (OS)
OS is defined as the time from randomization to death due to any cause.
Time frame: Up to approximately 46 months
Duration of response (DOR)
DOR is defined as the time from first documented evidence of complete response (CR) or partial response (PR) per PCWG and RECIST 1.1 criteria until progressive disease (PD) or death. PD per RECIST 1.1 is defined as at least a 20% increase in the sum of diameters of target lesions. In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of a least 5 mm. PD per PCWG is the appearance of \>2 new bone lesions on bone scan, that have been confirmed to not represent tumor flare, and are persistent for \>6 weeks. DOR will be assessed by BICR.
Time frame: Up to approximately 46 months
Time to first subsequent anticancer therapy (TFST)
TFST is defined as the time from randomization to initiation of the first subsequent anticancer therapy or death, whichever occurs first.
Time frame: Up to approximately 46 months
Time to pain progression (TTPP)
TTPP is defined as the time from randomization to pain progression based on the Brief Pain Inventory-Short Form (BPI-SF) Item 3 "worst pain in 24 hours" and by opiate analgesic use.
Time frame: Up to approximately 46 months
Plan to share: Yes — https://trialstransparency.msdclinicaltrials.com/pdf/ProcedureAccessClinicalTrialData.pdf
Data sharing details ↗ · externaldatasharing-msd.com
Started May 2024 (actual). Primary completion is estimated for Jan 2029, 55 months after the start.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is active, not recruiting, as verified in Nov 2026. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Opevesostat
Prostatic Neoplasms, Castration-Resistant →