A Phase 1 interventional study of JNJ-78278343 and JNJ-95298177 in Prostatic Neoplasms, sponsored by Janssen Research & Development, LLC. Recruiting at 6 sites in 2 countries. Open to male participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-03.
Sponsored by Janssen Research & Development, LLC (part of Johnson & Johnson) · Phase 1, Interventional, and Treatment
The purpose of this study is to identify the recommended phase 2 combination dose (RP2CD) of JNJ-78278343 in combination with JNJ-95298177 in Part 1 (Dose confirmation) of the study and to determine how safe and tolerable the RP2CD of JNJ-7827834 and JNJ-95298177 with or without JNJ-87189401 is for treatment of participants with metastatic castration-resistant prostate cancer (mCRPC; a stage of prostate cancer where the cancer has spread beyond the prostate and is resistant to hormonal therapy) in Part 2 (Dose expansion) of study.
7,046 studies on the registry are indexed under Prostatic Neoplasms; 1,580 are open to participants now.
This study's planned enrollment of 140 is above the median of 60 across 5,348 interventional studies indexed under Prostatic Neoplasms.
Browse Prostatic Neoplasms studies →Janssen Research & Development, LLC is the lead sponsor of 932 studies on the registry; 76 are open to participants now.
Of its 285 completed or terminated interventional studies of FDA-regulated products, 136 (48%) have results posted.
Counted across the registry records on this site, refreshed daily.
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.
Exclusion criteria:
Treatment with any anti-cancer or agents within 14 days prior to the first dose of study treatment; specific requirements for certain anti-cancer therapies are as follows:
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.
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Cancer that has spread to the leptomeninges, the thin layers covering the brain and spinal cord, and the fluid between them. It is not the same as brain metastases.
Criteria often treat it separately, and many studies leave it out even where treated brain metastases are allowed.
Cancer deposits in the brain from a cancer that started elsewhere in the body (CNS metastases include the spinal cord).
Studies differ: some leave out any brain metastases, some accept ones treated and stable for some weeks. Check what this study allows.
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 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.
PD-1, PD-L1 and CTLA-4 are proteins that act as brakes on the immune system. Checkpoint inhibitors, such as pembrolizumab or nivolumab, block them so the immune system can attack a cancer.
PD-L1 can also be measured in a tumour sample. Some scores count stained tumour cells only (TPS); others also count certain immune cells (CPS). The study names the score and the minimum it uses.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
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.
ECOG performance status
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Excipients
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Leptomeningeal disease
Cancer that has spread to the leptomeninges, the thin layers covering the brain and spinal cord, and the fluid between them. It is not the same as brain metastases.
Criteria often treat it separately, and many studies leave it out even where treated brain metastases are allowed.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Brain metastases
Cancer deposits in the brain from a cancer that started elsewhere in the body (CNS metastases include the spinal cord).
Studies differ: some leave out any brain metastases, some accept ones treated and stable for some weeks. Check what this study allows.
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.
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.
PD-1, PD-L1 and checkpoint inhibitors
PD-1, PD-L1 and CTLA-4 are proteins that act as brakes on the immune system. Checkpoint inhibitors, such as pembrolizumab or nivolumab, block them so the immune system can attack a cancer.
PD-L1 can also be measured in a tumour sample. Some scores count stained tumour cells only (TPS); others also count certain immune cells (CPS). The study names the score and the minimum it uses.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will receive JNJ-78278343 in combination with JNJ-95298177 in a dose de-escalation schedule in accordance with the Bayesian Optimal Interval Design (BOIN) design to determine the recommended phase 2 combination dose (RP2CD) regimen.
Drug: JNJ-78278343 · Drug: JNJ-95298177
Participants will receive JNJ-78278343 in combination with JNJ-95298177 at the RP2CD as determined in Part 1 of the study with or without JNJ-87189401 to confirm the safety and anti-tumor activity.
Drug: JNJ-78278343 · Drug: JNJ-95298177 · Drug: JNJ-87189401
JNJ-78278343 will be administered intravenously.
Also known as: Pasritamig
JNJ-95298177 will be administered intravenously.
Also known as: ARX517
JNJ-87189401 will be administered.
Number of Participants With Adverse Events (AEs) by Severity
An AE is any untoward medical occurrence in a participant participating in a clinical study that does not necessarily have a causal relationship with the pharmaceutical/biological agent under study. Severity will be graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) version 5.0. Severity scale ranges from Grade 1 (Mild) to Grade 5 (Death). Grade 1= Mild, Grade 2= Moderate, Grade 3= Severe, Grade 4= Life-threatening and Grade 5= Death related to adverse event. Cytokine release syndrome (CRS) and immune effector cell associated neurotoxicity syndrome (ICANS) will be graded according to the American Society for Transplantation and Cellular Therapy (ASTCT) guidelines and ocular events will be graded using the alternative scale provided in the protocol.
Time frame: Up to 2 years 2 months
Part 1: Number of Participants With Dose-Limiting Toxicity (DLT)
High grade hematologic or non-hematologic toxicities with exceptions and/or toxicities leading to treatment discontinuation will be regarded as DLT.
Time frame: Up To Day 22
Objective Response Rate (ORR)
ORR is defined as the percentage of participants who have a partial response (PR) or better according to the response evaluation criteria in solid tumors (RECIST) version 1.1 response criteria without evidence of bone progression according to prostate cancer working group 3 (PCWG3).
Time frame: Up to 2 years 2 months
Prostate-Specific Antigen (PSA) Response Rate
PSA response rate is defined as the percentage of participants with a decline of PSA of 50% or more from baseline.
Time frame: Up to 2 years 2 months
Radiographic Progression-Free Survival (rPFS)
rPFS is defined as the time from the date of first dose of any study treatment until the date of radiographic disease progression or death, whichever comes first.
Time frame: Up to 2 years 2 months
Time to Response (TTR)
TTR is defined for the responders as the time from the date of first dose of any study treatment to the date of first documented response.
Time frame: Up to 2 years 2 months
Duration of Response (DOR)
DOR will be calculated among responders (PR or better) from the date of initial documentation of a response (PR or better) to the date of first documented evidence of progressive disease, as defined in the PCWG3 or RECIST version 1.1 response criteria, or death due to any cause, whichever occurs first.
Time frame: Up to 2 years 2 months
Serum Concentration of JNJ-78278343
Serum samples will be analyzed to determine concentrations of JNJ-78278343.
Time frame: Up to 2 years 2 months
Serum Concentration of JNJ-95298177
Serum samples will be analyzed to determine concentrations of JNJ-95298177 (including ADC, total antibody and payload pAF-AS269).
Time frame: Up to 2 years 2 months
Serum Concentration of JNJ-87189401
Serum samples will be analyzed to determine concentrations of JNJ-87189401.
Time frame: Up to 2 years 2 months
Number of Participants With Anti-JNJ-78278343 Antibodies
Serum samples will be analyzed for the detection of anti-JNJ-78278343 antibodies using a validated assay method.
Time frame: Up to 2 years 2 months
Number of Participants With Anti-JNJ-95298177 Antibodies
Serum samples will be analyzed for the detection of anti-JNJ-95298177 antibodies using a validated assay method.
Time frame: Up to 2 years 2 months
Number of Participants With Anti-JNJ-87189401 Antibodies
Serum samples will be analyzed for the detection of anti-JNJ-87189401 antibodies using a validated assay method.
Time frame: Up to 2 years 2 months
Plan to share: Yes — The data sharing policy of Johnson \& Johnson Innovative Medicine is available at www.innovativemedicine.jnj.com/our-innovation/clinical-trials/transparency. As noted on this site, requests for access to the study data can be submitted through Yale Open Data Access (YODA) Project site at yoda.yale.edu.
Data sharing details ↗ · www.jnj.com
No publications or documents are linked to this record.
Started Jul 2025 (actual). Primary completion is estimated for Nov 2027, 28 months after the start.
Of 212 industry-sponsored phase 1 interventional studies under Prostatic Neoplasms, half reached primary completion within 37 months of starting (the median), counting those still running; a quarter within 20 and three quarters within 62. This study's planned 28 months is below that.
Counting every sponsor, half of 455 studies reached it within 43 months; a quarter within 23 and three quarters within 68.
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 ↗
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Studies of the drug tested here: Pasritamig
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