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JNJ-78278343

Phase 1

Prostatic Neoplasms | Small molecule | Oncology |Johnson & Johnson|Last Updated: Aug 28, 2026

Target and mechanism

Molecular targetKLK2
ModalitySmall molecule

Success Probability

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Market & Valuation

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Trial Design

CONTROLLED
Total Trials3
Total Enrollment711

FDA Designations

No designations recorded

Clinical trial landscape

JNJ-78278343 · 3 trials · 1 indication

Phase 1 3
NCT07082920A Study of JNJ-78278343 in Combination With JNJ-95298177 for Treatment of Prostate CancerProstatic Neoplasms
RECRUITING140 Analytics
NCT06095089A Study of JNJ-87189401 Combined With JNJ-78278343 for Advanced Prostate CancerProstatic Neoplasms
RECRUITING355 Analytics
NCT04898634A Study of JNJ-78278343, a T-Cell-Redirecting Agent Targeting Human Kallikrein 2 (KLK2), for Advanced Prostate CancerProstatic Neoplasms
ACTIVE NOT_RECRUITING216 Analytics
PHASE1RECRUITING
A Study of JNJ-78278343 in Combination With JNJ-95298177 for Treatment of Prostate Cancer
Prostatic NeoplasmsUnlock trial analytics
PHASE1RECRUITING
A Study of JNJ-87189401 Combined With JNJ-78278343 for Advanced Prostate Cancer
Prostatic NeoplasmsUnlock trial analytics
PHASE1ACTIVE NOT_RECRUITING
A Study of JNJ-78278343, a T-Cell-Redirecting Agent Targeting Human Kallikrein 2 (KLK2), for Advanced Prostate Cancer
Prostatic NeoplasmsUnlock trial analytics

Study Endpoints

Primary Endpoints

Number of Participants With Adverse Events (AEs) by Severity
Up to 2 years 2 months

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.

Part 1: Number of Participants With Dose-Limiting Toxicity (DLT)
Up To Day 22

High grade hematologic or non-hematologic toxicities with exceptions and/or toxicities leading to treatment discontinuation will be regarded as DLT.

Parts 1, 2C, 3 and 4: Number of Participants With Dose Limiting Toxicity (DLT)
Up to 21 days after first combination dose of study drugs

DLTs are specific adverse events (AEs) and are defined as any of the following: high grade non-hematologic toxicity or hematologic toxicity.

Part 1 and 2: Number of Participants With Adverse Events (AEs)
Up to 1 year and 10 months

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.

Part 1 and 2: Number of Participants With AEs by Severity
Up to 1 year and 10 months

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.

Secondary Endpoints

Objective Response Rate (ORR)
Up to 2 years 2 months
Prostate-Specific Antigen (PSA) Response Rate
Up to 2 years 2 months
Radiographic Progression-Free Survival (rPFS)
Up to 2 years 2 months
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Study Design & Arms

AllocationNON_RANDOMIZED
MaskingNONE
ModelSEQUENTIAL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Part 1: Dose ConfirmationEXPERIMENTALParticipants 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.
Part 2: Dose ExpansionEXPERIMENTALParticipants 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.
Part 1 (Dose Escalation)EXPERIMENTALParticipants will receive JNJ-78278343 + JNJ-87189401 escalated sequentially in Part 1 to select a recommended Phase 2 regimen (RP2R).
Part 2 (Dose Expansion)EXPERIMENTALParticipants with different disease settings in Parts 2A and 2B will receive JNJ-78278343+JNJ-87189401 at the RP2R selected in Part 1. Participants in Part 2C will receive apalutamide plus continued treatment with JNJ-87189401+JNJ-78278343 doublet.
Part 3EXPERIMENTALParticipants will receive JNJ-78278343 + JNJ-87189401 at one or more RP2R (s) selected in Part 1 along with standard of care (SOC) treatment with lutetium Lu-177 vipivotide tetraxetan. Dosing of JNJ-78278343+JNJ-87189401 will be escalated sequentially, as per study evaluation team (SET) decision.
Part 4EXPERIMENTALParticipants will receive JNJ-78278343 + JNJ-87189401 at one or more RP2R (s) along with JNJ-101556143. Dosing of JNJ-78278343+JNJ-87189401 along with JNJ-101556143 will be escalated sequentially to determine the RP2R of the combinations.
JNJ-78278343EXPERIMENTALParticipants will receive JNJ-78278343. The dose levels will be escalated based on the dose limiting toxicities (DLT) evaluation by the study evaluation team (SET) in Part 1 (dose escalation). In Part 2 (dose expansion), participants will receive JNJ-78278343 at recommended phase 2 dose (RP2D) as determined in Part 1. Participants who are still on study treatment (i.e., who are in Treatment Phase) at the time of the long term extension (LTE) will continue to receive study treatment until they reach a reason for discontinuation of treatment or until further notification by the sponsor of a different means for continued supply of study treatment, whichever occurs first.

Interventions

NameTypeDescription
JNJ-78278343DRUGJNJ-78278343 will be administered intravenously.
JNJ-95298177DRUGJNJ-95298177 will be administered intravenously.
JNJ-87189401DRUGJNJ-87189401 will be administered.
ApalutamideDRUGApalutamide will be administered.
Lutetium Lu-177 Vipivotide TetraxetanDRUGLutetium Lu-177 Vipivotide Tetraxetan will be administered as SOC treatment.
JNJ-101556143DRUGJNJ-101556143 will be administered.
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Eligibility Criteria

Age Range18 Years to N/A
SexMALE
Healthy VolunteersNo
Study Sites6

Inclusion Criteria: * Histologically confirmed adenocarcinoma of the prostate. Primary small cell carcinoma, carcinoid tumor, neuroendocrine (NE) carcinoma, or large cell NE carcinoma arising in the prostate are not allowed; however, adenocarcinomas with NE features (for example \[e.g.\], immunohis...

Countries:United StatesUnited KingdomAustraliaChinaFranceJapanNetherlandsSpain
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Recent Changes (Last 90 Days)

LOWAug 28, 2026NCT06095089lastUpdatePostDate: changed
MEDIUMAug 28, 2026NCT07082920primaryCompletionDate: changed
LOWAug 28, 2026NCT06095089lastUpdatePostDate: changed
MEDIUMAug 28, 2026NCT07082920primaryCompletionDate: changed
MEDIUMAug 14, 2026NCT07082920lastUpdatePostDate: changed
MEDIUMAug 14, 2026NCT07082920lastUpdatePostDate: changed
MEDIUMAug 14, 2026NCT07082920lastUpdatePostDate: changed
LOWJul 31, 2026NCT06095089lastUpdatePostDate: changed
LOWJul 31, 2026NCT06095089lastUpdatePostDate: changed
LOWJul 6, 2026NCT07082920lastUpdatePostDate: changed
LOWJul 6, 2026NCT06095089lastUpdatePostDate: changed
LOWJul 6, 2026NCT04898634primaryCompletionDate: changed
LOWJul 6, 2026NCT07082920lastUpdatePostDate: changed
LOWJul 6, 2026NCT06095089lastUpdatePostDate: changed
LOWJul 6, 2026NCT04898634primaryCompletionDate: changed

Frequently asked questions about JNJ-78278343

What is JNJ-78278343 used for?

JNJ-78278343 is an investigational small molecule being developed for the treatment of prostate cancer, specifically prostatic neoplasms. It is currently in Phase 1 clinical trials, which are studying the drug both as a monotherapy and in combination with other agents for advanced prostate cancer.

What does JNJ-78278343 target?

JNJ-78278343 targets KLK2, also known as human kallikrein 2. It is described as a T-cell-redirecting agent that targets this protein, which is associated with prostate cancer cells. This mechanism is being evaluated in clinical trials for the treatment of advanced prostate cancer.

Who makes JNJ-78278343?

JNJ-78278343 is being developed by Johnson & Johnson, a pharmaceutical company traded on the New York Stock Exchange under the ticker symbol JNJ. The drug is currently in Phase 1 clinical development for prostate cancer.

What phase is JNJ-78278343 in?

JNJ-78278343 is in Phase 1 clinical trials. It is an investigational drug, meaning it has not been approved by regulatory authorities and is still undergoing clinical development to evaluate its safety and efficacy in patients with prostate cancer.

What clinical trials is JNJ-78278343 in?

JNJ-78278343 is being studied in three Phase 1 clinical trials. NCT04898634 evaluates it as a monotherapy for advanced prostate cancer. NCT06095089 studies it in combination with JNJ-87189401, and NCT07082920 studies it in combination with JNJ-95298177. All trials enroll male patients aged 18 and older.

Is JNJ-78278343 the same as JNJ-87189401?

No, JNJ-78278343 and JNJ-87189401 are different investigational drugs. They are being studied together in a Phase 1 clinical trial (NCT06095089) for advanced prostate cancer, but they are distinct agents with separate mechanisms and are not alternative names for the same compound.