A Study of JNJ-78278343, a T-Cell-Redirecting Agent Targeting Human Kallikrein 2 (KLK2), for Advanced Prostate Cancer

Eligibility Criteria

Inclusion Criteria:

* Confirmed adenocarcinoma of the prostate which has spread to other body parts
* Part 1: Prior treatment with at least 1 prior novel androgen receptor (AR)-targeted therapy or chemotherapy
* Measurable or evaluable disease
* Concurrent use of any other anticancer treatment must be discontinued for at least 2 weeks before the first dose of study drug
* Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
* Prior surgical removal of testicles; or, for participants who have not undergone surgical removal of testicles, must be receiving ongoing androgen deprivation therapy (ADT) with a gonadotropin releasing hormone analog

Exclusion Criteria:

Disease conditions

* Active central nervous system (CNS) involvement
* Toxicity related to prior anticancer therapy has not adequately recovered

Prior/Concomitant Therapy

* Prior treatment with human kallikrein (KLK) 2-targeted therapy
* Received, or are receiving, medications that suppress the immune system within 3 days prior to the first dose of study drug
* Received or plans to receive any live, attenuated vaccine within 4 weeks prior to the first dose of study drug

Prior/Concurrent Medical Conditions

* Diagnosis of cancer other than prostate cancer within 2 years prior to the first dose of study drug
* Solid organ or bone marrow transplantation
* Major clotting diseases within one month prior to the first dose of study drug
* Active autoimmune disease within 12 months prior to the first dose of study drug
* Active infection
* Major diseases of heart and blood vessels within 6 months prior to the first dose of study drug
* Clinically significant lung diseases
* Active or chronic hepatitis B or hepatitis C infection
* Known positive test result for human immunodeficiency virus (unless stable on antiretroviral therapy with undetectable viral load)
* Any serious underlying medical conditions or other issue that would impair the ability of the participant to receive or tolerate the planned treatment