GI-102 (CD80-IgG4 Fc-IL2v3) in Combination With Pasritamig in Patients With Metastatic Castration-resistant Prostate Cancer (mCRPC) (JET-201)

The purpose of this clinical trial is to evaluate the safety, tolerability, and preliminary anti-cancer activity of GI-102 in combination with pasritamig in adult men with metastatic castration-resistant prostate cancer (mCRPC) whose cancer has progressed after previous treatment with a novel hormonal therapy (NHT).

Key Inclusion Criteria: * Male participants aged ≥18 years (or ≥19 years according to local regulatory requirements). * ECOG performance status of 0 to 1. * Histologically confirmed advanced prostate adenocarcinoma with measurable or evaluable disease. Adenocarcinoma with small cell or neuroendocrine (NE) features is permitted. However, primary small cell carcinoma, carcinoid tumor, mixed NE carcinoma, or large cell NE carcinoma (or pathologic evidence of conversion to) is disallowed. * Metastatic castration-resistant prostate cancer (mCRPC) with documented disease progression following at least one line of novel androgen receptor-targeted therapy. * PSA ≥2 ng/mL at screening. * No more than 2 prior taxane regimens and no prior cytotoxic chemotherapy other than taxane therapy. * Prior orchiectomy or ongoing androgen deprivation therapy with castrate testosterone levels. * Adequate organ and marrow function and adequate cardiovascular function. * Adequate recovery from prior anticancer therapy-related adverse events. * Willingness and ability to comply with study procedures and protocol-specified contraception requirements. Key Exclusion Criteria: * Active or prior CNS metastases, carcinomatous meningitis, or clinically unstable spinal cord compression. * Significant uncontrolled cardiovascular, pulmonary, hepatic, autoimmune, infectious, or other systemic disease. * Active or recent clinically significant infection, including active tuberculosis, hepatitis B, or hepatitis C. * Active pneumonitis or interstitial lung disease (ILD), or history of clinically significant pneumonitis/ILD. * Recent treatment with investigational products, prohibited immunomodulating agents, radiotherapy, major surgery, or other protocol-defined prohibited therapies. * Prior treatment with CD3-directed therapies, including KLK2-CD3 bispecific antibodies or other CD3-targeting T-cell engagers. * Known hypersensitivity to GI-102, pasritamig, or their excipients, or any other condition that may interfere with study participation or interpretation of results.