First-in-Human Study to Evaluate AZD8359 STEAP2 TCE in Participants With Prostate Cancer

Phase I/II Dose Escalation & Dose Optimization Study to Evaluate the Safety, Pharmacokinetics, Pharmacodynamics, and Efficacy of AZD8359, a CD8-guided T Cell-engaging Antibody That Targets STEAP2, in Adult Participants With Prostate Cancer

This study is being conducted to learn more about the safety, tolerability, and effectiveness of an experimental treatment for metastatic prostate cancer called AZD8359. The study is split into different modules which will look at AZD8359 delivered by different methods. The study is also further split into 2 parts, Part A which will test different dose levels and dosing schedules of AZD8359 to determine which doses are the best in terms of safety and side effects (dose escalation), and Part B will further test at least two AZD8359 doses in a larger group of participants (dose expansion).

This is a first-in-human, modular, Phase I/II, open label, multicenter study of AZD8359, in adult participants with metastatic prostate cancer. The study will consist of study modules, each evaluating the the safety, tolerability, preliminary efficacy, immune cell activation and anti-tumor activity of AZD8359. The study will also characterize the pharmacokinetics and immunogenicity of AZD8359.

Inclusion Criteria:

• Histologically confirmed diagnosis of adenocarcinoma of the prostate or neuroendocrine differentiated prostate cancer
• Surgically or medically castrated with serum testosterone levels ≤ 50 ng/dL (≤ 1.75 nmol/L)
• PSA value at screening should be ≥ 1ng/mL
• Evidence of disease progression within 6 months prior to screening
• Part A Participants should have received at least 2 prior approved systemic therapies for prostate cancer with at least one androgen receptor pathway inhibitor and at least one taxane regimen if amenable
• Part B Participants should have received an androgen receptor pathway inhibitor for metastatic hormone sensitive prostate cancer or metastatic castration resistant prostate cancer (mCRPC). No prior taxane treatment for mCRPC is allowed for Module 1 and 2 Part B patients
• Adequate organ function
• Body weight ≥ 35 kg

Exclusion Criteria:

• Any clinically relevant cardiac abnormalities such as QT prolongation or uncontrolled cardiac arrythmias
• All prior treatment-related adverse events must have resolved to Grade ≤ 2
• History of Grade ≥ 3 cytokine release syndrome or Grade ≥ 2 immune effector cell-associated neurotoxicity syndrome with prior therapy
• Active or prior documented autoimmune or inflammatory disorders within the past 3 years
• Prior exposure to any STEAP2 targeted agents or TCEs for prostate cancer