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A Multicenter, Open-label, Phase 2 Trial to Evaluate the Safety and Efficacy of 177Lu-PSMA-I&T in Patients with PSMA-Positive Metastatic Castration-Resistant Prostate Cancer in Japan

Phase 2 Trial of 177Lu-PSMA-I&T in Patients with PSMA-Positive Metastatic Castration-Resistant Prostate Cancer

Tanaka Yoshitomo

PDRadiopharma Inc.

2-14-1, Kyobashi,Chuo-ku, Tokyo

s-clinicaltrial-info@pdradiopharma.com

Miki Satoshi

PDRadiopharma Inc.

2-14-1, Kyobashi,Chuo-ku, Tokyo

+81-3-6263-0454

s-clinicaltrial-info@pdradiopharma.com

Recruiting

Oct. 22, 2025

Interventional

single arm study

open(masking not used)

uncontrolled control

single assignment

treatment purpose

1. Histologically or pathologically confirmed prostate adenocarcinoma without predominant small cell component.
2. Progressive disease by one or more of the following criteria:
(a) The starting point is when the serum or plasma PSA level exceeds 2.0 ng/mL, followed by two consecutive increases in PSA levels as measured thereafter. The interval between PSA measurements must be at least one week.
(b) Progression of measurable disease (RECIST 1.1) or presence of at least two new bone lesions (PCWG3 criteria).
3. Previous treatment with Androgen Receptor Signaling Inhibitor (e.g. abiraterone, enzalutamide, apalutamide, darolutamide).
(a) Must have received only one type previous ARSI.
(b) Must have been administered ARSI in the castration-sensitive or castration resistant setting.
(c) Must have progressed while on ARSI.
4. Effective castration with serum testosterone level of <50 ng/dL and plan to continue with chronic medical or surgical castration.
5. Patients with one or more measurable disease per RECIST ver.1.1.

1. Prior treatment with radioligand therapy including other lutetium-labeled compounds.
2. Treatment history of Radium-223 (Xofigo) within 12 weeks prior to informed consent.
3. Prior chemotherapy treatment for castration-resistant prostate cancer, Prior docetaxel use in the hormone-sensitive setting is permitted as long as no more than 6 doses were received, the last dose was administered >1 year prior to consent, and disease progression did not occur during docetaxel treatment.
4. Eastern Cooperative Oncology Group (ECOG) performance status (PS)>=2.
5. Patients with known HRR gene-mutation (BRCA 1/2 encompassing both germline and somatic) who have not been previously treated with Olaparib or Talazoparib.
6. Patients currently receiving other cytotoxic chemotherapy, immunotherapy, radioligand therapy, or investigational therapy.
7. Inadequate organ and bone marrow function as evidenced by:
(a) Hemoglobin < 8.0 g/dL.
(b) Absolute neutrophil count < 1.5 x 10^9/L.
(c) Platelet count < 100 x 10^9/L.
(d) AST/SGOT and/or ALT/SGPT > 3.0 x ULN.
(e) Total bilirubin > 2.0 x ULN unless patient has known Gilbert's syndrome and then may be 3.0 x ULN.
(f) Creatinine clearance (CrCl) < 50 mL/min based on the Cockcroft-Gault equation.
(g) Albumin < 2.75 g/dL
8. Known central nervous system (CNS) metastasis unless received therapy, asymptomatic and neurologically stable.
9. Patients receiving zoledronic acid for bone-targeted therapy must be on stable dose for 4 weeks prior to randomization.
10. Major surgery within 30 days of enrollment as determined by the Investigator.
11. Patients with active significant cardiac disease defined by any of the following:
(a) New York Heart Association class 3 or 4 congestive heart failure within 6 months of signing the Informed Consent Form (ICF) unless treated with improvement.
(b) Current diagnosis of electrocardiogram abnormalities with significant cardiac arrhythmias.
(c) History of long QT syndrome or known history of Torsades de Pointe.
(d) History of myocardial infarction, angina pectoris, or coronary artery bypass graft within 6 months of ICF signature.
12. Participants with symptomatic cord compression or clinical/radiological findings indicating impending spinal cord compression.
13. Patients with a superscan seen on baseline bone scan as determined by investigator.
14. Active malignancy other than low-grade non-muscle-invasive bladder cancer and non-melanoma skin cancer.
15. Patients who have previously received G-CSF for persistent neutropenia associated with prostate cancer treatment.
16. Patients infected with human immunodeficiency virus (HIV), hepatitis B virus (HBV) or hepatitis C virus (HCV). However, if their symptoms are adequately controlled, they may participate in the study at the discretion of the investigator (subinvestigator).
17. Patients with a partner of childbearing potential who are unwilling to prevent pregnancy during the study period and for 6 months after the last dose of study drug.
18. Patients with a pregnant partner who are unwilling to take precautions to prevent potential harm to the fetus.
19. Patients who are allergic to any of the active ingredients or additives of the investigational drug.

Male

Prostate Cancer

To confirm PSMA positivity, a single intravenous dose 296 MBq (+-10 percent) of R-241B is administered, followed by a PET/CT scan. Those who test positive will receive 7.4 GBq (+-10 percent) of R-242C intravenously every 6 weeks for 6 cycles while being maintained at castrate levels of testosterone (of <50 ng/dL). Additionally, up to four more doses of R-241B at 296 MBq (+-10 percent) will be administered intravenously during the long-term follow-up period, and PET/CT scans will be performed.

Proportion of participants with best overall response (BOR) of complete response (CR) or partial response (PR), as assessed by blinded central review, according to PCWG3-modified RECIST v1.1.

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