A Phase 1/2 Clinical Trial to Evaluate the Safety, Tolerability, Dosimetry, and Anti-tumor Activity of Ga-68-NGUL / Lu-177-DGUL in Patients With Metastatic Castration-resistant Prostate Cancer (mCRPC) Refractory to Standard Therapy

Inclusion Criteria: * Male patients of 19 years or older * Patients with metastatic diseases due to adenocarcinoma of the prostate as confirmed * Patients whose blood testosterone levels at the screening visit meet the castration criteria(\< 50 ng/dL) * Patients with advanced metastatic castration-resistant prostate cancer who have failed standard treatment or no longer have standard treatment available * Those who are maintaining androgen deprivation therapy (ADT) regardless of the type * Patients receiving bone resorption treatment who have maintained a stable dose for at least 4 weeks prior to baseline * Patients with positive lesions on Ga-68-NGUL PET scan * Patients with Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2 * Patients with an expected survival of 6months or more * Patients with confirmed adequate hematological function, renal and hepatic function according to the following criteria * Patients who have voluntarily consented to participate in this clinical trial and signed the informed consent form Exclusion Criteria: * Patients with hematologic malignancy, including lymphoma and solid cancers other than prostate cancer, within 3 years prior to baseline * Patients who have received chemotherapy, biotherapy, or immunotherapy for prostate cancer treatment within 4 weeks prior to baseline * Patients who have received radiation chemotherapy or radiation therapy within 12 weeks prior to baseline * Patients who have received high-dose chemotherapy requiring hematopoietic stem cell therapy within 2 years prior to baseline * Those who had previously received PSMA-targeted treatment or received radiopharmaceutical treatment, such as radium-223, within 6 months prior to baseline * Patients with symptomatic central nervous system metastases * Patients with unsuitable medical history or surgical/procedural history * Patients with severe drug hypersensitivity and a history of hypersensitivity to the investigational product and similar drugs * Patients receiving concomitant nephrotoxic drugs * Patients with severe claustrophobia that is not controlled with anti-anxiety medications * Patients with hypersensitivity reactions to components of the investigational product * If the partner is a female of childbearing potential, patients who do not intend to abstain from abstinence or use appropriate contraceptive methods for at least 3 months after the end of the clinical trial period and investigational product administration * Patients who have been administered with other investigational products or treated with clinical investigational devices within 4 weeks prior to baseline * Patients who cannot participate in the clinical trial as determined by other investigators