Study to Evaluate the Safety, Tolerability,Pharmacokinetics, and Antitumor Activity of a Thorium-227 Labeled Antibody-chelator Conjugate Alone and in Combination With Darolutamide, in Patients With Metastatic Castration Resistant Prostate Cancer

Inclusion Criteria * Ability to understand and sign an approved informed consent form. * Male adult patients (≥ 18 years of age). * ECOG PS of 0 or 1. * Life expectancy ≥ 6 months. * Histological, pathological and/or cytological confirmation of adenocarcinoma of the prostate without small cell or neuroendocrine features. * Previous treatment with at least one novel androgen axis drug (NAAD) (e.g. enzalutamide and/or abiraterone). * Patients must have prior orchiectomy and/or ongoing androgen deprivation therapy and a castrate level of serum testosterone (\<50 ng/dL or \<1.7 nmol/L). * Previous treatment with at least 1, but no more than 2 previous - taxane regimens. A taxane regimen is defined as a minimum exposure of 2 cycles of a taxane. If a patient has received only 1 taxane regimen, he is eligible, if refuses to receive a second taxane regimen, or is considered unsuitable to receive a second taxane regimen (e.g. intolerance). * Documented progression of mCRPC, as defined according to the Prostate Cancer Working Group 3 (PCWG3) guidelines. * Adequate bone marrow, liver, and renal function, as assessed by the following laboratory requirements, to be conducted within 14 days before start of study drug administration: * Hemoglobin \> 9.0 g/dL * Absolute neutrophil count (ANC) \> 1500/mm3 * White blood cell (WBC) count \> 3000/mL * Platelet count \> 100,000 /mm\*3 * Total bilirubin \< 1,5 x upper limit of normal (ULN) (except if confirmed history of Gilbert's disease) * ALT and AST ≤ 2.5 x ULN * Serum creatinine ≤ 1.5 X ULN and glomerular filtration rate (GFR ≥ 45 mL/min/1.73 m2, according to the MDRD (Modified Diet in Renal Disease) abbreviated formula. * Patients with partners of childbearing potential must be willing to use highly effective methods of birth control for the time period between the first administration of BAY 2315497 Injection to at least 6 months after the last administration of the study drug. * In the darolutamide BAY2315497 Injection combination escalation arm, patients at sites performing the PSMA and FDG PET/CTs should be able to tolerate the 3 radiotracer injections and the 3 whole body PET/CT scans. Exclusion Criteria * Diffuse bone or bone-marrow involvement (i.e. "superscan"). * Spinal cord compression or known brain metastases. * Known incompatibility to CT/MRI, bone scan or uncontrolled pain, which results in patient's lack of compliance with the CT/MRI and bone scan required for PCWG3 tumor assessment. * Clinically significant heart disease, as evidenced by myocardial infarction, arterial thrombotic events in the past 6 months, severe or unstable angina, or uncontrolled cardiovascular history. * Patients known to be affected by genetic defects linked to radiation Hypersensitivity. * Known history of myelodysplastic syndrome (MDS) / leukemia or with features suggestive of MDS/AML at any time point. * Concurrent or active cancer within the last 2 years with a distinct primary site or histology from the cancer being evaluated in this study, with the exception of cancer types with less than 30% likelihood of recurrence. * Known allergies, hypersensitivity, or intolerance to the study drug including excipients, or to contrast agents used in the diagnostic or exploratory imaging procedures required per protocol. * Any infection of National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) Version 5.0 Grade ≥ 2. * Known human immunodeficiency virus (HIV) infection. * Patients who have an active hepatitis B virus (HBV) or hepatitis C virus (HCV) infection requiring treatment. * Serious, non-healing wound, ulcer, or bone fracture. * Any systemic anti-neoplastic therapy (e.g. chemotherapy, immunotherapy or biological therapy \[including monoclonal antibodies\], PARP inhibitors) within at least 30 days prior to day of randomization (except for Luteinizing Hormone-releasing Hormone \[LHRH\] or Gonadotropin-releasing Hormone \[GnRH\]). * Previous high-dose chemotherapy, needing hemopoietic stem cell rescue, is prohibited. * Prior major surgery (excluding prostatic biopsies) must be at least 12 weeks prior to study entry. * Previous treatment with therapeutic PSMA-targeted agents. * Previous treatment with radium-223 dichloride or other radiopharmaceuticals, including but not limited to strontium-89 or samarium-153. * Prior definitive radiotherapy completed less than 6 weeks before start of the study drug administration * Inability to swallow oral medications * A gastrointestinal disorder or procedure which is expected to interfere significantly with absorption of darolutamide