Safety, Pharmacokinetics, and Preliminary Efficacy of VIR-5500 (AMX-500) in Prostate Cancer

The study will be conducted in 4 parts and will commence with dose escalation of VIR-5500 as a monotherapy (Part 1), followed by combination escalation (Part 3a), monotherapy dose expansion (Part 2) and combination dose expansion (Part 4a). * Part 1 (Monotherapy Dose Escalation): Single-agent VIR-5500 dose escalation * Part 2 (Monotherapy Dose Expansion): Single-agent VIR-5500 dose expansion * Part 3 (Combination Dose Escalation): VIR-5500 plus another therapeutic agent dose escalation o Part 3a (Combination Dose Escalation): VIR-5500 in combination with an androgen receptor signaling inhibitor (ARSI) (enzalutamide or darolutamide) * Part 4 (Combination Dose Expansion): VIR-5500 plus another therapeutic agent dose expansion o Part 4a (Combination Dose Expansion): VIR-5500 in combination with an ARSI (enzalutamide or darolutamide)

Duration of the study up to approximately 48 months.

Inclusion Criteria: Applicable to Parts 1 and 2 * Have metastatic disease, defined by ≥ 1 metastatic lesion that is present on baseline computed tomography (CT), magnetic resonance imaging (MRI), or bone scan imaging * Have documented progressive mCRPC based on ≥ 1 of the criteria (per PCWG3) * Have been treated with ≥ 1 second-generation androgen-signaling inhibitor, including abiraterone, apalutamide, darolutamide, and/or enzalutamide * Have been treated with ≥ 1 prior taxane regimens (e.g., docetaxel, cabazitaxel) * Are deemed unsuitable for standard of care Applicable to Part 2 Cohort 1 • Must have received standard-of-care radioligand-based therapies, including PSMA-targeted radiopharmaceutical therapy, such as 177Lu-PSMA-617 Applicable to Part 3a and Part 4a * Have metastatic CRPC, defined by ≥ 1 metastatic lesion that is present on baseline CT, MRI, or bone scan imaging that has documented progressive disease (PD) based on ≥ 1 of the following criteria (per PCWG3) * Have metastatic HSPC, defined by at least 1 and no more than 5 metastatic lesions with no visceral involvement that are present on baseline CT, MRI, or bone scan imaging * Have biochemical recurrent prostate cancer Exclusion Criteria: * Presence of dominant histopathological features representative of sarcomatoid, spindle cell, or neuroendocrine small cell components * Has acute or chronic infections * Has a concomitant medical or inflammatory condition that may increase the risk of toxicity to VIR-5500, per the Investigator * Has lesions in proximity of vital organs * Has known active CNS metastases and/or carcinomatous meningitis The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.