Overview

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
  • 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)

Eligibility

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.