Whole-Body Diffusion-Weighted Magnetic Resonance Imaging (MRI) as a Response Biomarker for Metastatic Prostate Cancer

A Study to Clinically Qualify Whole-Body Diffusion-Weighted Magnetic Resonance Imaging (MRI) in Patients With Metastatic Castration Resistant Prostate Carcinoma With Bone Metastases

The skeleton is the most frequent organ of distal metastases in prostate cancer, often representing the only site of metastatic disease. Still, assessment of response and progression to therapies in bone metastases remains a major unmet need, to aid treatment switch decisions, detecting primary/secondary resistance and to optimize drug development. The currently used standard imaging techniques, computed tomography (CT) and bone scintigraphy (BS), do not depict the true extent of bone metastases and are suboptimal in capturing biological changes occurring in response to treatment.

This results in treatment switch decisions too often being based on PSA changes, which is neither a surrogate of survival, nor an optimal response biomarker.Diffusion-weighted imaging (DWI) is a functional magnetic resonance imaging (MRI) technique that studies the movement of water molecules within a tissue and provides valuable information about the tissue microstructure and cellularity. Whole body MRI with DWI is highly accurate for bone metastases detection, outperforming the standard CT and BS and other imaging techniques when assessing bone metastases.

The investigators hypothesise that DWI changes are a response biomarker in bone metastases from metastatic castration resistant prostate cancer (mCRPC); these DWI changes can be detected as early as after 4 weeks of systemic treatment.

Inclusion Criteria:

• Men 18 or over years old.
• Patients with castration resistant prostate cancer.
• Evidence of bone metastases by any imaging technique.
• Patients due to start treatment with abiraterone or enzalutamide. In the exploratory cohorts, we will include patients due to start treatment with other systemic therapies for advanced prostate cancer (A-taxanes, B-radiopharmaceuticals, C-other therapies).
• Written (signed and dated) informed consent.

Exclusion Criteria:

• Contraindications to MRI.
• Inability of patient to tolerate whole body MRI (e.g. claustrophobia).
• Patients who have received radiotherapy within the last three months and with no bone metastases outside the radiotherapy field.