Biomarkers and Bone Imaging Dynamics Associated with Clinical Outcomes of Oral Cabozantinib Therapy in Metastatic Castrate-Resistant Prostate Cancer.


Department of Oncology Karmanos Cancer Center/Wayne State University, Detroit, Michigan. [Email]


Cabozantinib is a multitargeted tyrosine kinase inhibitor that demonstrated remarkable responses on bone scan in metastatic prostate cancer. Randomized trials failed to demonstrate statistically significant overall survival (OS). We studied the dynamics of biomarker changes with imaging and biopsies pretherapy and posttherapy to explore factors that are likely to be predictive of efficacy with cabozantinib.Experimental Design: Eligibility included patients with metastatic castrate-resistant prostate cancer with normal organ function and performance status 0-2. Cabozantinib 60 mg orally was administered daily. Pretherapy and 2 weeks post, 99mTc-labeled bone scans, positron emission tomography with 18F-sodium fluoride (NaF-PET) and 18F-(1-(2'-deoxy-2'-fluoro-β-D-arabinofuranosyl) thymine (FMAU PET) scans were conducted. Pretherapy and posttherapy tumor biopsies were conducted, and serum and urine bone markers were measured.