BoneProst: Prostate cancer and bone biomarkers

Introduction: Prostate cancer (PC) is the most common cancer amongst men in Denmark (4,519 new cases in 2016) and the second most common cause of cancer-related deaths (1,254 deaths in 2016). PC pts frequently develop bone metastases, reducing quality of life and survival. Cancer cells in the marrow trigger elevated bone resorption and an overproduction of weak bone, making cancer cells resistant and causing severe bone disease. Question: Can bone biomarkers (CTX: break-down; PINP: formation) be used for diagnosis and monitoring? Materials & Methods: Group1: 100 newly diagnosed PC pts (without bone metastases) - only base line. Group2a: ~25 PC pts suspected to have bone metastases but with a negative scintigraphy/NaF-PET - only base line. Group2b: 50 pts with newly confirmed bone metastases - follow for 3 years. Group3: 50 PC pts with newly identified castration-resistant PC - follow for 2 years. Primary variables: absolute and delta-values for CTX and PINP, occurrence or progression of bone metastases, and death. Results: Start of recruitment: September 2017 - status: 157 pts. Preliminary results: Group2b (12 pts): 3 months after castration median CTX levels are significantly elevated by 56% (p=0.0005) while PINP is unchanged (p=0.470). This results in a net bone loss based on CTX/PINP ratio (p=0.014). Group3 (35 pts): 43% of pts have CTX values at baseline that are above the 2x standard deviation cut-off based on Group1 (98 pts). Group3 (28 pts): 28% and 14% respond poorly to zoledronic acid treatment after 1 and 3 months, respectively. Group3 (21 pts): 6-8 months after treatment start 55% show signs of disease progression based on CTX development. Conclusions: CTX and PINP seem to be promising biomarkers that could be a future powerful supplement for diagnosis and monitoring of PC pts. Our trial is still ongoing and the last patient is expected to leave the trial in 4 years.