Factors predicting progression to castrate-resistant prostate cancer in patients with advanced prostate cancer receiving long-term androgen deprivation therapy.

OBJECTIVES - To assess time to progression to castrate-resistant prostate cancer (CRPC) and factors influencing longer-term outcomes in patients receiving ADT in an extension to the Triptocare study (NCT01020448).

This is pertinent as the Triptocare study did not show that urinary PCA3 score was a reliable marker of cancer stage in advanced prostate cancer and was not useful for assessing response 6 months after initiation of androgen deprivation therapy (ADT) with triptorelin 22.5 mg.

MATERIALS AND METHODS - An international, multicentre, non-interventional, observational, longitudinal, prospective study involving patients from the Triptocare study. CRPC status of patients was collected for up to 3 years from ADT initiation. Patient treatment and assessments were at the investigator's discretion. Co-primary endpoints were rate of CRPC 3 years after initiating ADT and median time to CRPC. An exploratory endpoint was association of Triptocare baseline variables (including TMPRSS2-ERG score and PCA3 score) and PCA-3 score at Triptocare last value available with CRPC onset.

REULTS - Of the 325 patients in the Triptocare study safety population, 180 patients were enrolled in the Triptocare LT study (102 received continuous and 78 received intermittent ADT). CRPC rates at 3 years were 24/102 (23.5%) and 6/78 (7.7%) patients in the continuous and intermittent ADT groups, respectively. Median time to CRPC was not reached for either group. PCA3 score status at baseline was the only variable associated with a higher risk of progression to CRPC in both the intermittent and continuous ADT groups; compared with a baseline PCA3 score ≥35, PCA3 score below the level of quantification (BLQ) had a hazard ratio (HR) of 20.04 (95% CI: 2.71-148.34) and a HR=9.44 (95% CI: 2.39-37.27), respectively. Baseline metastatic disease and testosterone were additionally associated with progression to CRPC in the continuous ADT population: HR=5.20 (95%CI: 1.68-16.06) and HR=0.995 (95%CI: 0.991-0.999), respectively.

CONCLUSIONS - In men with locally-advanced or metastatic prostate cancer, a PCA3 score ≥35 at time of initiating ADT may predict a lower risk of developing CRPC in the following 3 years. This article is protected by copyright. All rights reserved.

BJU international. 2016 Feb 25 [Epub ahead of print]

Alexandre de la Taille, Luis Martínez-Piñeiro, Patrick Cabri, Aude Houchard, Jack Schalken, Triptocare LT study group

INSERMU955Eq07 CHU Mondor Assistance Publique des Hopitaux de Paris, Créteil, France., Chairman of the Urology Unit, Infanta Sofía University Hospital, Madrid, Spain., Ipsen Pharma, Paris, France., Ipsen Pharma, Paris, France., Experimental Urology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.

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