Design of the AFFINITY study: A randomized phase III study of a novel clusterin inhibitor, custirsen, plus cabazitaxel/prednisone (CbzP) versus CbzP alone as second-line chemotherapy in metastatic castration-resistant prostate cancer (mCRPC).

TPS5103 Background: Custirsen enhances chemotherapeutic activity via inhibition of clusterin expression. Clusterin is a cytoprotective, antiapoptotic chaperone upregulated by anticancer therapies that confers treatment resistance. In a phase 2 study, mCRPC patients who had progressed within 6 mos of completing first-line docetaxel (DOC)/prednisone (P) and who were retreated with DOC/P and custirsen had a median overall survival of 15.8 mos. Lowering of serum clusterin level during second-line treatment was associated with significantly longer survival. CbzP has recently shown a survival advantage in patients with prostate cancer that has progressed after DOC therapy. The AFFINITY study was designed to evaluate in a larger study whether adding custirsen to CbzP will further improve survival in this patient population. Methods: AFFINITY was initiated in August 2012. Eligible patients in this phase 3, international, multicenter, open-label trial must have received ≥225 mg/m2 of DOC; have progressive disease ...