A. Peer

P112 Pre-treatment (pre-tx) neutrophil to lymphocyte ratio (NLR) in metastatic castration resistant prostate cancer (mCRPC) patients (pts) treated with ketoconazole (keto): Association with outcome and predictive model

37 Background: The CYP17 inhibitor Keto is active in mCRPC. The NLR, an index of systemic inflammation, is associated with prognosis in several types of cancer. We assessed the association between pre-tx NLR and outcome of mCRPC pts treated with keto.nnnMETHODSnWe performed a multicenter retrospective study of pts with mCRPC, who were treated with keto. We analyzed the pre-tx NLR and previously described factors associated with keto tx outcome as prior response to hormonal tx, pre-tx PSADT, and extent of metastatic disease (limited-axial skeleton/nodal vs extensive- appendicular skeleton/visceral). Progression free survival (PFS) was determined by the Kaplan-Meier method. Multivariate analyses using Cox regression model were performed to determine their independent effect, and to form a predictive model. A survival tree analysis was used to find the best NLR cut-off value.nnnRESULTSnFrom 1999-2011, 135 mCRPR pts were treated with keto. 67/135 (50%) had ≥ 50% PSA decline. Overall median PFS was 8 months (mos) (range 1-134 ). Excluded from the analysis were pts without available data on pre-tx NLR (n=8), and those with recent (≤1 mos) health event (surgery, n=1) or tx (steroids, n=3 or radiation, n=3) known to be associated with a change of blood counts. 120 pts were included in the analysis. 57 (48%) had an elevated pre-tx NLR >3. Risk factors associated with PFS (table) were pre-tx NLR >3, prior response to GnRH-a <24 mos and to AA <6 mos, and pre-tx PSADT <3 mos. The number of risk factors was used to categorize patients into three risk groups (table): favorable (0-1 factors), intermediate (2 factors), and poor (3-4 factors).nnnCONCLUSIONSnIn mCRPC pts treated with keto, pre-tx NLR, prior response to hormonal tx, and pre-tx PSADT are associated with PFS, and may be used to categorize pts into risk groups. [Table: see text].