Abstract: Objective · To determine whether pre-treatment prognostic nutritional index (PNI) level and its variation can predict the primary resistance to abiraterone (AA) and the prognosis in metastatic castration-resistant prostate cancer (mCRPC) patients treated with AA. Methods · A total of 112 mCRPC patients treated with AA were included in Department of Urology, Renji Hospital, Shanghai Jiao Tong University School of Medicine. PNI levels were measured before and one month after AA treatment. PNI was calculated preoperative laboratory parameters using the formula [10×serum albumin level (g/dL) + 0.005×lymphocyte (per μL) in the peripheral blood]. Univariate and multivariate Logistic regression analyses were used to identify predictive factors of initial efficacy to AA treatment. Univariable and multivariable Cox regression analyses were performed to determine the prognostic factors that were associated with prostate-specific antigen (PSA) progression-free survival (PSA-PFS), radiographic PFS (rPFS) and overall survival (OS). Results · Eighty-one of all 112 (72.3%) patients showed initial response to AA treatment, and 15 patients experienced PSA flare during AA treatment. In multivariate Logistic regression analysis, the high baseline PNI level, the decrease of PSA level during the first month of AA treatment and the elevation of PNI level during the first month of AA treatment were significantly correlated with the initial response to AA treatment. In multivariate Cox regression analyses, the low baseline PNI level remained significant predictor of OS, rPFS and PSA-PFS. Conclusion · Independent of PSA level variation, the elevation of PNI level during the first month of AA treatment and high baseline PNI level are significantly correlated with the initial response to AA treatment. In addition, low baseline PNI level is a negative independent prognosticator of survival outcomes in mCRPC patients treated with AA.

Key words: metastatic castration-resistant prostate cancer (mCRPC), abiraterone (AA), prostate-specific antigen flare (PSA flare), primary resistance