Early PSA Decline In Metastatic Prostate Cancer Treated With Abiraterone

Abstract

Abiraterone (AA) is indicated in mRCPC (metastatic castration-resistant prostate cancer) before or after chemotherapy, and in mHSPC (metastatic hormone-sensitive prostate cancer) as first line. A decrease in PSA is associated with improved clinical response and increased survival. Recent studies have proposed an earlier PSA evaluation, at 4 w, which could have an impact in prognosis. Our main objective is to analyze if an early PSA decline correlates with improved OS (overall survival) and PFS (progression-free survival) outcomes. We evaluated 120 patients with a mean age of 70,78 years from 3 different institutions, who started Abiraterone acetate + prednisone (AA+p) between February 2012 and July 2019. We collected PSA data at w number 4, 8, 12, 24, 48, 72 and 96. According to the 4-week PSA decrease, patients were classified into two groups: those in whom PSA decreased>30% (early responders = ER) and those in whom PSA decreased <30% (non-early responders = nER). Mean overall survival (OSm) and mean progression-free survival (SLPm) were calculated using the Kaplan-Meier method. The multivariable COX model was used to assess the effect on OS and PFS of both the PSA response rate at 4 w and other clinical-demographic variables. After a mean follow-up of 21,45 m (0-69), we analyzed the OS and PFS in the three groups: mHSPC, mRCPC pre-Chemotherapy and CPRCm post-Chemotherapy. We found a significant difference in mHSPC between ER and nER in mean OS (22,45 vs 10,5; p = 0,008) and mean PFS (20,54 vs 8,25; p = 0,011). In mRCPC there was no significant difference in survival but a trend is observed. Cox analysis showed an increased risk of death (HR 7,77; p = 0,025) and progression (HR 6,58; p = 0,026) for nER, but only in mHSPC. In mRCPC, pretreatment with chemotherapy appear as an independent factor in OS (HR 2,62; p = 0,003) and PFS (HR 2,60; p = 0,00). For both mHSPC and mRCPC, a higher PSA at the beginning of AA+p was related with an increased risk of death (p = 0,016; p = 0,00) and progression (p = 0,0011; p = 0,001). Evaluation of response to treatment for mHSPC and mRCPC remains a challenge. Early clinical or biological markers are needed to identify non-responders’ patients, in order to minimize patient exposure to adverse effects of ineffective therapies, as well as reduce costs and personalize the strategies. Our study confirmed that a PSA decrease >30% at 4 w correlates with a better outcome in OS and PFS, playing a role in prognosis.Abstract 4139; TablePatients characteristicsSamplemHSPC 23; mRCPC 97 (mRCPC pre-CH 69, mRCPC post-CH 28)DMYes 14,2%; No 85,8%HTYes 50,4%; No 49,6%StatinsYes 31%; No 69%Gleason6: 12,8%7: 32,1%;8: 29,4%;9:21,1%10: 4,6%TT1: 1,1%T2: 20,2%T3: 55,1%T4: 23,6%NN0: 57,1%N1: 31%N2: 7,1%N3: 4,8%1st TreatmentSurgery: 14,7%RT 25,9%HT 43,1%CH 1,7%AA+p 14,7% Open table in a new tab