When the time matters: Metastatic Castration Resistant Prostate Cancer (mCRPC) patients long responders to Abiraterone acetate (AA) in post-docetaxel setting

Background: The COU-AA 301 trial showed that AA improved survival for men with mCRPC progressing to docetaxel. No predictive factors are available to identify patients (pts) that may better respond to AA. In this trial the median duration of drug exposure was 7.4 months (range 0.2-25.6). Our aim was to describe clinical features of pts long responding to AA defined as those receiving AA in clinical practice for more than 12 months without evidence of disease progression.Patients and methods: A total of 143 mCRPC pts treated with AA for more than 12 months at 16 Italian centers from Oct 2011 to Jul 2014 were identified. Clinical records were retrospectively collected and analyzed. Descriptive statistics (median and range for continuous variables and absolute and percentage frequencies for categorical variables) were used to describe clinical features; the Cox regression model was used to detect and estimate statistical association between clinical features and duration of drug exposure; HR was reported for each unit x 100.Results: Median duration of treatment was 19.8 months (range 12-49) and 24% of patients still receive treatment. Median age was 73 years (range 47-87). Median PSA value at initial drug exposure was 38 ng/ml (range: 5-3850), Median Gleason score value was 8. Synchronous metastases to the primary were present in 33% of pts. Pts pretreated with chemotherapy were 88% and bone was the most frequent site of metastases (91%) with a remarkable 12% of pts had visceral disease (including lung, nonregional lymph nodes and liver). Pts receiving AA due to only PSA progression were 33%, while 54% of cases showed either PSA and radiological progression. PSA response ≥50% was observed in 80% of pts and those with measurable disease achieved a disease control rate of 88%. Risk of disease progression was stats associated with the following biomarkers values at baseline (before start AA): PSA (HR 1.10, p 0.008), alkaline fosfatase (HR 1.07,p 0.074) and LDH (HR 1.22, p 0.027). Regarding Gleason score surprising but in part according to what reported in clinical trials, higher Gleason was stats associated with less risk of disease progression (HR 0.82, p 0.012). Treatment was safe with 40% reporting only G1-G2 adverse events.Conclusions: Clinical features may help to better identify the “best responder patient”. A better understanding of the biological phenotype of mCRPC would lead to discover candidate predictive biomarkers of response. Background: The COU-AA 301 trial showed that AA improved survival for men with mCRPC progressing to docetaxel. No predictive factors are available to identify patients (pts) that may better respond to AA. In this trial the median duration of drug exposure was 7.4 months (range 0.2-25.6). Our aim was to describe clinical features of pts long responding to AA defined as those receiving AA in clinical practice for more than 12 months without evidence of disease progression. Patients and methods: A total of 143 mCRPC pts treated with AA for more than 12 months at 16 Italian centers from Oct 2011 to Jul 2014 were identified. Clinical records were retrospectively collected and analyzed. Descriptive statistics (median and range for continuous variables and absolute and percentage frequencies for categorical variables) were used to describe clinical features; the Cox regression model was used to detect and estimate statistical association between clinical features and duration of drug exposure; HR was reported for each unit x 100. Results: Median duration of treatment was 19.8 months (range 12-49) and 24% of patients still receive treatment. Median age was 73 years (range 47-87). Median PSA value at initial drug exposure was 38 ng/ml (range: 5-3850), Median Gleason score value was 8. Synchronous metastases to the primary were present in 33% of pts. Pts pretreated with chemotherapy were 88% and bone was the most frequent site of metastases (91%) with a remarkable 12% of pts had visceral disease (including lung, nonregional lymph nodes and liver). Pts receiving AA due to only PSA progression were 33%, while 54% of cases showed either PSA and radiological progression. PSA response ≥50% was observed in 80% of pts and those with measurable disease achieved a disease control rate of 88%. Risk of disease progression was stats associated with the following biomarkers values at baseline (before start AA): PSA (HR 1.10, p 0.008), alkaline fosfatase (HR 1.07,p 0.074) and LDH (HR 1.22, p 0.027). Regarding Gleason score surprising but in part according to what reported in clinical trials, higher Gleason was stats associated with less risk of disease progression (HR 0.82, p 0.012). Treatment was safe with 40% reporting only G1-G2 adverse events. Conclusions: Clinical features may help to better identify the “best responder patient”. A better understanding of the biological phenotype of mCRPC would lead to discover candidate predictive biomarkers of response.