The prognostic significance of prostate-specific antigen dynamics during abiraterone therapy in patients with high-risk metastatic hormone-sensitive prostate cancer.

Abstract

78 Background: The depth reduction in prostate-specific antigen (PSA) levels serves as a prognostic indicator for patients with high-risk metastatic hormone-sensitive prostate cancer (mHSPC) undergoing treatment with abiraterone. However, the potential impact of the duration of PSA level depth reduction on prognosis remains uncertain. Methods: We conducted a comprehensive review of data from 153 high-risk mHSPC patients undergoing first-line abiraterone therapy. The group analysis was conducted based on the alterations in PSA levels during abiraterone therapy. Kaplan-Meier survival curves and Cox proportional hazards regression analysis were used to evaluate the association between the trend and duration of PSA decline and treatment outcomes, which include PSA progression-free survival (PSA-PFS), radiographic progression-free survival (rPFS), and overall survival (OS). Results: Among the 153 patients treated, 85 exhibited a minimum PSA level of less than 0.2 ng/ml, 48 had a minimum PSA level ranging from 0.2 to 0.4 ng/ml, and 20 presented with a minimum PSA level exceeding 4 ng/ml.During abiraterone treatment, the lowest PSA level of <0.2 ng/ml was significantly associated with improved mPSA-PFS (51.0 vs. 18.5 vs. 6.9 months, P < 0.0001), mrPFS (52.0 vs. 24.3 vs. 10.3 months, P < 0.0001), and mOS (NR vs. 48.5 vs. 28.1 months, P < 0.0001). A reduction in PSA levels exceeding 90% was correlated with enhanced patient survival outcomes; additionally, a baseline PSA level of <80 ng/ml at the initiation of abiraterone therapy significantly improved patients' mPSA-PFS (43 .1 vs .26 .0 months, P=0 .01), mrPFS (46 .8 vs .27 .5 months, P=0 .01), and mOS (NR vs .43 .8 months, P=0.03).In the cohort with the lowest PSA levels (PSA < 0.2 ng/ml), achieving a PSA level of less than 0.2 ng/ml within six months and maintaining this level for over ten months significantly enhanced clinical outcomes, as evidenced by mPSA-PFS (NR vs. 26.9 months, P < 0.0001), mrPFS (NR vs. 27.5 months, P < 0.0001), and mOS (NR vs. 44.4 months, P < 0.0001). Cox regression analysis indicated that achieving a PSA level of less than 0.2 ng/ml within six months, sustaining this level for more than ten months, along with age and initial PSA at diagnosis were independent prognostic factors. Conclusions: In mHSPC patients undergoing first-line abiraterone treatment, a sustained improvement in PSA levels serves as an indicator of therapeutic response, while the rate and depth of PSA decline, along with its duration, are critical prognostic determinants.