Assessing Early Treatment Response in mCSPC using KELIM PSA Score: Implications for Survival

This study investigated the prognostic value of the prostate-specific antigen (PSA) elimination rate constant K (KELIM PSA) score in patients with metastatic castration-sensitive prostate cancer (mCSPC) treated with docetaxel.

This multicenter retrospective study included 105 patients diagnosed with prostate adenocarcinoma between January 2014 and June 2025, who received docetaxel for mCSPC and had at least three PSA measurements within the first 100 days of treatment. The KELIM score was calculated using PSA kinetics modeled with a nonlinear mixed effects model. Patients with KELIM PSA <1 (hereafter referred to as KELIM 0) were categorized as unfavorable, whereas those with KELIM PSA ≥1 (hereafter referred to as KELIM 1) were considered favorable.

A total of 105 patients were included in the study. The median age was 66.1 years (SD, 8.6). There were 53 and 52 patients in the KELIM PSA ≥1 and <1 groups, respectively. The median overall survival (OS) differed significantly according to the KELIM categories, with favorable KELIM patients having a median OS of 44 months compared to 24 months for those with unfavorable KELIM. The 1-, 3-, and 5-year OS rates were higher in the favorable KELIM group. Liver metastasis was also associated with poor survival outcomes. In univariable analysis, ECOG ≥2, older age, liver metastasis, and unfavorable KELIM were associated with worse OS. However, in multivariable analysis, only definitive treatment and advanced age remained independent prognostic factors for OS, while KELIM did not retain statistical significance.

The KELIM PSA score showed prognostic value in univariable analysis but did not retain independent significance in multivariable analysis. These exploratory findings support further evaluation of KELIM as a potential early response biomarker in mCSPC treated with docetaxel.