Outcomes of a Canadian real-world cohort of metastatic castration-sensitive prostate cancer patients stratified by early PSA nadir.

INTRODUCTION

Real-world data can complement trial analyses and validate biomarkers in metastatic castration sensitive prostate cancer (mCSPC) population.

METHODS

A prospective, multi-center cohort study recruited mCSPC patients across Canada between 2018 to 2021. Baseline characteristics, treatment patterns, and clinical outcomes were reported.

RESULTS

Two hundred and four mCSPC patients were enrolled, 87.3% with de-novo diagnoses, 63.2% with high-volume disease. Median PSA was 81 ng/ml (interquartile range [IQR] 19.3 - 339), median age 70 years, and 88.7% ECOG performance status of 0-1. 84.8% (n=173) received treatment intensification, mainly with ARPi (androgen receptor pathway inhibitors) (73%). A higher proportion of patients intensified with ARPi agents (56%) reached PSA nadir ≤0.2 ng/ml between 6-9 months of treatment initiation (PSA6-9mos≤0.2) compared to other treatments. Overall survival (OS) and time to castration-resistant prostate cancer (ttCRPC) were significantly better for PSA6-9mos≤0.2 compared with PSA6-9mos>0.2 [HR 10.68 (2.34-48.82) and 5.06 (1.81-14.14) respectively]. In multivariable analysis, PSA6-9mos>0.2 was significantly associated with poor 2-year survival [HR 29.32 (5.08-169.24)].

CONCLUSIONS

This multi-center prospective real-world mCSPC cohort confirms the prognostic significance of PSA nadir at 6-9 months in stratifying patient outcomes. mCSPC patients not achieving PSA nadir by 6-9 months could be considered for further treatment intensification.