Purpose: Anemia has been a known prognostic factor in metastatic hormone-sensitive prostate cancer (mHSPC). We therefore examined the effect of anemia on the efficacy of upfront abiraterone acetate (ABI) in patients with mHSPC.
Methods: We retrospectively evaluated 67 mHSPC patients with high tumor burden who received upfront ABI between 2018 and 2020 (upfront ABI group). We divided these patients into two groups: the anemia-ABI group (hemoglobin <13.0g/dL, n =21) and the non-anemia-ABI group (n =46). The primary objective was to examine the impact of anemia on the progression-free survival (PFS; clinical progression including death from any cause) of patients in the upfront ABI group. Secondary objectives included an evaluation of the prognostic significance of upfront ABI and a comparison with a historical cohort (135 mHSPC patients with high tumor burden who received androgen deprivation therapy (ADT/complete androgen blockade [CAB] group) between 2014 and 2019).
Results: We found that the anemia-ABI group had a significantly shorter PFS than the non-anemia-ABI group. A multivariate Cox regression analysis showed that anemia was an independent prognostic factor of PFS in the upfront ABI group (hazard ratio, 5.08; P =0.007). Patients in the non-anemia-ABI group were determined to have a significantly longer PFS than those in the non-anemia-ADT/CAB group (n =69) (P =0.002). However, no significant difference was observed in the PFS between patients in the anemia-ABI and the anemia-ADT/CAB groups (n =66). Multivariate analyses showed that upfront ABI could significantly prolong the PFS of patients without anemia (HR, 0.17; P = 0.003), whereas ABI did not prolong the PFS of patients with anemia.
Conclusion: Pretreatment anemia was a prognostic factor among mHSPC patients who received upfront ABI. Although the upfront ABI significantly improved the PFS of mHSPC patients without anemia, its efficacy in patients with anemia might be limited.