The impact of erythropoiesis-stimulating agents administration concomitantly with adjuvant anti-HER2 treatments on the outcomes of patients with early breast cancer: a sub-analysis of the ALTTO study.

Purpose: To assess whether erythropoiesis-stimulating agents (ESA) administration impacts the outcomes of patients with HER2-positive early breast cancer (EBC).

Methods: ALTTO (NCT00490139) patients were categorized by ESA use during adjuvant anti-HER2 treatment. Disease-free-survival (DFS), overall survival (OS), and time-to-distant recurrence (TTDR) were analyzed by ESA administration, with subgroup analyses according to prognostic factors. Log-rank tests and Cox modeling were performed. Adverse events (AEs) of ESA-interest were compared.

Results: Among 8381 patients recruited in ALTTO, 123 (1.5%) received ESA concomitantly with study treatment. The median age of patients receiving ESA was 54 years, 39.0% premenopausal, most had tumor size > 2 cm (56.9%), node-positive (58.5%), and positive estrogen receptor expression (61.8%). Median follow-up was shorter in the ESA group [6.1 years (IQR 5.3-7.0) vs. 6.9 years (6.0-7.1); p < 0.001]. There was no DFS difference by ESA administration (log-rank p = 0.70), with 3- and 7-year DFS of 89.2% (95% CI 81.8-93.8%) and 81.6% (71.4-88.5%) in ESA group vs. 88.3% (87.6-89.0%) and 80.0% (79.1-80.9%) in No-ESA group. In subgroup analyses, the interaction of ESA administration with menopausal status was statistically significant (unadjusted p = 0.024; stratified p = 0.033), favoring premenopausal women receiving ESA. We observed no significant association of ESA administration with OS (log-rank p = 0.57; 7-year OS in ESA 88.6% vs. 90.0% in non-ESA) or TTDR. ESA-interest AEs were experienced by eight (6.5%) patients receiving ESA and 417 (5.1%) in the No-ESA group (p = 0.41).

Conclusion: ESA administration to patients receiving adjuvant anti-HER2 treatment for HER2-positive EBC was safe and not associated with a negative impact on survival outcomes.