Identifying immune-related predictive factors for post-eribulin therapy in patients with HER2-negative advanced...

In the EMBRACE study, eribulin (ERI) monotherapy improved the overall survival (OS) of patients with HER2-negative advanced breast cancer (HER2-negative ABC). A post hoc analysis identified the baseline absolute lymphocyte count (ALC) as a predictive marker in the ERI arm; nevertheless, factors affecting post-ERI had not been well explored.

We retrospectively analyzed clinical data of 370 patients receiving ERI for HER2-negative ABC between July 2011 and June 2024 across 3 institutions. Clinical data, including ALC, were extracted. Statistical analyses included the log-rank test and Cox hazard model. The OS was defined as survival from ERI initiation (OS1) and from ERI termination (OS2).

Identical to the previous report, the OS1 was significantly improved in patients with ALC ≥ 1000/μL at ERI initiation and with ER-positive. Regarding the OS2, we identified independent factors which significantly improve the OS2 as follows: ALC ≥ 1000/μL at the termination of ERI, ≥ 120 days time-to-treatment-discontinuation of ERI, and first-line use of ERI. Furthermore, ALC was maintained during ERI therapy, whereas it significantly decreased in other regimens (P < 0.001).

An ALC ≥ 1000/μL at ERI completion was associated with an improved post-ERI OS (OS2). It is suggested that not only the factors at the initiation of ERI, but also the immunological status at the end of ERI, may have prognostic value after ERI.