KEY TAKEAWAYS
- The analysis was conducted on three randomized, pivotal phase III studies to evaluate the efficacy of eribulin vs. other chemotherapies in patients with metastatic breast cancer (MBC) who had low-level HER2 expression (HER2-low).
- The primary aim of the analysis was to compare the median overall survival (OS), median progression-free survival (PFS), and objective response rate (ORR) of eribulin vs. other chemotherapies in patients with HER2-low and HER2-0 MBC.
- The eligible patients had MBC and had received ≤2 (Study 301) or 2-5 (Studies 304, 305) prior lines of chemotherapy for advanced/recurrent/metastatic disease, including an anthracycline and a taxane.
- The results showed that eribulin was generally similar or improved compared to chemotherapy regarding PFS and OS in patients with HER2-low and HER2-0 MBC, irrespective of the study.
Breast cancer that expresses low levels of HER2 (HER2-low) is characterized by an IHC score of 1+ or 2+ without HER2 gene amplification or excess copy number as measured by ISH. Response to treatment may differ in HER2-low BC compared to BC with no HER2 expression. Therefore, researchers conducted a random post hoc analysis of three phase-III studies (Studies 301, 304, and 305) to compare eribulin to other chemotherapies in patients with metastatic breast cancer (MBC).
Patients with metastatic breast cancer who had received ≤2 (Study 301) or 2-5 (Studies 304, 305) prior lines of chemotherapy for advanced/recurrent/metastatic disease, including anthracycline and taxane, were included in the study. The patients were treated with eribulin compared to capecitabine (Study 301), vinorelbine (Study 304), or treatment of physician’s choice (TPC; Study 305). Median overall survival (OS), progression-free survival (PFS), and overall response rate (ORR) were analyzed per Response Evaluation Criteria In Solid Tumors (RECIST) v1.0 (Studies 301, 305) or v1.1 (Study 304) by an independent imaging review. ORR was measured in the intent-to-treat population (Studies 301, 304) and evaluable patients (Study 305).
There was a generally balanced distribution of baseline characteristics between the treatment arms across all studies, with all patients in Study 304 being Chinese. The results showed that the eribulin treatment had similar or better PFS and OS outcomes than chemotherapy, regardless of whether patients had HER2-low or HER2-0 MBC, across all studies. The PFS and OS results were similar among HER2-low, HER2-0, and HER2-positive patients who were randomized to receive eribulin. When comparing eribulin to capecitabine, the objective response rate (ORR) was similar in Study 301 for both HER2-low (8.8% vs. 10.4%) and HER2-0 patients (10.1% vs. 8.9%). Moreover, ORR generally favored eribulin over vinorelbine in Study 304 (HER2-low: 34.8% vs. 22.4%; HER2-0: 24.5% vs. 18.0%) and eribulin over treatment of physician’s choice (TPC) in Study 305 (HER2-low: 18.8% vs. 6.1%; HER2-0: 10.4% vs. 4.0%).
The efficacy of eribulin was observed irrespective of the HER2 status, and in patients with HER2-low status, eribulin showed comparable or slightly better outcomes than chemotherapy in each study.
Source: https://oncologypro.esmo.org/meeting-resources/esmo-congress/efficacy-of-eribulin-mesylate-in-her2-low-metastatic-breast-cancer-mbc-results-from-three-phase-iii-studies
Clinical Trial: https://clinicaltrials.gov/ct2/show/NCT00388726/
P.A. Kaufman1, C.J. Twelves2, A.H. Awada3, S. Im4, L. Vahdat5, B. Xu6, P. Yuan6, W. Hauck7, R. Xie8, B. Lalayan9, J. Cortés10. 259P – Efficacy of eribulin mesylate in HER2-low metastatic breast cancer (MBC): Results from three phase III studies. DOI:https://doi.org/10.1016/j.annonc.2022.07.298
