Prognosis of Invasive Lobular Carcinoma and Effectiveness of Eribulin in Clinical Practice: A Post Hoc Analysis of a 2-Year Post-Marketing Surveillance.

AIM: Invasive lobular carcinoma (ILC) is the second most common breast cancer type after invasive ductal carcinoma (IDC). Eribulin mesylate (eribulin) is a non-taxane microtubule dynamics inhibitor approved for advanced or metastatic breast cancer, including ILC and IDC. However, real-world data from eribulin-treated patients with advanced or metastatic ILC are scarce.

METHODS

This post hoc analysis of a Japanese multicenter, prospective, observational post-marketing surveillance (ClinicalTrials.gov: NCT02371174) evaluated data from eribulin-treated patients with ILC or IDC. Overall survival (OS) from the initiation of first-line chemotherapy, OS from the first date of eribulin administration, and time-to-treatment failure (TTF) were evaluated. OS from eribulin initiation was also evaluated by line of eribulin treatment (first-line, second-line, and third-line or later). Adverse drug reactions (ADRs) with ≥ 5% frequency in both groups were evaluated.

RESULTS

Among patients with ILC (n = 33) and IDC (n = 543), median OS from the initiation of first-line chemotherapy was 25.5 and 39.0 months, respectively (hazard ratio 1.94 [95% confidence interval 1.28-2.94]; p < 0.05), median OS from the first date of eribulin administration was 16.0 and 18.0 months, respectively (1.31 [0.87-1.97]), and TTF was 6 and 5 months (0.92 [0.65-1.32]). No significant differences were observed in median OS when stratified by line of eribulin treatment. Type and frequency of ADRs did not differ significantly between the groups.

CONCLUSION

OS and TTF after eribulin initiation were similar between ILC and IDC cases, suggesting that eribulin might be a beneficial treatment option for ILC.