P2-3-1 - Tle3 is a Useful Surrogate Marker for Predicting Eribulin Chemo-Sensitivity in Triple-Negative Breast Cancer

Abstract

Background: Eribulin mesylate (eribulin) is a microtubule dynamics inhibitor having an action mechanism that differs from taxane and vinca alkaloid. Eribulin does not have cross resistance due to an action mechanism that differs from other taxane drugs. Moreover, because it was effective against TNBC upon sub-analysis at phase III clinical trial 301, it is expected to become the key drug for chemotherapy against TNBC in the future. In this study, we investigated predictive factors regarding the therapeutic effect in eribulin chemotherapy using factors such as TLE3, beta-tubulin class III, GSTP1, etc. previously reported as being predictive factors of the therapeutic effect of taxane drugs.Methods: The subjects were 52 inoperable or metastasis / recurrent breast cancer cases that underwent chemotherapy using eribulin. The clinical benefit rate (CBR) was calculated regarding the efficacy thereof. Morphologies such as tissue-type, nucleus grade, etc. were compared by hematoxylin and eosin staining and the expression of ER, PR, HER2, Ki67, beta-tubulin class III, GSTP1, and TLE3 was compared by immunostaining regarding a needle biopsy specimen infiltrate prior to treatment.Results: The clinical effects were CBR 46.2 per cent. According to the intrinsic subtype classification: Luminal A: 16 cases: Luminal B: 12 cases: Luminal HER2: 2 cases: HER2 enriched: 3 cases: and TNBC: 19 cases. When the clinicopathological background and expression of each factor were investigated, TNBC was observed with significantly higher expression of TLE3 compared to non-TNBC; however, no significant difference was observed regarding other factors. Further, breast cancer patients with TLE3 expression had significantly higher CBR. Meanwhile, no significant difference was observed in beta-tubulin class III and GSTP1 expression.Conclusions: Our findings therefore suggest that TLE3 may be useful as a marker for predicting the therapeutic effect in eribulin chemotherapy for TNBC.