Abstract P2-20-17: Eribulin is an immune potentiator in breast cancer by up-regulation of human leukocyte antigen class I
Authors: Wada Asaka , Kutomi Goro , Hirohashi Yoshihiko , Kyuno Daisuke , Shima Hiroaki , Kuga Yoko , Torigoe Toshihiko , Takemasa Ichiro 
Published: March 2023

Abstract
Background: Eribulin, an anticancer drug that increases the overall survival (OS) of patients with metastatic recurrent breast cancer, inhibits microtubule polymerization, although the mechanism is different from that of other microtubule inhibitors (taxanes). A subgroup analysis revealed a low neutrophil-to-lymphocyte ratio (NLR) (&lt; 3) to be a prognostic factor of eribulin treatment. NLR has also been reported to be a predictive marker for cancer immunotherapy. Checkpoint inhibitor-based cancer immunotherapy is currently available for breast cancer. We hypothesized that eribulin improves breast cancer cell immune response. Immunological effector cytotoxic T lymphocytes (CTLs) recognize antigenic peptides presented by human leukocyte antigen (HLA) class I; HLA class I downregulation is frequently observed in breast cancer. Here, we evaluated the CTL response in eribulin-treated breast cancer cells. Materials and Methods: HLA class I expression before and after eribulin treatment was evaluated using immunohistochemistry in tumors from patients, and by immunofluorescence, flow cytometry, western blotting, and quantitative RT-PCR (qRT-PCR) in breast cancer cells (MDA-MB231 and MCF7). Factors that upregulate HLA class I were screened using RNA-seq. To evaluate T cell recognition, we generated cancer testis antigen (NY-ESO-1)-specific T cell receptor transduced-T cells (TCR-T cells). NY-ESO-1 cDNA was stably transduced into MCF7 and MDA-MB-231 cells. TCR-T cell reactivity with MCF7/NY-ESO-1 cells was analyzed using an ELISPOT assay. A combinatorial therapy model was established using eribulin and TCR-T. Results: HLA class I was upregulated after eribulin treatment in clinical samples. To confirm this, we treated breast cancer cells with eribulin and evaluated HLA class I expression. Eribulin increased HLA class I expression, as evidenced by immunofluorescence, flow cytometry, western blotting, and qRT-PCR. RNA-seq results on eribulin-treated cells showed that eribulin upregulated NLRC5, a master regulator of HLA class I. IFNγ ELISPOT assay revealed that eribulin increased IFNγ secretion by TCR-T cells (p&lt; 0.01), indicating that eribulin enhanced the immune response. These results suggest that eribulin and immunotherapy had a synergistic effect. Therefore, we established an eribulin and NY-ESO-1 combinatorial therapy model and showed that the combination group had a significantly lower number of viable cancer cells than the eribulin- and TCR-T-only groups (p&lt; 0.01). Conclusions: Eribulin increased the expression of HLA class I, probably by upregulating NLRC5 in breast cancer cells. It also enhanced TCR-T recognition in breast cancer cells. The combinatorial therapy model revealed the synergistic effect of eribulin and TCR-T. These results indicate that eribulin might be an immune potentiator and that combination therapy with immunotherapy can be effective for the treatment of breast cancer.
Citation Format: Asaka Wada, Goro Kutomi, Yoshihiko Hirohashi, Daisuke Kyuno, Hiroaki Shima, Yoko Kuga, Toshihiko Torigoe, Ichiro Takemasa. Eribulin is an immune potentiator in breast cancer by up-regulation of human leukocyte antigen class I [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-20-17.