Abstract P4-05-06: High absolute lymphocyte counts are associated with longer overall survival in patients with metastatic breast cancer treated with eribulin as the first-line chemotherpy. Combined analysis of two phase 2 study

Abstract

Background: Eribulin demonstrated improving overall survival of HER2-negative metastatic breast cancer in EMBRACE trial. Recently, ad hoc analysis of the trial showed that immune response markers such as absolute lymphocyte count (ALC) was associated with prognosis. However, blood cell count must be influenced by previous chemotherapy because the trial was targeted for late-line treatment.Previously we had conducted two phase 2 trials that estimated efficacy of eribulin as the first-lien chemotherapy for HER2-negative metastatic breast cancer in Japan. Base line ALC and NLR were examined for the participants of these trials to determine whether they were also associated with prognosis in the first-line setting. Patients and Methods: A total of 59 patients were enrolled this study including 35 patients of BIRICHEN trial (UMIN000006086; SpringerPlus 2016;5:164) for only first-line chemotherapy with eribulin and 24 patients who treated as the first-line chemotherapy in OMC-BC03 trial targeted for first and second line chemotherapy (UMIN000009568; Cancer Chemother Pharmacol 2018; 81:923). Pretreatment blood cell counts were collected from case report form and compared with survival data. Cutoff value of ALC was set at 1500/mm3 and that of NLR was set at 3 in accordance with ad hoc analysis of EMBRACE trial. The ethics committees of Osaka Medical College and Osaka City University approved the present study. Results: Median value of ALC was 1690/mm3(Quartile Q1,Q3: 1014, 2012) and that of NLR was 2.17(Q1,Q3: 1.54, 2.99). In comparison with ALC, overall survival (OS) was 132.6 months in the ALC-high group(>=1500;n=33) versus 76.4 months in the ALC-low group (< 1500; n=26). Hazard ratio(HR) was 0.52(95%CI; 0.27-1.01) with border line significancy. Progression free survival(PFS) is 28.0 months in the ALC-high group versus 20.4 months in the ALC-low group. HR was 0.91(95% CI; 0,51-1.60) without statistically significant difference. In NLR, OS was 20.7 months in the NLR-low group(<3;n=45) versus 4.6 months in the NLR-high group. HR was 0.40 (95%CI; 018-0.90) with statistical significance. PFS was 6.2 months in the NLR-low group versus 10.8 months in the NLR-high group (>=3; n=14). HR was 0.57 (95%CI; 0.25-1.30) without statistically significant difference. Conclusions: In the post hoc analysis of the EMBRACE trial, patients who assigned eribulin group with ALC 1500 or higher had better OS than those with ALC less than 1500, but no difference was observed in PFS. In addition, those with NLR less than 3 had better PFS and OS than those with NLR 3 or more. In comparison with the capecitabine group, although low NLR was a good prognostic factor not only in eribulin group but also in capecitabine group, high ALC was suggested to be a particular prognostic factor of eribulin. However, since EMBRACE study was a late line setting, there could be an effect of myelosuppression by pretreatment. Our first-line results did not affect bone marrow function by prior chemotherapy, but similar results were obtained. ALC may be a prognostic factor of eribulin regardless of the treatment line, suggesting that eribulin exerts its effect by acting on the immune microenvironment. Citation Format: Tsutomu Takashima, Kosei Kimura, Hidemi Kawajiri, Shinichiro Kashiwagi, Shinya Tokunaga, Shigehiko Nishimura, Satoru Noda, Hiroyo Oku, Ayana Ikari, Tomo Tominaga, Saki Maezawa, Junna Sakane, Mitsuhiko Iwamoto. High absolute lymphocyte counts are associated with longer overall survival in patients with metastatic breast cancer treated with eribulin as the first-line chemotherpy. Combined analysis of two phase 2 study [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-05-06.