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Abstract P5-17-05: Outcome of triple negative inflammatory breast cancer (TNIBC) treated with dose-dense dose intense neoadjuvant chemotherapy (NAC), prognostic impact of post NAC lymphovascular invasion and tumor infiltrating lymphocytes (TIL)

Background Inflammatory breast cancers (IBC) particularly triple negative (TN) subtype have poor prognosis. There are few series reporting IBC outcome according to their immunohistochemical profile. We have already shown the efficiency of dose dense dose intense chemotherapy in triple negative breast cancer (1). We report a series of TNIBC treated with dose dense anthracycline cyclophosphamide followed with taxane and analyzed the correlation between pathological complete response (pCR), pre and post NAC TIL, post NAC LVI and disease free survival (DFS). Methods Between January 2010 and December 2016, all patients with TNIBC seen at breast cancer disease center, St Louis hospital, Paris, France, were treated with neoadjuvant dose dense dose intense Cyclophophamide (1.2g/m2 d1) - Epirubicin (75mg/m2 d1) q2w (SIM regimen) followed with 12 injections of paclitaxel (80 mg/m2) qw or 4 injections of docetaxel (100 mg/m2) q3w. All patients have histologically proven TN tumors and no evidence of metastases assessed by initial FDG PET Scanner. Mastectomy and axillary clearance was performed after chemotherapy. pCR was defined as no residual invasive tumor in breast and lymph nodes. TIL and lymphovascular invasion were evaluated pre and post NAC by 2 independent anatomopathologists dedicated to breast cancer. Delta TILS was defined as the difference between post chemotherapy and pre chemotherapy TIL. Results Thirty TNIBC pts were treated, 28 underwent surgery and 2 progressed during chemotherapy. Median follow-up was 39 months (8 – 86). 9/30 patients (30%) achieved pCR. Median disease free survival (DFS) was 41 months (2 – 86). Median TIL infiltration at diagnosis was 11% (0-60) and dropped to 1% after chemotherapy (0 – 80). Median delta TIL was - 9% (-50% – +40%). TIL increase after chemotherapy was associated with a decrease of DFS (14 months vs not reached ; p = 0,0009). LVI was present on surgical specimens in 12 cases (12/30, 43%; 12/21 non pCR pts 57 %). Presence of LVI after chemotherapy was significantly associated with a decrease of DFS in the whole population (21 months vs not reached ; p = 0.008) and no significantly among the patients without pCR (23 months vs not reached; p = 0.07). Conclusion To the best of our knowledge, it is the best pCR rate reported in TNIBC (2). We showed in this retrospective series of 30 TNIBC that dose dense dose intense chemotherapy is efficient in this population. Presence of lymphovascular invasion and TIL after neoadjuvant chemotherapy in TNIBC are strong prognostic factors associated with DFS. Systematic determination of post NAC TIL and LIV could be a surrogate to propose adjuvant treatment after NAC in TNIBC. References 1. Giacchetti S, et al. Long-term survival of advanced triple-negative breast cancers with a dose-intense cyclophosphamide/anthracycline neoadjuvant regimen. Br J Cancer. 2014;110:1413. 2. Masuda H, Brewer TM, Liu DD, Iwamoto T, Shen Y, Hsu L, et al. Long-term treatment efficacy in primary inflammatory breast cancer by hormonal receptor- and HER2-defined subtypes. Ann Oncol. 2014;25:384–91. Citation Format: Campedel L, Binasker A, Blanc-Durand P, Becourt S, Ledoux F, Cuvier C, Gardnair C, Teixeira L, de Roquancourt A, Espie M, Giacchetti S. Outcome of triple negative inflammatory breast cancer (TNIBC) treated with dose-dense dose intense neoadjuvant chemotherapy (NAC), prognostic impact of post NAC lymphovascular invasion and tumor infiltrating lymphocytes (TIL) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-17-05.