Individual xenograft as a personalized therapeutic resort for women with metastatic triple-negative breast carcinoma

Findings A localized left breast ductal invasive triple-negative breast carcinoma (TNBC) was diagnosed in a 44-yearold woman. After surgery, she was treated with chemotherapy and radiation therapy in accordance with national guidelines. At the end of treatment, she had local and metastatic relapse with multiple sub-diaphragmatic lymph nodes. With her written consent, imagery-guided biopsies of a metastatic lymph node were performed, one sample being used for genomic analyses and another for immediate xenograft (Additional file 1: Supplementary methods). Because of the early metastases after docetaxel and epirubicin-cyclophosphamide, she received cisplatin but the disease progressed after 3 months. Meanwhile, the transcriptomic analysis of the metastatic sample enabled a molecular subclassification as Basal-Like 2 with EGFR mRNA overexpression [1,2]. We did not find any EGFR or K-RAS mutation. After successful engraftment of the metastastic samples, we tested eight different chemotherapies over 1 month on the xenograft model. The combination of paclitaxel and cetuximab was the most efficient (Figure 1A), so it was offered to the patient. After 3 months of this second-line treatment, the metabolic response was almost complete (Figure 1B, C). In compliance with French bioethics law (#2004-800, 06/08/2004), the patient had been informed of the research use of the part of her biopsy samples remaining after diagnosis had been established and did not oppose it. The treatment combining paclitaxel and cetuximab was discussed and approved in a multidisciplinary meeting and then offered to the patient. Informed written