Triple negative breast cancers (TNBCs) represent 15-20% of all breast cancers and are associated with higher recurrence and distant metastasis rate. Standard of care for early stage TNBC is ...anthracyclines combined with cyclophosphamide (AC) followed by taxanes, in the neo-adjuvant or adjuvant setting. This work aimed to identify predictive biomarkers of AC response in patient-derived xenograft (PDX) models of TNBC and to validate them in the clinical setting. By gene and protein expression analysis of 39 PDX with different responses to AC, we found that high expression of HORMAD1 was associated with better response to AC. Both gene and protein expression were associated with promoter hypomethylation. In a cohort of 526 breast cancer patients, HORMAD1 was overexpressed in 71% of TNBC. In a second cohort of 186 TNBC patients treated with AC, HORMAD1 expression was associated with longer metastasis-free survival (MFS). In summary, HORMAD1 overexpression was predictive of an improved response to AC in PDX and is an independent prognostic factor in TNBC patients treated with AC.
Triple-negative breast cancer (TNBC) patients with residual disease after neoadjuvant chemotherapy have a poor outcome. We developed patient-derived xenografts (PDX) from residual tumors to identify ...efficient chemotherapies and predictive biomarkers in a context of resistance to anthracyclines- and taxanes-based treatments.
PDX were established from residual tumors of primary breast cancer patients treated in neoadjuvant setting. TNBC PDX were treated by anthracyclines, taxanes, platins, and capecitabine. Predictive biomarkers were identified by transcriptomic and immunohistologic analysis. Downregulation of
was performed by siRNA in a cell line established from a PDX.
Residual TNBC PDX were characterized by a high tumor take, a short latency, and a poor prognosis of the corresponding patients. With the exception of BRCA1/2-mutated models, residual PDX were resistant to anthracyclines, taxanes, and platins. Capecitabine, the oral prodrug of 5-FU, was highly efficient in 60% of PDX, with two models showing complete responses. Prior treatment of a responder PDX with 5-FU increased expression of thymidylate synthase and decreased efficacy of capecitabine. Transcriptomic and IHC analyses of 32 TNBC PDX, including both residual tumors and treatment-naïve derived tumors, identified RB1 and TYMP proteins as predictive biomarkers for capecitabine response. Finally,
knockdown in a cell line established from a capecitabine-responder PDX decreased sensitivity to 5-FU treatment.
We identified capecitabine as efficient chemotherapy in TNBC PDX models established from residual disease and resistant to anthracyclines, taxanes, and platins. RB1 positivity and high expression of TYMP were significantly associated with capecitabine response.
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Triple‐negative breast cancer (TNBC) represents 10% of all breast cancers and is a very heterogeneous disease. Globally, women with TNBC have a poor prognosis, and the development of effective ...targeted therapies remains a real challenge. Patient‐derived xenografts (PDX) are clinically relevant models that have emerged as important tools for the analysis of drug activity and predictive biomarker discovery. The purpose of this work was to analyze the molecular heterogeneity of a large panel of TNBC PDX (n = 61) in order to test targeted therapies and identify biomarkers of response. At the gene expression level, TNBC PDX represent all of the various TNBC subtypes identified by the Lehmann classification except for immunomodulatory subtype, which is underrepresented in PDX. NGS and copy number data showed a similar diversity of significantly mutated gene and somatic copy number alteration in PDX and the Cancer Genome Atlas TNBC patients. The genes most commonly altered were TP53 and oncogenes and tumor suppressors of the PI3K/AKT/mTOR and MAPK pathways. PDX showed similar morphology and immunohistochemistry markers to those of the original tumors. Efficacy experiments with PI3K and MAPK inhibitor monotherapy or combination therapy showed an antitumor activity in PDX carrying genomic mutations of PIK3CA and NRAS genes. TNBC PDX reproduce the molecular heterogeneity of TNBC patients. This large collection of PDX is a clinically relevant platform for drug testing, biomarker discovery and translational research.
What's new?
Triple‐negative breast cancer (TNBC) is a highly heterogeneous disease in terms of molecular profile, histological features, clinical behavior, and drug response. Several clinical trials have been conducted for targeted therapies, but only in unselected TNBC patients, with disappointing results. This study shows that patient‐derived xenografts (PDX) reproduce the molecular heterogeneity of TNBC. The presented genomic analysis identifies several interesting targetable drivers, particularly in the PI3K and MAPK pathways. PDX models provide a unique opportunity to test various treatments on individual tumors: already, two specific inhibitors (dual PI3K/mTOR and MEK inhibitor) and their combination are providing encouraging results.
Malignant adenomyoepithelioma (AME) of the breast is an exceptionally rare form of breast cancer, with a significant metastatic potential. Chemotherapy has been used in the management of advanced AME ...patients, however the majority of treatments are not effective. Recent studies report recurrent mutations in the HRAS Q61 hotspot in small series of AMEs, but there are no preclinical or clinical data showing H-Ras protein as a potential therapeutic target in malignant AMEs. We performed targeted sequencing of tumours' samples from new series of 13 AMEs, including 9 benign and 4 malignant forms. Samples from the breast tumour and the matched axillary metastasis of one malignant HRAS mutated AME were engrafted and two patient-derived xenografts (PDX) were established that reproduced the typical AME morphology. The metastasis-derived PDX was treated in vivo by different chemotherapies and a combination of MEK and BRAF inhibitors (trametinib and dabrafenib). All malignant AMEs presented a recurrent mutation in the HRAS G13R or G12S hotspot. Mutation of PIK3CA were found in both benign and malignant AMEs, while AKT1 mutations were restricted to benign AMEs. Treatment of the PDX by the MEK inhibitor trametinib, resulted in a marked anti-tumor activity, in contrast to the BRAF inhibitor and the different chemotherapies that were ineffective. Overall, these findings further expand on the genetic features of AMEs and suggest that patients carrying advanced HRAS-mutated AMEs could potentially be treated with MEK inhibitors. Keywords: Adenomyoepithelioma, HRAS, PDX, MEK inhibitor
The receptor tyrosine kinase RET is implicated in the progression of luminal breast cancers (BC) but its role in estrogen receptor (ER) negative tumors is unknown. Here we investigated the expression ...of RET in breast cancer patients tumors and patient‐derived xenografts (PDX) and evaluated the therapeutic potential of Vandetanib, a tyrosin kinase inhibitor with strong activity against RET, EGFR and VEGFR2, in ER negative breast cancer PDX. The RT‐PCR analysis of RET expression in breast tumors of 446 patients and 57 PDX, showed elevated levels of RET in ER+ and HER2+ subtypes and in a small subgroup of triple‐negative breast cancers (TNBC). The activity of Vandetanib was tested in vivo in three PDX models of TNBC and one model of HER2+ BC with different expression levels of RET and EGFR. Vandetanib induced tumor regression in PDX models with high expression of RET or EGFR. The effect was associated with inhibition of RET/EGFR phosphorylation and MAP kinase pathway and increased necrosis. In a PDX model with no expression of RET nor EGFR, Vandetanib slowed tumor growth without inducing tumor regression. In addition, treatment by Vandetanib decreased expression of murine Vegf receptors and the endothelial marker Cd31 in the four PDX models tested, suggesting inhibition of tumor vascularization. In summary, these preclinical results suggest that Vandetanib treatment could be useful for patients with ER negative breast cancers overexpressing Vandetanib's main targets.
What's new?
Tyrosine kinase receptors have emerged as key targets in breast cancer treatment. Here the authors examine the role of REarranged during Transfection (RET) and epidermal growth factor receptor (EGFR) in estrogen receptor‐negative breast cancers. They show tumor regression induced by the multikinase inhibitor Vandetanib in cancers with high expression of RET or EGFR. In two cohorts of primary breast cancer and patient‐derived xenografts, one third of tumors showed expression of at least one of the two kinase receptors, underscoring Vandetanib's potential as an effective treatment option for estrogen receptor‐negative breast cancers with high expression of RET or EGFR.
Here, we investigated the clinical relevance of an unprecedented combination of three biomarkers in triple-negative breast cancer (TNBC), both in human samples and in patient-derived xenografts of ...TNBC (PDX-TNBC): EGFR, its recently identified partner (MT4-MMP), and retinoblastoma protein (RB).
IHC analyses were conducted on human and PDX-TNBC samples to evaluate the production of the three biomarkers. The sensitivity of cancer cells expressing or not MT4-MMP to anti-EGFR (erlotinib) or anti-CDK4/6 inhibitor (palbociclib) was evaluated
in 2D and 3D proliferation assays and
using xenografts and PDX-TNBC displaying different RB, MT4-MMP, and EGFR status after single (erlotinib or palbociclib) or combined (erlotinib + palbociclib) treatments.
EGFR and MT4-MMP were coexpressed in >70% of TNBC samples and PDX-TNBC, among which approximately 60% maintained RB expression. Notably, approximately 50% of all TNBC and PDX-TNBC expressed the three biomarkers. Single erlotinib and palbociclib treatments drastically reduced the
proliferation of cells expressing EGFR and MT4-MMP when compared with control cells. Both TNBC xenografts and PDX expressing MT4-MMP, EGFR, and RB, but not PDX-TNBC with RB loss, were sensitive to erlotinib and palbociclib with an additive effect of combination therapy. Moreover, this combination was efficient in another PDX-TNBC expressing the three biomarkers and resistant to erlotinib alone.
We defined a new association of three biomarkers (MT4-MMP/EGFR/RB) expressed together in 50% of TNBC and demonstrated its usefulness to predict the TNBC response to anti-EGFR and anti-CDK4/6 drugs used in single or combined therapy.
Background High-mobility group box 1 (HMGB1) is a major promotor of ischemic injuries and aseptic inflammatory responses. We tested its inhibition on neurological outcome and systemic immune response ...after cardiac arrest (CA) in rabbits. Methods and Results After 10 minutes of ventricular fibrillation, rabbits were resuscitated and received saline (control) or the HMGB1 inhibitor glycyrrhizin. A sham group underwent a similar procedure without CA. After resuscitation, glycyrrhizin blunted the successive rises in HMGB1, interleukin-6, and interleukin-10 blood levels as compared with control. Blood counts of the different immune cell populations were not different in glycyrrhizin versus control. After animal awakening, neurological outcome was improved by glycyrrhizin versus control, regarding both clinical recovery and histopathological damages. This was associated with reduced cerebral CD4
and CD8
T-cell infiltration beginning 2 hours after CA. Conversely, granulocytes' attraction or loss of microglial cells or cerebral monocytes were not modified by glycyrrhizin after CA. These modifications were not related to the blood-brain barrier preservation with glycyrrhizin versus control. Interestingly, the specific blockade of the HMGB1 receptor for advanced glycation end products by FPS-ZM1 recapitulated the neuroprotective effects of glycyrrhizin. Conclusions Our findings support that the early inhibition of HMGB1-signaling pathway prevents cerebral chemoattraction of T cells and neurological sequelae after CA. Glycyrrhizin could become a clinically relevant therapeutic target in this situation.
Oestrogen receptor-negative (ER-) breast cancer is intrinsically sensitive to chemotherapy. However, tumour response is often incomplete, and relapse occurs with high frequency. The aim of this work ...was to analyse the molecular characteristics of residual tumours and early response to chemotherapy in patient-derived xenografts (PDXs) of breast cancer.
Gene and protein expression profiles were analysed in a panel of ER- breast cancer PDXs before and after chemotherapy treatment. Tumour and stromal interferon-gamma expression was measured in xenografts lysates by human and mouse cytokine arrays, respectively.
The analysis of residual tumour cells in chemo-responder PDX revealed a strong overexpression of IFN-inducible genes, induced early after AC treatment and associated with increased STAT1 phosphorylation, DNA-damage and apoptosis. No increase in IFN-inducible gene expression was observed in chemo-resistant PDXs upon chemotherapy. Overexpression of IFN-related genes was associated with human IFN-γ secretion by tumour cells.
Treatment-induced activation of the IFN/STAT1 pathway in tumour cells is associated with chemotherapy response in ER- breast cancer. Further validations in prospective clinical trials will aim to evaluate the usefulness of this signature to assist therapeutic strategies in the clinical setting.
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