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TBCRC 001: Randomized Phase II Study of Cetuximab in Combination with Carboplatin in Stage IV Triple Negative Breast Cancer

ABSTRACT: Abstract Background. Epidermal growth factor receptor (EGFR) is a targetable molecule in basal-like breast cancer, which comprises most “triple negative” breast cancer (TNBC), the only breast cancer subtype without established targeted therapy. Methods. In this randomized phase II trial, metastatic TNBC patients received the anti-EGFR antibody cetuximab (250mg/kg/week iv) with carboplatin (AUC2/wk iv) added on progression, or concomitant cetuximab + carboplatin. Molecular subtyping was done on archival specimens and those with accessible tumors provided fresh tissue, before and after 7-14 days of therapy, for microarray analyses to explore EGFR pathway inhibition. Results. Of 102 TNBC patients 74% were of the basal-like molecular subtype. Response rate to cetuximab was 6% (2/31), and was 16% (4/25) to cetuximab + carboplatin after progression. Upfront cetuximab + carboplatin produced responses in 17% (12/71); 31% responded or had prolonged disease stabilization. Time to progression was 2.1 months (95% CI 1.8-5.5) and overall survival 10.4 months (95% CI 7.7-13.1) for those treated with the combination regimen. Among 16 patients with evaluable serial biopsies, genomic patterns of the EGFR pathway showed activated status in 13 and inhibition by therapy in 5. Conclusions. While most TNBC were basal-like, a significant proportion were different subtypes. The aggressive nature of metastatic TNBC leads to limited survival. Despite a promising preclinical rationale and evidence of EGFR pathway activation in most, targeted treatment with cetuximab as a single agent had marginal activity and cetuximab added to carboplatin demonstrated modest activity. Serial biopsies as part of metastatic breast cancer studies are feasible, and this study confirmed that the EGFR pathway was inhibited by therapy in only a minority suggesting ligand-independent activation in most tumors. Tissue acquisition and drug selection based upon individualized pathway activation status should be an important part of future studies of TNBC.

ORGANISM(S): Homo sapiens

PROVIDER: GSE23428 | GEO | 2012/07/14

SECONDARY ACCESSION(S): PRJNA131093

REPOSITORIES: GEO

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Project description:Abstract Background. Epidermal growth factor receptor (EGFR) is a targetable molecule in basal-like breast cancer, which comprises most “triple negative” breast cancer (TNBC), the only breast cancer subtype without established targeted therapy. Methods. In this randomized phase II trial, metastatic TNBC patients received the anti-EGFR antibody cetuximab (250mg/kg/week iv) with carboplatin (AUC2/wk iv) added on progression, or concomitant cetuximab + carboplatin. Molecular subtyping was done on archival specimens and those with accessible tumors provided fresh tissue, before and after 7-14 days of therapy, for microarray analyses to explore EGFR pathway inhibition. Results. Of 102 TNBC patients 74% were of the basal-like molecular subtype. Response rate to cetuximab was 6% (2/31), and was 16% (4/25) to cetuximab + carboplatin after progression. Upfront cetuximab + carboplatin produced responses in 17% (12/71); 31% responded or had prolonged disease stabilization. Time to progression was 2.1 months (95% CI 1.8-5.5) and overall survival 10.4 months (95% CI 7.7-13.1) for those treated with the combination regimen. Among 16 patients with evaluable serial biopsies, genomic patterns of the EGFR pathway showed activated status in 13 and inhibition by therapy in 5. Conclusions. While most TNBC were basal-like, a significant proportion were different subtypes. The aggressive nature of metastatic TNBC leads to limited survival. Despite a promising preclinical rationale and evidence of EGFR pathway activation in most, targeted treatment with cetuximab as a single agent had marginal activity and cetuximab added to carboplatin demonstrated modest activity. Serial biopsies as part of metastatic breast cancer studies are feasible, and this study confirmed that the EGFR pathway was inhibited by therapy in only a minority suggesting ligand-independent activation in most tumors. Tissue acquisition and drug selection based upon individualized pathway activation status should be an important part of future studies of TNBC. This series contains 36 microarrays that are from 18 patients with fresh frozen tissue available from the metastatic site. Pretreatment samples (Bx0) are available for two patients. Pretreatment and post single agent treatment (7-14 days after start of treatment with cetuximab; BxSingle) are available for three patients. Pretreatment and post combination treatment (7-14 days after start of treatment with cetuximab plus carboplatin; BxCombo) are available for eight patients. Two patients have a pretreatment sample, a sample after 7-14 days of treatment with single agent cetuximab, and a third sample 7-14 days on cetuximab plus carboplatin after switching to the combination arm upon progression on the single agent arm. Samples were hybridized with Stratagene common reference spiked with RNA from two breast cancer cell lines (ME16C and MCF-7) on Custom 1x44K Agilent microarrays. Arrays were scanned on an Axon 4000B scanner and analyzed with GenePix Pro software.

Project description:Purpose:Triple negative breast cancer (TNBC) commonly metastasizes to the brain and predicts poor prognosis with limited therapeutic options. TNBC frequently harbors BRCA mutations translating to platinum sensitivity; platinum response may be augmented by additional suppression of DNA repair mechanisms through poly(ADP-ribose)polymerase (PARP) inhibition. We evaluated brain penetrance and efficacy of Carboplatin +/- the PARP inhibitor ABT888, and investigated gene expression changes in murine intracranial (IC) TNBC models stratified by BRCA and molecular subtype status. Experimental design:Athymic mice were inoculated intra-cerebrally with BRCA-mutant: SUM149 (basal), MDA-MB-436 (claudin-low), or BRCA-wild-type: MDA-MB-468 (basal), MDA-MB-231BR (claudin-low) TNBC cells and treated with PBS control (IP, weekly), Carboplatin (50mg/kg/week, IP), ABT888 (25mg/kg/day, OG), or their combination. DNA-damage (?-H2AX) and apoptosis (cleaved-Caspase-3(cC3)) were assessed via IHC of IC tumors. Gene expression of BRCA-mutant IC tumors was measured. Results: Carboplatin+/-ABT888 significantly improved survival in BRCA-mutant IC models compared to control, but did not improve survival in BRCA-wild-type IC models. Carboplatin+ABT888 revealed a modest survival advantage versus Carboplatin in BRCA-mutant models. ABT888 yielded a marginal survival benefit in the MDA-MB-436 but not in the SUM149 model. BRCA-mutant SUM149 expression of ?-H2AX and cC3 proteins was elevated in all treatment groups compared to Control, while BRCA-wild-type MDA-MB-468 cC3 expression did not increase with treatment. Carboplatin treatment induced common gene expression changes in BRCA-mutant models.Conclusions: Carboplatin+/-ABT888 improves survival in BRCA-mutant IC TNBC models with corresponding DNA damage and gene expression changes. Combination therapy represents a promising treatment strategy for patients with TNBC brain metastases warranting further clinical investigation. reference x sample

Project description:Basal-like and triple negative breast cancer (TNBC) share common molecular features, poor prognosis and a propensity for metastasis to the brain. Amplification of EGFR occurs in ~50% of basal-like breast cancer and mutations in the epidermal growth factor receptor (EGFR) have been reported in up to ~ 10% of Asian TNBC patients. In non-small cell lung cancer several different mutations in the EGFR tyrosine kinase domain confer sensitivity to receptor tyrosine kinase inhibitors, but the tumourigenic potential of EGFR mutations in breast cells and their potential for targeted therapy is unknown. Constructs containing wild type, G719S or E746-A750 deletion mutant forms of EGFR were transfected into the ‘near normal’ MCF10A breast cells and their tumorigenic derivative, MCF10CA1a. These transfected lines were used to investigate the effects of EGFR over-expression and mutation on proliferation, migration, invasion, response to gefitinib, and tumour formation in vivo. We also carried out copy number analysis and whole exome sequencing of the MCF10A and MCF10CA1a cell lines. Both activating mutations of EGFR increased the proliferative ability of MCF10A and MCF10CA1a cell lines, and increased the anchorage-independent growth and sensitivity to gefitinib in MCF10A cells. In addition, the EGFR-E746-A750 deletion increased the migratory and invasive abilities of the MCF10CA1a cell line in vitro, and greatly increased the formation and growth of MCF10CA1a tumours in vivo. Compared to MCF10A cells, MCF10CA1a cells had large regions of gain on chromosome 9 and the long arm of chromosome 3, deletion in the short arm of chromosome 7, and mutations in many genes implicated in cancer. The EGFR E746-A750 deletion mutation, and to a lesser extent G719S, greatly enhance the oncogenic properties of MCF10A cell line, and increase sensitivity to gefitinib. Although the addition of EGFR E746-A750 renders the MCF10CA1a cells more tumourigenic in vivo it is not accompanied by increased sensitivity to gefitinib, perhaps because of additional mutations, including the PIK3CA H1047R mutation, that the MCF10CA1a cell line has acquired. Screening TNBC/basal-like breast cancer for EGFR mutations may prove useful for directing therapy but, as in non-small cell lung cancer cancer, accompanying mutations in PIK3CA may confer gefitinib resistance.

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TBCRC 001: Randomized Phase II Study of Cetuximab in Combination with Carboplatin in Stage IV Triple Negative Breast Cancer

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