Abstract PR-4: Gene amplification of anaplastic lymphoma kinase in inflammatory breast cancer.
Authors: Robertson Fredika M. 
Published: June 2012

Inflammatory breast cancer (IBC) is the most lethal form of breast cancer associated with a 40% 5-year survival in spite of appropriate multidisciplinary care, suggesting resistance to current therapies. IBC serves as a paradigm for tumors that have a program of accelerated metastasis and exhibit characteristics of an mesenchymal-epithelial transition, with robust expression of E-cadherin, and a lack of expression of ZEB1 and TFG beta. Although a few genes such as RHO-C GTPase have been shown to be expressed in IBC, to date, there has been no primary genetic alteration linked to the metastasis observed in IBC patients.

Methods: Using reverse phase proteomics, whole transcriptome analysis, fluorescence in situ hybridization, real time PCR and western blotting, we designed a discovery strategy to identify the signaling pathways that are activated in IBC, using tissue samples from primary IBC patients (core and skin punch biopsy samples), established IBC cell lines and newly developed new IBC cell lines and xenograft models, designated as FC-IBC-01, and FC-IBC-02, that were established from tumor cells isolated from IBC patients who had developed pleural effusion under an IRB-approved protocol.

Results: Activation of phospho-ALK-tyrosine 1586 as a common occurrence in IBC cell lines at a level similar to that found in non-small cell lung cancer (NSCLC) patients with ALK genetic abnormalities. Our studies revealed first time evidence for amplification (3–7 fold) of the receptor tyrosine kinase ALK in 13/15 IBC patient tumor specimens thus far examined by fluorescence in situ hybridization (FISH) and in 66% of IBC cell lines, including Mary-X, and the newly developed FC-IBC01, and FC-IBC02 xenograft models. Interestingly, ALK amplification is not detected in SUM149, SUM190 and KPL-4 cell lines which are the most commonly studied IBC cell lines. Tumor cells isolated from IBC patients with pleural effusion whose tumor was ALK amplified were very sensitive to the anti-proliferative effects of the small molecule cMet/ALK inhibitor crizotinib [PF-02341066] at submicromolar levels (IC50=0.88 nM) but were completely resistant to paclitaxel. Thus far we have not found EML4-ALK or NPM-ALK translocation in IBC cell lines nor have we identified ALK mutations at sites reported to be present large cell anaplastic lymphoma, NSCLC, or neuroblastoma. Analysis of signaling pathway maps reveal that ALK is a central regulator of tumor growth, survival and metastatic progression through its association to multiple downstream effectors including PI3K/AKT, mTOR, and JAK/STAT3. In contrast, cMet is not differentially expressed or phosphorylated in pre-clinical models of IBC. We are currently assessing the activities of the combination of PI3K/mTOR inhibitors and small molecule ALK inhibitors to determine synergistic effects.

Discussion: These studies are the first to suggest that ALK may be a primary molecular driver in the rapid metastasis exhibited in IBC and also suggests that proteomics based approaches are critically important to incorporate into studies to identify targets for development of effective treatments for IBC patients. Furthermore, these studies provide a critical path to clinical evaluation of ALK inhibitors in IBC patients with disease progression for whom there are few therapeutic options.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr PR-4.