We recently showed in preclinical models and now in patients in our recent neoadjuvant trial, that antiHER2 drug combinations, such as the monoclonal antibody trastuzumab plus the dual HER1/2 kinase inhibitor lapatinib (LT regimen), more completely inhibit the HER receptor network, and are highly effective, achieving substantially high rates of pathological complete response even without chemotherapy. However, even when HER signaling is completely abrogated, many tumors still acquire resistance. Therefore, it is important to understand resistance mechanisms and to identify well tolerated therapeutic strategies that can overcome or prevent this resistance. In this project we will investigate a novel approach to overcome resistance to HER2-targeted LT therapy based on our laboratory discovery that the mevalonate (MVA) pathway is one of the escape pathways that is activated in LT-resistant breast cancer cells, in which HER2 remains inhibited. In addition to cholesterol biosynthesis, the MVA pathway, via isoprenoid intermediates, can also generate cell proliferative and survival signals. Interestingly, we find that blocking this pathway with relatively nontoxic statins leads to remarkable growth inhibition and death of LT-resistant cells, while parental cells are only modestly affected. We therefore hypothesize that the MVA pathway can function as an escape route in HER2+ breast cancer with intrinsic or acquired resistance to potent antiHER2 treatments, by providing alternative survival and proliferative stimuli to bypass sustained HER2 inhibition. We further hypothesize that targeting the MVA pathway will provide a novel therapeutic strategy to overcome antiHER2 treatment resistance.
In Aim 1 we will evaluate the role of the MVA pathway in antiHER2 resistance in our diverse in vitro and in vivo models of resistance to HER2 targeted therapies and will identify predictive biomarkers for response to inhibitors of this pathway.
In Aim 2 we will elucidate the molecular mechanisms by which the MVA pathway mediates survival.
In Aim 3 we will investigate the predictive value of the MVA pathway for the clinical outcomes in our unique set of tumor specimens from our LT neoadjuvant trials, will assess in the ALTTO trial whether patients taking statins along with antiHER2 treatment have a better outcome, and will conduct a clinical trial to test the efficacy of statin in patients with metastatic disease who are resistant to antiHER2 drug combinations. If this study is successful, targeting the MVA pathway could provide a valuable new therapeutic strategy to overcome antiHER2 treatment resistance.

Public Health Relevance

Combined HER2-targeted (LT) therapy is superior to single agents, and is potentially curative even with no chemotherapy, but resistance is common. Our long term goal is to clarify the mechanisms of resistance to potent antiHER2 drug combinations, identify predictive markers of resistance, and develop novel low-toxic therapeutic strategies to overcome antiHER2 treatment resistance.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Specialized Center (P50)
Project #
1P50CA186784-01
Application #
8747138
Study Section
Special Emphasis Panel (ZCA1-RPRB-C (M1))
Project Start
Project End
Budget Start
2014-07-01
Budget End
2015-06-30
Support Year
1
Fiscal Year
2014
Total Cost
$293,121
Indirect Cost
$117,242
Name
Baylor College of Medicine
Department
Type
DUNS #
051113330
City
Houston
State
TX
Country
United States
Zip Code
77030
Guarducci, Cristina; Bonechi, Martina; Benelli, Matteo et al. (2018) Cyclin E1 and Rb modulation as common events at time of resistance to palbociclib in hormone receptor-positive breast cancer. NPJ Breast Cancer 4:38
Johnston, A N; Bu, W; Hein, S et al. (2018) Hyperprolactinemia-inducing antipsychotics increase breast cancer risk by activating JAK-STAT5 in precancerous lesions. Breast Cancer Res 20:42
Dasgupta, Subhamoy; Rajapakshe, Kimal; Zhu, Bokai et al. (2018) Metabolic enzyme PFKFB4 activates transcriptional coactivator SRC-3 to drive breast cancer. Nature 556:249-254
Rimawi, Mothaffar F; De Angelis, Carmine; Contreras, Alejandro et al. (2018) Low PTEN levels and PIK3CA mutations predict resistance to neoadjuvant lapatinib and trastuzumab without chemotherapy in patients with HER2 over-expressing breast cancer. Breast Cancer Res Treat 167:731-740
Bajgain, Pradip; Tawinwung, Supannikar; D'Elia, Lindsey et al. (2018) CAR T cell therapy for breast cancer: harnessing the tumor milieu to drive T cell activation. J Immunother Cancer 6:34
Niravath, Polly; Chen, Bingshu; Chapman, Judy-Anne W et al. (2018) Vitamin D Levels, Vitamin D Receptor Polymorphisms, and Inflammatory Cytokines in Aromatase Inhibitor-Induced Arthralgias: An Analysis of CCTG MA.27. Clin Breast Cancer 18:78-87
Zhao, Na; Cao, Jin; Xu, Longyong et al. (2018) Pharmacological targeting of MYC-regulated IRE1/XBP1 pathway suppresses MYC-driven breast cancer. J Clin Invest 128:1283-1299
Bhat, Raksha R; Yadav, Puja; Sahay, Debashish et al. (2018) GPCRs profiling and identification of GPR110 as a potential new target in HER2+ breast cancer. Breast Cancer Res Treat 170:279-292
Hertz, D L; Kidwell, K M; Hilsenbeck, S G et al. (2017) CYP2D6 genotype is not associated with survival in breast cancer patients treated with tamoxifen: results from a population-based study. Breast Cancer Res Treat 166:277-287
Yu, L; Liang, Y; Cao, X et al. (2017) Identification of MYST3 as a novel epigenetic activator of ER? frequently amplified in breast cancer. Oncogene 36:2910-2918

Showing the most recent 10 out of 28 publications