Inhibition of Brain Metastases in Breast Cancer

Institution: Scripps Research Institute
Investigator(s): Brunhilde Felding, Ph.D. -
Award Cycle: 2006 (Cycle 12) Grant #: 12NB-0176 Award: $464,750
Award Type: IDEA Competitive Renewal
Research Priorities
Detection, Prognosis and Treatment>Innovative Treatment Modalities: search for a cure

Initial Award Abstract (2006)

Today, nearly 30% of patients with advanced breast cancer are eventually diagnosed with brain lesions, making breast tumors the main source of metastatic brain disease in women. Brain metastases are often seen in younger patients with estrogen receptor negative and Her-2 positive tumors. The incidence brain metastasis is rising, as modern therapy extends the lives of many breast cancer patients but fails to inhibit development and progression of metastatic disease. Therefore, it is imperative to develop new, effective regimens that prevent and control this stage of breast cancer.

The goal of this project is to test the hypothesis that brain metastases in breast cancer can be inhibited with phage-displayed human antibodies against metastatic breast cancer cells. Phage are harmless, virus like particles that help the antibody to penetrate the tumor tissue. The feasibility of this approach is based on our previous work and ongoing study where we: (1) identified a new molecular target on metastatic breast cancer cells,(2) isolated function blocking antibodies against this target from combinatorial immunoglobulin libraries of cancer patients, (3) documented the reactivity of these antibodies with metastatic breast cancer cells regardless of the target organ they came from, and (4) most importantly, demonstrated that treatment with these antibodies can interfere with established metastatic disease.

Based on our progress and expert recommendations, we refined the aims for the continuation of this study as follows:
Investigate the inhibition of breast cancer brain metastases by treatment with phage-displayed or monomeric human scFv antibodies against the activated form of integrin av3, the novel target that we identified onmetastatic breast cancer cells.
Evaluate the efficacy of this treatment in an immune competent mouse model and assess treatment safety.
Use novel strategies for the selection of potentially therapeutic human antibodies that inhibit breast cancer brain metastases.

Our approach is to administer metastasis-directed scFv antibodies (i.e., the variable heavy and variable light antibody chains connected by a biologically inert linker) are displayed on filamentous phage, which have the capacity to penetrate into the brain when administered intranasally. Immunodeficient (SCID) mice with brain metastases caused by luciferase-tagged human beast cancer cells are treated with scFv-phage, and response is monitored by repeated non-invasive imaging. Antibody reactivity and specificity as well as neurotoxicity will be analyzed by histology. The efficacy of repeated phage antibody treatment is evaluated in immune competent mice. New inhibitory antibodies against breast cancer brain metastases will be isolated from libraries from normal donors and breast cancer survivors.

This project has a realistic potential to trigger a much needed breakthrough, as this therapeutic approach is directed against a particularly grim situation in advanced metastatic breast cancer that causes unspeakable pain and suffering.

Final Report (2009)

Brain metastases are among the most feared complications in breast cancer. Today, nearly 30% of patients with advanced breast cancer are eventually diagnosed with brain lesions, making breast tumors the main source of metastatic brain disease in women. However, treatment options are limited and in most cases prolong patient survival only for a few weeks or months, often associated with severe side effects. Therefore, it is imperative to develop new, effective regimens that prevent and control this stage of the disease. Thus, the goal of our project was to generate information toward a better understanding of mechanisms that allow the development of breast cancer brain metastases, identify new functional targets in this process, and work toward the establishment of new therapeutic approaches.

This grant allowed us to identify two key functional properties of human brain metastatic breast cancer cells that promote their survival and expansion within the brain tissue. The first set of properties was discovered through large-scale multidimensional proteomic analysis of brain homing breast cancer cells. This study revealed that brain metastatic cells primarily utilize oxidative phosphorylation for energy production, while cells from lesions outside the brain and primary tumors use glycolysis, as expected based on the known Warburg effect. Results from this work raised the possibility that targeting the functional differentiation in breast cancer brain lesions could provide a promising basis for the development of a novel therapeutic strategy. Our ongoing and future research seeks to identify the molecular mechanisms of the observed metabolic adaptation of brain metastatic breast cancer cells and is focused on mitochondrial complex I functions, narrowing the target range for potential therapeutic translation.

The second set of key properties of brain metastatic breast cancer cells was identified as mediated by a specific functional conformer of a breast cancer cell adhesion receptor, the integrin αvβ3. We found that constitutive expression of the high affinity conformer of αvβ3 controls brain metastatic growth and the ability of the tumor cells to recruit blood supply through angiogenesis. The mechanism relies on the ability of the activated tumor cell integrin to promote translational regulation of VEGF, a blood vessel growth promoting growth factor, in a hypoxia independent manner. This leads to continuous metastatic growth in the brain tissue. Importantly, this mechanism was specific for the brain microenvironment and not found in the breast. These results identify the high affinity conformer of breast cancer cell integrin αvβ3 as a new functional target for inhibition of brain metastatic growth. Having isolated antibodies from the immune repertoire of cancer patients that specifically recognize and inhibit the activated form of αvβ3, we evaluated the therapeutic effects of these antibodies in the mouse model. Importantly, antibody treatment inhibited the growth of even advanced metastases, but these responses were primarily seen for lesions outside the brain.

Thus, our current and future research is focused on developing efficient ways to deliver the antibodies to brain lesions, and to use small molecular inhibitors of integrin αvβ3 to curb brain metastatic growth. Our study provided important new information on mechanisms of brain metastasis in breast cancer. We further established new experimental approaches to investigate this understudied and very difficult to treat complication in breast cancer patients, and identified two new groups of functional targets for the development of novel therapeutic approaches to help patients whose breast cancer has spread to the brain.

Activation of tumor cell integrin alphavbeta3 controls angiogenesis and metastatic growth in the brain.
Periodical:Proceedings of the National Academy of Sciences of the United States of America
Index Medicus: Proc Nat Acad Sci, U S A
Authors: Lorger M, Krueger JS, O'Neal M, Staflin K, Felding-Habermann B
Yr: 2009 Vol: 106 Nbr: 26 Abs: Pg:10666-71

Capturing Changes in the Brain Microenvironment during Initial Steps of Breast Cancer Brain Metastasis.
Periodical:American Journal of Pathology
Index Medicus: Am J Pathol
Authors: Lorger M, Felding-Habermann B
Yr: 2010 Vol: Nbr: Abs: Pg:ePub

Targeting activated integrin alphavbeta3 with patient-derived antibodies impacts late-stage multiorgan metastasis.
Periodical:Clinical & Experimental Metastasis
Index Medicus: Clin. Exp. Metastasis
Authors: Staflin K, Krueger JS, Hachmann J, Forsyth JS, Lorger M, and Felding-Habermann B
Yr: 2010 Vol: Nbr: Abs: Pg:Mar 12, ePub

Maintaining and Engineering Neural Stem Cells for Delivery of Genetically Encoded Therapy to Brain Tumors
Periodical:Methods in Molecular Biology
Index Medicus: Methods Mol Bioll
Authors: Katz J, Krueger J, Felding-Habermann B, Snyder EY
Yr: 2009 Vol: 568 Nbr: Abs: Pg:249-59