Targeting Breast Cancer Metastasis to Bone

Institution: Stanford University
Investigator(s): Christopher  Contag , Ph.D. -
Award Cycle: 2014 (Cycle 20) Grant #: 20IB-0141 Award: $237,448
Award Type: IDEA
Research Priorities
Biology of the Breast Cell>Pathogenesis: understanding the disease



Initial Award Abstract (2014)

Metastasis is the process through which cancer cells depart from the primary tumor to colonize and grow in distant organs. Metastatic spread is responsible for most breast cancer deaths. Despite advances in early detection and treatment, many patients who are treated for early stage breast cancer develop metastatic disease years later. This renders the concept of “cure” an unfulfilled promise for all breast cancer patients. Bone is the most common site of breast cancer metastasis and the presence of small numbers of cancer cells in the bone marrow at the time of diagnosis is linked to the later development of metastatic disease. Small numbers of breast cancer cells appear to travel to bone during the earliest stages of breast cancer development, and acquire properties that are different from the primary tumor that may resist treatment. Thus, even with advances in the early detection and treatment of primary tumors, we will never cure breast cancer without creating better methods to target cancer cells lurking within the bone metastatic niche.

The question(s) or central hypotheses of the research: The goal of this grant is to use small human bone tissue fragments in culture dishes as a model system for testing therapies to prevent and treat breast cancer metastasis to bone. We predict that we can measure the response of breast cancer cells to treatment as they grow within the bone tissues.

The general methodology: We will isolate breast cancer cells from fresh human breast tumor tissues obtained from breast cancer patients undergoing surgery at Stanford, and then categorize them for the presence of two common treatment targets: ER (estrogen receptor), which is treated with tamoxifen, and Her-2, which is treated with Herceptin. Next we will transfer the ER and Her-2 breast cancer cells into small bone tissue fragments isolated from human hip replacement surgeries. We will then track the growth of the breast cancer cells within the bone tissues during treatment with tamoxifen and Herceptin. Showing that we can measure known targets during treatment with current drugs will prove that our model can be used to test new, more effective approaches to prevent and treat breast cancer metastasis to bone.

Innovative elements of the project: Breast cancer metastasis is usually studied in mice, but these experiments take many weeks or months, and human breast cells do not always grow well in the mouse skeleton. In addition, it is difficult to study specific breast cancer cell responses within the bone tissues of a mouse. We have developed a new culture system in which human breast cancer cells are grown in small human bone tissue fragments. We are using new methods to isolate and categorize breast cancer cells from primary tumors so that we can study how their properties and behavior change once they start to grow in the bone tissues. And finally, we can treat the breast cancer cells within this “metastatic niche” and measure responses within a matter of days to determine if, and how a drug is working.




Final Report (2016)

Most breast cancer deaths result from metastasis, a process in which cancer cells depart from the tumor in the breast and travel through the bloodstream to colonize and undermine the function of distant organs. Current treatments for this stage of disease are not curative, and better therapeutic strategies are needed to target breast cancer cells within the metastatic setting. The most common site of breast cancer metastasis is bone. We previously developed a model system for studying breast cancer cell responses within human bone tissue fragments isolated from hip replacement surgeries. The goal of this grant was to adapt our model system for testing therapies to prevent and treat breast cancer metastasis to bone. We predicted that we could measure the response of breast cancer cells to treatment agents as they grow within the bone fragments.

To establish proof-of-principle, we used breast cancer cells that exhibit one of the two common treatment targets: ER (estrogen receptor), which is targeted with Tamoxifen, or Her2 receptor, which is treated with Herceptin. We transferred the breast cancer cells into small bone tissue fragments and monitored cell numbers to show reductions following both treatments. We went on to perform an extended series of experiments in our bone tissue model to study Herceptin targeting. We showed that Herceptin specifically and reproducibly reduced the number of Her2+, but not Her2- breast cancer cells growing within bone tissue fragments, and that these responses were dramatically enhanced when we included human immune cells with Herceptin treatment. Our experiments demonstrated specific targeting of Her2+ breast cancer cells with Herceptin in our bone tissue model system through Herceptin-mediated inhibition of breast cancer cell proliferation and antibody-dependent cell cytotoxicity (ADCC).

Demonstrating the effective modulation of known clinical targets in our human bone tissue model has validated the use of our platform to evaluate new, more effective therapies to prevent and treat breast cancer metastasis to bone.




Conference Abstract (2016)

Targeting Breast Cancer Metastasis to Bone

King, Bonnie L., Ph.D1, Collyar Deborah2, Contag, Christopher H., Ph.D1.
1Stanford University School of Medicine, 2PAIR (Patient Advocates in Research)

Most breast cancer deaths result from metastasis, a process in which cancer cells depart from the tumor in the breast and travel through the bloodstream to colonize and undermine the function of distant organs. Current treatments for this stage of disease are not curative, and better therapeutic strategies are needed to target breast cancer cells within the metastatic setting. The most common site of breast cancer metastasis is bone. We previously developed a model system for studying breast cancer cell responses within human bone tissue fragments isolated from hip replacement surgeries. The goal of this grant was to adapt our model system for testing therapies to prevent and treat breast cancer metastasis to bone. We predicted that we could measure the response of breast cancer cells to treatment agents as they grow within the bone fragments.

To establish proof-of-principle, we used breast cancer cells that exhibit one of the two common treatment targets: ER (estrogen receptor), which is targeted with Tamoxifen, or Her2 receptor, which is treated with Herceptin. We transferred the breast cancer cells into small bone tissue fragments and monitored cell numbers to show reductions following both treatments. We went on to perform an extended series of experiments in our bone tissue model to study Herceptin responses. We showed that Herceptin specifically and reproducibly reduced the number of Her2+, but not Her2- breast cancer cells growing within bone tissue fragments. Demonstrating the effective modulation of known clinical targets in our human bone tissue model has validated the use of our platform to evaluate new, more effective therapies to prevent and treat breast cancer metastasis to bone.

In the interest of exploring issues relating to the future application of our research on bone metastasis, we also developed a survey to explore breast cancer patient experience and attitudes toward bone marrow exams. Bone marrow exams offer a window into the microenvironment of the bone metastatic niche and constitute a potentially valuable research tool for developing approaches to prevent and treat breast cancer metastasis. The goal of our survey was to explore the potential acceptance of these procedures as a research tool. Our survey was circulated to the METAvivor Foundation email list and was completed by 190 respondents. Preliminary analysis of these results will be presented.



Methods for culturing human femur tissue explants to study breast cancer cell colonization of the metastatic niche.
Periodical:Journal of Visualized Experiments
Index Medicus: J Vis Exper
Authors: Templeton ZS, Bachmann MH, Alluri RV, Maloney WJ, Contag CH, King BL.
Yr: 2015 Vol: 97 Nbr: Abs: Pg:1-10

Breast cancer cell colonization of the human bone marrow adipose tissue niche
Periodical:Neoplasia
Index Medicus:
Authors: Templeton ZS, Alluri RV, Lie W-R, Tamaresis JS, Bachmann M, Maloney WJ, Contag CH, King BL
Yr: 2015 Vol: 17 Nbr: 12 Abs: Pg:849-861