Detection, Prognosis, & Treatment: Delivering Clinical Solutions

Overview: The detection, prognosis, and treatment of breast cancer represent a slowly evolving landscape. Information filtering in from hypothesis-driven basic science is screened for clinical relevance and promising new strategies. Drugs are slowly advancing along the 10+ year “critical path” for translation into practical use. Better early detection and staging/prognosis for breast cancer remains a critical need. The use of combined imaging modalities is aimed at improving both sensitivity and selectivity to reduce unnecessary biopsies. Genetic profiling of tumors in patients continues to move in the direction of true individualized therapy. New information from stem cell biology, immunology, and the refined knowledge of cellular processes, such as DNA repair and hormone signaling, are continually being probed for new detection, prognosis, patient stratification, and novel treatment potential.

The CBCRP funded 15 new grants in 2009 to advance our Detection, Prognosis, & Treatment priority issue. Two of the CBCRP’s research topics are represented in this section:

Detection, Prognosis & Treatment Portfolio
Two newly funded projects focus on advancing early detection imaging technologies.

Much research effort is being made to improve two-dimensional X-ray mammography and MRI images, such that either 3-dimensional or tomography (imaging by sections) can improve changes of detecting a breast tumor in the breast. Jacob Nebeker at the University of California, San Diego is funded for a dissertation award to adapt a conventional ultrasound system to produce “speed of sound” ultrasonic images. This approach is especially amenable to improve detection in dense breast tissue (which is present in most pre-menopausal women). Thus, speed of sound tomographic images of the breast can resemble those of computed tomography (CT), but with somewhat lower resolution. The project complements a current CBCRP grant to Mr. Nebeker’s mentor, Dr. Thomas Nelson, to develop a dedicated ultrasound breast imaging instrument.

Imaging technologies also have the potential to assess treatment response in patients both in terms of tumor shrinkage and any preceding cellular changes. Lisa Singer from the University of California, San Francisco will compare two magnetic resonance imaging (MRI) technologies for their ability to assess neoadjuvant (prior to surgery or radiotherapy) chemotherapy response. The hypothesis is that tumor cell death as a result of neoadjuvant chemotherapy will increase localized water movement, which they can detect with a specific type of MRI and develop into a future clinical application. An advantage of the novel MRI technology is to eliminate the need for injected contrast agents to produce an image. Thus, the ability to monitor tumor physiological changes prior to actual tumor shrinkage would give clinicians a much greater lead time in evaluating an effective therapy.

Once cancer is detected there are numerous staging, treatment choices/failures, and survival/recurrence issues that create uncertainties in the eventual outcome for the disease and impact quality-of-life issues for the patient. Four new CBCRP innovative projects hope to advance our understanding into critical issues associated with treatment.

The widespread use of sentinel node biopsy has greatly reduced the need for more extensive axillary lymph node dissection as a method for breast cancer staging. Women subjected to axillary lymph node dissection are at risk for lymphedema (arm swelling), which is both painful and increases the risk for serious infection. Stephen Chen at the University of California, Davis will conduct a clinical trial to evaluate the use of axillary reverse mapping (ARM) to identify and preserve lymphatic channels and nodes draining the arm. When ARM is used as an adjunct to axillary lymph node dissection, it may reduce lymphedema incidence and result in improved quality of life. Dr. Chen has estimated that about 31% of breast cancer patients currently have node-positive disease, so the potential of ARM to improve axillary lymph node dissection is substantial. In fact, it is estimated that about 400,000 women in the US are currently suffering lymphedema as a result of breast cancer therapy.

Cancer patients still mainly receive broad-spectrum, non-specific chemotherapy, and even patients receiving newer targeted drugs often have decreased response or develop drug resistance. New approaches and technologies are needed to identify those tumors responsive or resistant to various drugs. Trent Northen at Lawrence Berkeley National Laboratory has developed methods for detection of sphingolipids in breast cancer cells and tissue slices using a state-of-the-art mass spectrometry approach, called Nanostructure-Initiator Mass Spectrometry (NIMS). Sphingolipids, often thought of only as cell structural components, have important roles in signal transmission and cell recognition; and, importantly, are associated with reduced sensitivity to programmed cell death and increased expression of drug-resistance p-glycoproteins. Working with a breast cancer cell line library developed by Dr. Joe Gray, they will create sphingolipid metabolite profiles. The data will be mapped to tumor tissues sections from patient samples to create “pathology-type” (microscopic) images showing the distribution. The ultimate goal is the able to use this technology to screen breast cancers prior to treatment to inform drug selection by predicting potential response and possible future resistance to specific drug therapy.

Little is known about the survival of newly diagnosed (de novo) patients with metastatic breast cancer vs. patients where metastatic disease recurs after a disease-free period. Sumanta Pal at the Beckman Research Institute of the City of Hope will investigate whether there is a difference in survival between two groups; and, secondly, if there is a difference in survival before and after the introduction of paclitaxel. Information from this study may be the first to indicate differences in survival trends with chemotherapy in these two disease processes and could ultimately lead to a change in the current therapeutic approach for both. Furthermore, this research could serve as the rationale for laboratory explorations of biological differences between de novo and recurrent metastatic breast cancer; perhaps yielding distinct, novel drug targets for both.

Finally, the CBCRP continues to support exploration into the intraductal approach to detect and treat breast cancer. Dixie Mills at the Dr. Susan Love Research Foundation received a conference award to support the 6th Symposium on the Intraductal Approach to Breast Cancer that was held on February 19-21, 2009, in Santa Monica. Topics ranged from inflammation, breast endoscopy, breast biology, and the potential for intraductal-based treatments. The diverse participants included more than 100 oncologists, epidemiologists, biostatisticians, surgeons, pathologists, radiologists, endocrinologists, and breast cancer advocates.

The stem cell theory for breast cancer continues to be intensively studied as the new approach to understanding such disease aspects as tumor cell heterogeneity, resistance to therapy, the “seeds” of metastasis, and disease recurrence after seemingly successful therapies that shrink tumors. Although amenable to study in model systems, such as mice, the ability to isolate breast cancer stem cells from patient samples had proven difficult and controversies exist in this field of research. Three new CBCRP-funded grants focus on exploiting stem cell biology in the therapeutic direction.

First, we need new research tools to isolate and target breast cancer stem cells. Claudia Gottstein from University of California, Santa Barbara is using her expertise in nanotechnology to explore a novel method of isolating tumor stem cells. Her technology-oriented approach is to create combinatorial libraries from circulating tumor cells isolated from the peripheral blood of patients who are in remission from breast cancer. Then, Dr. Gottstein and collaborators will test candidate antibodies using tumor samples having co-expression of CD44, a potentially useful stem cell biomarker. If successful, this project would simultaneously validate the stem cell hypothesis (at least in the context of circulating tumor cells), identify useful tumor antigens for future study, and develop new antibody reagents for additional projects.

Although it may be difficult to isolate breast cancer stem cells, new therapies could be developed to better sensitize the stem cell-like tumor population to make them more sensitive to other treatments. Frank Pajonk at the University of California, Los Angeles has been awarded two additional years of IDEA funding to explore a functional marker, namely low proteosome activity, characteristic of breast cancer stem cells. The function of the proteosome within cells is to degrade unneeded or damaged proteins by proteolysis. With further study of how tumor stem cells reduce their proteosome activity to lower their sensitivity to radiotherapy, Dr. Pajonk is in a position to identify new therapy targets, perhaps utilizing existing drugs or other compounds in development.

Finally, Xiaohua Wu at the Scripps Research Institute will analyze cancer stem cell populations for defects in DNA repair pathways, and also determine the efficacy of multiple clinical trial stage HDAC (histone deacetylase) inhibitors to sensitize breast cancer stem cells to chemotherapy drugs and/or radiation. HDAC enzymes remove acetyl groups from histones, which increases their DNA binding activity to condense chromatin and reduce transcription of various genes. The goal is to develop proof-of-principle that targeting DNA repair pathways combined with a screen of the many HDAC inhibitors currently in clinical trials will better target stem cells. Importantly, useful therapeutics may have been overlooked in prior studies, since they are traditionally evaluated for tumor shrinkage in short-term assays that could easily miss significant effects on the small, but critical, tumor stem cell population.

Two newly funded projects explore novel approaches for immunotherapy of breast cancer.

Brunhilde Felding-Habermann atthe Scripps Research Institute speculates that the immune repertoire of healthy elderly (over 80 years old) individuals will contain antibodies that are protective against cancer development and, if identified, these antibodies may provide a novel approach to inhibit breast cancer growth in patients. Dr. Felding-Habermann is funded to develop an antibody library from the genes of the “Wellderly”, a group of 1,000 healthy octogenarians. The risky element is the assumption that Wellderly breast cancer antibodies exist. Nevertheless, they will test antibodies for their ability to inhibit the growth of a cell line panel of inflammatory breast cancer. To complement this analysis, they will conduct a functional profile of the changes that occur with disease progression, identify determinants that seem to confer an advantage to the tumor, and look for overlap with tumor targets identified by screening the Wellderly antibody library.

As new information emerges on the immune system, especially the discovery and role of chemokines (e.g., chemoattractants to guide the migration of cells), more testing is required to find potential new ways of attacking breast cancer without resorting to exogenous non-specific chemotherapy or radiotherapy. Russell Pachynski at the Palo Alto Institute for Research & Education will study chemerin, a recently described chemo-attractant initially isolated from human inflammatory fluids (malignant ascites and rheumatoid synovial fluid). Chemokine-like receptor 1 constitutes the main cellular receptor for chemerin, and is expressed by macrophages, natural killer cells, and immature dendritic cells. Dr. Pachynski’s postdoctoral fellowship is aimed at evaluating chemerin as a novel immunotherapeutic agent using a mouse model of breast cancer.

Novel therapies or potential tumor drug targets are the focus of four newly funded grants.

Natural compounds and their derivatives still represent a tremendous untapped, potentially safer, resource for drug discovery and development. Jennifer Smith from University of California, Santa Barbara will study the mechanism of action of eribulin, a synthetic analog of the natural compound, halichondrin B from the marine sponges. Eribulin disrupts cellular microtubules by inhibiting their growth and affecting cell division. Ms. Smith in her dissertation research will determine how eribulin activity is influenced by stathmin, an important regulatory protein of microtubule dynamics. Working with her mentor, Dr. Leslie Wilson, she will alter the amounts of stathmin in cells and determine the effects on erubulin activity, microtubule dynamics, and breast tumor cell proliferation.

Cellular DNA repair mechanisms are an attractive target for developing new breast cancer therapies. Although a relatively few number of women have heritable defects in BRCA1 and BRCA2, many other patients with sporadic cancers show “BRCAness”—that is, traits shared with those occurring in either BRCA1- or BRCA2-mutation carriers. Kyoko Yokomori at the University of California, Irvine is funded to isolate and study small molecule inhibitors of condensin-1, a dual-mechanism target because it is involved both in chromosome organization during mitosis and in DNA repair. Condensin-1 interacts with PARP-1, which is being intensively studied due to the fact that BRCAness cancers rely on PARP-1 as a sole means of DNA repair. Dr. Yokomori hopes to develop condensing-1 inhibitors that could enhance the activity of PARP inhibitors currently in clinical development.

Cindy Benod from the University of California, San Francisco is funded for a postdoctoral fellowship to develop inhibitors of LRH-1 (liver receptor homolog-1), a novel protein  commonly found at high levels in breast tumor cells and surrounding adipose tissue. New information indicates that LRH-1 both enhances aromatase production (the only enzyme that converts androgen to estrogen) and controls the genes for two cyclins (which control the progression of cells through the cell cycle)—both of which are thought to be important in tumor growth. Thus, the discovery of LRH-1 specific inhibitors would provide a new route to block aromatase, and Dr. Benod’s research on cyclins would provide additional mechanistic information for future studies.

Finally, estrogens are hormones that bind to estrogen receptors that were once thought to occur only in the cell nucleus, and the detection of estrogen receptors in the nucleus is a basis for treatment decisions. However, other studies show that alternate, membrane-associated estrogen receptors (mER) play important roles in activating signaling cascades critical to other aspects of tumor growth. Richard Pietras at University of California, Los Angeles is funded for an IDEA project to study patient samples for the presence of mER and develop useful clinical test to quantify mER and compare its expression to nuclear ER. These studies could proved to be paradigm-shifting, since only about half of advanced breast cancers with expression of ER (and/or PR) respond to endocrine therapy, indicating a need for improved ER assays designed to correlate not only nuclear ER, but also mER with patient outcome.

Detection, Prognosis & Treatment Grants Listing
Compounds Blocking Assembly of LRH-1 in Breast Cancer
Benod, Cindy, Ph.D.
University of California, San Francisco
Award Type: Postdoctoral fellowship
$90,000

Reducing Surgical Morbidity of Breast Cancer Staging
Chen, Steven, M.D.
University of California, Davis
Award Type: IDEA
$149,983

Combating Breast Cancer with the Wellderly Immune Repertoire
Felding-Habermann, Brunhilde, Ph.D.
Scripps Research Institute
Award Type: IDEA
$284,850

Antibody-based Targeting of Breast Cancer Stem Cells
Gottstein, Claudia, M.D.
University of California, Santa Barbara
Award Type: IDEA
$150,000

6th Symposium on the Intraductal Approach to Breast Cancer
Dixie Mills, M.D.
Dr. Susan Love Research Foundation
Award Type: Joining Forces Conference
$25,000

Sound Speed Tomography for Early Breast Cancer Detection
Nebeker, Jakob
University of California, San Diego
Award Type: Dissertation
$74,392

Metabolite Imaging to Identify Drug Resistant Breast Cancer
Northen, Trent, Ph.D.
Lawrence Berkeley National Laboratory
Award Type: IDEA
$172,237

Chemerin as an Immunotherapeutic Agent in Breast Cancer
Pachynski, Russell, M.D.
Palo Alto Institute for Research & Education
Award Type: Postdoctoral fellowship
$90,000

Modulation of Breast Cancer Stem Cell Response to Radiation
Pajonk, Frank, M.D., Ph.D.
University of California, Los Angeles
Award Type: IDEA renewal
$250,000

Survival in de novo and recurrent metastatic breast cancer
Pal, Sumanta, M.D.
Beckman Research Institute of the City of Hope
Award Type: IDEA
$249,000

Membrane-associated Estrogen Receptors in Breast Cancer
Pietras, Richard, M.D., Ph.D.
University of California, Los Angeles
Award type: IDEA
$150,000

Diffusion-Weighted MRI in Monitoring Breast Cancer Treatment
Singer, Lisa
University of California, San Francisco
Award Type: Dissertation
$76,000

A Predictive Factor for Eribulin Treatment of Breast Cancer
Smith, Jennifer
University of California, San Francisco
Award Type: Dissertation
$76,000

Targeting DNA Repair Function of Breast Cancer Stem Cells
Wu, Xiaohua, Ph.D.
Scripps Research Institute
Award Type: IDEA
$284,850

Inhibitors of Condensin I as Chemotherapy for Breast Cancer
Yokomori, Kyoko, Ph.D.
University of California, Irvine
Award Type: IDEA
$100,000