More for Stage IV Research Fund at the
Metastatic breast cancer (MBC, also known as Stage IV) is breast cancer that has spread beyond the breast to other organs in the body. No one dies from cancer in the breast; deaths are due to metastasis to other parts of the body. Once breast cancer has metastasized it is a terminal disease – THERE IS NO CURE.
For decades, funding has focused on prevention, awareness, and early detection. Unfortunately, early detection and subsequent treatments do not guarantee a cure. Metastatic breast cancer can occur five, ten or many years after a person’s original diagnosis. Less than 10 percent of all breast cancer research dollars goes towards Stage IV. Despite all the emphasis on breast cancer, there has been no significant reductions in annual deaths from MBC.
The More for Stage IV fund was established in December 2016 at the University of Wisconsin Carbone Cancer Center. (UWCCC). Its mission is to encourage innovative research at the UWCCC and is specifically related to metastatic breast cancer and currently supports the following pilot projects.
What can be done after breast cancer becomes anti-estrogen therapy-resistant?
The majority of metastatic breast cancers are estrogen receptor (ER)-positive. Cancers that express this receptor are stimulated to grow in the presence of the hormone, estrogen. Thus, various anti-estrogens are used for the treatment of ER-positive metastatic breast cancers. However, over time, these cancers develop resistance to anti-estrogen therapies. One way this resistance happens is when the cells mutate their ER into forms that both no longer bind the drug and are “always on” (signal the cell to grow even in the absence of any estrogen). At this point, treatment options are much more limited.
More for Stage IV is funding these three projects focused on improving treatment options for patients with anti-estrogen resistant, metastatic breast cancer.
- The Xu laboratory has discovered that a potential drug, called DipG, which can overcome resistance to hormone-positive breast cancer and is a potential new anti-estrogen drug that was discovered in a screen of plant natural products as having strong ER-degrading properties. In contrast to current drugs, Dip G binds to a protein that regulates ER stability, meaning it should work even after cancers develop resistance to current therapies.
- In fact this is what Xu’s group saw when they tested Dip G on otherwise resistant breast cancer cells in the lab. Currently, her group is comparing Dip G to other ER-degrading drugs and working to improve its pharmaceutical properties.
Heidi Dvinge, PhD
- Anti-estrogen therapy-resistance is not one-size-fits-all, and mutations in ER vary across patients. Dvinge started with genetic data on over 1000 breast cancer patients and is now studying different resistant forms of ERs to find out if the receptor variants make the patients fully or partially resistant to anti-estrogen therapies.
- She expects these variations will be useful as biomarkers to predict patient response. She is also using these resistant forms of ER to find even more drugs that target it when others fail, similar to Dr. Xu’s work with Dip G.
- Some patients may have cancers that are not totally resistant to an anti-estrogen, they just may need higher drug doses to respond – especially if there are mutations in the ER gene. Using a low-dose, radioactively-labeled estrogen called FES, Wisinski and Fowler will use a PET/CT scan to look at increasing tamoxifen dosing. FES and tamoxifen compete for binding ER, so if the scan shows FES is able to bind to tumors, that means the drug dose may be too low and that a higher dose may be more likely to help the patient.
- If they see no FES binding to tumors in the scan, then the tamoxifen dose is optimal. They expect their trial will establish routine testing for ER mutations in metastatic breast cancer patients and will lead to maximizing the benefits of these drug therapies.
How can we quickly monitor changes in metastatic breast cancers and switch treatments accordingly?
For metastatic breast cancer patients, timing is crucial. You want to give the best drug for each patient as soon as possible and not waste time on a drug to which they are unlikely to respond. Biopsies, especially of metastatic sites, are invasive and do not provide a real-time snapshot of the current state of the metastatic cancer’s characteristics.
“Liquid biopsies” are simple blood draws from which cancer cells (circulating tumor cells, or CTCs) of DNA from cancer cells can be isolated and analyzed, essentially in real-time. More for Stage IV is funding these two research projects related to CTCs.
- Lang pioneered CTC research at UW Carbone, starting with metastatic prostate cancer. The androgen hormone receptor (AR) functions similarly to ER in breast cancers, and most of the resistant prostate cancers result from mutations in AR. Lang will continue to develop CTC technology for clinical use and O’Regan will bring her expertise as a breast cancer physician and researcher to move CTC work into breast cancer.
- Using blood samples from patients with metastatic breast cancer, Lang and O’Regan will isolate cancer cells and then analyze changes in DNA and protein levels. They can then monitor when and how the ER and other features of the cancer make it resistant to anti-estrogen therapy. They will also look to match patient samples to current FDA-approved drugs, to see if they can predict patient response to treatment with a particular focus on Taxol chemotherapy.
Can we improve immune-based therapies to treat metastatic breast cancer?
Immunotherapies have revolutionized the treatment of many different types of metastatic cancer. However, they are not approved for metastatic breast cancer because only a small fraction (~15 percent) appear to have a benefit. Most metastatic breast cancers are not highly mutated, so the patient’s immune system sees them as healthy, and not as the threat they really are.
More for Stage IV is funding research that seeks to make breast cancer cells more visible to the immune system, making it more likely that patients will see a benefit from immunotherapies.
- While the DNA of healthy cells is strictly located inside the nucleus, some unhealthy cells, such as a virus-infected cell, have DNA outside the nucleus which acts as a signal to the immune system. Extranuclear DNA is also found in a small number of cancers. Dr. Burkard proposes that extranuclear DNA levels can be increased in cancer cells by a class of drugs, the taxanes.
- Using 354 breast cancer samples, he and his research team will first measure the extranuclear DNA and immune signal levels in breast cancer. After treating the cells with taxanes, they will ask, do the extranuclear DNA levels increase? Do the immune signaling levels increase? If yes to both, then taxanes are likely to work well in combination with immunotherapy treatments to improve patient.