Although breast cancer diagnosis and mortality rates have steadily decreased over the last three decades, about 40,450 women in the U.S. were expected to lose their lives to breast cancer in 2016. The decrease in breast cancer incidence coupled with ongoing innovative research provides hope for the future. A PubMed search generated nearly 8,000 research articles related to breast cancer research published to date in peer-reviews journals in 2016 alone, making selecting the top five quite a challenge. The five below reflect either top new breast cancer treatments or breakthroughs in potential markers and causes.
Many women who have the BRCA1 genetic mutation decide to have preventive mastectomies due to the high risk of breast cancer. Using samples of breast tissue donated by women with the faulty BRCA1 gene, researchers in Australia discovered cells in apparently healthy women with a high risk of developing into cancer. The discovery was based on 10 years of research on stem cells in the breast, tied to identification of a marker protein called RANK. In preclinical models using breast tissue samples, the researchers were able to either delay or prevent tumors from forming. RANK-Ligand inhibitors are already used in patients with osteoporosis and bone metastases from breast cancer.
“By thoroughly dissecting how normal breast tissue develops, we have been able to pinpoint the precise cells that are the culprits in cancer formation. It is very exciting to think that we may be on the path to the 'holy grail' of cancer research, devising a way to prevent this type of breast cancer in women at high genetic risk,” said Professor Jane Visvader, a member of the research team. Although these findings are promising, it will be several years before researchers know if this is an effective strategy for preventing breast cancer in high-risk women, particularly those with the BRCA1 mutation.
Triple-Negative Breast Cancer Research
As many as one in five breast cancers are triple-negative, which means they lack "receptors" known to fuel most breast cancers, such as estrogen, progesterone, and HER2. Currently, there is no standard chemotherapy for treatment-resistant triple-negative breast cancers that have spread or relapsed.
Now in phase 2 clinical trials, treatment with an antibody called sacituzumab govitecan (IMMU-132) halted cancer progression in patients with triple-negative breast cancer for nearly 6 months, twice as long as other treatments. The antibody drug finds the cancer cells and delivers chemotherapy only to those cells. This enables a higher safe dosage of chemotherapy, while minimizing damage to surrounding healthy tissues. It does so by targeting a protein known as Trop-2, found in most triple-negative breast cancers.
The U.S. Food and Drug Administration has given this drug "breakthrough" status, a distinction used to expedite review of promising new treatments for life-threatening conditions. If research progresses as planned, the last hurdle before bringing this therapy to market will be positive results from a phase 3 clinical trial.
HER2+ Breast Cancer Research
About one in 10 breast cancers are HER2+. Current treatments for this type of breast cancer only deactivate cancer cells, but these can reactivate at any time. In some invasive forms of breast cancer, excessive levels of HER2 leads to uncontrolled growth of cells, making it far more difficult to treat.
Researchers at the Institute of Cancer Research in London found that a combination of two cancer drugs, trastuzumab (Herceptin) and lapatinib (Tyverb), resulted in complete obliteration of all signs of breast cancer in 11% of patients in just 11 days. This “dynamic duo” caused tumors to shrink so significantly that 17% of patients no longer needed chemotherapy. While the research is preliminary, the results are promising. This has the potential for highly targeted, tailored cancer treatment to combat HER2+ breast cancer without chemotherapy. The latter often results in serious side effects including killing all rapidly dividing cells in the body such as hair follicles and healthy bone marrow cells.
A study published in May 2016 provides scientists with a near-perfect picture of the genetic events that cause breast cancer. While there are about 20,000 genes in the human genome, 93 of those genes will convert a normal breast cell into a breast cancer cell when mutation occurs. Researchers discovered that 60% of the mutations responsible for cancer are found in just 10 of these genes. The good news is that pharmaceuticals and biotech companies can start developing new drugs based on mutated genes and proteins. The bad news is they will likely only focus on new therapeutics for the 10 genes responsible for the majority of these mutations, leaving rarer mutations in the dark.
"This study brings us closer to getting a complete picture of the genetic changes at the heart of breast cancer and throws up intriguing clues about the key biological processes that go wrong in cells and drive the disease,” said Dr. Emma Smith of Cancer Research UK.
A Potential New Screening Option
Mammography is considered the gold standard for breast cancer detection, supplemented by ultrasound and MRI in women with dense breasts or others at high risk. Researchers successfully discovered that the presence of isotopes carbon-13 and nitrogen-15 in certain proportions in a tissue sample can reveal whether tissue is healthy or cancerous. Although it may be a decade before this blood test becomes a widely available screening option, researchers believe a simple blood test has the potential to not only detect breast cancer, but to also monitor it.