The gist: This article discusses a potential way to improve chemotherapy treatment for triple-negative breast cancer (TNBC), but it has only been tested in mice so far, so it is not yet known whether it would work for humans. The method would use drugs called HIF inhibitors to make breast cancer cells more responsive to chemotherapy. HIF inhibitors are already being used in humans with other conditions, so clinical trials may soon be able to show whether they work for TNBC.
“Triple-negative breast cancer is as bad as it sounds. The cells that form these tumors lack three proteins that would make the cancer respond to powerful, customized treatments. Instead, doctors are left with treating these patients with traditional chemotherapy drugs that only show long-term effectiveness in 20 percent of women with triple-negative breast cancer. Now, researchers at The Johns Hopkins University have discovered a way that breast cancer cells are able to resist the effects of chemotherapy—and they have found a way to reverse that process.
“A report of their findings was published online in the journal Proceedings of the National Academy of Sciences on Dec. 1.
“Triple-negative breast cancers account for about 20 percent of all breast cancers in the United States, and 30 percent of all breast cancers in African-American women. In addition to being resistant to chemotherapy, they are known to include a high number of breast cancer stem cells, which are responsible for relapses and for producing the metastatic tumors that lead to the death of patients with cancer. Previous research revealed that triple-negative breast cancer cells show a marked increase in the activity of many genes known to be controlled by the protein hypoxia-inducible factor (HIF). Given these past results, a research team directed by Gregg Semenza, M.D., Ph.D., decided to test whether HIF inhibitors could improve the effectiveness of chemotherapy.”
The gist: New research shows that triple-negative breast cancer (TNBC) patients who have a particular molecule called miR-21 near their tumor, but not actually in the tumor cells, have worse clinical outcomes. This opens up the future possibility that doctors could check for miR-21 in order to better understand a patient’s disease and make treatment decisions.
” ‘Triple-negative’ breast cancer (TNBC) occurs in patients whose cells do not express receptors for estrogen, progesterone, and/or human epidermal growth factor receptor 2 (ER-/PR-/HER2-). Because of the absence of these predictive biomarkers, treatment assignment can be difficult. Now, researchers report that high levels of the microRNA miR-21 in the tumor microenvironment, but not in the tumor epithelia (cancer cells), are associated with worse clinical outcomes for patients with TNBC, thus identifying a possible TNBC prognostic biomarker, according to a study in The American Journal of Pathology.
“TNBC accounts for 15% to 20% of breast cancer cases, and patients have shorter recurrence-free survival (RFS) and breast cancer-specific survival (CSS) relative to other major subgroups. It is likely that different subtypes of TNBCs exist, and the heterogeneity may be responsible for a wide variation in response to treatment. ‘Predictive biomarkers for therapeutic response prediction and novel therapeutic targets that address distinct biological features of TNBC subgroups are needed for these patients,’ says Lorenzo F. Sempere, PhD, head of the Laboratory of microRNA Diagnostics and Therapeutics at Van Andel Research Institute in Grand Rapids, MI. ‘These findings add support to the growing importance of miRNA-based diagnostics.’ “
“Most patients with triple-negative breast cancer should undergo genetic testing for mutations in known breast cancer predisposition genes, including BRCA1 and BRCA2, a Mayo Clinic-led study has found. The findings come from the largest analysis to date of genetic mutations in this aggressive form of breast cancer. The results of the research appear in the Journal of Clinical Oncology.
” ‘Clinicians need to think hard about screening all their triple-negative patients for mutations because there is a lot of value in learning that information, both in terms of the risk of recurrence to the individual and the risk to family members. In addition, there may be very specific therapeutic benefits of knowing if you have a mutation in a particular gene,’ says Fergus Couch, Ph.D., professor of laboratory medicine and pathology at Mayo Clinic and lead author of the study.
“The study found that almost 15 percent of triple-negative breast cancer patients had deleterious (harmful) mutations in predisposition genes. The vast majority of these mutations appeared in genes involved in the repair of DNA damage, suggesting that the origins of triple-negative breast cancer may be different from other forms of the disease. The study also provides evidence in support of the National Comprehensive Cancer Network (NCCN) guidelines for genetic testing of triple-negative breast cancer patients.
“Triple-negative breast cancer is a specific subset of breast cancer that makes up about 12 to 15 percent of all cases. The disease is difficult to treat because the tumors are missing the estrogen, progesterone and HER-2 receptors that are the target of the most common and most effective forms of therapy. However, recent studies have suggested that triple-negative breast cancer patients might harbor genetic mutations that make them more likely to respond to alternative treatments like cisplatin, a chemotherapy agent, or PARP inhibitors, anti-cancer agents that inhibit the poly (ADP-ribose) polymerase (PARP) family of enzymes.”
“The authors compare the clinical outcome and sites of relapse of TNBC in BRCA1 mutation carriers and non–carriers who received adjuvant chemotherapy. Results suggest that BRCA1 mutation carriers with TNBC had similar survival rates and sites of recurrence to non–carriers after treatment with conventional chemotherapy.”
Editor’s note: This article describes a breast cancer study that compared patients with BRCA1 mutations to patients without BRCA1 mutations. It was found that, after conventional chemotherapy, BRCA1-positive patients with triple-negative breast cancer had similar survival rates and sites of recurrence to BRCA1-negative patients.