What's Intriguing And Concerning About Early Results For Keytruda In Breast Cancer

Note: This is an opinion piece about the recent news that the drug Keytruda has shown promise for treating triple-negative breast cancer (TNBC). It does not necessarily reflect the views of Cancer Commons.

“At first glance, it’s hard to get excited about the preliminary results of an early phase trial study of pembrolizumab (Keytruda, MK-3475) in women with triple-negative breast cancer (TNBC). The non-randomized study has, so far, yielded an overall response rate of 18.5 percent – only 5 among 27 evaluable patients.

“The findings drew attention at the San Antonio Breast Cancer Symposium, in part because TNBC is a notoriously hard-to-treat form of the disease. The work* was presented by Dr. Rita Nanda, of the University of Chicago, who led a multinational list of authors including academics and several Merck employees.

“Keytruda is a monoclonal antibody given by infusion. When it binds PD-1, as it’s engineered to do with high affinity, it can unleash the body’s normal immune cells to fight a tumor. Recently, the FDA approved Keytruda for use in advanced melanoma. Last week, at the annual meeting of the American Society of Hematology, investigators reported preliminary findings that the drug is well-tolerated and may be helpful in Hodgkin’s lymphoma.”

Phase III Results Demonstrate Significant Pathological Complete Response for Nab-Paclitaxel in Neoadjuvant Breast Cancer–

The gist: The drug nab-paclitaxel (aka Abraxane) has shown promise for patients with early-stage, high-risk breast cancer. Nab-paclitaxel is an injectable version of the chemotherapy drug paclitaxel. In a clinical trial, tumors disappeared in 38% of the patients who took nab-paclitaxel, compared to 29% of patients who took conventional paclitaxel. Learn more about the treatment, and its side effects, here.

“The German Breast Group (GBG) said nab-paclitaxel (ABRAXANE®) demonstrated significant benefit for patients with early high risk breast cancer when compared to conventional solvent-based paclitaxel. The findings are from the GeparSepto clinical trial sponsored by GBG and conducted together with the German AGO-B study group involving over 1200 patients, which is the largest randomized Phase III study ever completed with nab-paclitaxel and the first one completed in high risk early breast cancer. The results were presented by the coordinating investigator Michael Untch, M.D., Berlin in General Session 2 on December 10th, at the 2014 San Antonio Breast Cancer Symposium.

“The study found a statistically significant and clinically meaningful 9% absolute improvement from 29% to 38% (p=<0.001) in the pCR (pathological complete response) rate, when neoadjuvant (preoperative) chemotherapy was started with nab-paclitaxel instead of conventional solvent-based paclitaxel followed by epirubicin/cyclophosphamide given all before surgery. Pathological complete response after neoadjuvant treatment for breast cancer is a surrogate marker for long-term efficacy.

“ ‘The phase III study provided a head-to-head comparison of weekly nab-paclitaxel with weekly conventional paclitaxel followed by epirubicin/cyclophosphamide in both arms before surgery. Our findings clearly demonstrate nab-paclitaxel is superior to paclitaxel in achieving pCRs in early high risk breast cancer,’ Prof. Dr. Michael Untch.”

Early Trial of New Drug Shows Promise for Patients with Triple-Negative Breast Cancer

The gist: A drug called pembrolizumab (aka Keytruda or MK-3475) has shown promise for people with metastatic triple-negative breast cancer (TNBC) whose tumors have high levels of a protein called PD-L1.  It was recently tested in patients in a clinical trialPembrolizumab is already approved by the U.S. Food and Drug Administration (FDA) for treating melanoma. It is an immunotherapy, meaning that it boosts a patient’s own immune system to fight cancer. More research will determine just how well pembrolizumab might work for TNBC.

“In patients with metastatic triple-negative breast cancer—a disease with no approved targeted therapies—infusion of pembrolizumab produced durable responses in almost one out of five patients enrolled in a phase-Ib clinical trial, according to data presented Dec. 10, at the 2014 San Antonio Breast Cancer Symposium.

“The multi-center, non-randomized trial was designed to evaluate the safety, tolerability and antitumor activity of bi-weekly infusions of pembrolizumab (MK-3475, marketed as Keytruda®). The researchers enrolled 27 patients, aged 29 to 72 years, who had metastatic triple-negative breast cancer that either relapsed after treatment for early stage disease or progressed on therapy for advanced disease.

” ‘For this group of patients our treatment options are limited to chemotherapy,’ said study director Rita Nanda, MD, assistant professor of medicine and associate director of the breast medical oncology program at the University of Chicago.

“All patients in the study had triple-negative tumors with high levels of a protein called programmed death-ligand 1 (PD-L1). This protein can suppress the immune system’s efforts to eliminate cancer cells. Pembrolizumab is a monoclonal antibody designed to help reactivate a person’s own immune system to help fight the tumor.”

Toughest Breast Cancer May Have Met Its Match

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.”

Prognostic Role Found for miR-21 Expression in Triple-Negative Breast Cancer

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.’ “

Triple-Negative Breast Cancer Patients Should Undergo Genetic Screening

“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.”

Outcome of Triple Negative Breast Cancer: Comparison of Sporadic and BRCA1-Associated Cancers

“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.