Intermountain Healthcare Researchers Launch Major Three-Year Genomics Breast Cancer Study

Cancer researchers at Intermountain Medical Center and the Intermountain Healthcare Precision Genomics Program in Salt Lake City are launching a three-year study to determine if a blood test that looks for DNA from a cancer tumor can be used to complement mammography to improve the way breast cancer is diagnosed.

The goal of this new genomics study is to show whether screening patients for the presence of circulating tumor DNA, known as ctDNA, can successfully detect breast cancer using a blood draw.

Breast cancer is the second-leading cause of cancer deaths in women, behind only lung cancer, with an estimated 40,610 deaths each year from the disease. Nearly 253,000 new cases of invasive breast cancer are diagnosed each year, along with about 60,000 non-invasive, early-stage cases, according to the American Cancer Society.

The Intermountain study is unique in that researchers will also help develop a specific test to check for ctDNA, and will have access to both mammography results and the DNA blood test results, which will allow a direct comparison of the “liquid-based biopsy” to be made.

The idea behind the science is simple, though researchers say the execution is not yet proven: Little pieces of DNA that come from dying cells end up in the peripheral blood stream, including circulating tumor cells. The goal of researchers is to use those markers to identify breast cancer, perhaps even before mammography can detect it, said Lincoln Nadauld, MD, PhD, co-lead investigator of the study and executive director of the Intermountain Healthcare Precision Genomics Program.

“As a tumor is growing, some of the cells will die and their DNA will end up in the peripheral blood stream,” Dr. Nadauld said. “We’re able to distinguish DNA from cancer vs. DNA from normal cells. The idea is to leverage DNA to see if we can detect that it comes from a tumor.”

In the study, patients with known breast cancer will be compared with those in a screening group.

“We don’t know what we’ll see yet,” said Brett Parkinson, MD, co-lead investigator of the study, who is also imaging director and medical director of the Intermountain Medical Center Breast Care Center in Murray. “We might find those who have breast cancer will have a negative blood test and learn it’s not a good screening tool.”

Even a successful blood test isn’t expected to replace mammography outright. If it detects the circulating tumor DNA, imaging would be needed to find the tumor. But it could help eliminate unneeded biopsies, Dr. Parkinson added.

Dr. Nadauld said cancers have mutations in their DNA that aren’t always unique.

“Sometimes those are the same whether it’s a breast cancer or a colon cancer. If we do create a blood test, it’s possible it would detect mutant DNA, but it might look so similar it would be hard to tell what kind of cancer it came from,” he said. “That’s part of what this trial is going to accomplish. We want to determine the signature for early breast cancer.”

If successful, a liquid biopsy might also be used to monitor a breast cancer survivor for recurrence, Dr. Nadauld said. It might even lead to development of similar tests for different types of cancer. But that would be a challenge for the future.

“We want to approach this with laser-like focus,” he said. “It’s needed to help us diagnose breast cancer. We need to detect it earlier, when it’s curable.”

Breast cancer survival depends largely on finding the disease early —and mammography is the only screening exam that’s been shown by multiple randomized clinical trials to reduce the mortality rate for breast cancer. Since 1991, the death rate from breast cancer is down 38 percent, largely because mammography screening tests lead to early detection.

Although mammography finds most breast cancers, it may not detect malignancy in women who have dense breast tissue, especially premenopausal women, or those under 50.

“We pick up most breast cancer in women with average breast density,” said Dr. Parkinson. “When breast tissue is denser, we can miss up to 30 percent of breast cancers.”

Mammography also has a false-positive or call-back rate of 10 percent, which may subject women to additional imaging and emotional duress. Plus, a mammogram can be uncomfortable, since breast tissue is compressed for imaging, which also exposes a woman to a small amount of radiation. Mammography may also be inconvenient, often requiring women to take time off work, he noted.

For those, and perhaps other reasons, mammography screening rates in the United States are low. In Utah, only about 65 percent of eligible women are screened, despite Intermountain Healthcare’s recommendations that women over 40 undergo yearly screening mammography. All major medical and advocacy organizations agree that screening every year after a woman is 40 saves more lives. About 20 percent of breast cancers occur in women under 50.

Dr. Nadauld said the unusual confluence of three factors weigh in Intermountain’s favor on this quest, starting with access to a lot of patients in one place who are getting mammograms, which are the gold standard screening test for breast cancer. Second, the researchers have access to the results of those mammograms; they know if the results were positive or negative. The third major factor is Intermountain’s genomic technology capability.

“This is the big conversation right now in all of oncology — the use of liquid biopsy to determine how to screen for breast cancer, a woman’s risk of recurrence, and how to monitor their treatment,” Dr. Nadauld said.

The study is being made possible by a generous donation from the Beesley Family Foundation.

Genetic Targets to Chemo-Resistant Breast Cancer Identified

Research led by Dr. Carlos Arteaga, Director of the Harold C. Simmons Comprehensive Cancer Center, has identified potential targets for treatment of triple negative breast cancer, the most aggressive form of breast cancer.

Increased activity of two genes, MCL1 and MYC, is associated with the development of chemotherapy resistance. The increased action of these two genes boosts mitochondrial oxidative phosphorylation, which promotes the growth of chemotherapy-resistant cancer stem cells, the research showed.

“Alterations in these two genes are easily detectable with tumor gene tests in current use. Combinations of drugs that inhibit MCL1 or MYC, or both, have the potential to reduce the development of chemotherapy resistance and should be studied in clinical trials,” said Dr. Arteaga, Professor of Internal Medicine at UT Southwestern Medical Center. Dr. Arteaga holds The Lisa K. Simmons Distinguished Chair in Comprehensive Oncology.

Most breast cancers can be treated with hormone therapy, but about 15 percent of cases are triple negative breast cancer, meaning the cancer cells are not influenced by hormones like estrogen or progesterone. These triple negative breast cancers must, therefore, be treated with chemotherapy, which is toxic to healthy cells as well as cancer cells. Furthermore, most triple negative breast cancers eventually become resistant to chemotherapy and the cancer then spreads unchecked.

Drugs that inhibit activity of the MCL1 or MYC genes are in development, Dr. Arteaga said. These drugs, given in conjunction with standard chemotherapies, could potentially slow or even prevent the development of chemotherapy resistance, improving the outlook for this aggressive form of breast cancer.

The research was conducted at Vanderbilt-Ingram Cancer Center and appears in the journal Cell Metabolism. The research was supported by the Susan G. Komen for the Cure Foundation, the Breast Cancer Research Foundation, a National Institutes of Health Breast Cancer SPORE grant, and a Vanderbilt-Ingram Cancer Center Support Grant.

The Simmons Cancer Center at UT Southwestern is one of 49 NCI-designated Comprehensive Cancer Centers in the U.S. and the only one in North Texas. It is also one of 30 U.S. cancer research centers to be designated by the National Cancer Institute as a National Clinical Trials Network Lead Academic Site.

UT Southwestern, one of the premier academic medical centers in the nation, integrates pioneering biomedical research with exceptional clinical care and education. The institution’s faculty has received six Nobel Prizes, and includes 22 members of the National Academy of Sciences, 18 members of the National Academy of Medicine, and 14 Howard Hughes Medical Institute Investigators. The faculty of more than 2,700 is responsible for groundbreaking medical advances and is committed to translating science-driven research quickly to new clinical treatments. UT Southwestern physicians provide care in about 80 specialties to more than 100,000 hospitalized patients, 600,000 emergency room cases, and oversee approximately 2.2 million outpatient visits a year.

Drug Combo Gangs Up to Take on Triple-Negative Breast Cancer

Researchers find novel combination disrupts multiple factors in aggressive type of cancer

In the hunt for novel treatments against an aggressive form of breast cancer, researchers combined a new protein inhibitor with a chemotherapy drug to create a powerful combination that resulted in cancer cell death.

Triple-negative breast cancer is a subtype that does not express hormone receptor or HER2. It occurs in approximately 15 percent of patients with breast cancer. This subtype tends to be more aggressive and targeted therapeutic treatment options are lacking.

In this work, the drugs studied were each tested separately in triple-negative breast cancer cell lines and in mice with the disease. The researchers then implemented the treatments in combination. The combination produced a synergistic effect that was more effective than either drug alone. The cancer cells treated with the drug combination were less likely to multiply or spread in cell culture and were less viable in an animal model.

Preliminary data had shown that inhibiting proteins called cyclin dependent kinases, or CDKs, might be effective against triple negative breast cancer. In this study, researchers tested a pharmaceutical grade CDK inhibitor called CYC065. Additionally, researchers used the chemotherapy drug eribulin, which had shown promise in prior clinical trials for the treatment of triple-negative breast cancer.

“In this pre-clinical study, we showed that the combination of CYC065 and eribulin had a synergistic effect against the growth and progression of triple-negative breast cancer. New therapeutic targets and treatment strategies are crucial to improve outcomes for women with this aggressive breast cancer subtype,” says study author Jacqueline S. Jeruss, M.D., Ph.D., director of the Breast Care Center at the University of Michigan Comprehensive Cancer Center.

From the early days of her career, Jeruss was interested in how signaling pathway alterations could impact the development of breast cancer. What makes a mammary cell change to allow for lactation but then regress when that function is no longer needed? What orchestrates cell regulation to allow for such carefully mediated physiologic changes? And what processes occur over time that cause the cellular deregulation leading to cancer development in certain patients, but not in others?

Her work led her to the implementation of CDK inhibitors for the treatment of triple negative breast cancer. She found that these drugs could help to block the harmful impact of overexpression of cancer promoting cyclin E/CDKs, proteins that were inhibiting the tumor suppressant action of the TGF-beta/SMAD3 pathway. CDK inhibitors can block the impact of cyclin E/CDK action, helping to restore the beneficial effects of the TGF-beta/SMAD3 pathway, and thus facilitating cancer cell death.

In the current study, published in Oncotarget, the combination treatment of the CDK inhibitor CYC065 with the chemotherapy eribulin, resulted in less viable triple negative breast cancer cells, smaller tumor colonies, decreased cell migration, and small tumor size in an animal model.

Researchers also identified specific transcription factors that were impacted by CYC065. These processes likely work together to promote cancer cell death.

“We have begun to identify a network of vulnerable and targetable signaling components within the triple negative cancer cells that can be exploited with CDK inhibitor and chemotherapy treatment to promote triple negative breast cancer cell death,” Jeruss says.

The research was done with triple negative breast cancer cells in culture and in an animal model. The next step is for researchers to develop a clinical trial to test the drug combination in patients with triple-negative breast cancer.

Tibetan Yoga Practice May Improve Sleep Quality for Breast Cancer Patients Receiving Chemotherapy

Participating in twice-weekly practice of Tibetan yoga may reduce sleep disturbances and improve sleep quality in breast cancer patients receiving chemotherapy, according to a study from researchers at The University of Texas MD Anderson Cancer Center.

The research, published in the journal Cancer, found that women who practiced Tibetan yoga at least two times a week reported less daytime disturbances, better sleep quality and sleep efficiency over time, compared to those practicing less often and to women in an active control group receiving usual care.

Sleep disturbances and fatigue are two of the most frequent and debilitating side effects experienced by cancer patients undergoing chemotherapy, explained lead author Lorenzo Cohen, Ph.D., professor of Palliative, Rehabilitation, and Integrative Medicine and director of the Integrative Medicine Program. Patients often describe poor sleep quality, insomnia, and excessive drowsiness.

“Previous research has established that yoga effectively reduces sleep disturbances for cancer patients, but have not included active control groups or long-term follow-up,” said Cohen. “This study hoped to address previous study limitations.”

For the randomized study, 227 women with stage I-III breast cancer undergoing chemotherapy at MD Anderson Cancer Center were randomized to one of three groups: a Tibetan yoga program, a simple-stretching program, or a waitlist control group receiving usual care. Participants in the Tibetan yoga program and the stretching program attended four 75-90 minute classes during their chemotherapy treatment.

Participants in the Tibetan yoga program were taught one-on-one by a trained instructor, with each class focusing on controlled breathing, visualization, meditation and postures. Patients were encouraged to practice daily, at home outside of class.

Prior to starting the interventions, participants completed baseline questionnaires and wore an actigraphy watch, which monitors rest and activity cycles, 24 hours a day for seven days to assess sleep quality. Follow-up assessments were conducted one week after the end of intervention and three, six, and 12 months later.

Sleep disturbances and fatigue were assessed using the self-reported Pittsburgh Sleep Quality Index and the Brief Fatigue inventory. Participants also wore actigraphs 24 hours a day for seven days at each study time point to measure sleep.

There were no statistically significant group differences in total sleep disturbances or fatigue levels over time, but participants in the Tibetan yoga group reported fewer daily disturbances one week post-treatment than either of the other groups.

Additionally, long-term sleep benefits emerged over time for those who practiced Tibetan yoga at least two times a week. Compared to those who practiced less often, these patients reported fewer daily disturbances three months post-treatment, as well as better sleep quality and efficiency at six months post-treatment. These patients also reported fewer daily disturbances three months and better sleep efficiency six months relative to the usual care control group.

“While the effects of this intervention were modest, it is encouraging to see that the women who practiced yoga outside of class had improved sleep outcomes over time,” said Cohen.

The study and findings were limited by several factors, including a lack of blinded group assignments and challenges with recruiting patients undergoing chemotherapy, resulting in just a 56 percent participation rate.

Planned future research will focus on shorter in-class instruction and increasing patient engagement in yoga practice outside of the instructional classes.

Immunotherapy treatment option for selected breast cancer patients, genetic study suggests

Immunotherapy drugs could help some breast cancer patients based on the genetic changes in their tumours, researchers at the Wellcome Trust Sanger Institute and their collaborators find. Published today (13 September) in Cancer Research, scientists identify particular genetic changes in a DNA repair mechanism in breast cancer.

The results open up the possibility to another therapy option for around 1,000 breast cancer patients in the UK, who could benefit from existing drugs.

Breast cancer is the most common cancer in the UK, affecting nearly 55,000 women a year. Globally it accounts for nearly 1.7 million cancer cases.

In the study, scientists found that a particular group of breast cancer patients have genetic changes, or mutations, that occur because of an abnormality of a DNA repair mechanism known as mismatch repair*. These mutations are found in other cancers, such as colorectal cancer, but are rarely looked for in breast cancer.

Colorectal cancers with deficient mismatch repair have recently been treated with immunotherapies called checkpoint inhibitors in the US**, including the drug pembrolizumab. Immunotherapies exploit the fact that, under the influence of check point inhibitors, highly mutated tumour cells can be recognised as ‘foreign’ by the patient’s immune system.

The results of this new study suggest that these immunotherapies could also be effective for some breast cancer patients based on the same mutation patterns seen in their tumours. Therefore clinical trials are required to determine if immunotherapies could help selected breast cancer patients.

In the study, the team analysed the whole genome sequences of 640 breast cancer tumours. They looked for patterns in the mutations, known as mutational signatures, which indicated abnormalities in the mismatch repair mechanism. From the mutational signatures, the team identified 11 tumours that had the mismatch repair defects causing the breast cancer.

Dr Serena Nik-Zainal, lead author from the Wellcome Trust Sanger Institute, said: “We’ve unequivocally found mismatch repair deficient breast cancers. As these tumours have the same mutational signatures as those of other cancers, like colorectal cancer, they should in theory respond to the same immunotherapy drugs. Our results suggest expanding the cohort of cancer patients that could possibly be treated with checkpoint inhibitors to include these mismatch repair deficient breast cancer patients.”

Dr Helen Davies, first author from the Wellcome Trust Sanger Institute, said: “Using whole genome sequencing we can start to stratify breast cancer patients into different categories based on their mutational signatures. Current clinical criteria means these tumours would not have been detected as being deficient in the mismatch repair pathway. We have shown that there is in fact another category of breast cancers – those with defective mismatch repair.”

Professor Karen Vousden, Cancer Research UK’s chief scientist, said: “Immunotherapies have shown promise for some cancer patients, but the challenge for doctors has been predicting which patients they are likely to help. This study, using a technique called whole genome sequencing, reveals more about the genetic patterns that could show which women with breast cancer are more likely to respond to immunotherapy treatments. The next step will be to test this approach in clinical trials to find out if identifying these patterns and using them to tailor breast cancer treatments helps to improve survival.”

Spaser can detect, kill circulating tumor cells to prevent cancer metastases, study finds

A nanolaser known as the spaser can serve as a super-bright, water-soluble, biocompatible probe capable of finding metastasized cancer cells in the blood stream and then killing these cells, according to a new research study.

The study found the spaser can be used as an optical probe and when released into the body (possibly through an injection or drinking a solution), it can find and go after circulating tumor cells (CTCs), stick to them and destroy these cells by breaking them apart to prevent cancer metastases. The spaser absorbs laser light, heats up, causes shock waves in the cell and destroys the cell membrane. The findings are published in the journal Nature Communications.

The spaser, which stands for surface plasmon amplification by stimulated emission of radiation, is a nanoparticle, about 20 nanometers in size or hundreds times smaller than human cells. It has folic acid attached to its surface, which allows selective molecular targeting of cancer cells. The folate receptor is commonly overexpressed on the surface of most human cancer cells and is weakly expressed in normal cells.

The discovery was made by researchers at Georgia State University, the University of Arkansas for Medical Sciences, the University of Arkansas at Little Rock and the Siberian Branch of the Russian Academy of Science.

“There is no other method to reliably detect and destroy CTCs,” said Dr. Mark Stockman, director of the Center for Nano-Optics and professor of physics at Georgia State. “This is the first. This biocompatible spaser can go after these cells and destroy them without killing or damaging healthy cells. Any other chemistry would damage and likely kill healthy cells. Our findings could play a pivotal role in providing a better, life-saving treatment option for cancer patients.”

Metastatic cancer occurs when cancer spreads to distant parts of the body, often to the bone, liver, lungs and brain, through a process called metastasis. Many types of cancers refer to this as stage IV cancer. Once cancer spreads, it can be difficult to control, and most metastatic cancer can’t be cured with current treatments, according to the National Institute of Health’s National Cancer Institute. One of the most dangerous ways metastasizing occurs is through the CTCs, which this study aims to detect and destroy using spasers.

The spasers used in this study measure just 22 nanometers, setting the record for the smallest nanolasers. A nanometer is one-billionth of a meter. Most results were obtained with a gold, spherical nanoparticle surrounded by a silica shell and covered with a uranine dye, which is widely used for tracing and biomedical diagnostics.

The researchers studied the spaser’s capabilities in vitro in human breast cancer cells with high folate receptor expression and endothelial cells with low folate receptor expression, as well as in mouse cells in vivo.

They found cells with spasers demonstrated high image contrasts with one or many individual “hot spots” at different laser energies above the spasing threshold. The presence of spasers was confirmed with several optical and electron microscopy techniques, which revealed an initial accumulation of individual spasers on the cell membrane followed by their entrance into the cell cytoplasm.

The study also found low toxicity of the spasers for human cells. At the same time, the spasers subjected to laser irradiation selectively killed the tumor cells without damaging the healthy ones.

Based on the study’s results, spaser-based therapeutic applications with high-contrast imaging is a promising field. The data suggest spasers have high potential as therapeutic and diagnostic agents that integrate optical diagnosis and photothermal-based cell killing, using just a few laser pulses to kill cancer cells.

A new HER2 mutation, a clinical trial and a promising diagnostic tool for metastatic breast cancer

There is a group of metastatic breast cancers that has the HER2 gene amplified – the cells have many copies of it – which leads to enhanced activity of the product enzyme, a tyrosine kinase. HER2 has been established as a therapeutic target in breast cancer, and breast cancers in which the HER2 gene is not amplified do not, in general, respond to HER2-directed therapeutic approaches.

A few years ago, when the research teams of Dr. Matthew Ellis and others carried out a molecular characterization of breast cancer tumors, they found a new mutation in HER2 that was different from gene amplification but also resulted in tyrosine kinase being constantly activated.

“In this particular activation mechanism, the cells develop a subtle mutation within the functional part of the HER2 gene that activates the enzyme,” said Ellis, professor and director of the Lester and Sue Smith Breast Center, part of the National Cancer Institute-designated Dan L Duncan Comprehensive Cancer Center at Baylor College of Medicine. “The mutation locks the enzyme into an ‘on’ position.”

Ellis and his colleagues developed a preclinical model to study this new HER2 mutation and discovered that the enhanced enzymatic activity could trigger tumor formation. Furthermore, these tumor cells were sensitive to an experimental drug, neratinib. With this information in hand, the researchers took the next step.

“We launched a phase II clinical trial of neratinib in patients with metastatic breast cancer carrying a HER2 mutation,” Ellis said. “Finding patients that are positive for a HER2 mutation required a national collaboration because we had to screen hundreds of patients to identify the 2 to 3 percent that have a tumor driven by a HER2 mutation. The results of the clinical trial were encouraging in that about 30 percent of the 16 patients treated with neratinib had a meaningful clinical response showing significant disease stabilization or regression. Neratinib was well tolerated by most patients.”

“This is the first time we had a reasonable number of patients treated for HER2 mutations in whom we could estimate the response rate.”

The number of patients who could potentially benefit from this new treatment approach is estimated to be in the thousands. The researchers estimate that as many as 200,000 patients are likely to be living with metastatic breast cancer today in the United States. Based on the estimate that the new mutation is present in 2 to 3 percent of cases, the researchers calculated that approximately 4,000 to 6,000 patients with metastatic breast cancer carry a HER2 mutation and are therefore potential candidates for neratinib treatment.

Circulating tumor DNA analysis, a promising diagnostic tool

To identify the patients in this study who carried the new HER2 mutation, the researchers required tissue from the tumor, a biopsy, from which they could extract and sequence the genetic material to determine the presence of the HER2 mutation. This task turned out to be a major challenge because for 20 to 30 percent of the patients the researchers did not have sufficient material to make the diagnosis.

“To assist in our ability to identify patients with HER2 mutation-positive tumors, we conducted circulating tumor DNA analysis,” Ellis said. “The tumor’s DNA is released into the human bloodstream, and we were able to determine the presence of the mutation in blood samples from the patients. Importantly the circulating tumor DNA results were highly concordant with the tumor sequencing results, and they were much easier to determine. Notably, the blood test was sensitive enough that we could use it as a tool to determine eligibility for the clinical trial.”

In addition to bringing to the table a novel treatment for metastatic breast cancer carrying a HER2 mutation, the researchers have tested the value of the circulating tumor DNA as a disease-monitoring marker.

“A circulating tumor DNA-based blood test also could therefore be potentially used to monitor tumor progression and to determine whether patients are responding or not to treatment after just one month of therapy,” Ellis said.

Ellis also is a McNair Scholar at Baylor.

Read all the details of this study, the full list of contributors and their financial support in Clinical Cancer Research.

A new HER2 mutation, a clinical trial and a promising diagnostic tool for metastatic breast cancer

There is a group of metastatic breast cancers that has the HER2 gene amplified – the cells have many copies of it – which leads to enhanced activity of the product enzyme, a tyrosine kinase. HER2 has been established as a therapeutic target in breast cancer, and breast cancers in which the HER2 gene is not amplified do not, in general, respond to HER2-directed therapeutic approaches.

A few years ago, when the research teams of Dr. Matthew Ellis and others carried out a molecular characterization of breast cancer tumors, they found a new mutation in HER2 that was different from gene amplification but also resulted in tyrosine kinase being constantly activated.

“In this particular activation mechanism, the cells develop a subtle mutation within the functional part of the HER2 gene that activates the enzyme,” said Ellis, professor and director of the Lester and Sue Smith Breast Center, part of the National Cancer Institute-designated Dan L Duncan Comprehensive Cancer Center at Baylor College of Medicine. “The mutation locks the enzyme into an ‘on’ position.”

Ellis and his colleagues developed a preclinical model to study this new HER2 mutation and discovered that the enhanced enzymatic activity could trigger tumor formation. Furthermore, these tumor cells were sensitive to an experimental drug, neratinib. With this information in hand, the researchers took the next step.

“We launched a phase II clinical trial of neratinib in patients with metastatic breast cancer carrying a HER2 mutation,” Ellis said. “Finding patients that are positive for a HER2 mutation required a national collaboration because we had to screen hundreds of patients to identify the 2 to 3 percent that have a tumor driven by a HER2 mutation. The results of the clinical trial were encouraging in that about 30 percent of the 16 patients treated with neratinib had a meaningful clinical response showing significant disease stabilization or regression. Neratinib was well tolerated by most patients.”

“This is the first time we had a reasonable number of patients treated for HER2 mutations in whom we could estimate the response rate.”

The number of patients who could potentially benefit from this new treatment approach is estimated to be in the thousands. The researchers estimate that as many as 200,000 patients are likely to be living with metastatic breast cancer today in the United States. Based on the estimate that the new mutation is present in 2 to 3 percent of cases, the researchers calculated that approximately 4,000 to 6,000 patients with metastatic breast cancer carry a HER2 mutation and are therefore potential candidates for neratinib treatment.

Circulating tumor DNA analysis, a promising diagnostic tool

To identify the patients in this study who carried the new HER2 mutation, the researchers required tissue from the tumor, a biopsy, from which they could extract and sequence the genetic material to determine the presence of the HER2 mutation. This task turned out to be a major challenge because for 20 to 30 percent of the patients the researchers did not have sufficient material to make the diagnosis.

“To assist in our ability to identify patients with HER2 mutation-positive tumors, we conducted circulating tumor DNA analysis,” Ellis said. “The tumor’s DNA is released into the human bloodstream, and we were able to determine the presence of the mutation in blood samples from the patients. Importantly the circulating tumor DNA results were highly concordant with the tumor sequencing results, and they were much easier to determine. Notably, the blood test was sensitive enough that we could use it as a tool to determine eligibility for the clinical trial.”

In addition to bringing to the table a novel treatment for metastatic breast cancer carrying a HER2 mutation, the researchers have tested the value of the circulating tumor DNA as a disease-monitoring marker.

“A circulating tumor DNA-based blood test also could therefore be potentially used to monitor tumor progression and to determine whether patients are responding or not to treatment after just one month of therapy,” Ellis said.

Ellis also is a McNair Scholar at Baylor.

Radiation Therapy Prior to Surgery Reduces the Risk of Secondary Tumors in Early-Stage Breast Cancer Patients

Breast cancer patients receiving neoadjuvant radiation therapy have improved cancer-free survival over adjuvant radiation

Moffitt Cancer Center researchers launched a first of its kind study comparing the long-term benefits of radiation therapy in women with breast cancer either before surgery (neoadjuvant) or after surgery (adjuvant). Their study, published in the June 30 issue of Breast Cancer Research, found that patients who have neoadjuvant radiation therapy have a significantly lower risk of developing a second primary tumor at any site.

The majority of patients who have early stage breast cancer have surgery to remove their tumor or a complete mastectomy. Surgery is commonly followed by radiation therapy, which has been shown to increase relapse-free survival. However, in some cases, patients may require neoadjuvant radiation therapy to decrease the size of the tumor before surgery.  Currently, there are no studies that have analyzed the long-term effects of neoadjuvant radiation therapy on breast cancer patients.

Moffitt researchers compared the overall survival and the time to diagnosis of a second tumor, if any, of 250,195 breast cancer patients who received either neoadjuvant or adjuvant radiation therapy. They analyzed patient outcomes from a National Cancer Institute (NCI) registry database of cancer incidence and survival rates in the United States.  They included female patients in the analysis who were diagnosed between 1973 and 2011 with early-stage breast cancer. The analysis included 2,554 women who received localized neoadjuvant breast radiation therapy before surgery and 247,641 women who received localized adjuvant breast radiation therapy after surgery.

The researchers discovered that among the breast cancer patients who tested positive for the estrogen receptor (ER) biomarker, patients who had neoadjuvant radiation therapy had a significantly lower risk of developing a second primary tumor than patients who had adjuvant radiation therapy. This was true for patients who underwent both partial and complete mastectomies.  The researchers found that delaying surgery due to neoadjuvant radiation therapy was not a detriment to survival.

A number of recent studies have suggested that radiation therapy may re-educate and stimulate the immune system to target cancer cells. “The observed benefit of neoadjuvant radiation therapy aligns with the growing body of literature of the immune activation effects of radiation, including shrinking of untreated metastases outside the radiation field,” explained Heiko Enderling, Ph.D., associate member of Moffitt’s Integrated Mathematical Oncology Department.

Study shows biomarkers can predict which ER-positive breast cancer patients respond best to first-line therapy

Two challenges in treating patients with estrogen-positive breast cancer (ER+) have been an inability to predict who will respond to standard therapies and adverse events leading to therapy discontinuation. A study at The University of Texas MD Anderson Cancer Center revealed new information about how the biomarkers retinoblastoma protein (Rb) and cytoplasmic cyclin E could indicate which patients will respond best to current first-line therapies.

The study also discovered that combining the current therapy with autophagy inhibitors will result in using one-fifth of the dosage of the standard treatment, which could significantly reduce side effects associated with this therapy. Findings were published in the June 27 issue of Nature Communications.

Standard treatment, consisting of palbociclib, often has adverse side effects and not all ER+ patients respond to the therapy. Palbociclib inhibits proteins called CDK4 and CDK6 (CDK4/6) and tumor cells escape this inhibition by activating autophagy, a process allowing cancer cells to thrive even when starved of nutrients. By combining palbocicilb with autophagy inhibitors in cells that express normal Rb and nuclear cyclin E, the dose of palbociclib was significantly reduced.

Khandan Keyomarsi, Ph.D., professor of Experimental Radiation Oncology, led a team that demonstrated how CDK4/6 and autophagy inhibitors synergistically induce cell senescence in Rb-positive cytoplasmic cyclin E-negative cancers. CDK4/6 inhibitors are approved by the Food and Drug Administration (FDA).

“Our findings could impact the majority of ER+ and HER2-negative breast cancers accounting for about 60 percent of advanced breast cancers,” said Keyomarsi. “We demonstrated for the first time evidence that Rb and cytoplasmic cyclin E status have a very strong effect on predicting response to the current standard first-line therapy for this population of patients, hormonal therapy plus palbociclib.We also discovered that by inhibiting the pathway such as autophagy that causes tumor cells to escape palbociclib growth inhibition, CDK4/6 inhibitor was more effective.”

Deregulation of cell cycle checkpoint proteins, such as CDK4/6, is a key hallmark of cancer, resulting in uncontrolled cellular growth and tumor formation. Some CDK4/6 inhibitors, including palbociclib, ribociclib and abemaciclib, have shown potential in pre-clinical and clinical studies in numerous solid tumors. Palbociclib has demonstrated benefits in Phase II and III trials in advanced ER+ breast cancers, doubling progression-free survival compared to drugs such as letrozole or fulvestrant, and is currently being evaluated clinically in other solid tumors.

“Data provided through The Cancer Genome Atlas revealed alterations in the CDK4/6/cyclin D pathway in about 35 percent of the patients, making them an ideal population for targeting CDK4/6,” said Keyomarsi. “Our study revealed that inhibition of CDK4/6 and autophagy pathways cooperate to induce sustained growth inhibition and senescence in vitro and in vivo, in breast and other solid tumors and showed how autophagy inhibition can significantly decrease the dose of palbociclib required to treat breast cancer patients. We believe this new strategy can improve the efficacy of other CDK4/6 inhibitor treatments like ribociclib and abemaciclib.”

The team’s findings indicated how Rb and cyclin E status predicts response to a combination of CDK4/6 and autophagy inhibition in pre-clinical models and that autophagy blockade is successful in reversing resistance to palbociclib.

“Palbociclib resistance is a significant limitation of this treatment which is not curative and does not prolong survival even though transient responses and prolongation of response have formed the basis of FDA approval,” said Keyomarsi. “Our study provides evidence that models of hormone receptor-negative cancer and even non-breast cancer malignancies can respond to the combination of palbociclib and autophagy inhibition, when selected based on Rb and cyclin E isoform status, representing a completely new therapeutic opportunity for these cancers.”

Keyomarsi and colleagues anticipate future clinical studies based on this pre-clinical and clinical evidence with the aim of developing translational and clinical applications.

Custom built molecule shows promise as anti-cancer therapy

Scientists at the University of Bath funded by Cancer Research UK have custom-built a molecule which stops breast cancer cells from multiplying in laboratory trials, and hope it will eventually lead to a treatment for the disease.

But perhaps even more importantly the method they used to create the molecule has potential to be applied to develop new treatments for a wide range of cancers and other diseases.

The team, from the Department of Biology & Biochemistry, working with colleagues at the University of Queensland in Australia and the University of Bristol, modified a protein which can interfere with cell multiplication in many cancers, including breast cancer, by binding with another protein and rendering it inactive.

They took a small piece of the protein, called a peptide, that is known to be important in binding, and modified it to retain the structure otherwise lost when cut out. The modification has the additional advantage of protecting the peptide from being broken down within cells. The resulting molecule still binds to its target protein and inhibits cancer cell multiplication, but crucially can travel across cell membranes to get at it. The full-sized proteins, which the peptides are taken from, are usually too large to protect from breakdown or to cross protective cell membranes so this removes a literal barrier to developing treatments.

The study is published in the journal ACS Chemical Biology

Dr Jody Mason, one of the lead researchers on the project, said: “Peptides have the potential to be incredibly potent drugs which are exquisitely specific for their target. However they are easily broken down in the body, much like when we eat a steak. We have modified the peptides so that they retain the structure they have within the full-size protein and can therefore bind to the target “

Professor David Fairlie, from the University of Queensland added “This is a particularly challenging cancer target involving intertwined proteins and large surfaces that must be blocked. International collaborations like this one have the potential to combine resources and scientific skills from multiple disciplines to conquer difficult problems in targeting human disease.”

Dr Justine Alford, Cancer Research UK’s senior science information officer, said: “This early study may have laid the groundwork for a potential new treatment for certain cancers by creating a sophisticated designer molecule that can effectively block a cancer-fuelling target in cells.

“Cancer survival is improving, but people still die from their disease, so we need to develop innovative ways such as this that could help more people survive in the future.” The team now intend to continue to work on the molecule to improve its stability, with a long-term view to it eventually becoming a cancer drug, although this is still years away.

They are also interested in finding other candidate peptides for similar trials.

The researchers believe that other small peptides are a promising avenue of research to create new treatments for different types of cancer, and potentially other diseases such as Alzheimer’s disease

A patent study on the great new hope emerging from marine derived anticancer drugs

Microtubule dynamics govern crucial cellular functions and this is why microtubules are one of the most attractive anticancer drug targets. Microtubule targeting agents (MTAs) have the ability to treat a wide range of cancers. However, drug induced cytotoxicity and adverse side effects have hindered their development. Another major setback is multiple drug resistance in tumor cells. These limitations have prompted the need to develop novel MTAs from alternative sources, with better therapeutic efficacies. Recently, MTAs from marine sources have grabbed much attention due to their unique tubulin binding features and remarkable ability to reduce tumor progression.

The authors have summarized some of the most promising marine derived MTAs by systematically searching patent databases such as USPTO, Espacenet and WIPO for recent patents published from 2006 up to 2016. After a critical data analysis, only those patents focusing on the chemical synthesis and/or modifications of marine derived MTAs along with a significant demonstration of their in vitro and/or in vivo activity have been reviewed.

The survey of recent patents revealed that chemically modified versions of marine derived MTAs, overcoming drug resistance and their novel combination therapies increasing the overall efficacy, have positioned them as future anticancer blockbusters. Of particular interest are dolastatin, laulimalide, peloruside, hemiasterlin, halichondrin, eribulin mesylate, discodermolide, dictyostatin, cryptophycin and their analogs which have significant antiproliferative potency against a wide array of cancers and are also able to overcome multidrug resistance. A deeper understanding of the molecular mechanisms behind the specific drug interactions and of microtubule molecular biology in general, combined with innovative therapeutic regimen would lead to major advances in the field of cancer therapy.

Talking Breast Cancer for Men’s Health Awareness Week

Males account for less than 1 percent of all breast cancer cases in the United States. In 2017, an estimated 2,470 American men will be diagnosed with the disease; 460 will die.

While rare among men, breast cancer symptoms, diagnosis and survival are similar for both genders. Men experience many of the same primary symptoms or signs of breast cancer: a lump or swelling in the chest area or new irregularities on the skin or nipples, such as redness, scaliness or puckering. Because male breasts generally have less tissue than female, it’s easier to detect lumps. However, some men with breast cancer never display obvious signs of the disease or fail to notice them.

“Both men and women benefit from being aware of their bodies and seeking care with their primary care providers for changes,” said Richard Schwab, MD, oncologist with Moores Cancer Center at UC San Diego Health.

The earlier breast cancer is detected, the better the chances of recovery and survival. In the earliest stages, the five-year survival rate (the percentage of people who live at least five years after diagnosis, excluding other causes of death) is 99 percent. If the cancer has spread to local lymph nodes, the 5-year survival rate drops to 85 percent. If the cancer metastasizes to more distant parts of the body, the rate falls to 27 percent.

As with women, men have a higher risk of developing cancer if they have a family history of breast disease or a mutation in a breast cancer risk gene, such as BRCA1 or BRCA2. In addition, age, high levels of radiation, elevated levels of estrogen (which can be caused by genetic conditions), other diseases, some kinds of medical treatment and lifestyle can increase a man’s risk of breast cancer.

Study discovers proteins which suppress the growth of breast cancer tumors

Researchers at the University of Birmingham have found that a type of protein could hold the secret to suppressing the growth of breast cancer tumours.

The research, published today in Oncogenesis, examined the role Proline-Rich Homeodomain protein (PRH) can play in the progression of breast cancer tumours and could, in turn, help to better determine the prognosis for patients with the disease.

Dr Padma Sheela Jayaraman, of the University of Birmingham’s Institute of Cancer and Genomic Sciences, said: “PRH is a protein that controls and regulates when genes are switched on or off.

“However, prior to our research, the role of this protein in breast cancer has been poorly understood.

“Public databases show that, in a large number of breast cancer patients with a poor prognosis, the activity of the PRH gene had decreased.

“However, it was not known whether the amount of PRH protein was also lower in these patients as protein levels had not been recorded.”

The researchers used a special staining process on breast cancer tissue removed during biopsy to observe the levels and location of PRH proteins in breast cancer cells. They found that in a small study there were changes in PRH proteins in tumour cells compared to normal cells that were consistent with the decreased activity of the PRH gene in the public database.

Dr Jayaraman added: “In the laboratory, we found that when PRH protein levels are reduced in a breast tumour the cells are more able to divide, speeding up the progression of the tumour.

“Moreover, we identified some of the genes which are regulated by PRH and specifically contribute to the increased cell division.”

The researchers also carried out tests in a tumour model of mammary cancers, increasing PRH levels to observe the effect.

“We made the significant finding that high levels of PRH actually blocked the formation of the tumours, therefore our data suggests that PRH can block tumour formation in some breast cancers,” added Dr Jayaraman.

“We propose that monitoring PRH protein levels or activity in patients with breast cancer could be particularly important for assessing their prognosis.

“In addition, since PRH is known to be important in multiple cell types, this work has important implications for other types of cancer.

“We are now working to investigate the importance of PRH in prostate cancer and in cancer of the bile duct, a type of liver cancer.”

Three-Week Radiation Therapy Treatment Given Post Mastectomy Is Safe and Effective

Rutgers Cancer Institute of New Jersey research shows low toxicity in shorter treatment course

A shorter course of radiation therapy given to breast cancer patients following mastectomy is safe and effective and cuts treatment time in half. That is according to data from a phase II clinical trial conducted by Rutgers Cancer Institute of New Jersey investigators and other colleagues who examined a hypofractionated regimen given over three weeks versus the traditional six week course of treatment. The work appears in the current online edition of the Journal of Clinical Oncology (http://ascopubs.org/doi/full/10.1200/JCO.2016.70.7158).

When there is a concern that cancer cells may remain in the chest wall and lymph node regions following a mastectomy, a patient may be given targeted radiation over a five to six week period to further treat the breast cancer. “Receiving radiation for that long of a period becomes a quality of life issue for many patients. This includes the inconvenience of frequent travel to the treatment facility, as well as fatigue and other common side effects that can cause lost time at work and other challenges,” notes the work’s senior investigator Bruce G. Haffty, MD, professor and chair, Department of Radiation Oncology at Rutgers Cancer Institute, Rutgers Robert Wood Johnson Medical School and Rutgers New Jersey Medical School.

Researchers explored an accelerated course of radiation that cut treatment time in half. Currently, there is limited data supporting this type of treatment in this patient population.

From 2010 to 2014, 67 eligible patients with stage II to IIIa breast cancer were enrolled at Rutgers Cancer Institute of New Jersey and Huntsman Cancer Institute at the University of Utah. A dose of 36.63 Gy (a unit of radiation measurement) was given in 11 fractions of 3.33 Gy each.  The fractions were delivered over a three-week period to the chest wall and area lymph nodes.  The treatment also allowed for an optional four fractions (3.33 Gy each) of radiation to the chest wall at the mastectomy scar area, resulting in a total of 15 treatments over three weeks.

The aim was to not have any reported treatment toxicities of grade three or above. After a median follow up of 32 months, no grade three toxicities or higher were reported. There were 29 grade two toxicities reported, with a majority being skin rash followed by fatigue, similar to what may be experienced with the longer five to six week course of treatment. The estimated three-year survival rate of the cancer not coming back to the breast area was 89.2 percent.  The estimated three-year survival rate for the cancer not coming back and spreading beyond the breast was 90.3 percent.

“While shorter courses of radiation therapy have been adopted in patients receiving radiation therapy to the breast alone after lumpectomy, there has not been adoption of shorter courses of treatment to the chest wall and lymph nodes after mastectomy. This trial demonstrated the safety of this shorter course approach in a prospective phase II study,” notes Dr. Haffty.

Based on this study, a larger post-mastectomy randomized trial has been developed through the Alliance Cooperative Group with Haffty and current study investigators Matt Poppe of the Huntsman Cancer Institute and Atif J. Khan of Memorial Sloan Kettering Cancer Center leading the effort.  In this phase III trial, a shorter course of radiation in the post-mastectomy, post-reconstruction setting will be compared to the more conventional five to six week course of treatment.

For Women at Risk of Hereditary Breast Cancer, Multigene Test Could Help Extend Life Expectancy

Value in Health, the official journal of the International Society for Pharmacoeconomics and Outcomes Research (ISPOR), announced today the publication of new research indicating that testing for variants in 7 cancer-associated genes (versus the usual process of testing in just 2 genes) followed by risk-reduction management could cost-effectively improve life expectancy for women at risk of hereditary breast cancer. The report of these findings, A Multigene Test Could Cost-Effectively Help Extend Life Expectancy for Women at Risk of Hereditary Breast Cancer, was published in the April 2017 issue.

Using hypothetical cohorts of women at risk of hereditary breast cancer, the authors used a decision-analytic model to compare the relative cost and effectiveness of two test strategies for detecting pathogenic genetic variants: 1) the usual BRCA1/2 test strategy, and 2) a next-generation 7-gene strategy that tests for variants not only in BRCA1 and BRCA2, but also in TP53, PTEN, CDH1, STK11, and PALB2. The authors then used these test results to select appropriate breast cancer risk reduction treatments / therapies.

In the base-case scenario for 50- and 40-year-old women undergoing genetic testing, the incremental cost-effectiveness ratio (ICER) for the 7-gene test strategy compared with the BRCA1/2 test strategy was $42,067 and $23,734 per life-year gained, or $69,920 and $48,328 per quality-adjusted life-year gained, respectively. At these ICER levels, the 7-gene test strategy would be considered cost effective according to the World Health Organization guidelines.

“Pathogenic variants in the BRCA1 and BRCA2 genes explain only about 15% of the breast cancer familial relative risk,” said lead author Yonghong Li, PhD, Quest Diagnostics, USA, “while pathogenic variants in other genes, including TP53, PTEN, CDH1, and PALB2 contribute further to the familial relative risk. The results of this study,” Dr. Li added, “demonstrate the potential value of newer testing options that allow for the simultaneous analysis of expanded panels of additional genes whose pathogenic variants confer moderate to high risk for breast cancer.”

Rogue Breast Tumor Proteins Point to Potential Drug Therapies

For patients with difficult-to-treat cancers, doctors increasingly rely on genomic testing of tumors to identify errors in the DNA that indicate a tumor can be targeted by existing therapies. But this approach overlooks another potential marker — rogue proteins — that may be driving cancer cells and also could be targeted with existing treatments.

If DNA can be described as the body’s genetic blueprint, proteins can be thought of as the construction workers who carry out the plan. Studying the blueprint can be vital to understanding genetic diseases, including cancer, but that focus also means that some problems arising with the workers may be missed.

Studying mice with breast tumors transplanted from patients, researchers at Washington University School of Medicine in St. Louis, The Broad Institute of MIT and Harvard, and Baylor College of Medicine have analyzed the proteins present in these tumors. The researchers demonstrated that some protein alterations can be used to identify drugs that may work against some cancers. The work is part of the National Cancer Institute’s (NCI) Clinical Proteomic Tumor Analysis Consortium efforts.

The study is published March 28 in Nature Communications.

“Proteins carry out most of the biological functions in the cell,” said senior author Li Ding, PhD, an associate professor of medicine at Washington University. “Knowing the DNA sequence does not automatically tell us everything about the proteins doing work in the cells. This is another layer of tumor complexity that we need to explore to identify new therapies.”

Ding said recent advances in a technology called mass spectrometry and in techniques to analyze massive quantities of data have made complex studies of the proteins in tumor cells possible. Another reason to prioritize the systematic study of proteins in tumors — cancer proteomics — is that the vast majority of cancer therapies developed from genetic studies actually target proteins.

“Identifying the rogue proteins of cancer is an important pathway toward developing new drugs,” said co-author R. Reid Townsend, MD, PhD, a professor of medicine and director of the Proteomics Shared Resource at Washington University.

“We can use proteomics to confirm and validate our genomics findings,” said Ding, also an assistant director of The McDonnell Genome Institute at Washington University School of Medicine. “In addition, it’s another tool to uncover additional events that drive cancer and are specific to individual patient tumors, including the amount of the ‘rogue’ protein, its specific form, or the type and extent of chemical modifications of the proteins that we know are treatable with approved or investigational drugs. We also can test these therapies in the mice before we evaluate them in patients.”

Steven A. Carr, PhD, of the Broad Institute, said the team analyzed a chemical modification called phosphorylation, which plays a central role in how healthy, as well as diseased, cells communicate.

“Disruption or enhancement in such signaling is often directly related to disease mechanism and can be targeted for therapy,” Carr said.

The researchers studied 24 tumor samples from breast cancer patients after the samples were transplanted into mice. Twenty-two of the transplanted samples retained their genetic and proteomic identities as specific types of breast cancer. A proteomic analysis of the tumors also identified multiple protein targets that have the potential to respond to drugs.

For example, the researchers showed dialed-up activity of multiple protein pathways that could be targeted with investigational drugs called PI3K inhibitors and mTOR inhibitors, separately and in combination, depending on the tumor. They also showed that drugs against a type of breast tumor called HER2 positive breast cancer — such as the dual ERBB2/EGFR inhibitor lapatinib — potentially could benefit more patients than currently receive them, if analysis of the tumor proteins is taken into consideration.

While most of these tumor models recapitulated specific types of breast cancer, Ding said the scientists were surprised to see that two of the 24 tumors evolved into a completely different type of cancer after transplantation into the mice. Instead of breast cancer, they resembled lymphoma and were driven by the cancer-causing virus Epstein-Barr, according to the researchers. Lymphomas are cancers of immune cells that may have arisen from lymphatic tissue present in the breast tumors transplanted into the mice.

The analysis of the lymphoma-like cancers was the first proteomic study of this type of tumor. Though unintentional, Ding said the analysis provides an explanation for why investigational drugs that inhibit a protein called BTK have been effective in treating patients with lymphoma.

“Since it is the proteins that interact directly with drugs, the strength of studying proteomics in patient-derived tumor models is the ability to test drug treatment in the mice,” Ding said. “With advances in cancer proteomics that increase the speed of measurement, we are moving toward a future that includes genomic and proteomic analyses of patient tumors.”

Co-author Matthew J. Ellis, MD, PhD, of Baylor, agreed. “The mouse work is promising enough to adapt these technologies for real time analysis of patient materials so that clinical trials can be designed to test this new diagnostic and drug selection approach,” he said.

Other key contributors to this project are Kuan-lin Huang, a PhD student in genomics and bioinformatics at Washington University; Shunqiang Li, PhD, an assistant professor of medicine at Washington University; Philipp Mertins, PhD, of The Broad Institute; and Sherri Davies, a senior scientist at Washington University.

Scientists Find Possible Achilles Heel of Treatment Resistant Cancers

Scientists identify two signaling proteins in cancer cells that make them resistant to chemotherapy, and show that blocking the proteins along with chemotherapy eliminate human leukemia in mouse models.

Reporting results March 20 in Nature Medicine, researchers at Cincinnati Children’s Hospital Medical Center suggest that blocking the signaling proteins c-Fos and Dusp1 as part of combination therapy might cure several types of kinase-driven, treatment-resistant leukemia and solid tumor cancers.

These include acute myeloid leukemia (AML) fueled by the gene FLT3, lung cancers fueled by genes EGFR and PDGFR, HER2-driven breast cancers, and BCR-ABL-fueled chronic myeloid leukemia (CML), according to Mohammad Azam, PhD, lead investigator and a member of the Division of Experimental Hematology and Cancer Biology.

“We think that within the next five years our data will change the way people think about cancer development and targeted therapy,” Azam says. “This study identifies a potential Achilles heel of kinase-driven cancers and what we propose is intended to be curative, not just treatment.”

The weak spot is a common point of passage in cells (a signaling node) that appears to be required to generate cancer cells in both leukemia and solid tumors. The node is formed by the signaling proteins c-Fos and Dusp1, according to study authors. The researchers identified c-Fos and Dusp1 by conducting global gene expression analysis of mouse leukemia cells and human chronic myeloid leukemia (CML) cells donated by patients.

CML is a blood cancer driven by an enzyme called tyrosine kinase, which is formed by the fusion gene BCR-ABL. This fusion gene is the product of translocated chromosomes involving genes BCR (chromosome 22) and ABL (chromosome 9). Analysis of human CML cells revealed extremely high levels of c-FOS and DUSP1 in BCR-ABL-positive chemotherapy resistant cells.

Cancer sleeper cells

Cancer cells often become addicted to the mutated gene that causes them, such as BCR-ABL in kinase-driven chronic myeloid leukemia. Most chemotherapies work by blocking molecular pathways affected by the gene to shut down the disease process. In the case of CML, a chemotherapy called imatinib is used to block tyrosine kinase, which initially stops the disease. Unfortunately the therapeutic benefit is temporary and the leukemia comes back.

Azam and colleagues show in their CML models that signaling from tyrosine kinase – and growth factor proteins that support cell expansion (like interleukins IL3, IL6, etc.) – converge to dramatically elevate c-Fos and Dusp1 levels in the cancer cells.

Working together these molecules maintain the survival of cancer stem cells and minimal residual disease. The dormant cells wait around under the radar screen to rekindle the disease by acquiring additional genetic mutations after initially effective chemotherapy.

Azam says Dusp1 and c-Fos support the survival of cancer stem cells by increasing the toxic threshold needed to kill them. This means conventional imatinib chemotherapy will not eliminate the residual disease stem cells. Doctors can’t just increase the dose of chemotherapy because it doesn’t target the Dusp1 and c-Fos proteins that regulate toxic threshold.

Targeting c-Fos and Dusp1

After identifying c-Fos and Dusp1, the authors tested different treatment combinations on mouse models of CML, human CML cells, and mice transplanted with human leukemia cells. They also tested treatments on B-cell acute lymphoblastic leukemia (B-ALL).

The treatment combinations included: 1) solo therapy with just the tyrosine kinase inhibitor, imatinib; 2) solo treatment with just inhibitors of c-Fos and Dusp1; 3) treatment with all three combined – imatinib along with molecular inhibitors of c-Fos and Dusp1.

As suspected, treatment with imatinib alone initially stopped CML progression but the leukemia relapsed with the continued presence of residual disease cells. Treatment with c-Fos and Dusp1 inhibitors alone significantly slowed CML progression and prolonged survival in a majority of mice but wasn’t curative. Treatment for one month with c-Fos/Dusp1 inhibitors and imatinib cured 90 percent of mice with CML, with no signs of residual disease cells.

Azam and his colleagues also point to an interesting finding involving solo treatment with just the deletion of c-Fos and Dusp1. This eliminated expression of the signaling proteins and was sufficient to block B-ALL development, eradicating the disease in mouse models.

Next steps

The authors stress that because the study was conducted in laboratory mouse models, additional research is needed before the therapeutic strategy can be tested in clinical trials.
They are following up the current study by testing c-Fos and Dusp1as treatment targets for different kinase-fueled cancers, including certain types of lung cancer, breast cancers and acute forms of leukemia.

A Vulnerability in Triple-Negative Breast Cancer Could Improve Treatment Outcomes

Ludwig researchers have shown that triple-negative breast cancer cells ramp up production of a key component of DNA in response to chemotherapy and that targeting this pathway could undermine their resistance to such therapies.

A team of researchers led by Alex Toker of the Ludwig Center at Harvard has discovered a metabolic weakness in triple-negative breast cancer (TNBC) cells that may be exploited to quell their resistance to chemotherapy.

TNBC is notoriously aggressive and is difficult to treat because its cells lack the targetable receptors found in other forms of breast cancer. Only about 30 percent of TNBC patients achieve a pathologic complete response, or a complete eradication of active cancer cells, following chemotherapy. Those who do frequently relapse shortly afterward.

“Trying to understand the mechanisms that contribute to cancer’s resistance to therapy is a major mission here at the Ludwig Center at Harvard,” said Alex Toker.

In the new study, published online in the journal Cancer Discovery, Toker, an investigator at the Ludwig Center at Harvard Medical School, and his team including lead author Kristin Brown, formerly of the Ludwig Center at Harvard and now at Peter MacCallum Cancer Center in Melbourne, Australia, outline a newly discovered chink in the armor of TNBC cells. This “metabolic vulnerability” can be used to circumvent chemotherapy resistance.

The scientists demonstrated that chemotherapy effectively reprograms TNBC cells to ramp up production of the pyrimidine nucloetides, key building blocks of DNA. This heightens the cells’ DNA repair abilities and ultimately results in greater resistance to chemotherapies that work by damaging the DNA of rapidly dividing cells.

“This actually makes sense if you think about it, because if a tumor cell is going to repair DNA and therefore evade the death-inducing effects of chemotherapy, the only way they can really do that is by rebuilding DNA, and the only way to rebuild DNA is to make more nucleotides,” Toker said.

Toker and his team reasoned that blocking the pyrimidine synthesis pathway in TNBC cells would hinder their DNA repair abilities and make them more susceptible to the DNA-damaging effects of chemotherapy. To test this hypothesis, the team exposed TNBC cells in the lab to a drug combination of doxorubicin, a commonly used chemotherapy agent, and leflunomide, a known inhibitor of dihydroorotate dehydrogenase (DHODH), a crucial enzyme in the biochemical reactions that generate pyrimidines.

“One of the major reasons we chose leflunomide is because we wanted a rapid path to clinical impact, and leflunomide is already FDA-approved and widely used to treat autoimmune diseases such as rheumatoid arthritis,” Toker said.

Toker’s group found that leflunomide blocked the increase of pyrimidine nucleotides in TNBC cells, thus impairing their ability to repair the DNA damage dealt by doxorubicin, and resulting in increased cancer cell death.

The scientists then repeated the experiment in mice that had been transplanted with human TNBC cells. “We found that treating the mice with doxorubicin or leflunomide alone only slowed tumor growth, but that a combination therapy involving both drugs resulted in significant tumor regression,” Toker said.

Importantly, the combination therapy in mice did not cause any weight loss or gain in the animals – an indication that the drug regimen might be reasonably well-tolerated in humans.

“One of the things we would like to do is develop clinical trials in patients with this combination strategy, whether it be with leflunomide or some other drugs that are coming online that might have better pharmacological properties in patients,” Toker said.

In the meantime, Toker said his group is moving forward with plans to investigate the molecular basis of increased pyrimidine biosynthesis in TNBC cells.

“There is something about this pathway in triple negative breast cancer that is especially important,” Toker said. “We don’t know what the genetic basis underlying it is, but it’s something we would really like to find out.”