A £10 million interdisciplinary collaboration is to target the most challenging of cancers using nanomedicine.
“We are going to pierce through the body’s natural barriers and deliver anti-cancer drugs to the heart of the tumour.” – George Malliaras
While the survival rate for most cancers has doubled over the past 40 years, some cancers such as those of the pancreas, brain, lung and oesophagus still have low survival rates.
Such cancers are now the target of an Interdisciplinary Research Collaboration (IRC) led by the University of Cambridge and involving researchers from Imperial College London, University College London and the Universities of Glasgow and Birmingham.
“Some cancers are difficult to remove by surgery and highly invasive, and they are also hard to treat because drugs often cannot reach them at high enough concentration,” explains George Malliaras, Prince Philip Professor of Technology in Cambridge’s Department of Engineering, who leads the IRC. “Pancreatic tumour cells, for instance, are protected by dense stromal tissue, and tumours of the central nervous system by the blood-brain barrier.”
The aim of the project, which is funded for six years by the Engineering and Physical Sciences Research Council, is to develop an array of new delivery technologies that can deliver almost any drug to any tumour in a large enough concentration to kill the cancerous cells.
Chemists, engineers, material scientists and pharmacologists will focus on developing particles, injectable gels and implantable devices to deliver the drugs. Cancer scientists and clinicians from the Cancer Research UK Cambridge Centre and partner sites will devise and carry out clinical trials. Experts in innovative manufacturing technologies will ensure the devices are able to be manufactured and robust enough to withstand surgical manipulation.
One technology the team will examine is the ability of advanced materials to self-assemble and entrap drugs inside metal-organic frameworks. These structures can carry enormous amounts of drugs, and be tuned both to target the tumour and to release the drug at an optimal rate.
“We are going to pierce through the body’s natural barriers,” says Malliaras, “and deliver anti-cancer drugs to the heart of the tumour.”
Dr Su Metcalfe, a member of George Malliaras’s team and who is already using NanoBioMed to treat Multuple Sclerosis, added “the power of nanotechnology to synergise with potent anti-cancer drugs will be profound and the award will speed delivery to patients.”
Researchers at the Complutense University of Madrid (UCM) have developed a hybrid nanoplatform that locates tumours using three different types of contrast simultaneously to facilitate multimodal molecular medical imaging: magnetic resonance imaging (MRI), computed tomography (CT) and fluorescence optical imaging (OI).
The results of this study, led by the UCM Life Sciences Nanobiotechnology research team directed by Marco Filice and published in ACS Applied Materials & Interfaces, represent a major advance in medical diagnosis since just one session using a single contrast medium yields more precise, specific results with higher resolution, sensitivity and capacity to penetrate tissues.
“No single molecular imaging modality provides a perfect diagnosis. Our nanoplatform is designed to enable multimodal molecular imaging, thus overcoming the intrinsic limitations of each single image modality while maximising their advantages,” noted Marco Filice, a researcher in the Department of Chemistry and Pharmaceutical Sciences at the Complutense University of Madrid and the director of the study.
The platform, which has been tested on mice, targets solid cancers such as sarcomas. “However, due to its flexibility, the proposed nanoplatform can be modified, and with a suitable design of recognition element siting, it will be possible to expand detection to more types of cancer,” Filice said.
Named after the Roman god Janus, usually depicted as having two faces, these nanoparticles also “have two opposing faces, one of iron oxide embedded in a silica matrix that serves as a contrast medium for MRI and another of gold for CT,” explained Alfredo Sánchez, a researcher in the UCM Department of Analytical Chemistry and the first author of the study.
In addition, a molecular probe sited in a specific manner in the golden area permits fluorescence optical imaging while a peptide selective for hyperexpressed receptors in tumours (RGD sequence) and sited on the silica surface enveloping the iron oxide nanoparticles identifies the tumour and makes it possible to direct and transport the nanoplatform to its target.
Once the research team had synthesised the nanoparticles and determined their characteristics and toxicity, they then tested them in mouse models reared to present a fibrosarcoma in the right leg. The nanoparticle was injected in the tail. “Excellent imaging results were obtained for each modality tested,” reported Filice.
Although there is still much to do before these experiments can be applied to humans, this research shows that personalised treatment is closer than ever to becoming a reality, thanks to nanotechnology and biotechnology.
More information: Alfredo Sánchez et al, Hybrid Decorated Core@Shell Janus Nanoparticles as a Flexible Platform for Targeted Multimodal Molecular Bioimaging of Cancer, ACS Applied Materials & Interfaces (2018). DOI: 10.1021/acsami.8b10452
Allison, who is the chair of Immunology and executive director of the Immunotherapy Platform, is the first MD Anderson scientist to receive the world’s most coveted award for discoveries in the fields of life sciences and medicine. Allison won for his work in launching an effective new way to attack cancer by treating the immune system rather than the tumor, according to a release.
“I’m honored and humbled to receive this prestigious recognition,” Allison says in a statement. “A driving motivation for scientists is simply to push the frontiers of knowledge. I didn’t set out to study cancer, but to understand the biology of T cells, these incredible cells to travel our bodies and work to protect us.”
Allison shares the award with Tasuku Honjo, M.D., Ph.D., of Kyoto University in Japan. When announcing the honor, the Nobel Assembly of Karolinska Institute in Stockholm noted in a statement that “stimulating the ability of our immune system to attack tumor cells, this year’s Nobel Prize laureates have established an entirely new principle for cancer therapy.”
The prize recognizes Allison’s basic science discoveries on the biology of T cells, the adaptive immune system’s soldiers, and his invention of immune checkpoint blockade to treat cancer. According to MD Anderson, Allison’s crucial insight was to block a protein on T cells that acts as a brake on their activation, freeing the T cells to attack cancer. He developed an antibody to block the checkpoint protein CTLA-4 and demonstrated the success of the approach in experimental models.
Allison’s work led to development of the first immune checkpoint inhibitor drug which would become the first to extend the survival of patients with late-stage melanoma. Follow-up studies show 20 percent of those treated live for at least three years with many living for 10 years and beyond, unprecedented results, according to the cancer center.
“Jim Allison’s accomplishments on behalf of patients cannot be overstated,” says MD Anderson president Peter WT Pisters, M.D., in a statement. “His research has led to life-saving treatments for people who otherwise would have little hope. The significance of immunotherapy as a form of cancer treatment will be felt for generations to come.”
“I never dreamed my research would take the direction it has,” Allison adds. “It’s a great, emotional privilege to meet cancer patients who’ve been successfully treated with immune checkpoint blockade. They are living proof of the power of basic science, of following our urge to learn and to understand how things work.”
A new cancer therapy using nanoparticles to deliver a combination therapy direct to cancer cells could be on the horizon, thanks to research from the University of East Anglia.
The new therapy, which has been shown to make breast cancer and prostate cancer tumours more sensitive to chemotherapy, is now close to entering clinical trials.
And scientists at UEA’s Norwich Medical School have confirmed that it can be mass-produced, making it a viable treatment if proved effective in human trials.
Using nanoparticles to get drugs directly into a tumour is a growing area of cancer research. The technology developed at UEA is the first of its kind to use nanoparticles to deliver two drugs in combination to target cancer cells.
The drugs, already approved for clinical use, are an anti-cancer drug called docetaxel, and fingolimod, a multiple sclerosis drug that makes tumours more sensitive to chemotherapy.
Fingolimod cannot currently be used in cancer treatment because it also supresses the immune system, leaving patients with dangerously low levels of white blood cells.
And while docetaxel is used to treat many cancers, particularly breast, prostate, stomach, head and neck and some lung cancers, its toxicity can also lead to serious side effects for patients whose tumours are chemo-resistant.
Because the nanoparticles developed by the UEA team can deliver the drugs directly to the tumour site, these risks are vastly reduced. In addition, the targeted approach means less of the drug is needed to kill off the cancer cells.
“So far nobody has been able to find an effective way of using fingolimod in cancer patients because it’s so toxic in the blood,” explains lead researcher, Dr. Dmitry Pshezhetskiy from the Norwich Medical School at UEA.
“We’ve found a way to use it that solves the toxicity problem, enabling these two drugs to be used in a highly targeted and powerful combination.”
The UEA researchers worked with Precision NanoSystems’ Formulation Solutions Team who used their NanoAssemblr technology to investigate if it was possible to synthesise the different components of the therapy at an industrial scale.
Following successful results on industrial scale production, and a published international patent application, the UEA team is now looking for industrial partners and licensees to move the research towards a phase one clinical trial.
Also included within the nanoparticle package are molecules that will show up on an MRI scan, enabling clinicians to monitor the spread of the particles through the body.
The team has already carried out trials in mice that show the therapy is effective in reducing breast and prostate tumours. These results were published in 2017.
“Significantly, all the components used in the therapy are already cleared for clinical use in Europe and the United States,” says Dr. Pshezhetskiy. “This paves the way for the next stage of the research, where we’ll be preparing the therapy for patient trials.”
“New FTY720-docetaxel nanoparticle therapy overcomes FTY720-induced lymphopenia and inhibits metastatic breast tumour growth,” by Heba Alshaker, Qi Wang, Shyam Srivats, Yimin Chao, Colin Cooper and Dmitri Pchejetski was published in Breast Cancer Research and Treatment on 10 July 2017.
“Core shell lipid-polymer hybrid nanoparticles with combined docetaxel and molecular targeted therapy for the treatment of metastatic prostate cancer,” by Qi Wang, Heba Alshaker, Torsten Böhler, Shyam Srivats, Yimin Chao, Colin Cooper and Dmitri Pchejetski was published in Scientific Reports on 19 July 2017.
More information: Heba Alshaker et al. New FTY720-docetaxel nanoparticle therapy overcomes FTY720-induced lymphopenia and inhibits metastatic breast tumour growth, Breast Cancer Research and Treatment (2017). DOI: 10.1007/s10549-017-4380-8
Qi Wang et al. Core shell lipid-polymer hybrid nanoparticles with combined docetaxel and molecular targeted therapy for the treatment of metastatic prostate cancer, Scientific Reports (2017). DOI: 10.1038/s41598-017-06142-x
Extracellular vesicle-like metal-organic framework nanoparticles are developed for the intracellular delivery of biofunctional proteins. The biomimetic nanoplatform can protect the protein cargo and overcome various biological barriers to achieve systemic delivery and autonomous release. Credit: Zheng Lab/Penn State
A biomimetic nanosystem can deliver therapeutic proteins to selectively target cancerous tumors, according to a team of Penn State researchers.
A biomimetic nanosystem can deliver therapeutic proteins to selectively target cancerous tumors, according to a team of Penn State researchers. Using a protein toxin called gelonin from a plant found in the Himalayan mountains, the researchers caged the proteins in self-assembled metal-organic framework (MOF) nanoparticles to protect them from the body’s immune system. To enhance the longevity of the drug in the bloodstream and to selectively target the tumor, the team cloaked the MOF in a coating made from cells from the tumor itself.
Blood is a hostile environment for drug delivery. The body’s immune system attacks alien molecules or else flushes them out of the body through the spleen or liver. But cells, including cancer cells, release small particles called extracellular vesicles that communicate with other cells in the body and send a “don’t eat me” signal to the immune system.
“We designed a strategy to take advantage of the extracellular vesicles derived from tumor cells,” said Siyang Zheng, associate professor of biomedical and electrical engineering at Penn State. “We remove 99 percent of the contents of these extracellular vesicles and then use the membrane to wrap our metal-organic framework nanoparticles. If we can get our extracellular vesicles from the patient, through biopsy or surgery, then the nanoparticles will seek out the tumor through a process called homotypic targeting.”
Gong Cheng, lead author on a new paper describing the team’s work and a former post-doctoral scholar in Zheng’s group now at Harvard, said, “MOF is a class of crystalline materials assembled by metal nodes and organic linkers. In our design, self-assembly of MOF nanoparticles and encapsulation of proteins are achieved simultaneously through a one-pot approach in aqueous environment. The enriched metal affinity sites on MOF surfaces act like the buttonhook, so the extracellular vesicle membrane can be easily buckled on the MOF nanoparticles. Our biomimetic strategy makes the synthetic nanoparticles look like extracellular vesicles, but they have the desired cargo inside.”
The nanoparticle system circulates in the bloodstream until it finds the tumor and locks on to the cell membrane. The cancer cell ingests the nanoparticle in a process called endocytosis. Once inside the cell, the higher acidity of the cancer cell’s intracellular transport vesicles causes the metal-organic framework nanoparticles to break apart and release the toxic protein into cytosol and kill the cell.
“Our metal-organic framework has very high loading capacity, so we don’t need to use a lot of the particles and that keeps the general toxicity low,” Zheng said.
The researchers studied the effectiveness of the nanosystem and its toxicity in a small animal model and reported their findings in a cover article in the Journal of the American Chemical Society.
The researchers believe their nanosystem provides a tool for the targeted delivery of other proteins that require cloaking from the immune system. Penn State has applied for patent protection for the technology.
Materials provided by Penn State. Original written by Walt Mills. Note: Content may be edited for style and length.
Survival rates in pancreatic cancerlinked to inverse correlation between specific oncogene and tumor suppressant, Tel Aviv University researchers say
A new Tel Aviv University study pinpoints the inverse correlation between a known oncogene — a gene that promotes the development of cancer — and the expression of an oncosuppressor microRNA as the reason for extended pancreatic cancer survival. The study may serve as a basis for the development of an effective cocktail of drugs for this deadly disease and other cancers.
The study, which was published in Nature Communications, was led by Prof. Ronit Satchi-Fainaro, Chair of the Department of Physiology and Pharmacology at TAU’s Sackler Faculty of Medicine, and conducted by Hadas Gibori and Dr. Shay Eliyahu, both of Prof. Satchi-Fainaro’s multidisciplinary laboratory, in collaboration with Prof. Eytan Ruppin of TAU’s Computer Science Department and the University of Maryland and Prof. Iris Barshack and Dr. Talia Golan of Chaim Sheba Medical Center, Tel Hashomer.
Pancreatic cancer is among the most aggressive cancers known today. The overwhelming majority of pancreatic cancer patients die within just a year of diagnosis. “Despite all the treatments afforded by modern medicine, some 75% of all pancreatic cancer patients die within 12 months of diagnosis, including many who die within just a few months,” Prof. Satchi-Fainaro says.
“But around seven percent of those diagnosed will survive more than five years. We sought to examine what distinguishes the survivors from the rest of the patients,” Prof. Satchi-Fainaro continues. “We thought that if we could understand how some people live several years with this most aggressive disease, we might be able to develop a new therapeutic strategy.”
Calling a nano-taxi
The research team examined pancreatic cancer cells and discovered an inverse correlation between the signatures of miR-34a, a tumor suppressant, and PLK1, a known oncogene. The levels of miR-34a were low in pancreatic cancer mouse models, while the levels of the oncogene were high. This correlation made sense for such an aggressive cancer. But the team needed to see if the same was true in humans.
The scientists performed RNA profiling and analysis of samples taken from pancreatic cancer patients. The molecular profiling revealed the same genomic pattern found earlier in mouse models of pancreatic cancer.
The scientists then devised a novel nanoparticle that selectively delivers genetic material to a tumor and prevents side effects in surrounding healthy tissues.
“We designed a nanocarrier to deliver two passengers: (1) miR-34a, which degrades hundreds of oncogenes; and (2) a PLK1 small interfering RNA (siRNA), that silences a single gene,” Prof. Satchi-Fainaro says. “These were delivered directly to the tumor site to change the molecular signature of the cancer cells, rendering the tumor dormant or eradicating it altogether.
“The nanoparticle is like a taxi carrying two important passengers,” Prof. Satchi-Fainaro continues. “Many oncology protocols are cocktails, but the drugs usually do not reach the tumor at the same time. But our ‘taxi’ kept the ‘passengers’ — and the rest of the body — safe the whole way, targeting only the tumor tissue. Once it ‘parked,’ an enzyme present in pancreatic cancer caused the carrier to biodegrade, allowing the therapeutic cargo to be released at the correct address — the tumor cells.”
Improving the odds
To validate their findings, the scientists injected the novel nanoparticles into pancreatic tumor-bearing mice and observed that by balancing these two targets — bringing them to a normal level by increasing their expression or blocking the gene responsible for their expression — they significantly prolonged the survival of the mice.
“This treatment takes into account the entire genomic pattern, and shows that affecting a single gene is not enough for the treatment of pancreatic cancer or any cancer type in general,” according to Prof. Satchi-Fainaro.
Research for the study was funded by the European Research Council (ERC), Tel Aviv University’s Cancer Biology Research Center (CBRC) and the Israel Science Foundation (ISF).
American Friends of Tel Aviv University (AFTAU) supports Israel’s most influential, comprehensive and sought-after center of higher learning, Tel Aviv University (TAU). TAU is recognized and celebrated internationally for creating an innovative, entrepreneurial culture on campus that generates inventions, startups and economic development in Israel. For three years in a row, TAU ranked 9th in the world, and first in Israel, for alumni going on to become successful entrepreneurs backed by significant venture capital, a ranking that surpassed several Ivy League universities. To date, 2,400 patents have been filed out of the University, making TAU 29th in the world for patents among academic institutions.
Researchers in Sweden have succeeded in taking the next step toward using man-made nanoscale compounds in the fight against cancer. A recent proof-of-concept study showed that dendrimers, which were first introduced in the 1980s, may be used to introduce compounds that essentially trick cancer cells into performing self-destructive tasks.
Dendrimers, or cascade molecules, are organically synthesized large molecules that match nature’s peptides and proteins with respect to size and structure. Researchers from KTH Royal Institute of Technology took advantage of these qualities – and cancer cells’ appetite for adsorbing large molecules – by loading the material with an organic sulfur compound (OSC) which is also a key ingredient in amino acids, peptides and proteins.
Applying these to cultured human cancer cells sets in motion a process that distracts cancer cells from their normal task of multiplying, and instead go to work on picking apart disulfide bonds in the dendrimers, says Michael Malkoch, a professor of fiber and polymer technology at KTH.
Malkoch says that this activity releases an increased concentration of reactive oxygen radicals (ROS), which eventually induces cell death. Unlike treatments like chemotherapy, the effect is selective toward cancer cells, leaving the healthy ones unaffected since healthy cells have a higher tolerance for ROS.
The nanomaterial is finally broken down by the body, he says.
The article was published in Journal of the American Chemical Society, and is co-authored by Malkoch, KTH doctoral student Oliver Andrén and Aristi P. Fernandes of Karolinska Institutet.
Their results show that the platform is worth continued research with clinical tests in which dendrimers are preprogrammed with large and specific numbers of organic disulfide bonds, Malkoch says.
“We’ve just scratched the surface for what you can do with dendrimers. We have previously tested using similar materials as a part of a leg patch – a type of adhesive that in some cases enables treatment of bone fractures without screws and plates,” he says. “You can imagine future applications where the material is used to coat implants around cancer tumors and thereby enable therapy treatment at a localized level.”
Magnetic particle imaging is a new, up-and-coming, safe and highly sensitive tracer imaging technique that works by detecting super-para-magnetic iron oxide nano-particles with high image contrast (that is, no background tissue signal). The technique, which does not use any ionizing radiation, can be used to image anywhere inside the body, which means that it could be promising for detecting and monitoring tumors. Researchers in the US are now the first to have used MPI to passively detect cancer by basically exploiting the abnormal leakiness of tumor blood vessels – a finding that bodes well for the early detection of cancers like breast cancer in patients at risk for the disease.
Biomedical imaging is important at every stage of diagnosing and treating cancer, beginning with initial screening, through to diagnosis, treatment planning and monitoring. The biggest challenge here is to be able to reliably distinguish tumour tissue from healthy tissue, something that is not as easy as it sounds.
“Conventional anatomical techniques, such as X-ray, X-ray computed tomography (CT), ultrasound and magnetic resonance imaging (MRI), are very useful for detecting the tissue architecture changes that generally accompany cancer, but the native contrast of tumours may not differ sufficiently from healthy tissue for a confident diagnosis, especially for metastatic or so-called diffuse tumours” explains lead author of the study Elaine Yu, who is completing her Bioengineering PhD in Steven Conolly’s lab at the University of California at Berkeley (UCB). “This is why exogenous contrast agents, such as iodine (for X-ray and CT) and gadolinium (for MRI) are often administered to highlight crucial vascular differences between normal and cancerous tissue for more precise screening.”
Exploiting the EPR effect
Contrast agents are all injected intravenously, but the way they highlight tumours differs considerably. Nanosized agents are better than conventional low molecular weight agents in one respect because they are not immediately excreted by the kidneys if designed to be large enough. They are thus able to circulate in the blood for extended periods of time. The naturally leaky vasculature of some tumours also allows nanosized particles to preferentially end up in tumour tissue, where they can be held. This is known as the enhanced permeability and retention (EPR) effect.
“Our work is the first to exploit the EPR effect with the high sensitivity and contrast afforded by magnetic particle imaging (MPI),” says Yu. “We have succeeded in imaging tumours in rats with vivid tumour-to-background contrast. “Thanks to its high sensitivity and good signal throughout the entire body, we were able to clearly capture the nanoparticle dynamics in the tumour: so-called rim enhancement, peak particle uptake at six hours after administration and eventual clearance beyond 48 hours.”
Synthesizing the SPIOs
The MPI-tailored superparamagnetic iron oxide nanoparticle (SPIO) tracers were synthesized by team members at LodeSpin Labs and by Kannan Krishnan’s lab at the University of Washington (UW), and were designed for optimal imaging resolution and long blood circulation time. “The iron oxide nanoparticles were made by thermolysis of iron III oleate in 1-octadcene, with subsequent oxidation to achieve the desired magnetic behaviour and coated with the biocompatible coating MPAO-PEG,” explains Yu.
The researchers injected the nanoparticles into the tail veins of rats and then performed a series of MPI scans as the nanoparticles travelled through the circulation. Thanks to the EPR effect, the particles preferentially accumulated in tumours and were retained there for up to six days.
Imaging the SPIO electronic moment
MPI was first developed by Philips Research in 2005 and is a tracer imaging technique that directly measures the location and concentration of SPIO nanoparticles in vivo. It images the SPIO electronic moment, which is 22 million times more intense than nuclear MRI moments. When a time-varying exciting field is applied, it causes the moments of the SPIOs to instantaneously “flip”, thereby inducing a signal in a receiver coil.
“The advantages of MPI are its superb contrast and sensitivity, which could very soon rival the dose-limited sensitivity of nuclear medicine techniques,” Conolly tells nanotechweb.org. “This is very exciting, since MPI does not rely on ionizing radiation. The scanner and iron oxide tracer are also thought to be safe for humans. Indeed, some SPIO agents are already FDA or EU safety approved for human use in other clinical applications.”
MPI tracers are excreted through the liver
Importantly, the MPI tracers are excreted through the liver, rather than through the kidneys, and there is evidence that SPIOs could be safer than iodine and gadolinium for patients with chronic kidney disease. “Given all these advantages, we are very hopeful that MPI could play an important role in early-stage cancer detection. Indeed, we are particularly focusing on early-stage breast cancer detection in the subpopulation of women with radiologically dense breast tissue and who are at high risk for cancer (because of, for example, BRCA1 or BRCA2 defects, or family history of the disease).”
Conolly says that he and his colleagues are now working hard to improve MPI in terms of resolution and sensitivity. “We are also studying MPI for stem-cell tracking, detecting pulmonary embolism, brain perfusion to detect and monitor strokes or traumatic brain injuries, and T-cell immunotherapy studies in collaboration with researchers at Berkeley, the University of California at San Francisco, UW, Case Western, Harvard and Stanford. We would also like to follow up on several promising demonstrations of MPI-guided magnetic fluid hyperthermia exploiting the unique ‘focusing’ capabilities of MPI to selectively heat tumours or to release chemotherapeutic agents specifically into a tumour. We are doing this work with University of Florida collaborators.”
MIT is constructing, at the heart of the campus, a new 200,000-square-foot center for nanoscience and nanotechnology. This advanced facility will be a place for tinkering with atoms, one by one—and for constructing, from these fantastically small building blocks, the innovations of the future. Watch the MIT Video then Read More …
“Science is not only the disciple of Reason, but also one of Romance and Passion ~ Stephen B. Hawking
Nanotechnology is so small it’s measured in billionths of meters, and it is revolutionizing every aspect of our lives …
The past 70 years have seen the way we live and work transformed by two tiny inventions. The electronic transistor and the microchip are what make all modern electronics possible, and since their development in the 1940s they have been getting smaller. Today, one chip can contain as many as 5 billion transistors. If cars had followed the same development pathway, we would now be able to drive them at 300,000 mph and they would cost just $6.00 (US) each.
But to keep this progress going we need to be able to create circuits on the extremely small, nanometer scale. A nanometer (nm) is one billionth of a meter and so this kind of engineering involves manipulating individual atoms. We can do this, for example, by firing a beam of electrons at a material, or by vaporizing it and depositing the resulting gaseous atoms layer by layer onto a base.
Stanford researchers accidentally discovered that iron nanoparticles invented for anemia treatment have another use: triggering the immune system’s ability to destroy tumor cells.
Ironnanoparticles can activate the immune system to attack cancer cells, according to a study led by researchers at the Stanford University School of Medicine.
The nanoparticles, which are commercially available as the injectable iron supplement ferumoxytol, are approved by the Food and Drug Administration to treat iron deficiency anemia.
The mouse study found that ferumoxytol prompts immune cells called tumor-associated macrophages to destroy cancer cells, suggesting that the nanoparticles could complement existing cancer treatments. The discovery, described in a paper published online Sept. 26 in Nature Nanotechnology, was made by accident while testing whether the nanoparticles could serve as Trojan horses by sneaking chemotherapy into tumors in mice.
“It was really surprising to us that the nanoparticles activated macrophages so that they started to attack cancer cells in mice,” said Heike Daldrup-Link, MD, who is the study’s senior author and an associate professor of radiology at the School of Medicine. “We think this concept should hold in human patients, too.”
Daldrup-Link’s team conducted an experiment that used three groups of mice: an experimental group that got nanoparticles loaded with chemo, a control group that got nanoparticles without chemo and a control group that got neither. The researchers made the unexpected observation that the growth of the tumors in control animals that got nanoparticles only was suppressed compared with the other controls.
Getting macrophages back on track
The researchers conducted a series of follow-up tests to characterize what was happening. Experimenting with cells in a dish, they showed that immune cells called tumor-associated macrophages were required for the nanoparticles’ anti-cancer activity; in cell cultures without macrophages, the iron nanoparticles had no effect against cancer cells.
Before this study was done, it was already known that in healthy people, tumor-associated macrophages detect and eat individual tumor cells. However, large tumors can hijack the tumor-associated macrophages, causing them to stop attacking and instead begin secreting factors that promote the cancer’s growth.
The study showed that the iron nanoparticles switch the macrophages back to their cancer-attacking state, as evidenced by tracking the products of the macrophages’ metabolism and examining their patterns of gene expression.
Furthermore, in a mouse model of breast cancer, the researchers demonstrated that the ferumoxytol inhibited tumor growth when given in doses, adjusted for body weight, similar to those approved by the FDA for anemia treatment. Prior studies had shown that the nanoparticles are metabolized over a period of about six weeks, and the new study showed that the anti-cancer effect of a single dose of nanoparticles declined over about three weeks.
The scientists also tested whether the nanoparticles could stop cancer from spreading. In a mouse model of small-cell lung cancer, the nanoparticles reduced tumor formation in the liver, a common site of metastasis in both mice and humans. In a separate model of liver metastasis, pretreatment with nanoparticles before tumor cells were introduced greatly reduced the volume of liver tumors.
Potential clinical applications
The study’s results suggest several possible applications to test in human trials, Daldrup-Link said. For instance, after surgery to remove a potentially metastatic tumor, patients often need chemotherapy but must wait until they recover from the operation to tolerate the severe side effects of conventional chemo. The iron nanoparticles lack the toxic side effects of chemotherapy, suggesting they might be given to patients during the surgical recovery period.
“We think this could bridge the time when the patient is quite sick after surgery, and help keep the cancer from spreading until they are able to receive chemotherapy,” said Daldrup-Link.
The nanoparticles may also help cancer patients whose tumors can’t be completely removed. “If there are some tumor cells left after surgery, the situation that cancer surgeons call positive margins, we think it might work to inject iron nanoparticles there, and the smaller tumor seeds could potentially be taken care of by our immune system,” Daldrup-Link said.
The fact that the nanoparticles are already FDA-approved speeds the ability to test these applications in humans, she added.
The new findings will also help cancer researchers conduct more accurate evaluations of nanoparticle-drug combinations, Daldrup-Link said. “In many studies, researchers just consider nanoparticles as drug vehicles,” she said. “But they may have hidden intrinsic effects that we won’t appreciate unless we look at the nanoparticles themselves.”