Tag Archives: translational research

A breakthrough against Chronic Lymphocytic Leukemia…thank the mice!

A challenge that science communicators frequently face when discussing the process whereby a scientific discovery eventually leads to a medical breakthrough is the time that this often takes, indeed by the time that the reports of exciting clinical trial outcomes start to appear in the press the role of the scientists who made the initial discoveries is often relegated to a passing comment…if it is mentioned at all. An example of this comes from the Weizmann Wave blog, produced by the Weizmann Institute of Science.

You may remember reports last month on the very promising results of a small clinical trial where a new immunotherapy technique was used to eradicate cancer cells in patients with Chronic Lymphocytic Leukemia (CLL), a blood cancer for which currently available treatments are often inadequate.  That trial, conducted by scientists at the University of Pennsylvania led by Professor Carl June, involved removing T-cells from the patient, treating the cells with a lentiviral vector that encodes for a Chimeric Antigen Receptor which recognises a protein named CD19 that is found on B-cells, including the cancer cells responsible for CLL, and then infusing the transformed T-cells back into the patients.  As the reported in the Los Angeles Times the results were dramatic, within a few weeks of the infusion the modified T-cells expanded rapidly and targeted the cancer cells in all three paients, so that a year later two of the three patients were still in complete remission.

It’s exciting stuff but as the Weizmann Wave reports the Press Release issued by Penn Medicine noted that this was a “cancer treatment breakthrough 20 years in the making” but “didn’t, however, explain those “20 years in the making.””. The Weizmann Wave goes on to discuss the pioneering basic scientific research undertaken by Professor Zelig Eshhar at theWeizman Institute of Science in the late 1980’s, which you can read about here.

Of course between the basic research undertaken by Prof. Eshhar and his colleagues in the 1980’s and the clinical trial whose outcome was announced last month there was a lot of work to be done. It would be impractical to describe all the different discoveries that made this immunotherapy possible, but one discovery in particular highlights the importance of animal research to this breakthrough.

There have been previous attempts to use Chimeric Antigen Receptors to target T-cells to attack cancer, but these had disappointing results in clinical trials.  A major improvement made by the University of Pennsylvania team was to include an additional motif – named the CD137 co-stimulatory molecule- which greatly enhances the cancer killing ability of the infused T-cells.  In a recent paper published in the Journal of Cancer the University of Pennsylvania team point out that the decision to include CD137 (called 4-1BB in mice) in their Chimeric Antigen Receptor construct was based on promising results in studies undertaken in mice:

 Our group has tested a CAR directed against CD19 linked to the CD137 (4-1BB) co-stimulatory molecule signaling domain to enhance activation and signaling after recognition of CD19. By inclusion of the 4-1BB signaling domain, in vitro tumor cell killing, and in-vivo anti-tumor activity and persistence of CART-19 cells in a murine xenograft model of human ALL (acute lymphoblastic leukemia) is greatly enhanced”

Indeed, in a paper published by Professor June and colleagues in the journal Molecular Therapy in 2009 they describe this work in much more detail, highlighting just how groundbreaking the results were:

Previous in vitro studies have characterized the incorporation of CD137 domains into CARs.10,11,29 Our results represent the first in vivo characterization of these CARs and uncover several important advantages of CARs that express CD137 that were not revealed by the previous in vitro studies. We demonstrated that CARs expressing the CD137 signaling domain could survive for at least 6 months in mice bearing tumor xenografts. This may have significant implications for immunosurveillance, as well as for tumor eradication. For example, in a mouse prostate cancer xenograft model, survival of CAR+ T cells for at least a week was required for tumor eradication.30

Long-term survival of the CARs did not require administration of exogenous cytokines, and these results significantly extend the duration of survival of human T cells expressing CARs shown in previous studies.17,31 To our knowledge, this is the first report demonstrating elimination of primary leukemia xenografts in a preclinical model using CAR+ T cells. Furthermore, complete eradication was achieved in some animals in the absence of further in vivo therapy, including prior chemotherapy or subsequent cytokine support.

The long-term control of well-established tumors by immunotherapy has rarely been reported. Most preclinical models in a therapeutic setting have tested tumors that have been implanted for a week or less before initiation of therapy.32 After establishing leukemia 2–3 weeks before T cell transfer, we found that many animals had long-term control of leukemia for at least 6 months. The efficacy of targeted, adoptive immunotherapy in this xenograft model of primary human ALL compares favorably to our prior experience testing the antileukemic efficacy of single cytotoxic (ref. 27 and data not shown) or targeted agents,26 where we have observed extension of survival but not cure of disease. Additionally, we have not previously observed the ability to control xenografted ALL for a period of as long as 6 months.”

These results led directly to the clinical trial reported last month.

So there you have it, behind the headlines are years of graft by hard-working and innovative scientists, who utilised a wide range of experimental approaches – among which animal studies figure prominently – to develop a novel therapy for CLL. As Professor Bruce Levine points out in the video above, the key to success is often keeping one hand in the basic research lab and the other in the clinic.

Paul Browne

Addendum: Scienceblogger Erv has written an excellent commentary on this study

Taming the Wolf: a new treatment for Lupus

Earlier today we posted a commentary on PeTA’s misleading propaganda by Professor Anthony Garro of UMass Dartmouth.   At the time I mentioned that it was a pity that Prof. Garro was not able to write more about the role of animal research in 21st century medicine, but a recent story in Nature News provides an excellent example, showing how research on mice and monkeys was crucial to the development of a new drug for lupus.

The autoimmune disease lupus, or to give it its full name Systemic Lupus Erythematosus (SLE), affects over 100,000 people in the United States, causing damage to a variety of tissues in the body and a wide range of symptoms ranging from fever, headache and  joint pains to anemia and renal failure. While there is no cure for lupus it can be treated successfully, though current treatments do not work well for all patients. Continue reading

Laying the foundations of medical research

For the past couple of weeks a debate has been raging on the Opposing Views website between Speaking of Research’s Dario Ringach and the anti-vivisectionist Ray Greek. It has been a debate shaped by Dr. Greek’s attempts to persuade readers to agree with his very narrow concept of what prediction means in biology and his frankly impoverished view on the role of basic research in advancing medical science, and to oblige those debating them to accept a playing field rigged to set them at a disadvantage.  Judging by Dario’s most recent opinion piece and an article written a couple of days ago on the role of basic research Dr. Greek failed in this attempt.

British biochemist Sir Tim Hunt, who won the Nobel Prize for medicine in 2001.

Among all the discussion was one comment that directed readers to an excellent example of the value of basic research and the how study of animal models made many key discoveries possible. Earlier this week the BBC aired a program in their Beautiful Minds series featuring Sir Tim Hunt, who was awarded the Nobel Prize in 2001 for his research on how the cell cycle – through which cells grow and divide – is controlled.  Sir Tim’s work focused on the role of a family of proteins known as cyclins and as the Beautiful Minds program explains the initial breakthrough came from studies of the fluctuations in the pattern of protein expression during the cell cycle in sea urchin eggs.  This discovery was followed swiftly by the demonstration that cyclins were also present in yeast, clams and frogs, allowing Sir Tim and his colleagues to predict that they would have a role in regulating the cell cycle in many species,  including humans, a prediction that was soon confirmed to be true (1).

This program is a reminder that while discussion of animal research tends to focus on animals such as mice, rats and monkeys a lot is being learned about the fundamentals of our physiology through research on more humble model organisms, a diverse collection that includes not just sea urchins and clams but also nematode worms and flies .  These animals, along with other model organisms such as yeast and bacteria, enable us to study how living things work at a very fundamental level, laying the theoretical foundations for future applied and translational research that yields innovative treatments for disease and injury. At the same time, researchers studying other aspects of physiology often require higher mammals. The study of complex brain functions, including vision, hearing, memory, attention and motor planning, as well as how these functions fail in diseases of the central nervous system, is a prime example of this.

If you haven’t watched the Beautiful Minds series yet I strongly urge you to do so, the programs provide a fascinating (if not always flattering) insight into how science works.  And don’t delay: they are only available to view on the BBC iPlayer for another 7 days!

Paul Browne

1)      Pines J.  and Hunter T. “Isolation of a human cyclin cDNA: evidence for cyclin mRNA and protein regulation in the cell cycle and for interaction with p34cdc2.” Cell Volume 58(5), Pages 833-846 (1989)  PubMed: 2570636

Magic Bullets and Monoclonals: A Breakthrough in Bioscience

The Federation of American Societies for Experimental Biology (FASEB) is one of the world’s largest and most influential scientific organizations, representing as it does 23 independent scientific societies and over 90,000 individual scientists.  As a coalition that represents tens of thousands of US medical researchers FASEB has policies and positions on all kinds of issues which affect scientific research, from federal funding of research to the legal status of embryonic stem cells and human cloning, and you will probably not be altogether surprised to learn that FASEB has taken a very strong position in support of animal research and the scientists who undertake it.

FASEB also takes its responsibility to educate and inform members of the public about the role of biomedical research very seriously and has produced the excellent Breakthroughs in Bioscience, a series of essays written with the help of leading scientists on the research that led to important advances in medicine. While these essays do not of course focus solely on the role of animals in research, key discoveries have after all been made through approaches as disparate as clinical observations and X-ray crystallography,  they do illustrate how important animal research has been as an integral and frequently vital part of the research process.

The most recent essay entitled Magic Bullets and Monoclonals: An Antibody Tale is a great example of this;  I would encourage anyone who is interested in finding out how the role of antibodies in the immune system was first uncovered and how this eventually lead to the development of these “magic bullets” to read it.

A couple of years ago I wrote on the Pro-Test blog about the role of animal research in the development of the monoclonal antibody drug Lucentis that is used to treat the wet form of age-related macular degeneration, a common form of blindness , but it is only one example out of many.  The Breakthroughs in Bioscience essay focuses on the development other monoclonal antibody drugs including Rituximab, a treatment for cancers of the immune system such as non-Hodgkin lymphoma, infliximab, a treatment for autoimmune diseases such as rheumatoid arthritis, and trastuzumab, better known as Herceptin and used to treat breast cancer. While the essay discusses how animals were vital to the production of these monoclonal antibody drugs, the contribution of animal research to the development of these treatments went far beyond just that, as the following two examples illustrate.

Herceptin (1) targets the HER2/neu receptor, a protein whose normal function is to regulate the growth of cells but which is produced in excess in some breast cancers where it promotes tumor growth. HER2 was first discovered to have a role in cancer through studies of cancer in rats and mice, and scientists following up on this discovery then found that it was over-produced in some breast cancers.  Subsequently research in transgenic mice enabled scientists to understand how HER2 promoted tumor growth, while xenograft models where  immunodeficient mice wre injected with  of HER2 positive human breast cancer cells were used to screen candidate monoclonal antibodies, eventually identifying the antibody that was taken into successful human trials as trastuzumab.

The story was similar for infliximab, which works by blocking the action of a chemical messenger called Tumour Necrosis Factor-alpha (TNF-alpha) that promotes inflammation and is a key factor in the development of several autoimmune disorders.  Studies in rodents and dogs played a key role in the isolation and identification of TNF-alpha, and in subsequently animal research that demonstrated its role in both the normal immune system and in inflammatory and autoimmune diseases. This work included studies in transgenic mice which provided the definitive evidence that TNF-alpha plays a crucial role in the development of rheumatoid arthritis , which formed the basis for studies which demonstrated that a chimeric human/mouse monoclonal antibody against TNF-alpha could protect transgenic mice which produced human TNF-alpha from inflammation-induced cachexia (2). Follow up studies in transgenic mice expressing human TNF-alpha provided important pre-clinical information about the safety of infleximab (3).

The examples above show just how important animal research is to both basic research which seeks to understand what is going on in normal physiology and disease, and translational research which seeks to take that knowledge and apply it to developing treatments that can be used effectively in the clinic.  We’re delighted by the work that FASEB is doing to ensure that the public is aware of how all types of research contribute to medical progress, and hope that they continue these efforts for many years to come.

Paul Browne

1)      Pegram M. and Ngo D. “Application and potential limitations of animal models utilized in the development of trastuzumab (HerceptinR): A case study”  Advanced Drug Delivery Reviews Volume 58, Pages 723-734 (2006) DOI:10.1016/j.addr.2006.05.003

2)      Siegel S.A. et al. “The Mouse/Human Chimeric Monoclonal Antibody cA2 Neutralizes TNF In Vitro and Protects Transgenic Mice from Cachexia and TNF Lethality In Vivo” Cytokine Volume 7(1), Pages 15-25 (1995) DOI:10.1006/cyto.1995.1003

3)      European Medicines Agency report http://www.ema.europa.eu/humandocs/PDFs/EPAR/Remicade/190199en6.pdf

Addiction Research as an Example of Translational Biomedical Research

In science, “translation” embodies the concept that data gathered in one situation is meaningful for data gathered in another. Applied biomedical research seeks to translate laboratory research into effective treatments or cures. It spans many levels of study. In oncology (the field of cancer biology), some individuals study how cancerous cells grown in a dish operate and grow and how best you can destroy them. Others study tumor growth in animal models; they do this because the behavior of cells in a dish does not always fully predict how cancer will grow in a living body. Because we want to understand how cancer occurs and progresses in humans, yet other scientists use epidemiological or imaging techniques to directly study cancer patients. Information gained at one level informs and fosters the understanding of information gathered at other levels. No single experiment or scientist answers everything – it’s the collective work of the larger group of researchers working at all levels that pushes things forwards. This is how translation is made possible.

A hotly debated question in translational research is whether data gathered in animals 1) always, 2) often, 3) rarely or 4) never is meaningful for our understanding of human biology. Though most scientists and clinical practitioners feel strongly that it is often predictive, explicit examples are required to convince the broader public.  Clear evidence of translational value is found in research on the biology of drug addictions – something that I study in my laboratory. A large number of both rats and humans find drugs of abuse (cocaine, heroin methamphetamine, nicotine, etc.), when ingested, to be incredibly rewarding and will engage in significant drug-seeking behaviors to obtain it. In that sense, the study of these drugs’ effects on rats translates well (though not perfectly) to its effects on humans. Importantly, it translates “well enough” to make the rat a useful model organism in which to explore how drugs of abuse take control of some individuals by altering their brain chemistry. We have made excellent progress in this area over the last 15 years.

Of all areas of biomedical research, the study of the brain poses the biggest challenge for translational research because it is this organ that differs most across species. There is no doubt that a mouse’s brain is dramatically different from that of a monkey which is still different from that of a human. But do those superficial differences matter? Not as much as you might think! Let’s go back to the earlier example of drug abuse. Addictive drugs are chemicals that, when ingested, make their way into the brain where they alter the activity of brain cells, consequently changing the function of circuits in the brain that mediate reward. This is why they make people experience euphoria, relaxation and a sense of well-being after they take them. Remarkably, despite obvious differences in the brain, rats also very much enjoy the effects of these drugs. When offered an opportunity, they will take them voluntarily (e.g., press a button to trigger an injection of the drug). Even more impressively, even fish find addictive drugs rewarding. So, actually, despite the superficial differences, there is a huge amount going on in the brain that is similar across model organisms. This is because the anatomical differences between rat and human brains are actually much smaller than what is shared between them: common sets of circuits with similar functions.

This point is crucial. If fish and rats can be used to predict some of the responses of humans to addictive drugs, they can be used in translational research to explore the therapeutic effects of drugs used to treat brain disorders, such as addictions, as well.

It is important, however, to distinguish between what an animal model can reveal and what it cannot. In the case of chemical addictions, animal models can help you to understand the physiological and basic behavioral processes that drugs act on to alter the body. Again, studying the effects of an addictive drug in rats can help us to understand how it alters the reward circuit and how that relates to drug seeking. Here, translation is excellent. At the same time, it does not fully recapitulate the psychosocial consequences of drug taking in people. Because the drug is available for free, rats do not have to steal to get money to buy it. Because they are not expected to show up to work on time and be productive, drug use does not cause them to get fired from their jobs. Because they do not get married, they are not at risk of divorce when their drug-taking behavior gets out of control. Because they do not share needles, they are not at risk of hepatitis C or HIV infection. So, from a biological perspective, study of addiction can be modeled well in rats, but the psychosocial consequences are not. Rat researchers have revealed the neural mechanisms by which addictive drugs act in exquisite detail, and all modern, FDA-approved treatments for drug dependence arose from basic, mechanistic studies in animals (examples include Revia for the treatment of alcohol dependence and Chantix for smoking cessation). Clinical researchers then are able to tell us whether and how these treatments affect psychosocial functions in drug users. In that sense, like our colleagues who study cancer, we integrate study from many levels together to fully understand the biology and psychosocial consequences of drug abuse and its treatment.

It is because research at many levels integrates so well that providers of clinical intervention often closely study and attend to studies conducted in animals. An international society called the College on the Problems of Drug Dependence brings together scientists, physicians and social workers who are particularly interested in solving problems relating to addiction. Here, each attendee carefully studies the results of the other researchers – with studies in humans designed based upon clinical observations, and clinical tests being spurred by rat studies.  There is little doubt in the group – whether one consults patient-oriented researchers or people that examine cells growing in a dish – that studies of living animals are a critical part to the overall translational effort to stem the impact of addictions on affected individuals. Though animal research will not solve all of the mysteries of addiction, or of any complex human disease process, it is a foundational part of most areas of biomedical research and patients, patient advocacy groups and treatment providers overwhelmingly support it.

Regards

David Jentsch