Tag Archives: Herceptin

The First Decade of the Human Genome: What’s on the Horizon?

To mark the 10th anniversary of the sequencing of the human genome the BBC aired a documentary yesterday evening entitled “Miracle cure: a decade of the human genome” that can be viewed on the BBC iPlayer.  It was an enjoyable look at what has been accomplished since the famous announcement at the White House in June 2000, and while I think the program could have done with exploring some of the science in more depth, it gave a good overview and didn’t shrink from the sheer complexity of many of the questions that face scientists who are now attempting to understand the genome.

Sophie Longton holds a vial containing a gene therapy treatment that may one day cure her of cystic fibrosis. Image Courtesy of the BBC.

The program followed three individuals as they sought to understand what impact the knowledge gained from studying the genome could have on illnesses that have affected them, breast cancer, cystic fibrosis, and alcoholism, and what basic, applied, and clinical research is currently underway. The case of a woman whose breast cancer is linked to a defective BRCA1 gene turned to discussion of the potential for the development of personalized medicine – treatments that are tailored to the genetic makeup of an individual patient’s cancer cells. Animal research plays a very important role in the development of targeted therapies that can be used in personalized medicine, and an early example of this is the drug Herceptin, which is used to treat cancers that express the HER2 gene.

The cystic fibrosis thread focussed on the development of gene therapy and clinical trials now underway under the direction of Professor Eric Alton of the UK Cystic Fibrosis Gene Therapy Consortium. These gene therapy trials use lipid spheres to transport working copies of the CFTR gene – defective in cystic fibrosis – to the lungs of patients, and the particular lipid formulation used in these trials, known as  GL67A was selected after careful evaluation against other candidates, first in CF mice and then in sheep (1).  Mice models of cystic fibrosis have helped researchers to understand more about the disease and to assess therapies, but until very recently research has been hampered by the lack of a large animal model of cystic fibrosis that models the lung pathology of cystic fibrosis.  This situation finally changed in 2008 when scientists at the Universities of Iowa and Missouri produced genetically modified pigs that lack the CFTR gene and develop all the pathologies that are characteristic of cystic fibrosis in humans. This new animal model for cystic fibrosis will be very useful for evaluating the safety and efficiency of new gene therapy techniques as the science advances.

Finally the thread on the influence on genetics on alcoholism was a reminder of just how complex the interaction between an array of genetic variations and the environment can be, and that while it may be possible to identify factors that predispose an individual towards a particular condition it is often difficult, if not impossible, to identify a single cause that tips the balance. Considering the enormous damage caused to society by addiction, and the high failure rate of addiction treatment programs, there is no doubt that addiction research is a neglected area within biomedical science.  This is sad because research into the physiological underpinnings of addiction can aid the development of more effective treatment programs. Hopefully the identification of genes that predispose certain individuals to addiction will help society to realise that science can make an important contribution to solving this medical and social problem.

Paul Browne

1)       Griesenbach U, Alton EW; UK Cystic Fibrosis Gene Therapy Consortium. “Gene transfer to the lung: lessons learned from more than 2 decades of CF gene therapy.” Adv Drug Deliv. Rev. Volume 61(2), Pages 128-39 (2009) DOI: 10.1016/j.addr.2008.09.010.

Herceptin: When personalized medicine and animal research meet.

Personalized medicine is very popular among medical researchers these days, and it’s not hard to see why. By tailoring treatment to fit an individual patient, for example by using information about their genetic makeup, scientists hope to make treatments more effective while at the same time avoiding or minimizing adverse effects.

Anti-vivisectionist Dr. Greek writes about personalized medicine as if one could do this work without relying on animal research at all.

For example, he writes:

When will personalized medicine become a reality?

We are already seeing it, with breast cancer being a prime example. Breast cancer treatment is now determined in part based on a patient’s genetic makeup. About 25-30 percent of breast cancer patients overexpress the HER2 oncogene, which is a gene involved in the development of cancer. The overexpression results in an increase in the replication of the cancer cells. Physicians are now able to identify which breast cancer patients overexpress HER2 and give them Herceptin, a monoclonal antibody that inhibits HER2

This is true…  but where did Herceptin come from?   Does he know?

Herceptin, a humanized mouse monoclonal antibody. Image courtesy of Andrey Ryzhkov.

The basic research that led to the development of Herceptin (Trastuzumab) goes back to work by Milstein and Kohler who discovered the potential for using antibodies to fight disease.    They developed the first methods to produce monoclonal antibodies using mice.   Both Milstein and Kohler went on to win the Nobel Prize partly for this work.

Harold Varmus (now back as Director of the National Cancer Institute) showed that disturbances in some gene families could turn the cells cancerous.  He also went on to win the Nobel Prize for this work.  Robert Weinberg subsequently discovered in rats that a mutant gene (named “neu”) encoding a tyrosine kinase promoted cancer features in cells, contributing to the development of neuroglioblastoma tumors.

Later, Axel Ullrich and collaborators at Genentech cloned the human HER2/neu gene.  Work at UCLA Dennis Slamon and colleagues showed HER2 over-expression in 25% of patients with aggressive breast cancer.

Through screening studies on monoclonal antibody candidates in vivo in mice implanted with HER-2 positive human tumors the group at Genentech then developed the mouse 4D5 (parent of Herceptin) and showed that 4D5 could suppress the growth of HER2 tumor cells as well as enhance the ability of the host immune system to kill them.   A collaboration between UCLA and Genentech then demonstrated that radio-labeled 4D5 localized to HER2-expressing tumors in both mice and human patients.

With the information obtained from animal experiments, Genentech created Herceptin by humanizing the 4D5 mouse antibody directed at HER2.   The ability of Herceptin to prevent tumor growth was then assessed in mice implanted with HER-2 positive human tumor xenografts, and the concentration of Herceptin required in the blood to achieve anti-tumor activity was determined before starting human clinical trials.

So, you see…  Herceptin was derived from a mouse antibody.

Let me repeat: a mouse antibody!

Clinical trials in humans subsequently showed the effectiveness of Herceptin to treat HER2 positive breast cancer.

Perhaps, Dr. Greek and other animal rights activists should carefully listen to the experts that were actually involved in the process of developing Herceptin (a drug he appears to thinks highly of) which, indeed, benefits so many women battling breast cancer.   A drug derived from mice, and developed in mice.

Here is what Robert Weinberg had to say about Dr. Greek’s views on research:

Dr. Greek says the silliest things, […] implying that people are not studying human tumors, and implying that the kinds of experiments that one can do in mice can be done as well in humans — truly mindless!

I couldn’t have said it better.

Dario Ringach

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