Tag Archives: monoclonal antibody

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

Taking a BiTE out of non-Hodgkin’s lymphoma

Non-Hodgkin’s lymphoma (NHL) is a diverse family of cancers that affect a part of the body’s immune system known as the lymphatic system.  In NHL white blood cells become cancerous and develop into tumors at key points in the lymphatic system known as the lymph nodes, before spreading to other tissues.  About 50,000 Americans develop NHL every year, and while effective treatments such as Rituximab are available they don’t work for all patients and every year NHL kills nearly 20,000 people in the USA.

So it’s not surprising that the news that Blinatumomab, a novel treatment developed by the German firm Micromet, has performed very well in early clinical trials has been greeted with enthusiasm by cancer  research charities and the stock market alike.

In the trials (1) published this week in the prestigious journal Science, Blinatumomab was given to 38 NHL patients who had not responded to other treatments. In 7 of these patients tumors were found to have shrunk dramatically while in 4 patients the tumors disappeared completely.  Blinatumomab is the first BiTE antibody to enter clinical trials, and its innovative design combines a portion of an antibody, a protein produced by the immune system that binds to foreign material in the body, that targets the cancer cell with a portion of an antibody that binds to the T-cells of the immune system.  The BiTE antibody directs the T-cell to the cancer cell, which the T-cell then destroys.  Blinatumomab was developed after earlier studies using animal models of NHL had shown that antibodies could direct T-cells to target cancer cells, and it was hoped that the BiTE antibodies would do this more effectively. Of course before it was assessed in human clinical trials the BiTE antibody  Blinatumomab was studied in mouse models of NHL, since it was important to determine that they could target circulating immune cells to the tumors (2).

The contribution of animal research to the development of Blinatumomab was not limited to the evaluation of anti-cancer activity and pre-clinical safety, it was also crucial to manufacturing Blinatumomab itself*. BiTE antibodies are produced by heavily modifying a type of antibody known as a monoclonal antibody that binds very specifically to a particular target in the body. The first step of monoclonal antibody production is the immunization of an animal, usually a rodent, with the protein such as a cancer cell protein to which you wish the antibody to bind.  Animals are required for this step because an immune system is needed to produce the immune cells that recognize the target protein, and humans cannot be used for this process both because they cannot be injected with a disease-bearing agent in order to make antibodies, and because the human body does not produce antibodies to the human proteins that researchers often wish to target. Blood samples containing cells that produce antibodies against the foreign protein are then taken from the animal. These antibody producing cells are fused with a special cancer cell to produce a hybrid cell, or hybridoma, which can be grown almost indefinately in the petri dish and produce a large supply of monoclonal antibodies.  These monoclonal antibodies can then in their turn be modified to produce antibody derived drugs such as Rituximab and Blinatumomab.

We hope that larger trials of Blinatumomab against NHL confirm the results of this early trial, and that it will go on to be a valuable addition to the range of treatments available to fight this deadly disease.

* While hybridoma based monoclonal antibody production methods have been very successful, and are vital to current efforts to develop antibody based medicines, replacement technologies that require far fewer animals are currently being developed.  In the coming decades it is hoped that hybridoma based methods will increasingly be replaced by improving in vitro technologies, for example antibody phage libraries that display vast numbers of human or animal antibody fragments and can be used to identify antibodies specific for a particular target. This is a good example of the 3Rs in practise.

Paul Browne

1) Bargou R. et al. “Tumor regression in cancer patients by very low doses of a T cell-engaging antibody.” Science Volume 321(5891), pages 974-977 (2008).

2) Dreier T. et al. “T cell costimulus-independent and very efficacious inhibition of tumor growth in mice bearing subcutaneous or leukemic human B cell lymphoma xenografts by a CD19-/CD3- bispecific single-chain antibody construct.” J. Immunol. Volume 170(8), pages 4397-4402 (2003)