- Sep 25, 1998For your information. --Matt--
Breakthrough Therapies for Leukemia Are at Hand, Researchers Conclude
- Less Toxic, Immune-Based Treatments Show Tremendous Promise -
WASHINGTON, Sept. 25 /PRNewswire/ -- Scientists from around the globe
gathered today to announce breakthrough studies that show the body's immune
system can be manipulated to help patients fight cancer. Dubbed
Immunotherapy, the scientists agree these treatments show the most promise in
launching an effective attack against leukemia, lymphoma and myeloma since the
introduction of chemotherapy 50 years ago.
"We are on the verge of ushering in an entirely new approach to fighting
leukemia and lymphoma," said Dwayne Howell, President of the Leukemia Society
of America. "Within the next few years, the treatment for these patients will
be greatly improved."
Attending the first Symposium on Immunotherapy of Leukemia and Lymphoma, many
authorities in hematology, oncology, molecular genetics and immunology will be
briefed on the latest research findings on the application and effectiveness
of immunotherapies, which use cells of the immune system to prompt a tumor-
killing response. Traditional chemotherapy and radiation, while tremendously
helpful in the fight against leukemia and lymphoma, are toxic and attack
healthy as well as cancerous cells in the body. Immunotherapies are targeted
-- more specific and less toxic for the patient -- and are able to
differentiate between cancerous and most non-cancerous cells, leaving most
normal cells unharmed.
The findings to be presented at the symposium demonstrate that immunotherapy
may be particularly effective against hematologic, or blood- related cancers:
leukemia, lymphoma and myeloma. Today, these cancers strike over 100,000
Americans each year and kill over 57,000.
Immunotherapy may be most effective when combined with other conventional
treatments, like chemotherapy and radiation, to increase survival rates by
improving the success of treatment, prolonging a patient's remission or even
putting relapsed patients back into remission.
"Finding a cure for leukemia and lymphoma is the ultimate goal. As
physicians, though, we also look for ways to contain the disease in the
interim, allowing patients to lead long, normal lives. We're very hopeful
that immunotherapy may be coupled with chemotherapy and radiation therapy to
achieve this," Dr. Marshall Lichtman, the Leukemia Society's executive vice
president for research, said.
The Three Primary Categories of Immunotherapy
Antibodies, which are proteins produced by white blood cells, can recognize
antigens on cancer cells -- molecules on a cell that help the immune system
decipher whether it is foreign or normal. Scientists have found that, like
other foreign cells in the body, many cancer cells express antigens that could
potentially serve as antibody targets. Antibody-based therapies currently
being studied exploit the ability of antibodies themselves to destroy cancer
cells, or use antibodies as vehicles -- like smart bombs -- to carry a toxic
agent, a radioisotope or a drug directly to a tumor site. Researchers have had
the most success with antibodies made by mouse cells, known as monoclonal
antibodies -- which are engineered in a laboratory to recognize and attack a
specific antigen on tumor cells.
Last year, the FDA approved the use of Rituxan(R), a monoclonal antibody used
to treat patients with relapsed non-Hodgkin's lymphoma. Currently, scientists
are reporting promising results from various other clinical (human) trials
using antibody-based therapy. One such study at the Fred Hutchinson Cancer
Research Center (FHCRC) uses antibodies, armed with a radioactive isotope, to
target leukemia cells that may reappear in a relapse after a bone marrow
transplant in patients with acute myelogenous leukemia. Patients receive this
targeted treatment in preparation for the bone marrow transplant, in addition
to the high-dose chemotherapy or radiation normally used prior to
transplantation. Another study at FHCRC has shown the effectiveness of using
an antibody to carry a drug to leukemia cells, achieving remission without the
toxicity usually observed with conventional chemotherapy. This targeted
antibody approach allows the delivery of greater amounts of either radiation
or drugs -- increasing the chance of a more lasting remission. Because the
delivery is so targeted, it causes less damage than non-targeted therapies.
Cellular Immune Therapy
Based on the promising results seen in patients with renal cell cancer and
melanoma, scientists are also concentrating their efforts on cellular immune
therapy -- or adoptive immunotherapy -- to treat patients with leukemia or
lymphoma before they receive bone marrow transplants, or afterwards, if the
patient relapses. In the laboratory, scientists isolate and then stimulate
the immune system's disease-fighting lymphocytes, primarily T lymphocytes, so
that they can recognize and attack cancerous cells in the body.
Cellular immune therapy is also leading to breakthroughs in the success of
bone marrow transplants. For example, researchers know that T lymphocytes
have the ability to attack cancer cells. Therefore, to prevent or offset
potential cancer recurrence after an allogeneic (donor) bone marrow
transplant, physicians can give the patient a subsequent infusion of donor T
lymphocytes to suppress the tumor cells.
Cellular therapy is also at the heart of studies aimed at improving the
outcome of autologous bone marrow transplants, in which the patient's own stem
cells are used. Scientists are studying ways to trick the body into thinking
that it's own leukemia cells are foreign, and attack them. This triggered
immune response can prevent the patient from relapsing, the rate of which is
excessively high in autologous bone marrow recipients.
Also being discussed at this Symposium is the development of vaccines to treat
leukemia, lymphoma and myeloma. Unlike traditional vaccine therapy, this
approach does not prevent the disease. Instead, it lessens the chance of its
recurrence by stimulating immune response to the tumor.
Currently, scientists at Stanford University and the University of Southampton
in England are studying the effectiveness of cancer vaccines. These new
technique use proteins or genes unique to the tumor to generate an immune
response stronger than what might occur naturally. At this stage, these
vaccines are being tested on patients with lymphoma. However, the same
concept can apply to other blood cancers, including myeloma and myeloid
"It's important to understand that these early studies show the utility of a
new, third approach to the treatment of leukemia and lymphoma, known as
Immunotherapy. Our hope is that this approach will increase the cure rate and
decrease the side effects of current therapy," Dr. Lichtman said.
The two-day symposium is sponsored by The Leukemia Society of America, which
dedicated $20 million a year to scientific research for leukemia, lymphoma,
myeloma and Hodgkin's disease in 1998, and Berlex Pharmaceuticals. Held on
September 26-27, the Symposium on Immunotherapy of Leukemia and Lymphoma will
involve more than 200 scientists from the fields of hematology, oncology,
molecular genetics and immunology.
SOURCE Leukemia Society of America
CO: Leukemia Society of America
ST: District of Columbia
09/25/98 08:11 EDT http://www.prnewswire.com
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