From NY Times:
nytimes.com
November 27, 1997
FDA Approves Genetically Engineered Lymphoma Drug
By LAWRENCE M. FISHER
SAN FRANCISCO -- The Food and Drug Administration on Wednesday approved a new genetically engineered drug for the treatment of non-Hodgkin's lymphoma.
The drug, Rituxan, was approved for treating so-called low-grade or
follicular B-cell non-Hodgkin's lymphoma, a slow-growing but fatal and
incurable cancer of the immune system. It will be made and marketed by
Genentech Inc. of South San Francisco.
In clinical trials, Rituxan was shown to be comparable to chemotherapy
in slowing progression of the disease, but with the advantage of fewer
side effects.
Rituxan is the first of a class of drugs called monoclonal antibodies to
be approved for treating cancer, but FDA officials said there are at
least two dozen such drugs in various stages of clinical trials.
Monoclonals, which are genetically engineered copies of powerful immune
system proteins, were one of the first technologies pursued by the
biotechnology industry, but have until recently failed in most
applications.
"To me this is a milestone for monoclonal antibody technology for this
field," said Dr. Kathryn Stein, director of monoclonal antibodies for
the FDA's center for biologicals evaluation and research.
Most impressive is the fact that Rituxan is a so-called "naked"
antibody, meaning that it is not linked to a radioactive or chemical
drug, but is itself an anticancer therapy, she said. "It really is a
turning point."
Because monoclonal antibodies were initially produced in mice, they
caused allergic reactions in human beings, which limited their
effectiveness. The antibodies now advancing in the clinic have been
genetically engineered to be either chimerized, about half human, or
humanized, more than 90 percent human.
Rituxan follows Reopro, from Centocor Inc., an antibody for the
prevention of blood-clotting in heart patients, which was approved in
1996.
"Unquestionably, monoclonals are gathering momentum," said Viren Mehta,
an analyst with Mehta and Isaly in New York. "While it has clearly taken
some time for the basic elements of the science to come together, we now
have the second important monoclonal in a year, and this is just the
beginning."
The most common side effects of Rituxan were moderate flu-like symptoms
that occurred in the majority of patients during the first infusion. And
unlike the typical four- to six-month chemotherapy regimen or high-dose
radiation treatment, Rituxan can be administered in four infusions on an
outpatient basis over a 22-day period.
"Although it is not a cure, we finally have a cancer agent that can be
effective with less serious side effects than with conventional
chemotherapy," said Dr. Myron Czuczman, assistant professor of medicine
at Roswell Park Cancer Institute in Buffalo, N.Y., and a key
investigator of the new drug. "This is exciting news, especially for
elderly patients and relapsed patients who have failed at least one
standard treatment regimen."
Rituxan is the first drug for Idec Pharmaceuticals Inc., a small biotech
company, which discovered the antibody, and licensed it to Genentech for
development. The two companies will share manufacturing, marketing and
sales in the United States, with F. Hoffman-La Roche Ltd. of Switzerland
and Zenyaku Kogyo Company Ltd. of Japan picking up European and Asian
sales. La Roche owns a majority interest in Genentech.
Genentech also has a monoclonal antibody of its own invention in
clinical trials for the treatment of breast cancer, and plans to develop
more drugs based on this technology for other solid tumors.
Monoclonal antibodies target proteins implicated in the cause or
maintenance of cancer, so they can be more specific than a chemical drug
that simply kills fast-growing cells. The more specific a drug, the
lower the toxicity, meaning physicians can prescribe higher doses
without running into serious side effects.
Rituxan works by binding to a protein known as the CD20 antigen on the
surface of mature B cells and B-cell tumors. Then it recruits the body's
natural defenses to attack and kill both malignant and normal mature B
cells.
Because stem cells present in the bone marrow lack the CD20 antigen they
are not affected by the drug, and in clinical studies returned to normal
levels within several months of the completion of treatment. Once
Rituxan has cleared the body the stem cells can mature into normal
differentiated cells like B cells.
Idec shares closed Wednesday at $35, down 9/16, in Nasdaq trading.
Genentech shares closed at $58 5/16, up 1/8, in Nasdaq trading. Analysts
said the modest movement in the stock reflected the fact that most
investors already assumed Rituxan would be approved.
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