n033  1108  03 Oct 80
 
BC-INTERFERON
(Newhouse 002)
By PATRICK YOUNG
Newhouse News Service
    WASHINGTON - The American Cancer Society, which is spending $5.8
million to test the effectiveness of interferon against four types of
cancer, has discovered that some freeze-dried supplies of the drug
lose their potency if stored too long.
    None of the 112 cancer patients tested thus far was treated with
interferon that had been reduced in strength, according to the cancer
society. And its scientists now are switching from freeze-dried,
room-temperature storage of interferon to preservation of the drug by
conventional freezing.
    ''There was no loss of potency in the interferon used so far because
we used it within a few weeks of getting it,'' said Dr. Frank J.
Rauscher Jr., the society's vice president for research. But some
interferon stored for later use was found to have lost some of its
biological activity.
    Rauscher reviewed the potency problem and the most recent treatment
results at a meeting Wednesday and Thursday with researchers
conducting the interferon tests.
    ''We are seeing a 25 percent to 40 percent positive response rate,''
he said. The results vary depending on the type of cancer treated,
ranging from complete remission to minor reduction in tumor size.
    ''We're not dealing with a magic bullet,'' Rauscher said. ''I'm
enthusiastic ... . But when I say 40 percent are responding, that
means that 60 percent are not responding. So we have to learn why
that 60 percent didn't respond.''
    Interferon occurs naturally in the body. It was discovered in 1957
and found to aid the body in battling viruses. In recent years, some
research indicated it was effective in treating cancer.
    The American Cancer Society tests began last year at a number of
medical centers in cases of recurrent breast cancer, multiple myeloma
(a cancer of the bone marrow), lymphoma (cancer of the lymph system),
and melanoma (cancer of the skin pigment cells).
    The federal government's National Cancer Institute is preparing its
own $10 million interferon study.
    Only human interferon will work in humans, and the substance is
difficult to obtain from cells growing in the laboratory. Different
cells make slightly different types of interferon.
    The cancer society currently is using interferon obtained from white
blood cells called leukocytes. It is this type that can lose potency
if freeze-dried.
    The problem fiientists in Finland and Sweden.
The cancer society initially thought the discovery might explain why
its tests weren't proving as succecal activity just before it is
given to patients. Stored interferon is checked periodically fency. Thus, said -
Rauscher, the society satisfied itself that no
patient got ineffective interferon.
    The society also has ordered supplies of a type of interferon that
is obtained from connective-tissue cells called fibroblasts. This
version of the drug - unlike the leukocyte variety - doesn't lose
potency after freeze-drying, Rauscher said.
    The National Cancer Institute will use both types of interferon in
its test. The leukocyte interferon will be frozen; the fibroblast
interferon will be preserved by freeze-drying.
RB     END YOUNG
 
    
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a567  1927  18 Oct 80
sa
BC-APN--Interferon, adv 02-3 takes,400-1,320
$adv 02
AGENCIES AND RADIO OUT
Controversial Drug Remains Controversial
For release Sun., Nov. 2
From AP Newsfeatures
APN PRINT SUBSCRIBERS HAVE BEEN MAILED ONE ILLUSTRATION
    EDITOR'S NOTE - Few new drugs of recent years have caught more
attention than interferon as possible anti-cancer agents. Research
proceeds, amid some positive findings, but the chance of a quick
breakthrough is receding. Here's a progress report on the clinical
testing to date.
By BRIAN SULLIVAN
AP Science Writer
    NEW YORK (AP) - Whatever role the drug interferon may ultimately
play in the battle against cancer, clearcut scientific results still
seem a long way off.
    Clinical research so far has shown that interferon does indeed have
an effect on cancer - and that it has relatively few side effects.
    But results have been mixed and research has been slowed by a
shortage of the drug and preparations of insufficient purity.
    ''Interferon is still in the earlier stages of clinical testing,''
the American Cancer Society points out.
    And now researchers are reporting new laboratory findings that show
just how complicated interferon is. There may be, for example, as
many as l0 to l5 different genes that produce different series of
interferon.
    This could both complicate the use of the various strains of
interferon, and also explain the varying responses in patients to the
drugs being tested. In the long run, the full understanding of
interferon lies in further discoveries through basic research.
    One researcher who believes that interferon is ''clearly promising''
is Dr. Susan Krown of Memorial Hospital Sloan-Kettering Cancer
Center, who has given the drug to l8 patients. But she adds:
    ''Most of the interferon studies so far haven't proven anything
except that we need to do more studies.
    ''People have read things that make them think this is some kind of
miracle cure,'' Dr. Krown says. ''Because interferon is scarce and
our studies are limited, we have to turn down patients every day who
have invested a lot of emotional energy in trying to get interferon.
    ''When they can't get it, they feel like they're being cheated out
of something that's the answer for them. It's sad.''
    In a report of her work with the drug to a recent cancer meeting,
Dr. Krown attempted to put the role of interferon into perspective.
    ''I think it likely that interferon's potential in man will be best
realized not as a single agent, but rather in combination with
chemotherapy or as an adjutant to surgery when tumor burden is low.''
    And many researchers now believe it could take a decade before all
the questions are answered and interferon can take its place in the
arsenal of weapons against cancer.
    ''Attaining this end,'' Dr. Krown concludes, ''will require
continued investigation of the mechanism of interferon's action, the
possible variation in therapeutic activity of different types of
interferon and clinical trials with interferon preparations of
increasing purity.''
    MORE
    
ap-ny-10-18 2225EDT
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a568  1935  18 Oct 80
BC-APN--Interferon, adv 02-1st add,420
$adv 02
AGENCIES AND RADIO OUT
For release Sun., Nov. 2
NEW YORK: increasing purity.''
    The mixed reactions among researchers are due to such findings as
those reported earlier this year showing ''some significant response''
in only four of l4 patients with the bone cancer called multiple
myeloma, and a ''partial response'' in five of l6 women with breast
cancer - results less impressive than previous studies reported by
European scientists.
    However, the results are significant enough ''to satisfy us that the
interferon used, even though it is only one one-thousandth pure, has
definite anti-cancer activity,'' says Dr. Frank J. Rauscher, senior
vice president for research of the American Cancer Society.
    Because of this potential, trials will continue with these aims:
    Why does interferon help some patients and not others? How long do
the benefits last? What are the optimal doses, which may have been too
low? How long should treatment be continued? What will be the results
in combining interferon with other drugs? What are the differences
among the three different forms of interferon?
    The widespread public interest and expectation in interferon began
with an unusual move - the announcement in August, l978, by the
American Cancer Society that it was allocating $2 million on short
notice for the initial purchase of the costly drug for the early
clinical trials at l0 institutions. The ACS contribution has reached a
total of $5.8 million.
    The cost of treating a single patient can range up to $30,000 now,
the ACS says.
    Last June, the Shell Oil Co. gave the ACS $1 million for the
interferon work. It also gave another $1 million to the Interferon
Foundation in Houston. The foundation co-founders, Leon Davis and Roy
Huffington, say they hope to raise $20 million over the next two
years for research. The National Cancer Institute has a $9 million
research program and the National Institute of Allergy and Infectious
Diseases has allocated $3.59 million.
    But more ice water has been thrown on any immediate widespread use
of interferon by the American Society of Clinical Oncology, an
organization of cancer specialists.
    A society resolution warned that it can be a ''toxic drug that
causes chills, fever, lowered blood pressure and depression of blood
counts'' - all this in a substance once described as virtually free of
side effects.
    ''Any benefit achieved has frequently been equivocal and very
transitory,'' the resolution said. ''There is no evidence or even
remote suggestion that interferon may be curative for advanced cancer.
    ''At this time, there is no acceptable evidence that interferon is
capable of extending life expectancy for cancer patients regardless of
type, or stage of malignant disease.''
    MORE
    
ap-ny-10-18 2234EDT
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a569  1949  18 Oct 80
BC-APN--Interferon, adv 02-2nd add,500
$adv 02
AGENCIES AND RADIO OUT
For release Sun., Nov. 2
NEW YORK: malignant disease.''
    In the new basic research, the discovery of multiple genes for
interferon was reported in a recent issue of the British journal
Nature by Shigekazu Nagata, Ned Mantei and Charles Weissmann of the
Institute for Molecular Biology at the University of Zurich. They
concluded that at least eight but perhaps as many as l0 or l5 distinct
interferon genes exist.
    Researchers at the Wellcome Research Laboratories in England,
Geoffrey Allen and Karl H. Fantes, reporting on a family of structural
genes for human leukocyte interferon, say ''possibly, different
interferon gene products have different biological activities,'' or
different functions toward different target cells, or may be induced
by different viruses.
    The three known forms of interferon are: human leukocyte interferon,
made from white blood cells; human fibroblast interferon, made from
connective tissue cells; and immune or lymphoblastoid interferon,
which involves the so-called ''T'' lymphocytes that play a role in the
body's natural defense mechanism or immune reactions.
    One possible approach to the problem of short supply may be the use
of recombinant DNA or ''gene splicing'' techniques to produce
interferon, by isolating genes of human interferon and splicing them
into bacteria where they grown to become ''factories'' for producing
the substance.
    Another possibility is to synthesize the interferon itself, or part
of it. To do this, researchers will need to know the precise chemical
structure of the molecule.
    A human leukocyte interferon has been synthesized and cloned, report
several researchers from Genentech, Inc., of San Francisco, and the
Roche Institute for Molecular Biology, Nutley, N.J. This interferon
protected squirrel monkeys from a usually lethal virus infection. The
work suggests a fresh look at interferon's original attraction, as an
anti-viral agent.
    For now, however, efforts by the ACS are centering on enlarging the
available supply of interferon for clinical testing.
    The ACS is considering the purchase, ''very soon,'' of another $2
million in leukocyte interferon, to expand the original clinical
trials on four different types of tumors. The Finnish production
laboratory of Dr. Kari Cantell is behind its timetable, having
delivered three-fourths of the promised 40 billion units of the
leukocyte variety at a cost of $2 million. Cantell hopes to complete
the order by the end of the year.
    A grant of $1.4 million was made recently to Roswell Park Memorial
Institute in Buffalo to produce about 24 billion units of fibroblast
interferon.
    In evaluating the clinical testing so far, the Cancer Society's Dr.
Rauscher says it has achieved its original major objectives, one of
which was to determine if interferon is active against human cancers.
''It is,'' he says, ''with 25 to 40 percent of patients with each of
the four types of tumors under test showing some degree of
response.''
    A most interesting aspect of the clinical testing, Dr. Rauscher and
others believe, is that ''the crude preparations of interferon so far
available, having been shown to be active and of relatively low
toxicity, may in fact be the prototypes of a whole new class of
compounds for the treatment of cancer.
    ''However,'' the ACS says, ''a tremendous amount of research remains
to be done before this view can be confirmed. Interferon is still in
the earliest stages of clinical testing.
    END ADV
    
ap-ny-10-18 2247EDT
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a030  0120  24 Oct 80
PM-Cancer Treatment,610
Breast Cancer Becoming a ''Curable'' Disease, Doctors Say
By KEVIN McKEAN
AP Science Writer
    NEW YORK (AP) - A treatment combining surgery and drugs is making
breast cancer a ''curable'' disease, according to a long-term study of
the therapy which has been used for more than a decade.
    The drugs have unpleasant side effects for patients, but when used
after surgery improved the survival rate of women who were seen as
likely to experience more cancer, the study said.
    ''This represents a substantial advance and places breast cancer
among the curable cancers like Hodgkin's disease,'' said Dr. Ezra
Greenspan of Mount Sinai School of Medicine, who is a longtime
advocate of chemotherapy.
    Greenspan and Dr. Richard Cooper of the State University of New York
at Buffalo called a news conference in New York to discuss the latest
results from Cooper's study of drug therapy.
    The results were presented Thursday at a meeting of the Chemotherapy
Foundation, of which Greenspan is chairman and medical director.
    The study followed 100 breast cancer patients who had operations to
remove the cancer. The patients then had nine months of chemotherapy
with five different anti-cancer drugs, some with and some without
additional radiation therapy.
    Cooper said that all of the women were considered likely to have a
recurrence of the cancer. In all of them, doctors had found evidence
of cancer in at least four of the dozen or so lymph nodes commonly
removed for analysis at the time of surgery.
    Spread of cancer to the lymph nodes is considered a sign that the
disease is more likely to reappear.
    But eight years after the last of the 100 women was treated, 68 are
alive and cancer-free, compared with an expected disease-free
survival of fewer than 15 with surgery alone, Cooper said.
    The disease-free survival rate of about 70 percent among the women
approaches the rate for women in whom no lymph nodes are cancerous,
Cooper said.
    ''In other words, the data has stood the test of time and one must
realize that we're witnessing the cure of a substantial number of
breast cancers,'' Greenspan said.
    The anti-cancer drugs caused hair loss, weight gain and even nausea
and vomiting in some women, Cooper said, but most side effects went
away after treatment.
    In another cancer study, published in today's edition of the Journal
of the American Medical Association, doctors at the Medical College
of Wisconsin in Milwaukee suggest radiation therapy may extend the
lives of some patients with inoperable lung cancer.
    The study concentrated on inoperable lung cancer patients who had
no, or few, symptoms of the disease. There is a medical controversy
over whether such patients should be treated at all since the evidence
is mixed on whether it does any good.
    But Drs. James Cox, Ritsuko Komaki and Donald Eierst said that in
their study, radiation seemed to extend the lives of patients for whom
the treatment kept tumors from growing.
    Meanwhile, in Atlanta, a Washington University medical school
professor said researchers will begin treating animals shortly with a
powerful new form of interferon, an anti-viral agent found in the
body's immunity system.
    ''More work needs to be done before we tell people with terminal
cancer there is hope on the horizon,'' said Dr. William J. Catalona.
    Type II interferon is 200 times more effective at killing cancer
cells than the Type I now used in experiments on humans, he told the
clinical congress of the American College of Surgeons on Wednesday.
    The new form is more difficult to work with than Type I because it
can only be produced by white blood cells, Catalona said. Type I
interferon can be produced by any cell stimulated with certain
chemicals.
    
ap-ny-10-24 0420EDT
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a237  1546  24 Oct 80
AM-Interferon-Aspirin,510
Aspirin and Arthritis Drugs May Block Interferon
By KEVIN McKEAN
AP Science Writer
    NEW YORK (AP) - Aspirin and many prescription arthritis drugs
apparently can block the effect of interferon, a finding that poses
questions for research into the potent natural anti-viral substance.
    Scientists at Duke University and Wellcome Research Laboratories
have discovered that aspirin and the arthritis drugs reduce the extent
to which interferon protects cells against viruses, provided the
drugs are added before interferon has a chance to go to work.
    The scientists stressed their work was done in mouse cells growing
in an artificial medium, and there was no guarantee the same thing
would happen in live animals, much less human beings.
    Nevertheless, if confirmed, the effect of aspirin on interferon
might be important for the current trials of interferon in human
cancer patients, some of whom may have taken aspirin without their
doctors' knowledge.
    The new study could throw doubt on the wisdom of taking aspirin for
a cold or other virus-caused diseases, as it raises the possibility
that aspirin inhibits the body's production of interferon, enabling
cold viruses to multiply more rapidly. Whether this would affect the
duration or severity of a cold is unknown.
    Interferon is a natural substance produced by the body as a first
line of defense against viruses. It may also provide some protection
against cancer, and hundreds of cancer patients have taken it in
experiments to find out whether this would be useful in treatment.
    ''This might make interferon a more useful modality (treatment) if
we can enhance its effectiveness by knowing what things interfere with
it,'' said Dr. David Lang of his research.
    The study, published in the current Proceedings of the National
Academy of Sciences, was done by Drs. Raveendran Pottathil and Lang,
both formerly of Duke and now at the University of Maryland, and Drs.
Kuttikkat Chandrabose and Pedro Cuatrecasas of the Wellcome labs at
Research Triangle Park, N.C. The laboratories are a subsidiary of the
British pharmaceutical firm Burroughs Wellcome Co.
    The scientists said aspirin and the arthritis drugs, which included
indomethacin, phenylbutazone and oxyphenylbutazone, apparently
inhibit some early step in the biochemical process by which interferon
makes cells resistant to viruses.
    The extent of inhibition was proportional to the extent to which
each of the drugs blocks an enzyme known as ''cyclooxygenase'' which
is essential to the manufacture of prostaglandins, hormone-like
chemicals found throughout the body.
    The link between prostaglandins and interferon adds another piece to
the still unsolved puzzle of how interferon works.
    If the drugs also inhibit interferon in living animals, then
patients taking interferon for therapy might have to stay away from
the drugs or take them in moderation. Patients in such studies are
routinely told not to take other drugs, but some disobey.
    The study also may explain why people who take aspirin for a cold
seem to have more virus particles in their mucus as a result.
    Pottathil said he is seeking funds to investigate whether aspirin
and the other drugs have the same effect in living mice. And
Chandrabose said the scientists hope to cooperate with doctors at the
University of North Carolina to see whether the drugs have any effect
on cancer patients taking interferon for therapy.
    
ap-ny-10-24 1845EDT
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a032  0159  25 Oct 80
PM-Interferon-Aspirin,520
Aspirin May Slow a Potent Natural Virus Fighter
By KEVIN McKEAN
AP Science Writer
    NEW YORK (AP) - Aspirin, the drug thousands of Americans reach for
at the sign of a cold or flu, may inhibit the work of interferon,
which is being studied as a possible cancer-fighting drug, researchers
say.
    The finding is the result of preliminary test-tube research and
needs more work for confirmation. But the discovery may lead to
questions about some of the research done to date on interferon, a
natural substance that is the body's first line of defense against
viruses.
    Scientists have speculated that interferon may provide some
protection against cancer.
    Scientists at Duke University in Durham, N.C., and nearby Wellcome
Research Laboratories, working with mouse cells growing in an
artificial medium, found that aspirin and several common arthritis
drugs limited the extent to which interferon could protect cells
against virus infection.
    The scientists said there is no way to tell whether aspirin and the
other drugs would have the same effect in live animals.
    If the drugs do work the same way in humans, questions may be raised
about the highly publicized studies of interferon's effect on human
cancer. Patients in those studies are warned not to take aspirin or
other drugs, but some do anyway.
    ''This might make interferon a more useful modality (treatment) if
we can enhance its effectiveness by knowing what things interfere with
it,'' said Dr. David Lang, one of the authors of the study.
    It also could influence a doctor's determination of whether to
prescribe aspirin for virus infections like the common cold.
    Doctors have known for several years that taking aspirin increases
the number of virus particles present in the mucus of cold victims.
The new study suggests a possible reason why - aspirin may lower the
body's interferon defense slightly and allow viruses to proliferate.
    The study was done by Drs. Raveendran Pottathil and Lang, both
formerly of Duke but now of the University of Maryland where Lang is
chairman of pediatrics. Drs. Kuttikkat Chandrabose and Pedro
Cuatrecasas of the Wellcome labs at Research Triangle Park, N.C., also
participated.
    The results were published in the current issue of the Proceedings
of the National Academy of Sciences.
    The scientists said aspirin and the arthritis drugs - which included
indomethacin, phenylbutazone and oxyphenylbutazone - apparently
slowed down some early step in the biochemical process by which
interferon makes cells resistant to viruses.
    The extent of inhibition was proportional to the extent to which
each of the drugs blocked an enzyme known as ''cyclooxygenase'' which
is essential to the manufacture of prostaglandins, hormone-like
chemicals found throughout the body.
    The link between prostaglandins and interferon adds another piece to
the still unsolved puzzle of how interferon works.
    Pottathil said he is seeking funds to investigate whether aspirin
and the other drugs have the same effect in living mice.
    Chandrabose said the scientists hope to cooperate with doctors at
the University of North Carolina to see whether the drugs have any
effect on cancer patients taking interferon for therapy.
    
ap-ny-10-25 0458EDT
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a060  0432  12 Nov 80
PM-Interferon,470
Interferon: A Cancer Weapon, But Not 'The Cure'
By WARREN E. LEARY
AP Science Writer
    WASHINGTON (AP) - Interferon may prove to be a major weapon against
cancer, but the anti-viral protein is not ''the cure'' people hope
for, says a prominent researcher.
    Dr. William E. Stewart, chairman of the first annual International
Congress for Interferon Research, said Tuesday that the public has
been oversold on interferon.
    ''There isn't any simplistic cure for cancer,'' said Stewart, of the
Sloan-Kettering Institute for Cancer Research in New York City.
    ''Interferon is not going to live up to all the expectations,'' he
said in an interview. ''Interferon will be important, but it will be
supplemental to present therapies, although possibly replacing some.''
    Stewart noted, however, that interferon research has benefited from
the public interest in a quick cure for cancer. Many researchers now
are looking at the body proteins and have made significant advances
in just a couple of years, he said.
    ''The progress has been breathtaking,'' Stewart said.
    In just the last year, for example, scientists have been able to
decipher the arrangement of amino acids that make up several different
types of interferon proteins, he said.
    This information is essential if researchers are to learn how to
synthesize the substances and to find their active components.
    Interferon is a broad term used to describe the naturally occurring
proteins. No one is sure how many different kinds of interferon are
in the body, but the proteins found in different types of cells have
different properties.
    Scientists recently established three general categories - alpha,
beta and gamma - in which to put interferons according to
similarities.
    The scientific interest in interferons goes far beyond its potential
against cancer, Stewart said.
    Some of the few substances known to act against viruses, they can
inhibit cell growth. There also is evidence they can muster the body's
immune system to fight disease, he said.
    Although these properties inspire interest in the therapeutic
potential of interferon, results so far have been mixed.
    Researchers at the meeting reported some response in patients given
interferon for varying cancers as well as viral diseases, such as
hepatitis. But the results were mixed and in no case overwhelming.
    For example, American breast cancer studies show that only a third
of the women with the disease got a ''partial response'' with
interferon treatment. Better results were noted, however, in some
European studies.
    Dr. Thomas C. Merigan of Stanford University reported that in pilot
tests with victims of hepatitis-B, alpha interferon eradicated the
disease in only 25 percent of the cases. However, when combined with
another antiviral agent called ARA-A, the treatment worked in 44
percent of the cases.
    Merigan said the results were promising enough to go ahead with
larger-scale controlled tests.
    Stewart said the recent promise of getting larger quantities of
purer interferon should mean many more clinical tests to find out what
interferon can, and cannot, do.
    
ap-ny-11-12 0732EST
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a229  1215  29 Nov 80
AM-Interferon,610
Scientists Say Two Types Of Interferon Can Work Better Than One
By KEVIN McKEAN
AP Science Writer
    NEW YORK (AP) - Some types of interferon seem to boost the potency
of other types of this natural virus-fighting substance, scientists
have found. The discovery adds insight to the search for interferon
treatments for virus-caused diseases and cancer.
    Scientists at the University of Texas Medical Branch at Galveston
found that combinations of interferons combatted mouse tumors more
effectively than the sum of the tumor-fighting powers of each
interferon alone.
    The finding follows a similar study at the university last year
showing that interferons also boost each other's power to fight
viruses.
    While the conclusions are based on animal and cell-culture
experiments and do not apply directly to humans, ''these results hold
the promise that combined interferon therapy in humans might increase
the efficacy of the interferon therapy and might lower the required
interferon dosage levels,'' the scientists said.
    W. Robert Fleischmann Jr., Kathryn M. Kleyn and Samuel Baron
published their report in the latest Journal of the National Cancer
Institute.
    Interferon is a natural substance discovered 23 years ago which
helps protect the body against viruses. Because it can shrink some
animal tumors, it is also under study as a possible cancer treatment.
It is expensive to manufacture and difficult to purify, and results
against human cancer have often been disappointing.
    The Texas scientists found that, in mice, a relatively new and
unstudied type of interferon known as ''immune'' interferon seemed to
boost the anti-tumor potency of a more conventional type, called
''virus-induced'' interferon.
    Tumors in animals treated with the virus-induced interferon alone
grew more slowly than in untreated animals. But the delay in growth
was nearly doubled when the two interferons were combined, despite the
fact that the immune interferon alone had virtually no effect on the
tumors.
    All but one of the 76 mice eventually died from the transplanted
leukemia which was used in the experiment, the scientists said. But
Fleischmann said in a telephone interview that against other mouse
cancers less resistant to interferon, the combined treatment has
sometimes achieved cures.
    ''We showed you could add something which didn't have any effect to
something which had a modest effect and get a much greater effect,''
he said.
    This shows that ''whatever the results of the clinical interferon
trials so far, we may not have used the best methods for those trials
although we used the best methods available at the time. The best may
be yet to come in interferon's role in therapy,'' Fleischmann said.
    Baron, Howard Johnson and Jerzy Georgiades of the Medical Branch
plan to work with Jordan Gutterman of the M.D. Anderson Hospital and
Tumor Institute in Houston to see whether the human form of immune
interferon can boost the power of other human interferons in cancer
patients.
    The scientists have been able to manufacture and purify the immune
interferon, but are still working to get it to remain stable in frozen
storage.
    Most interferon trials with patients so far - including the
much-publicized American Cancer Society trial which Gutterman heads -
have used human ''leukocyte'' interferon.
    Leukocyte interferon is the best-studied and most readily available
form, and is broadly related to virus-induced interferon in the
mouse. The third known type of human interferon, also similar to mouse
virus-induced interferon, is called ''fibroblast'' interferon.
Scientists suspect several more types of human interferons may yet be
found.
    
ap-ny-11-29 1515EST