       TreatmentUpdate 62 - Volume 7, No. 8 - August 1995
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       Published by Community AIDS Treatment Information
       Exchange (CATIE), 420-517 rue College St., Toronto,
       ONT Canada M6G 4A2
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       I  HIV/AIDS THEORY

       A. HIV/AIDS: an overall picture

       What usually happens when people first become infected with
HIV is that the virus infects many cells which, in turn, produce a
huge number of viruses (detectable in blood samples). The immune
system responds by producing T cells which attack HIV-infected
cells. Later, B cells make antibodies to attack the virus. During
this response people may experience symptoms of a flu-like syndrome.
Levels of HIV in the blood quickly fall and symptoms clear. For many
years the immune system appears to "trap" the virus in the lymph
nodes and tissues. Although infected people may live for many years
without symptoms, the virus continues to infect CD4+ cells and other
cells, such as macrophages.

       Infected CD4+ cells may not immediately begin to turn into
'virus factories.' Research suggests that HIV stays silent in those
cells until the cells are activated. Activation may occur because
the immune system is stimulated by other infections, but given that
HIV-infection is a chronic infection, some researchers think the
virus itself could cause the activation signal. Once the cell
becomes activated, the virus can take over and cause the cell to
produce new viruses. Over many years (10 to 15) this hidden
infection may destroy many CD4+ cells. In the final years of HIV
infection, it appears that lymph nodes become damaged and contain
fewer cells. When they collapse, the nodes release HIV which enters
the blood, and it is believed that this may increase the amount of
HIV in the blood. Although researchers have an overall picture of
what happens to an HIV-infected immune system, many questions remain
unanswered.

       * MONKEYS WITH AIDS

       State of the art research on HIV-infected humans and monkeys
infected with the related SIV suggest that events in the lymph nodes
and tissues are important. Research teams are studying lymph nodes
to try and understand how HIV infection damages them. In this issue
of TreatmentUpdate we present reports on:

       - a study looking at what happens to T cells in the lymph
         nodes of HIV-infected subjects

       - studies of AZT's effects on the amount of HIV in T cells in
         the blood (viral load)

       - results from trials of newer anti-HIV agents called
         proteinase or protease (they mean the same thing)
         inhibitors.

       REFERENCES:

              1. Koup RA, Safrit JT, Cao Y. et al. Temporal
       association of cellular immune responses with initial control
       of viraemia in primary Human Immunodeficiency Virus type 1
       syndrome. Journal of Virology 1994;64(7):4650-4655.

              2. Panteleo G. Menzo S. Vaccarezza M, et al. Studies
       in subjects with long-term non-progressive Human
       Immunodeficiency Virus infection. New England Journal of
       Medicine 1995;323(4):209-216.

              3. Embretson J. Zupanic M, Ribas IL. Massive covert
       infection of helper T lymphocytes and macrophages by HIV
       during the incubation of AIDS. Nature 1993;362:359-362.

              4. Fields BN. AIDS: time to turn to basic science.
       Nature 1994;369:95-96.

              5. Rosenberg YJ, Lewis MG, Leon EC, et al. Viral DNA
       burden and decline in percentage of CD4-positive cells in the
       lymphoid compartments of SIV-infected macaques. AIDS Research
       and Human Retroviruses 1994;10(10):1269-1276.


       B. Benefit(s) from anti-HIV drugs

       * BACKGROUND

       Although a number of anti-HIV drugs are licensed for the
treatment of HIV/AIDS, ultimately none of these drugs improve
survival compared to subjects who do not use these drugs. Even
though AZT can cause statistically significant increases in CD4+
cell counts, the benefit is temporary. Drug manufacturers are trying
to find other ways to show that their products provide benefit to
users. What's more, doctors and their patients with HIV/AIDS may not
be sure when to start or stop using those drugs. As one American
doctor noted:

          "I remember when [AZT] increased everyone's CD4+ cell
          counts; when it increased CD4+ cell counts when they were
          greater than [200 cells]; when it increased CD4+ cell
          counts for long periods; when it raised them for only a
          few weeks; when high [CD4/CD8] ratios were good; and when
          [CD4/CD8] ratios were no longer important (long term
          survivors had high CD8+ cell levels)."

       Moreover, since 98% of CD4+ cells are located in the lymph
nodes/tissues, it is not clear that measuring 2% of lymphocytes in
the blood will provide accurate information as to how well anti-HIV
agents work. Research teams are trying to bridge the gap between the
two locations of cells by devising various tests and studying lymph
node samples from subjects with HIV/AIDS and also from monkeys with
SIV/AIDS.

       * LYMPH NODES/TISSUES

       SIV is related to HIV and can cause AIDS in certain monkeys.
Researchers studying monkeys with "early-stage SIV-infection" found
that:

       - lymph nodes with normal proportions of CD4+ and CD8+ cells
         usually occur in monkeys with low levels of SIV-infection
         of cells in the blood.

       - In monkeys with AIDS, less than normal proportions of CD4+
         and CD8+ cells were found in lymph nodes, while increased
         numbers of SIV-infected blood cells were detected. The
         decline in CD4+ and CD8+ cells in the lymph nodes may occur
         before the number of SIV infected cells in the blood
         increases.

       The results of further studies of lymph nodes of HIV-
infected subjects using anti-HIV drugs may prove interesting. Among
humans with breast cancer (without HIV infection), the proportion of
CD4+ and CD8+ cells in lymph nodes can be different from that found
in healthy humans without breast cancer.

       * VIRAL LOAD

       One lab test that is receiving increased attention is the
viral load test. This usually refers to the amount of cells infected
with HIV in the blood. The theory underpinning this test is that
AIDS is a condition caused by a virus. Treatment with anti-HIV
agents should reduce the amount of virus being made by HIV-infected
cells. Therefore people using these drugs should benefit from a
decline in viral production. As well, among patients using anti-HIV
drugs, an increased viral load may suggest that HIV has become
resistant to these drugs. There are tests that can measure the
amount of virus in the blood (outside of blood cells), however,
detecting changes in viral load may not always be useful nor linked
to the development of symptoms or survival.

       There is also the issue of measuring viral load in lymph
nodes and its relation to viral load in the blood. Given recent
findings from human lymph node analyses (see next article) that
report no relation between viral load and the number of T-cells
being destroyed, there is reason to wonder about the role of such
testing. Hopefully this issue will become clear over the next year.
The following example illustrates this difficulty:

          "Spencer Cox, a member of the AIDS-treatment watchdog
          group TAG, cites the infamous example of arrhythmia, in
          which the heart beats irregularly. Applying common sense,
          researchers assumed that arrhythmia was a surrogate marker
          for cardiac failure. Two drugs were developed that
          suppressed arrhythmia quite effectively, but bath drugs
          also caused fatal heart attacks. If you take out the word
          arrhythmia and put in the wards viral burden, says Con,
          we're having the same conversation."

       According to Dr. Deborah Cotton (Mass. General Hospital, and
Harvard Medical School, Boston), "the only sure way to tell whether
a drug works...is to conduct large clinical trials that measure
actual survival and [the development of symptoms of AIDS]."

       A problem with this approach is that people with HIV/ AIDS do
not have the time to wait for those results.

       REFERENCES:

              1. Harris PJ. CD4+ cell counts as surrogate markers
       for progression to AIDS. Annals of Internal Medicine
       1994;120(1):88.

              2. Rosenberg YJ, Lewis MG, Leon EC, et al. Viral DNA
       burden and decline in percentage of CD4-positive cells in the
       lymphoid compartments of SIV-infected macaques. AIDS
       Research and Human Retroviruses 1994;10(10):1269-1276

              3. Whitford Pj Alam SM, George WD and Campbell AM.
       Flow cytometric analysis of tumour-draining lymph nodes in
       breast cancer patients. European Journal of Cancer
       1992;28(2/3):350-356.

              4. Margolis LB, Glushakova S. Baibakov B and
       Zimmerberg J. Syncytium formation in cultured human lymphoid
       tissue: fusion of implanted HIV glycoprotein
       14/120-expressing cells with native CD4+ cells. AIDS Research
       and Human Retroviruses 1995;11(6):697 704.

              5. Schoofs M. A new AIDS trial tries to stop HIV by
       attacking it early. Village Voice 15 August, 1995, pages
       23-25.


       C. Looking inside lymph nodes

       * BACKGROUND

       The slow loss of CD4+ cells over time eventually weakens the
immune system's ability to keep infections under control. Most CD4+
cells (98%) are found in lymph nodes and tissues and in organs such
as the spleen. Only 2% of these cells are in the blood. Therefore,
researchers are studying what happens to these cells in the lymph
nodes of HIV-infected humans and SIV-infected monkeys. Although HIV
can infect and destroy CD4+ cells, these cells may also be destroyed
in other ways. CD4+ cells have the ability to destroy themselves
through a method called programmed cell death (PCD) or apoptosis.
Cells of the immune system that are exhausted and unable to fight
infections can also undergo apoptosis. Researchers describe these
cells as anergic. One research team in the USA has recently released
their results from a study of lymph nodes taken from 67 HIV-infected
subjects in various stages of HIV/AIDS and from 15 healthy,
non-HIV-infected subjects for comparison. They also looked at the
amount of cells which were undergoing apoptosis.

       * RESULT-INSIDE THE NODES

       In the lymph nodes taken from HIV-infected subjects the
researchers found that the level of apoptosis was not related to the
CD4+ cell count nor the number of T cells that were infected with
HIV. All lymph nodes taken from HIV-infected subjects showed some
level of apoptosis, while the researchers detected apoptosis in only
50% of lymph node samples from the non-HIV-infected subjects. The
difference in the number of cells undergoing apoptosis between the
two groups was statistically significant, that is, not likely due to
chance alone. The researchers also found that in addition to CD4+
cells, CD8+ and B cells were also undergoing apoptosis.

       * WHAT CAUSES APOPTOSIS?

       Cells of the immune system can capture invading microbes (or
pieces of them) and take them to the lymph nodes where many more
cells can be alerted and activated to prepare them for fighting the
infection. The research team thinks that the activation of cells by
the immune system of people with HIV/AIDS either prepares cells to
engage in or directly cause apoptosis. Activation may also result
from the continuous attacks on the immune system by HIV, thereby
causing apoptosis of T and B cells on a regular basis. Levels of
apoptosis in the blood of HIV-infected subjects in this study were
very low compared to levels in the lymph nodes. Finally, the level
of apoptosis in the lymph nodes of HIV-infected subjects was not
related to viral load.

       * WHAT NEXT?

       Further research needs to be done to investigate these
events. If the cells that are undergoing apoptosis are exhausted
immunologically (anergic), that is they cannot perform their
functions such as controlling infections, apoptosis may not
necessarily be a bad event as such cells are not useful. It is
critical that researchers discover just how HIV weakens the immune
system and how CD4+ and other cells become anergic.

       In related research, another team has found that exposing
healthy, non-HIV-infected CD4+ cells to the HIV protein gp120 can
trigger those cells to commit suicide.

       REFERENCES:

              1. Muro-Cacho CA, Pantaleo G and Fauci AS. Analysis of
       apoptosis in lymph nodes of HIV-infected persons: intensity
       of apoptosis correlates with the general state of activation
       of the lymphoid tissue and not with disease or viral burden.
       Journal of Immunology 1995; 154:5555-5566.

              2. Laurent-Crawford AG, Coccia E, Krust B and
       Hovanessian AG. Membrane expressed HIV envelope glycoprotein
       heterodimer is a powerful inducer of cell death in uninfected
       CD4+ target cells. Research in Virology 1995;146:5-17.

              3. Cohen JJ. Exponential growth in apoptosis.
       Immunology Today 1995;16(7):346-348.


       D. AZT and ddI--samples from lymph nodes

       * STUDY DETAILS

       To discover changes in the production of HIV in 16 subjects
using anti-HIV drugs, one research team in the USA has been
comparing blood and lymph node samples of HIV-infected subjects. The
researchers reported data on 16 subjects (1 female, 15 males) whose
average CD4+ cell count was about 400 cells. All subjects had used
AZT between 300 and 600 mg/day for at least 6 months before
entering this study. The researchers randomly assigned 10 subjects
to receive continued AZT and 6 others to continue taking AZT and ddI
200 mg twice daily. Researchers took blood and lymph node samples at
the beginning of the study and again 8 weeks later.

       * RESULTS--CONTINUED AZT

       Production of virus from HIV-infected cells in the lymph
nodes remained relatively high during the 8 weeks of the study while
it remained "relatively unchanged" in cells taken from the blood.

       * RESULTS-AZT AND DDI

       Cells taken from lymph of 4 subjects receiving both drugs had
a "sharp decrease" in production of HIV by the 8th week of the
study. This change, when compared with the results from subjects who
used AZT alone was not statistically significant. In the remaining 2
subjects, production of HIV increased in one and remained stable in
the other. Again, production of HIV in cells in the blood remained
low. Statistically significant changes in the amount of viruses in
the blood occurred in 4 of 6 subjects.

       * LYMPH NODES VERSUS BLOOD

       The researchers confirmed that the amount of HIV produced by
infected cells was greater in the lymph nodes (ranging from 3 to 200
times more) than in cells taken from blood. Decreases in the amount
of HIV in the blood happened simultaneously with decreases in the
lymph nodes. Unfortunately the researchers did not explain why they
decided to test lymph node samples after only 8 weeks, nor did they
release data on survival or the incidence of life-threatening
infections. They concluded by stating that measuring the amount of
virus in the blood (but not inside blood cells) likely reflects the
changes in production of HIV in the lymph nodes.

       REFERENCES:

              1. Cohen OJ, Pantaleo G. Holodniy M, et al. Decreased
       Human Immunodeficiency Virus type I plasma viraemia during
       antiretroviral therapy reflects down regulation of viral
       replication in lymphoid tissue. Proceedings of the National
       Academy of Sciences USA 1995;92:6017-6021.

              2. Simmonds P. Zhang LQ, McOmish F. et al.
       Discontinuous sequence change of Human Immunodeficiency Virus
       (HIV) type 1 env sequences in plasma viral and lymphocyte
       associated proviral populations in viva: implications for
       pathogenesis. Journal of Virology 1991;65(11):6266-6276.

              3. Lin HJ, Siwak EB, Lauder LT and Holinger FB.
       Single-strand conformational polymorphism study of HIV type I
       RNA and DNA in plasma, peripheral blood mononuclear cells,
       and their virologic cultures. Journal of Infectious Diseases
       1995;171:1619-1622.


       E. Understanding HIV infection and redirecting research

       * BACKGROUND

       In early 1995, 2 research teams working independently
published results from their experiments using anti-HIV drugs in
HIV-infected humans. Data from these studies suggest that huge
numbers of CD4+ cells and HIV are produced and destroyed every day.
The drugs used in these experiments included ABT-538 (Ritonavir) and
L-735,524, and nevirapine. Detailed reports on protease drugs appear
in the section on anti-HIV agents. The two research teams had
mathematicians and both produced equations to try and explain the
changes in CD4+ cell counts and HIV. Although the results of their
experiments may be useful when making decisions about the effects of
anti-HIV agents, the researchers clearly did not understand the
complex interplay between the immune system and HIV. Unfortunately,
this lack of understanding extends beyond the 2 research teams and
it may also explain why no effective therapy for AIDS has been
developed 15 years into the AIDS epidemic.

       * A LOT OF VIRUSES

       The results from the 2 teams suggest that millions of viruses
are created and destroyed every day in the bodies of people with
HIV/AIDS. Treating HIV-infected subjects with ABT-538 and other
drugs reduced the amount of virus in the blood and temporarily
raised CD4+ cell counts. As well, the researchers' reports suggest
that HIV continuously infects new uninfected cells and therefore
treatment with drugs that can block HIV infection of uninfected
cells may stop the damage to the immune system caused by
HIV-infection. The two teams may have been impressed by the huge
number of HIVs found (as many as 1 million viruses in a drop of
blood) and the increased CD4+ cell counts in the blood samples of
their subjects. Other researchers have also found large numbers of
HIVs in the blood of subjects with or without AIDS. In some cases
these viruses were not able to infect cells. Had the 2 teams looked
beyond HIV/AIDS, they would have found that in another chronic viral
infection-Hepatitis B-a drop of blood from symptom-free subjects can
have as many as "one billion [viruses]." Thus, the amount of virus
in the blood may not be related to the development of symptoms.

       * WHERE HIV IS MADE

       Most CD4+ cells are found in lymph nodes and tissues and
organs such as the spleen. Most HIV-infected cells are also found in
lymph nodes and tissues. These HIV-infected cells produce the
viruses that eventually appear in the blood. There are also cells
that can survive infection by HIV, and as these cells travel
throughout the body, they release the virus. In a person infected
with HIV there may be "100 billion or 25% of all CD4+ cells"
infected with HIV. In most of these cells, HIV is "silent" and these
cells are not producing viruses. However, between 1 and 2 billion of
those cells are "actively producing HIV." Although standard anti-
HIV agents can reduce the amount of virus in the blood, "the number
of virus-infected cells is not substantially affected." Researcher
Jay Levi (University of California, San Francisco) thinks that
treatment should focus on cells chronically infected with HIV.

       * THE VIRUS FACTORY

       HIV-infected cells:

       - produce more viruses
       - produce chemicals that weaken the immune system
       - trigger T cell suicide (apoptosis)

       As well, viral proteins such as gp120 that come into contact
with T cells may also set those cells for destruction either by
apoptosis or attacks by the immune system. Stopping the "continuous
production of HIV or its proteins" may be a more useful objective
than blocking infection of new cells.

       * VACCINE'S

       To date, most attempts at making anti-HIV vaccines have
focused on the production of antibodies that attack the virus. HIV
can be spread by an infected cell coming into contact with an
uninfected cell (called cell-to-cell transmission). Antibodies
cannot block cell-to-cell transmission. Moreover, anti-HIV
antibodies can help the virus infect cells. Researchers have to find
ways to boost the ability of T cells to find and destroy HIV-
infected cells.

       * CD8+ CELLS

       It appears that people who can produce a strong T cell-based
immune response may be able to contain HIV infection. As well,
research on "Long term symptom-free survival of [people] with HIV
infection" suggests that a "strong" antiviral response by CD8+ cells
targets HIV-infected cells and this type of response may be
important.

       * BETTER THERAPIES

       Attempts to boost the ability of T cells to destroy HIV-
infected cells and contain the infection are underway. In some cases
these involve:

       - infusions of CD4+ or CD8+ cells
       - injections of drugs such as IL-12
       - vaccines that help T cells fight infected cells

       By destroying virus-infected cells, production of HIV will
decrease. Until a cure is developed, therapies that can reduce the
production of HIV from infected cells may be a reasonable goal.

       REFERENCES:

              1. Wei X, Ghosh SK, Taylor ME, et al. Viral dynamics
       in Human Immunodeficiency Virus type 1 infection. Nature
       1995;373: 117- 122.

              2. Ho DD, Neumann AU, Perelson AS, et al. Rapid
       turnover of plasma virions and CD4 lymphocytes in HIV-1
       infection. Nature 1995;373:123-126.

              3. Levy JA. HIV research: a need to focus on the right
       target. Lancet 1995;345:1619-1621.

              4. Garbuglia AR, Salvi R. Di Caro A, et al. Peripheral
       lymphocytes of clinically non-progressor patients harbour
       inactive and uninducible HIV proviruses. Journal of Medical
       Virology 1995;46:116-121.

              5. Kozlowski PA, Black KP, Shen L and Jackson S. High
       prevalence of serum IgA HIV-1 infection-enhancing antibodies
       in HIV- infected persons: masking by IgG. Journal of
       Immunology 1995;154:6163-6173.

              6. Brander C, Pichler WJ and Corradin G.
       Identification of HIV protein-derived cytotoxic T lymphocytes
       (CTL) epitopes for their possible use in a synthetic vaccine.
       Clinical and Experimental Immunology 1995;100:107-113.

              7. Bridges SH and Sarver. Gene therapy and immune
       restoration for HIV disease. Lancet 1995;345:427432.


       II  ANTI-HIV AGENTS

       A. Interesting results from a short AZT study

       * STUDY DETAILS

       Researchers in England recruited 11 subjects with AIDS who
had never used AZT. Their average CD4+ cell count was 118 cells at
the start of the study. They received 1,000 mg/day of AZT, but
subjects who could not tolerate this dose could reduce their dose to
800 or 500 mg/day. Nurses took blood samples from subjects before
they began using AZT and then every 4 days "during the first month
of [the study]", and "[then once per month]." Subjects remained in
the study for an average of 80 days.

       * RESULTS

       Levels of HIV in the blood fell to 10% of their pre-AZT
level. On average, the decrease in virus levels reached its lowest
point 7 days after subjects began using AZT. Despite continued use
of AZT in seven subjects, the amount of virus in their blood began
to increase to their pre-study levels. In three of the seven the
increase was "rapid, occurring over a few weeks."

       * LOOKING FOR RESISTANCE

       Generally, the increase in virus levels despite continued use
of AZT might suggest that HIV-infected cells had become resistant to
the drug's anti-HIV effects. However, technicians could find "no
association between the early [increase in viral levels] and [drug-
resistant virus]" in the blood samples of the 7 subjects whose
levels of virus in the blood "returned towards" their pre-AZT
values. While technicians detected viruses with some level of AZT
resistance, there were not enough of these viruses to account for
the increased levels of HIV in the blood.

       * CAUTION ABOUT VIRAL LOAD

       The detailed analysis of blood samples in this study suggest
that large quantities of HIV are produced by HIV-infected cells.
Although HIV levels in the blood increased despite continued use of
AZT, the researchers could not find enough drug-resistant virus to
account for the increase. Measuring the amount of virus in the blood
or virus in white blood cells (viral load) is one laboratory test
that is becoming more common in clinical trials of anti-HIV agents.
The study researchers warn that "since we do not know [how] HIV-1
causes damage to the immune system,

          "the principle that virus suppression will produce a major
          clinical benefit must remain an article of faith."

       REFERENCES:

              1. Loveday C, Kaye S. Tenant-Flowers M, et al. HIV-1
       RNA serum-load and resistant viral genotypes during early
       Zidovudine therapy. locket 1995;345:1619-1621.


       B. Protease inhibitors

       * BACKGROUND

       Drugs such as AZT, ddC, ddI, and 3TC are supposed to work by
preventing HIV infection of new, uninfected cells. These drugs
affect the viral enzyme RT (reverse transcriptase). Treatment with
these drugs can result in temporarily increased CD4+ cell counts and
decreased production of virus by HIV-infected cells. As well, short
term use of AZT can temporarily boost cell-mediated immunity, an
arm of the immune system that is severely damaged in AIDS.
Nevertheless, some of the beneficial effects begin to fade "within 3
[to] six months" of use. It is important to remember that "AZT
prevents the infection of new cells, but not the production of virus
from cells already infected [by HIV]." The loss of AZT's beneficial
effects may be due to the development of virus that can resist its
effects, the increasing toxicity over time of AZT, or other unknown
reasons. Doctors and their patients are experimenting with various
combinations of AZT and related compounds "with the hope that
[production of HIV can be reduced for longer periods of time] and
delay or prevent the development of [HIV that can resist] these
[drugs]."

       * ANOTHER APPROACH

       Another approach is to use drugs that can affect different
parts of an HIV-infected cell and reduce its production of virus. A
number of drugs that can affect the viral enzyme called "HIV
proteinase" are being developed. Drugs that affect the activity of
that enzyme are called proteinase or protease inhibitors. In
TreatmentUpdate 51 we reported results from an American study using
a combination of a protease inhibitor (saquinavir) with drugs such
as AZT and ddC. In this issue we publish reports on:

       - a study of saquinavir
       - HIV that is resistant to protease drugs
       - results from short term trials of protease inhibitors

       REFERENCES:

              1. Loveday C, Kaye S. Tenant-Flowers M, et al. HIV RNA
       serum-load and resistant viral genotypes during early
       Zidovudine therapy. Lancet 1995;345:820.

              2. Levy JA. HIV research: a need to focus on the right
       target. Lancet 1995;345:1619-1621.

              3. Jurriaans S. Weverling GJ, Goudsmit J. et al.
       Distinct changes in HIV type I RNA versus p24 antigen levels
       in serum during short term Zidovudine therapy in asymptomatic
       individuals with and without progression to AIDS. AIDS
       Research and Human Retroviruses 1995;11(4):473479.

              4. Nowak MA, Bonhoeffer S. Loveday C, et al. HIV
       results in the frame: results confirmed. Nature 1995;375:193

              5. Holodniy M, Mole L, Margolis D, et al.
       Determination of Human Immunodeficiency Virus RNA in plasma
       and cellular viral DNA genotypic Zidovudine resistance and
       viral load during Zidovudine-didanosine combination therapy.
       Journal of Virology 1995;69(6):3510-3516.

              6. Lipsky JJ. The glimmer of HIV proteinase
       inhibitors. Lancet 1995;345:936-937.

              7. Richmann DD. Protease uninhibited. Nature
        1995;374:494.

       C. Saquinavir for HIV

       * STUDY DETAILS

       Researchers in England reported results from testing
saquinavir on 44 male subjects "with few or no symptoms of HIV
infection." Subjects had less than 501 CD4+ cells and had not used
any anti-HIV agents before entering this study. The researchers
approved the use of drugs to prevent various infections while in the
study. Drugs included acyclovir (no more than 1 gram), amphotericin
B lozenges, fluconazole and "standard [PCP prevention]." The trial
lasted for 4 months and researchers randomly assigned subjects to
receive different doses of saquinavir, "25, 75, 200 or 600 mg all
three times daily." Neither subjects nor researchers knew which
subjects received which dose. Due to the small number of subjects in
this study, no results of statistical significance could be
calculated from these tests.

       * RESULTS

       - CD4+ cells

       Among subjects who were in the 600 mg group, there was a
trend of increased CD4+ cell counts. Half of the subjects in this
group had an increase of 104 CD4+ cells by the 6th week of the
study.

       - Infections/cancer

       One subject in the 25 mg group developed a bacterial
infection in his lungs for which he received amoxicillin. One
subject in the 600 mg group developed Kaposi's sarcoma. Both of
these events happened during the 4th week of the study.

       - HIV

       In analyzing blood samples from subjects, technicians
detected virus producing cells in 91% of samples at the start of the
study. In some subjects in the 200 and 600 mg groups, production of
HIV fell to one tenth of their pre-study levels. The researchers did
state that, "in most [subjects] there was no significant change in
[production of HIV from infected cells]."

       - Toxicity

       The researchers noted that "Saquinavir was well tolerated"
and side effects were "mild". One subject in the 200 mg group
developed a headache which cleared without treatment or interruption
of his use of the drug. While some subjects had increased levels of
liver enzymes and ions (calcium, phosphates, potassium) and lower
levels of neutrophils and white blood cells, these did not appear to
be affected by the dose of saquinavir used. Moreover, none of these
changes made subjects ill.

       * WHAT NEXT?

       Results from this study suggest that higher doses of
saquinavir may cause an increase of CD4+ cells in subjects with no
or few symptoms of HIV infection and who have never used drugs such
as AZT. The researchers do not know if these increased CD4+ cell
counts will result in a reduced risk of developing a life-
threatening infection or cancer or in improved survival compared to
other subjects who do not use saquinavir.

       Saquinavir is supposed to work by affecting the viral enzyme
"HIV proteinase". This enzyme is used in the final stages of the
viral "assembly line" in infected cells. Without the help of this
enzyme, the viruses produced are not supposed to be able to infect
cells. Despite use of saquinavir, technicians were still able to
detect intact and infectious samples of HIV in subjects at each dose
level. The manufacturer is providing the drug on a compassionate
basis to some people with HIV/AIDS. Doctors interested in obtaining
this drug for their patients may call: 1-800-257-3741.

       REFERENCES:

              1. Kitchen VS, Lkinner C, Ariyoshi K. et al. Safety
       and activity of saquinavir in HIV infection. Lancet
       1995;345:952-955.

              2. Lipsky JJ. Glimmer of HIV proteinase inhibitors.
       Faucet 1995;345:936-937.


       D. Experiments with pretense drugs produce surprising results

       * BACKGROUND

       In early 1995,2 research teams working independently testing
a number of anti-HIV drugs found some surprising results. In their
studies subjects received one of the following: the protease
inhibitors ABT-538 or MK-639 (formerly L-735,524) or nevirapine
which affects another viral enzyme RT (reverse transcriptase). The
reports from these studies focused on changes in CD4+ cells and HIV
in the blood and mathematical relationships between those 2
variables. Unfortunately we cannot provide the usual details on
subjects because the researchers have yet to release them.

       * PROTEASE INHIBITORS

       In one of the studies, 18 HIV-infected subjects with CD4+
cell counts ranging between 36 and 490 cells received either 600 mg
or 1200 mg of ABT-538 daily for 20 days. The researchers found that
"every [subject] had a rapid and dramatic decline in [the amount of
HIV in their blood] over the first 2 weeks of the study]." On
average, the amount of virus in their blood fell to one-sixty-sixth
of its pre-study level. The decline in the quantity of virus was not
related to the CD4+ cell counts of subjects at the start of the
study. In all subjects, CD4+ cell counts increased during the first
2 weeks.

           (When questioned about the value of increased CD4+ cell
           counts in subjects receiving anti-HIV drugs, the head of
           one of the research teams said that "we have reason to
           believe that the cells that are coming back are not
           entirely functional. Clearly patients are improved...But
           it's not the same functional level that you would see in
           another patient whose CD4+ cells are on the way down.")

       After the 2nd week of the study, HIV began to develop
resistance and viral production increased. In addition, CD4+ cell
counts began to decline in some subjects. Researchers found a
similar trend when subjects used MK-639 at doses between 1600 and
2400 mg/day. The researcher noted that "there were no significant
differences in viral clearance rates in subjects treated with
ABT-538, [MK-639] or [nevirapine]." Perhaps the most useful idea to
take from these 2 studies was a comment by researcher DD Richman, an
expert on HIV drug resistance:

          "if a drug doesn't have an effect by day 14 [it is not
          worth developing]."

       That HIV could develop resistance to a drug in as little as 2
weeks may not be unique to protease inhibitors. In an analysis of
blood samples from subjects in a Dutch trial of AZT, researchers
found that production of HIV in some subjects began to increase just
after 4 weeks of therapy. By the 8th week, production of HIV had
increased to a level almost 10 times greater than in the 4th week.

       * HIV RESISTANCE TO SEVERAL PROTEASE INHIBITORS

       Meanwhile, researchers working for the pharmaceutical firm
Merck have found that when HIV does become resistant to one protease
inhibitor, it also becomes resistant to several other related
protease inhibitors. The researchers were testing Merck's protease
inhibitor MK-639 in HIV-infected humans and found that after 6
months of use, HIV had developed resistance not only to Merck's drug
but also to:

       + XM 323
       + A-80987
       + Saquinavir
       + VX-478
       + SC-52151

       The concentration of these drugs needed to suppress
production of HIV by 95% had doubled 6 months after using MK-639.
These findings suggest that combination therapy with these protease
inhibitors may not prevent the development of HIV that is resistant
to all of them. Moreover, if a person using one of these drugs
develops virus that is resistant to it, the virus is also likely to
be resistant to the other, related, drugs.

       - AG 1343

       At Agouron Pharmaceuticals (San Diego) research teams using
computer simulations have developed a group of proteinase inhibitors
that may be different from the ones listed above. Agouron has been
testing one of their protease inhibitors, AG 1343, in HIV-infected
humans in England. They plan to conduct further testing in San
Francisco using 30 subjects who will receive a variety of doses of
AG 1343 in the form of tablets.

       REFERENCES:

              1. Wei X, Ghosh SK, Taylor ME, et al. Viral dynamics
       in Human Immunodeficiency Virus type I infection. Nature
       1995;373:117- 122.

              2. Ho DD, Neumann AU, Perelson AS, et al. Rapid
       turnover of plasma virions and CD4 lymphocytes in HIV-1
       infection. Nature 1995;373: 123-126.

              3. Vacca JP, Dorsey BD, Schlief WA, et al. L-735,525:
       an orally bioavailable Human Immunodeficiency Virus type 1
       protease inhibitor. Proceedings of the National Academy of
       Sciences USA 1994;91:4096-4100.

              4. Cohen J. High turnover of HIV in blood revealed by
       new studies. Science 1995;267:179.

              5. Kempf DJ, March KC, Denissen JF, et al. ABT-538 is
       a potent inhibitor of Human Immunodeficiency Virus protease
       and has high oral bioavailablilty. Proceedings of the
       National Academy of Sciences USA 1995;92:2484-2488.

              6. Condra JH, Schlief WA, Blahy OM, et al. In viva
       emergence of HIV-1 variants resistant to multiple protease
       inhibitors. Nature 1995;374:569-571.

              7. Jurriaans S. Weverling GJ, Goudsmit J. et al.
       Distinct changes in HIV type I RNA versus p24 antigen levels
       in serum during short-term Zidovudine therapy in
       asymptomatic individuals with and without progression to
       AIDS. AIDS Research and Human Retroviruses 1995;11(4):473479.

              8. Reich SH, Melnick M, Davies JF, et al. Protein
       structure-based design of potent orally bioavailability,
       nonpeptide inhibitors of Human Immunodeficiency Virus
       protease. Proceedings of the National Academy of Sciences USA
       1995;92:3298-3302.

              9. Nichols D. Agouron pharmaceuticals extends clinical
       testing of HIV drug into US. Press release. July 6, 1995.

             10. Eberle J. Bechowsky B. Rose D, et al. Resistance of
       HIV type I to proteinase inhibitor Ro 31-8959. AIDS Research
       and Human Retroviruses 1995;11(6):671-676.

             11. Schoofs M. A new AIDS trial tries to stop HIV by
       attacking it early. Village Voice 15 August, 1995, pages
       23-25.


       E. AZT-virus production and worsening symptoms

       * STUDY DETAILS

       Researchers in Amsterdam analysed blood samples from 28
subjects with HIV infection, looking for changes in production of
HIV by infected cells (a double blind placebo-controlled study). All
subjects were men with no symptoms of HIV infection who had received
AZT 1,000 mg/day taken as 500 mg twice daily for 2 years. Their
average CD4+ cell count was 287 cells. Monitoring of these subjects
extended to 4 years after entering the study.

       * RESULTS

       The researchers found that 4 years after entering the study
16 subjects remained symptom-free ("non-progressors") and the other
12 developed AIDS ("progressors"). The researchers looked for
differences between the 2 groups. They found that after 4 weeks of
AZT, both groups had statistically significant decreases in the
level of HIV in the blood, "but a much stronger decline was observed
in the group of non-progressors." Among the non-progressors, the
amount of virus in their blood fell to one-tenth of their pre-AZT
level. By the 8th week of AZT use, the amount of virus in the blood
increased and reached a level close to that of the progressor group.
The researchers did not provide data beyond the first 8 weeks of the
study.

       * OTHER STUDIES

       Other studies have also found that use of AZT decreases the
amount of virus in the blood of subjects in the first 2 to 6 weeks
of use. However, "the favourable effect of [AZT] on [levels of HIV
in the blood] was lost within 3 to 6 months."

       * SI AND NSI

       When cells are in physical contact with one another, HIV can
move from an infected cell to the next cell and infect it. When this
happens to several adjacent cells, giant clumps of cells called
syncytia can form. Viruses that can cause syncytia are called SI
(syncytia-inducing) and viruses that cannot are called NSI
(nonsyncytia inducing). The amount of HIV found in the blood of
subjects with or without SI or NSI strains of HIV was not different.

       * FOUR WEEKS?

       That a change in the amount of HIV in the blood after only 4
weeks of AZT treatment could be linked to the development of
symptoms of HIV infection years later is interesting and raises many
questions. First, should HIV-infected people who are free of
symptoms take AZT 1,000 mg/day for 4 weeks and have the amount of
HIV in their blood checked and compared with the pre-AZT level?
Second, is 4 weeks of AZT therapy enough "treatment"? Clearly,
making important decisions based on laboratory tests for HIV alone
may not be the best course of action. Further data, on the type of
infections and survival of subjects may be helpful in forming a
useful analysis of this study. It is not clear why there was a
difference between the 2 groups' response to the drug in the first
place.

       REFERENCES:

              1. Jurriaans S. Weverling GJ, Goudsmit J. et al.
       Distinct changes in HIV type I RNA versus p24 antigen levels
       in serum during short-term Zidovudine therapy in asymptomatic
       individuals with and without progression to AIDS. AIDS
       Research and Human Retroviruses 1995;1 1(4):473-479.

       Copyright (c) 1995.  Non-commercial reproduction encouraged.
       Distributed by AEGIS, your online gateway to a world of
       people, knowledge, and resources.

