Fact Sheet Number 417
- WHAT ARE TREATMENT INTERRUPTIONS?
- WHICH PATIENTS ARE BEING STUDIED,
AND WHY?
- WHAT ARE THE RISKS?
- WHAT ARE THE POSSIBLE BENEFITS?
- WHAT DOES THE RESEARCH SHOW?
- THE BOTTOM LINE
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PrintINTERRUPTIONS?
Many people with HIV infection stop taking antiviral medications
for various reasons. In most cases, their viral load climbs very
quickly and their T-cell count drops. In late 1997, however, an
HIV patient in Berlin stopped taking medications. His viral load
climbed briefly, then dropped and stayed undetectable.
This patient started medications soon after he was infected.
Maybe HIV didn’t have a chance to damage his immune system. Maybe
his viral load increase was like a vaccination that stimulated
his immune system to control the virus.
Researchers immediately tried to copy the Berlin patient’s
success in other patients. They stopped treatment for a certain
period of time, or until the viral load climbed to a certain point.
This kind of treatment interruption is called “STI”
which means either “structured” or “strategic”
treatment interruption.
ARE BEING STUDIED, AND WHY?
STI studies are divided according to three groups of HIV patients:
- HIV is under control; antiviral treatment started within
six months of infection. These “primary infection”
patients, like the Berlin patient, may have the best chance
to control HIV without medications.
- HIV is under control; treatment started more than six
months after infection. These “chronic infection”
patients may just want a break from taking medications, or may
want to reduce side effects.
- HIV is not controlled by antiviral medications. These
“drug-resistant” patients may want a break from
side effects, may be waiting for new treatment options, or may
want to experiment with shifting their virus back to the “wild
type” that is more drug-sensitive.
Doctors and patients should plan treatment interruptions.
Viral load and T-cell levels should be carefully monitored. Just
skipping doses has more risks and does not contribute to knowledge
about HIV treatments.
The most obvious risks of an STI are that the viral load will
climb and the T-cell count will drop. These risks are greatest
for people whose virus is not under control. If you have only
50 T-cells, losing another 10 might have serious consequences.
Stopping and re-starting medications could make it easier for
the virus to develop resistance to medications. Surprisingly,
there is very little evidence of resistance developing in people
who took part in studies of STIs.
This risk may be greatest for people taking drugs like Efavirenz
(Sustiva®) that stay in the body much longer than other antiviral
drugs. They could be discontinued before other drugs in a regimen,
but this has not been carefully studied.
Also, if the viral load increases while people are off medications,
people might be more likely to transmit HIV infection to others.
On the other hand, if they are off medications, they might be
more likely to transmit the wild type virus, not drug-resistant
virus.
People ending a treatment interruption might have a hard time
re-starting medications.
BENEFITS?
Ideally, an STI would have several benefits:
- Stimulate the immune system. The best case is immune
control of HIV without antiviral medications.
- Allow patients to take less medication. This should
reduce side effects and lower drug costs for individuals
and public programs.
RESEARCH SHOW?
Many people who stop antiviral drugs feel better, at least for
a short time. However, long-term benefits are unclear.
Primary infection: During an STI, viral loads go up
and T-cell counts go down except for very rare exceptions. Researchers
cannot predict who will control HIV without drugs.
Chronic infection: Again, viral loads go up and T-cell
counts go down. Patients in this group who control HIV without
antiviral medications are very rare. Researchers are adding immune-boosting
therapies to treatment interruptions.
For a few drug-resistant patients, it seems that medications
were not doing anything, because when they stopped, viral loads
and t-cell counts didn’t change very much. In some cases, HIV
shifts back to a more “wild type” virus that is not
resistant to antiviral medications. Scientists are not sure that
this is a good thing, because the wild type virus is stronger
than virus that is resistant to several drugs.
HIV patients stop antiviral treatments for various reasons. In
very rare cases, treatment interruption has led to immune system
control of HIV without medications. However, there is no way to
predict when this will happen.
If we can learn how to use treatment interruptions, patients
might be able to take periods of time off of antiviral drugs.
This could mean fewer side effects and lower drug costs. However,
we will have to learn how to minimize drug resistance and transmission
of HIV, and learn the best scheduling of treatment interruptions
to avoid long term increases in viral load and decreases in T-cells.
Revised August 7, 2002
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New Mexico AIDS Education and Training Center
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