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HIV and personalized medicine

Personalized medicine is a hot topic worldwide, offering the promise of tailoring drugs to match the genetic variability of diseases, for maximum efficacy.

As a Center of Excellence for HIV treatment, the Infectious Diseases Institute (IDI) is entering the realm of pharmacogenomics, in seeking to find optimal antiretroviral drug regimens for patients who have developed viral resistance to standard first or second line therapy.

The Human Immunodeficiency Virus replicates very rapidly when it is not held in check by antiretroviral drugs, and genetic mutations can quickly emerge that confer resistance to the drugs to which the virus has been exposed.  HIV patients receive combination therapy, a mixture of three different classes of drugs that work by different biological pathways, to keep the virus at bay.  One of the main reasons why viral resistance occurs is that patients forget to take their antiviral drugs on time or miss treatment for a period of time.  A drop in the drug concentration in the patient’s system for only an hour or two can be enough to allow the virus to break through.

Viral resistance testing is relatively expensive at $120 per test, compared with Uganda’s annual average healthcare spending per head of $106, and so at IDI it is reserved for cases where patients have a consistently detectable viral load (particularly if they are taking second-line antiretroviral treatment), which means the HIV is replicating fast and the drugs they are currently taking have little effect.  By sequencing viral RNA taken from the patient, doctors at IDI can see which viral genes have mutated, and check with published literature which drugs will be rendered ineffective by the particular mutations.  The doctors can then select a new combination of drugs in the various classes that still have activity against the mutated virus.

Mortality in unchecked HIV infection is high – 30% of HIV patients with virologic failure and weak immunity die within one year - so the new pharmacogenomics technology and personalized medicine approach for treating resistant strains of HIV have potential to save lives.

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