HIV pharmacogenomics: Closer to personalized therapy?

Pharmacogenomics classically focuses on host nuclear genetic polymorphisms that can be used to predict adverse drug reactions (ADRs). Because ADRs are defined as any noxious, unintended, and undesired drug effects, loss of efficacy due to the development of antiretroviral drug resistance and both acute and cumulative adverse effects of antiretroviral therapy can be considered ADRs. In order to address these types of antiretroviral-associated ADRs, pharmacogenomic testing methods have expanded to include molecular assays that characterize extranuclear genetic material (e.g. HIV and mitochondrial genomes), as well as the host nuclear genetic material. Recent molecular advances permit high resolution resistance testing that detects loss of therapeutic efficacy through the use of phenotypic, genotypic and/or virtual phenotypic resistance testing. These assays use complex technical and interpretative methods to improve the therapeutic efficacy of antiretroviral therapy. The resistance assays demonstrate the utility of pharmacogenomic testing for patients undergoing lifelong and complex antiretroviral therapies. Future applications of antiretroviral-directed pharmacogenomic tests range from quantitative detection of mitochondrial depletion as an early surrogate marker for drug toxicity, to qualitative analysis of host immune haplotypes, and metabolic/transporter genetic polymorphisms for predicting disease progression. In summary, pharmacogenomic testing for HIV-positive patients provides proof of principle that these tests can be used clinically to improve outcomes for patients undergoing complex and sustained drug regimens.