There are certain elements essential to the individualization of HIV treatment: treatment history, viral load, CD4, drug resistance, viral fitness, and tropism.

The Fundamentals – treatment history, viral load, and CD4

• Treatment history, viral load, and CD4 are the key components of clinical monitoring and informed treatment decisions at all stages of therapy.

Drug Resistance Information – phenotype and genotype

• The goal of treatment is virologic suppression. Resistance testing provides insights into drug susceptibility, facilitating more informed treatment decisions about which drugs are likely to be effective and which are not; consistent use of resistance testing helps to optimize background therapy and improve long-term therapy outcomes.

Viral Fitness – Replication Capacity (RC)

Replication Capacity (RC) measures how well a patient’s virus is able to replicate compared to a wild-type reference virus. Although drug resistance mutations enable viruses to replicate in the presence of a drug, they may do so at some fitness cost to the viruses. Understanding how fit a patient's virus is may provide insight in a highly complex case; In some circumstances, RC may inform decisions about when to delay, start, stop, switch or interrupt therapy. RC is included with PhenoSenseGT®, PhenoSense® and PhenoSense® Integrase.

Tropism

Tropism testing is a new tool for HIV treatment. HIV tropism is determined by the co-receptors, CCR5 and CXCR4, utilized by the virus to enter a CD4+ cell. Current U.S. Department of Health and Human Services (DHHS) guidelines recommend that a co-receptor tropism assay should be performed whenever the use of a CCR5 inhibitor is being considered. Co-receptor tropism testing might also be considered for patients who exhibit virologic failure on a CCR5 inhibitor.

When used together, viral load, CD4 count, treatment history, viral phenotype and genotype, and replication capacity, included with PhenoSenseGT and PhenoSense, as well as tropism, form a solid foundation for making antiviral treatment decisions to optimize background therapy and achieve long-term therapy success.