This study will help identify which ARV candidates should be prioritized for pediatric use in resource-limited settings

Children in resource-limited settings are increasing experiencing treatment failure, as defined by virologic, immunologic, and/or clinical criteria. There are few studies of HIV resistance mutations in children failing first line NNRTI therapy in resource limited settings. The emergence of treatment failure and drug resistance in children on ART emphasizes the urgency for developing evidence-based second-line and salvage treatment strategies. Pediatric treatment is complicated by a number of factors, including having fewer numbers of ARVs approved by drug safety agencies and the lack of pediatric formulations. This further shortens the list of available second-line ARVs as compared to adults.

Despite the growing number of children on second-line therapy worldwide, there are limited data on efficacy of second-line PI therapy in children after NRTI-NNRTI failure. There are currently no options for third-line/salvage regimens for children in resource-limited settings. New drugs and drug classes are approved for use in children by the US FDA but are not routinely available outside of high-income settings.

Also, there are no data on the resistance patterns of children failing second-line therapy in resource-limited settings to guide clinical management and ARV procurement. Clinicians need evidence-based guidelines for how to manage children with treatment failure, and access to the drugs necessary to construct potent and durable third-line regimens.

TASER-P is a longitudinal observational cohort study to monitor for treatment failure to second-line ART in Asian children.

Inclusion Criteria:

• Age < 18 years old
• Have confirmed HIV infection
• Are being switched to or treated with second-line ART. Second-line ART is defined as the second regimen with a major antiretroviral class switch. For example, a switch from an NNRTI-based to a PI-based regimen or vice versa
• Caregivers give informed consent. Children will be asked to give assent if they know their HIV status and have reached the minimum age to give assent according to each site's institutional review board regulations

Exclusion Criteria:

• Started mono- or dual- therapy as the first ART therapy
• Failing first-line triple nucleoside reverse transcriptase inhibitor regimen
• Are being switched to or treated with second-line ART without failure of first-line therapy (i.e., for toxicity)
• Caregiver +/- child (if asked to give assent) refuses to participate in this study
• Have not been enrolled in TApHOD

HIV-positive children <18 years old who are have switched to or treated with second-line ART at one of the participating TREAT Asia Pediatric HIV Observational Database (TApHOD) sites.