Elvitegravir (EVG) Cerebrospinal Fluid (CSF) Pharmacokinetics in HIV-Infected Individuals

The proposed project will be a prospective, open-label treatment trial of 14 HIV-infected adults. Participants will be enrolled in two tracks. Track A will enroll participants who have been taking E/C/F/TDF to E/C/F/TAF for at least 12 weeks. Track B will enroll participants who are not taking ART and no prior exposure to elvitegravir and no genotypic drug resistance to any component of E/C/F/TDF to E/C/F/TAF. CSF and blood will be collected twice in Track A (two on-treatment assessments) and three times in Track B (one pre-treatment, two on-treatment assessments). If possible, we plan to time assessments to bridge the transition from E/C/F/TDF to E/C/F/TAF so that all participants will ideally have one CSF collection on each regimen, enabling a paired comparison of tenofovir concentrations between the two tenofovir formulations. We estimate that 28 on-treatment CSF collections will be sufficient to provide a small-sample estimate of the distribution of elvitegravir, tenofovir and TAF into CSF.

Inclusion criteria

• Adult men or women aged 18-60 years. Able and willing to provide informed consent.
• Presence of HIV-1 infection as documented by a licensed ELISA test kit and confirmed by Western blot or HIV RNA.
• Track A (Currently taking E/C/F/TDF or E/C/F/TAF): Taking E/C/F/TDF or E/C/F/TAF for at least 3 months prior to screening and undetectable plasma HIV-1 RNA (≤ 40 copies/mL)
• Track B (Currently not taking ART): Off ART for at least 3 months. Prior exposure to TDF and FTC will be allowed but subjects must not have primary genotypic drug resistance mutations to elvitegravir, tenofovir, or emtricitabine (see Exclusion Criteria)
• Plasma HIV-1 RNA ≥ 5,000c/mL and CD4+ T-cell count ≥200cells/mm3.

Exclusion criteria

• Track B: Presence of primary drug resistance mutations for EVG, tenofovir, or emtricitabine.
• Use of drugs of abuse or alcohol which would interfere with adherence or completion of this study. While on-study, subjects will be instructed not to consume alcohol for 48 hours prior to pharmacokinetic sampling days.
• Pregnancy or breast-feeding. Women of childbearing potential must have a negative serum or urine pregnancy test within 14 days prior to study entry and day of entry.
• Chronic, severe, or other medical conditions that, in the opinion of the investigator, would interfere with the subjects ability to participate in the protocol.
• Use of prohibited protocol-specified drugs, prescription or over-the-counter, within 14 days prior to study entry.
• Bleeding abnormality or other contraindication to lumbar puncture.
• Moderate or severe cognitive impairment by history or based on Montreal Cognitive Assessment.
• Hepatitis B surface antigen (HBsAg) positive (Positive anti-HBs antibody and negative HBsAg results are acceptable)
• Hepatitis C antibody (HCV Ab) positive
• Laboratory parameters documented within 21 days prior to study entry that would increase the risk for adverse events:

• Hemoglobin < 12.5 g/dL for men; < 11.5 g/dL for women;
• Platelet count < 100,000 platelets/mm3;
• AST (SGOT) or ALT (SGPT) > 1.5 x the upper limit of normal (ULN);
• Estimated GFR<70 ml/min
• Weight less than 50 kg