# "Hair Extensions": Using Hair Levels to Interpret Adherence, Effectiveness and Pharmacokinetics with Real-World Oral PrEP, the Vaginal Ring, and Injectables

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA, SAN FRANCISCO · 2020 · $759,666

## Abstract

PROJECT SUMMARY/ ABSTRACT
Three lessons of the PrEP (pre-exposure prophylaxis) clinical trials - that adherence is critical to effectiveness,
that pharmacologic adherence measures are more reliable than self-report, and that daily pill-taking is difficult
–must be applied to the next phase of HIV prevention research. This phase will investigate oral PrEP roll-out
and optimization in high incidence settings, as well as novel long-acting methods for preventing HIV infection,
such as injectables or vaginal rings. The vaginal ring prevented HIV acquisition in two recent trials, but poor
adherence to consistent ring insertion dampened overall effectiveness. Injectable PrEP with long-acting
cabotegravir is of interest, but will require adequate drug levels to be effective, especially at the end of dosing
intervals and with missed visits. Pharmacologic metrics integrate biology (pharmacokinetics, PK) and behavior
(adherence) and will be crucial to interpreting effectiveness with real-world oral PrEP, rings and injectables.
 Our group has helped pioneer the use of small hair samples (which are easy to collect, store and ship) to
monitor exposure (PK) and adherence to antiretrovirals (ARVs). During the first funding period of this R01,
we made significant progress on our original aims, demonstrating that hair levels of ARVs, which monitor
long-term exposure, are stronger predictors of treatment success than self-reported adherence (or plasma
levels) in HIV-infected pregnant women, children, and adults. We have also shown preliminary utility of hair
levels of tenofovir (TFV)/emtricitabine (FTC) to monitor adherence and toxicities with oral PrEP.
 This proposal will leverage three important trials to explore key knowledge gaps that will arise in the
next phase of HIV prevention work: The Sustainable East Africa Research in Community Health (SEARCH)
trial (Dr. Havlir, chair and co-I) has just launched a large study providing oral PrEP to at-risk individuals in 16
communities in Africa. The HIV Open-Label Prevention Extension (HOPE) study in the Microbicide Trials
Network (MTN) (Dr. Baeten, chair and co-I) will assess open-label use of the dapivirine vaginal ring. The
Long-Acting Antiretroviral Therapy in Non-adherent HIV-Infected Individuals Trial (A5359, Dr. Castillo-
Mancilla, co-chair and co-I)) in the AIDS Clinical Trials Group (ACTG) will examine long-acting injectables in
HIV-infected patients with a history of poor adherence. All 3 trials will collect hair and plasma for drug levels,
and track robust outcomes, to allow us to 1) investigate hair levels as metrics of adherence with the vaginal
ring and oral PrEP in Africa and examine patterns of adherence (e.g. daily, around periods of risk, just prior to
visits) by combining data in plasma and hair; and 2) examine hair levels as easy-to-collect metrics for PK
monitoring with the use of injectables. The overarching goal of this renewal is to develop an integrated
package of highly predictive biologic ad...

## Key facts

- **NIH application ID:** 9880401
- **Project number:** 5R01AI098472-09
- **Recipient organization:** UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
- **Principal Investigator:** Monica Gandhi
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $759,666
- **Award type:** 5
- **Project period:** 2011-12-15 → 2022-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9880401

## Citation

> US National Institutes of Health, RePORTER application 9880401, "Hair Extensions": Using Hair Levels to Interpret Adherence, Effectiveness and Pharmacokinetics with Real-World Oral PrEP, the Vaginal Ring, and Injectables (5R01AI098472-09). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9880401. Licensed CC0.

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