Influence of Participant Perceptions of Adherence-Related Interactions with Study/Study Team on Drug Levels: HPTN069 Analysis of Self-Reported Adherence Experiences While on Study

Adherence to HIV pre-exposure prophylaxis (PrEP) study drug is critical for safety, tolerability, and efficacy trials, and may be affected by how adherence is communicated by the study staff to trial participants. Increasingly, clinical trials investigating PrEP are creating and implementing 'participant-centered' approaches that discuss potential non-adherence neutrally (without negative judgement) and support efforts to adhere versus insisting on perfect adherence. In the HPTN069/ACTG A5305 study, we evaluated participant experiences of potentially negative adherence-related interactions with study teams using ten items to characterize the frequency of such experiences. We related these individual items and a combined set of seven negative experience items (total negative experience score) to drug concentrations (detectable or consistent with daily-dosing). The exploratory analyses used logistic regression for each experience item on the full sample and disaggregated by sex. Several experiences were related to drug detection and to daily-dosing, although more so for participants identifying as men than women. Total negative experience scores associated with not having detection drug concentrations for the full sample, and remained significant even when controlling for sex, age, and race. Daily dosing was associated with total negative experience score for men in the sample. Additional investigations into adherence-related interactions with study teams that are most problematic or helpful in general and uniquely for men and women are warranted.

Safety and tolerability of injectable Rilpivirine LA in HPTN 076: A phase 2 HIV pre-exposure prophylaxis study in women

BACKGROUND

Daily oral TDF/FTC is protective against HIV infection when used for pre-exposure prophylaxis (PrEP). However, daily adherence to oral PrEP is difficult for many; therefore, finding alternative PrEP strategies remains a priority. HPTN 076 evaluated the long-acting injectable form of rilpivirine (RPV), known as RPV LA for safety, pharmacokinetics and acceptability.

METHODS

HPTN 076 (NTC 02165202) was a phase 2, double-blind, 2:1 randomized trial comparing the safety of 1200mg RPV LA (LA) to placebo (P). The study included a 28-day oral run-in phase of daily, self- administered oral RPV (25 mg), with directly observed oral dosing about six times. Of 136 enrolled sexually active, HIV-uninfected, low HIV-risk African (100) and US (36) adult women, injectable product was administered in two gluteal, intramuscular (IM) injections once every eight weeks to 122 participants following the oral run-in phase. A maximum of six injection time points occurred over a 48-week period. Acceptability, safety, tolerability and pharmacokinetic (PK) data were collected throughout the study. This paper includes primary endpoint data collected up to the week 52 post enrollment.

FINDINGS

The median age of the enrolled population was 31 years (IQR: 25,38), median weight 75 kg (IQR: 64, 89), median body mass index (BMI) 30 (IQR: 27, 35), 46% married, 94% Black and 60% unemployed. A total of 122 (80 LA, 42 P) women received at least one injection and 98 (64 LA, 34 P) received all six injections. During the injection phase, three women withdrew from the study (2 LA, 1 P) and 16 women discontinued study product (10 LA, 6 P). Fourteen women (11 LA and 3 P) discontinued oral study product and did not enter the injection phase. Study product discontinuations were not significantly different between the two arms throughout. Of the product discontinuations in the injection phase, 8% in LA and 5% in P arm were due to adverse events (AEs), including one randomized to the P arm with prolonged QTc interval on EKG. The proportion of women who experienced Grade 2 or higher AEs during the injection phase as the primary outcome was not significantly different between the two arms [73.8%, 95% CI: (63.2%, 82.1%) for LA and 73.8%, 95% CI: (58.9%, 84.7%), p>0.99]. Transient Grade ≥2 liver abnormalities occurred in 14% of women in the LA arm compared with 12% in P arm. Three LA women (4%) developed Grade 3 injection site reactions compared with none in P arm. In participants who received at least 1 injection, the geometric mean of overall RPV trough concentrations (Ctrough) was 62.2 ng/mL. In participants who received all six injections, the geometric mean of CTrough through the injection phase and after the last injection were 72.8 ng/mL and 100.9 ng/mL, respectively. At week 52 (eight weeks after last injection), the geometric mean of RPV Ctrough was 75.0 ng/mL. At the last injection visit (Week 44), 80 % of women who answered acceptability questions strongly agreed that they would think about using- and 68% that they would definitely use a PrEP injectable in the future.

INTERPRETATION

RPV LA IM injections every eight weeks in African and US women were safe and acceptable. Overall, despite more injection site reactions and pain in the participants receiving RPV LA the injections were well tolerated. Data from this study support the further development of injectable PrEP agents.