Pharmacokinetics and tolerability of cabotegravir and rilpivirine long-acting intramuscular injections to the vastus lateralis (lateral thigh) muscles of healthy adult participants

Cabotegravir + rilpivirine administered via intramuscular gluteal injections is the first complete long-acting (LA) regimen approved for maintaining HIV-1 virologic suppression. The vastus lateralis (lateral) thigh muscle could be a potential alternative site of administration in circumstances such as injection site fatigue, intolerability, or contraindication for gluteal administration. Cabotegravir and rilpivirine pharmacokinetics and participant tolerability were evaluated following single intramuscular injections to the lateral thigh. Healthy adult participants received 4 weeks of daily oral cabotegravir (30 mg) and rilpivirine (25 mg), followed by a 10- to 14-day washout and single 3 mL intramuscular injections of cabotegravir LA 600 mg and rilpivirine LA 900 mg to the lateral thigh. Safety, tolerability, and pharmacokinetics were evaluated through 52 weeks post injection. Pharmacokinetic parameters were estimated using non-compartmental analysis. Fifteen participants (female at birth, n = 6) enrolled. Median age was 33 years. Median weight was 93.6 kg. Median body mass index was 31.4 kg/m2. One participant withdrew due to pregnancy after oral dosing before receiving an injection. Plasma concentrations at Weeks 4 and 8 were 15.4- and 5.3-fold above the protein-adjusted 90% inhibitory concentration for cabotegravir and 4.7- and 2.4-fold for rilpivirine, respectively. The most common injection site reactions were pain [28/28 (100%)], induration [15/28 (54%)], and swelling [12/28 (42%)]; 94% were Grade 1 or 2. Cabotegravir and rilpivirine plasma pharmacokinetic profiles observed in this study support further evaluation of thigh administration in target populations of people living with HIV-1. Tolerability of cabotegravir + rilpivirine LA intramuscular lateral thigh injections was similar to gluteal administration.

Expanded Multivariable Models to Assist Patient Selection for Long-Acting Cabotegravir + Rilpivirine Treatment: Clinical Utility of a Combination of Patient, Drug Concentration, and Viral Factors Associated With Virologic Failure

BACKGROUND

Previously reported post hoc multivariable analyses exploring predictors of confirmed virologic failure (CVF) with cabotegravir + rilpivirine long-acting (CAB + RPV LA) were expanded to include data beyond week 48, additional covariates, and additional participants.

METHODS

Pooled data from 1651 participants were used to explore dosing regimen (every 4 or every 8 weeks), demographic, viral, and pharmacokinetic covariates as potential predictors of CVF. Prior dosing regimen experience was accounted for using 2 populations. Two models were conducted in each population-baseline factor analyses exploring factors known at baseline and multivariable analyses exploring baseline factors plus postbaseline model-predicted CAB/RPV trough concentrations (4 and 44 weeks postinjection). Retained factors were evaluated to understand their contribution to CVF (alone or in combination).

RESULTS

Overall, 1.4% (n = 23/1651) of participants had CVF through 152 weeks. The presence of RPV resistance-associated mutations, human immunodeficiency virus-1 subtype A6/A1, and body mass index ≥30 kg/m2 were associated with an increased risk of CVF (P < .05 adjusted incidence rate ratio), with participants with ≥2 of these baseline factors having a higher risk of CVF. Lower model-predicted CAB/RPV troughs were additional factors retained for multivariable analyses.

CONCLUSIONS

The presence of ≥2 baseline factors (RPV resistance-associated mutations, A6/A1 subtype, and/or body mass index ≥30 kg/m2) was associated with increased CVF risk, consistent with prior analyses. Inclusion of initial model-predicted CAB/RPV trough concentrations (≤first quartile) did not improve the prediction of CVF beyond the presence of a combination of ≥2 baseline factors, reinforcing the clinical utility of the baseline factors in the appropriate use of CAB + RPV LA.

1584. CARISEL A Hybrid III Implementation Effectiveness Study of implementation of Cabotegravir plus Rilpivirine Long Acting (CAB+RPV LA) in EU Health Care Settings Key Clinical and Implementation Outcomes by Implementation Arm

Background

Cabotegravir + Rilpivirine Long Acting (CAB+RPV LA) every 2 months is a recommended regimen in European and US treatment guidelines for PLWH with virological suppression and no known resistance to CAB or RPV. CARISEL, an implementation study, is the first study where all participants switched from standard oral therapy to 2 monthly CAB+RPV. Key clinical and implementation secondary endpoints are reported.

Methods

This single arm study enrolled virologically-suppressed PLWH to receive CAB+RPV LA 2-monthly at 18 clinics in 5 EU countries, conducted from Sept 2020-Feb 2022. Clinics with no prior experience with CAB+RPV LA were preferentially selected. Sites were randomized to standard implementation (Arm-S) or enhanced implementation (Arm-E) which included additional implementation strategies. Proportion of participants with plasma HIV-1 RNA ≥50c/mL and &lt; 50c/mL at Month 12 (FDA Snapshot algorithm, ITT-E) were reported. Adverse events, COVID-related events, clinic visit length, and safety were analyzed by implementation arm.

Results

72% of clinics (13/18) had no experience with CAB+RPV LA at study start. 430 enrolled and treated participants were included with 25% female, 18% black, and a mean baseline age of 44 yrs (30% &gt; 50 years). At Month 12, 87% of participants maintained virologic suppression in each implementation arm (Table 1) and 1 participant (1/430; 0.23%) in Arm-E experienced confirmed virologic failure. Grade 1–2 AEs were reported in Arm-E:99% vs Arm-S: 97%; Grade 3–4 drug-related AEs reported in Arm-E: 4%, Arm-S: 8%. ISRs were reported in 86% of participants; 98% were mild or moderate, median duration of 3 days and a low proportion of participants discontinued treatment due to ISR (6%). Total time in clinic decreased more in Arm-E than Arm-S; visit length varied by country (Table 2). COVID was diagnosed in 16% of participants. COVID-19 related protocol deviations reported in 3% of participants. There were no discontinuations and no snapshot failures due to COVID-19.

Conclusion

Regardless of implementation arm, CAB+RPV LA was a highly effective and well tolerated, consistent with clinical outcomes in the Phase 3 clinical program. Clinic visit lengths varied by country and decreased over time. COVID-19 did not lead to treatment disruption or study discontinuation.

Disclosures

Stephane De Wit, PhD, AstraZeneca: Grant/Research Support Fabrice Bonnet, PhD, Gilead: Grant/Research Support|Gilead: Honoraria|MSD: Grant/Research Support|MSD: Honoraria|ViiV Healthcare: Grant/Research Support|ViiV Healthcare: Honoraria Rebecca DeMoor, M.S., GlaxoSmithKline: Employee Gilda Bontempo, MD, ViiV Healthcare: Employee|ViiV Healthcare: Stocks/Bonds Christine Latham, MS, ViiV Healthcare: Employee|ViiV Healthcare: Stocks/Bonds Martin Gill, BSc, GlaxoSmithKline: Employee Monica Hadi, PhD, Evidera: Employee Savita Bakhshi Anand, PhD, Evidera: Employee Cassidy Gutner, PhD, ViiV Healthcare: Employee Mounir Ait-Khaled, PhD, GlaxoSmithKline: Stocks/Bonds|ViiV Healthcare: Employee Jean A. van Wyk, MB,ChB; MFPM, ViiV Healthcare Limited: I am an employee of ViiV Healthcare|ViiV Healthcare Limited: Stocks/Bonds Maggie Czarnogorski, MD MPH, ViiV Healthcare: Employee|ViiV Healthcare: Stocks/Bonds.