Safety and pharmacokinetics of oral and long-acting injectable cabotegravir or long-acting injectable rilpivirine in virologically suppressed adolescents with HIV (IMPAACT 2017/MOCHA): a phase 1/2, multicentre, open-label, non-comparative, dose-finding study

BACKGROUND

Combined intramuscular long-acting cabotegravir and long-acting rilpivirine constitute the first long-acting combination antiretroviral therapy (ART) regimen approved for adults with HIV. The goal of the IMPAACT 2017 study (MOCHA [More Options for Children and Adolescents]) was to assess the safety and pharmacokinetics of these drugs in adolescents.

METHODS

In this phase 1/2, multicentre, open-label, non-comparative, dose-finding study, virologically suppressed adolescents (aged 12-17 years; weight ≥35 kg; BMI ≤31·5 kg/m2) with HIV-1 on daily oral ART were enrolled at 15 centres in four countries (Botswana, South Africa, Thailand, and the USA). After 4-6 weeks of oral cabotegravir (cohort 1C) or rilpivirine (cohort 1R), participants received intramuscular long-acting cabotegravir or long-acting rilpivirine every 4 weeks or 8 weeks per the adult dosing regimens, while continuing pre-study ART. The primary outcomes were assessments of safety measures, including all adverse events, until week 4 for oral cabotegravir and until week 16 for long-acting cabotegravir and long-acting rilpivirine, and pharmacokinetic measures, including the area under the plasma concentration versus time curve during the dosing interval (AUC0-tau) and drug concentrations, at week 2 for oral dosing of cabotegravir and at week 16 for intramuscular dosing of cabotegravir and rilpivirine. Enrolment into cohort 1C or cohort 1R was based on the participant's pre-study ART, meaning that masking was not done. For pharmacokinetic analyses, blood samples were drawn at weeks 2-4 after oral dosing and weeks 4-16 after intramuscular dosing. Safety outcome measures were summarised using frequencies, percentages, and exact 95% CIs; pharmacokinetic parameters were summarised using descriptive statistics. This trial is registered at ClinicalTrials.gov, NCT03497676, and is closed to enrolment.

FINDINGS

Between March 19, 2019, and Nov 25, 2021, 55 participants were enrolled: 30 in cohort 1C and 25 in cohort 1R. At week 16, 28 (97%, 95% CI 82-100) of the 29 dose-evaluable participants in cohort 1C and 21 (91%; 72-99) of the 23 dose-evaluable participants in cohort 1R had reported at least one adverse event, with the most common being injection-site pain (nine [31%] in cohort 1C; nine [39%] in cohort 1R; none were severe). One (4%, 95% CI 0-22) participant in cohort 1R had an adverse event of grade 3 or higher, leading to treatment discontinuation, which was defined as acute rilpivirine-related allergic reaction (self-limiting generalised urticaria) after the first oral dose. No deaths or life-threatening events occurred. In cohort 1C, the week 2 median cabotegravir AUC0-tau was 148·5 (range 37·2-433·1) μg·h/mL. The week 16 median concentrations for the every-4-weeks and every-8-weeks dosing was 3·11 μg/mL (range 1·22-6·19) and 1·15 μg/mL (<0·025-5·29) for cabotegravir and 52·9 ng/mL (31·9-148·0) and 39·1 ng/mL (27·2-81·3) for rilpivirine, respectively. These concentrations were similar to those in adults.

INTERPRETATION

Study data support using long-acting cabotegravir or long-acting rilpivirine, given every 4 weeks or 8 weeks, per the adult dosing regimens, in virologically suppressed adolescents aged 12 years and older and weighing at least 35 kg.

FUNDING

The National Institutes of Health and ViiV Healthcare.

Asian participants' experience in phase 3/3b studies of long-acting cabotegravir and rilpivirine: Efficacy, safety, pharmacokinetic, and virological outcomes through week 96

OBJECTIVES

Cabotegravir + rilpivirine (CAB + RPV) dosed monthly or every 2 months is the first complete long-acting (LA) regimen recommended by treatment guidelines for the maintenance of HIV-1 virological suppression. This post hoc analysis summarizes outcomes for Asian participants through week 96.

METHODS

Data from Asian participants naive to CAB + RPV randomized to receive dosing every 4 weeks (Q4W) or every 8 weeks (Q8W) in the FLAIR (NCT02938520) and ATLAS-2M (NCT03299049) phase 3/3b studies were pooled. The proportion of participants with plasma HIV-1 RNA ≥50 and <50 copies/mL (per FDA Snapshot algorithm), incidence of confirmed virological failure (CVF; two consecutive HIV-1 RNA ≥200 copies/mL), pharmacokinetics, safety, and tolerability through week 96 were assessed.

RESULTS

Overall, 41 Asian participants received CAB + RPV (Q8W, n = 17; Q4W, n = 24). At week 96, 83% (n = 34/41) of participants maintained HIV-1 RNA <50 copies/mL, none had HIV-1 RNA ≥50 copies/mL, and 17% (n = 7/41) had no virological data. No Asian participant met the CVF criterion. Drug-related adverse events occurred in 44% (n = 18/41) of participants; none were Grade ≥3. All injection site reactions were Grade 1 or 2; median duration was 2 days and most resolved within 7 days (90%, n = 390/435). CAB and RPV trough concentrations remained well above their respective protein-adjusted 90% inhibitory concentrations (CAB, 0.166 μg/mL; RPV, 12 ng/mL) through week 96.

CONCLUSIONS

CAB + RPV LA demonstrated high efficacy, with no participants having CVF, and an acceptable safety profile in Asian participants through week 96. These data support CAB + RPV LA as a complete regimen for the maintenance of HIV-1 virological suppression in Asian individuals.

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.

Efficacy, safety, and pharmacokinetics by BMI category in Phase 3/3b cabotegravir + rilpivirine long-acting trials

BACKGROUND

Cabotegravir + rilpivirine (CAB + RPV) is a guideline-recommended long-acting (LA) injectable regimen for the maintenance of HIV-1 virologic suppression. This post hoc analysis summarizes CAB + RPV LA results by baseline body mass index (BMI) category among Phase 3/3b trial participants.

METHODS

Data from CAB + RPV-naive participants receiving every 4 or 8 week dosing in FLAIR, ATLAS, and ATLAS-2 M were pooled through Week (W) 48. Data beyond W48 were summarized by study (FLAIR through W96 and ATLAS-2 M through W152). HIV 1 RNA <50 and ≥50 copies/mL, confirmed virologic failure (CVF; two consecutive HIV-1 RNA ≥200 copies/mL), safety and tolerability, and plasma CAB and RPV trough concentrations were evaluated by baseline BMI (<30 kg/m2 [lower];  ≥ 30 kg/m2 [higher]).

RESULTS

Among 1245 CAB + RPV LA participants, 213 (17%) had a baseline BMI ≥30 kg/m2. At W48, 92% vs. 93% of participants with lower vs. higher BMI had HIV-1 RNA <50 copies/mL, respectively. Including data beyond W48, 18 participants had CVF; those in the higher BMI group (n = 8) all had at least one other baseline factor associated with CVF (archived RPV resistance-associated mutations or HIV 1 subtype A6/A1). Safety and pharmacokinetic profiles were comparable between BMI categories.

CONCLUSION

CAB + RPV LA was efficacious and well tolerated, regardless of baseline BMI category.Main point summary: CAB + RPV LA is effective in the maintenance of HIV-1 virologic suppression in adults regardless of BMI category, with longer-length needles (≥2 inches) recommend for those with BMI ≥30 kg/m2 to accommodate individual body habitus and ensure appropriate 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.

Extended Analysis of HIV Infection in Cisgender Men and Transgender Women Who Have Sex with Men Receiving Injectable Cabotegravir for HIV Prevention: HPTN 083

HPTN 083 demonstrated that injectable cabotegravir (CAB) was superior to oral tenofovir disoproxil fumarate-emtricitabine (TDF-FTC) for HIV prevention in cisgender men and transgender women who have sex with men. We previously analyzed 58 infections in the blinded phase of HPTN 083 (16 in the CAB arm and 42 in the TDF-FTC arm). This report describes 52 additional infections that occurred up to 1 year after study unblinding (18 in the CAB arm and 34 in the TDF-FTC arm). Retrospective testing included HIV testing, viral load testing, quantification of study drug concentrations, and drug resistance testing. The new CAB arm infections included 7 with CAB administration within 6 months of the first HIV-positive visit (2 with on-time injections, 3 with ≥1 delayed injection, and 2 who restarted CAB) and 11 with no recent CAB administration. Three cases had integrase strand transfer inhibitor (INSTI) resistance (2 with on-time injections and 1 who restarted CAB). Among 34 CAB infections analyzed to date, diagnosis delays and INSTI resistance were significantly more common in infections with CAB administration within 6 months of the first HIV-positive visit. This report further characterizes HIV infections in persons receiving CAB preexposure prophylaxis and helps define the impact of CAB on the detection of infection and the emergence of INSTI resistance.

Long-acting cabotegravir and rilpivirine dosed every 2 months in adults with HIV-1 infection: 152-week results from ATLAS-2M, a randomized, open-label, Phase 3b, noninferiority study

BACKGROUND

Cabotegravir (CAB) + rilpivirine (RPV) dosed intramuscularly monthly or every 2 months is a complete long-acting (LA) regimen for the maintenance of HIV-1 virologic suppression. Here, we report the ATLAS-2M study Week 152 results.

METHODS

ATLAS-2M is a Phase 3b, randomized, multicenter study assessing the efficacy and safety of CAB+RPV LA every 8 weeks (Q8W) vs. every 4 weeks (Q4W). Virologically suppressed (HIV-1 RNA <50 copies/mL) individuals were randomized to receive CAB+RPV LA Q8W or Q4W. Endpoints included the proportion of participants with plasma HIV-1 RNA ≥50 copies/mL and <50 copies/mL, incidence of confirmed virologic failure (CVF; two consecutive measurements of ≥200 copies/mL), safety, and tolerability.

RESULTS

1045 participants received CAB+RPV LA (Q8W, n=522; Q4W, n=523). CAB+RPV LA Q8W demonstrated noninferior efficacy vs. Q4W dosing, with 2.7% (n=14) and 1.0% (n=5) of participants having HIV-1 RNA ≥50 copies/mL, respectively. The adjusted treatment difference in proportions was 1.7% (95% CI 0.1 to 3.3), meeting the pre-specified noninferiority threshold of 4%. At Week 152, 87% of participants maintained HIV-1 RNA <50 copies/mL (Q8W, 87% [n=456]; Q4W, 86% [n=449]). Overall, 12 (2.3%) participants in the Q8W arm and two (0.4%) participants in the Q4W arm had CVF. Eight and 10 participants with CVF had treatment-emergent resistance-associated mutations to RPV and integrase inhibitors, respectively. Safety profiles were comparable, with no new safety signals observed since Week 48.

CONCLUSIONS

These data demonstrate the durability of virologic suppression with CAB+RPV LA Q8W or Q4W for ∼3 years, and confirm the long-term efficacy, safety, and tolerability of CAB+RPV LA as a complete regimen for the maintenance of HIV-1 virologic suppression.

Practical dosing guidance for the management of clinician-administered injections of long-acting cabotegravir and rilpivirine

Cabotegravir (CAB) and rilpivirine (RPV) is the first complete long-acting (LA) injectable regimen recommended by treatment guidelines for the maintenance of HIV-1 virologic suppression in people with HIV-1 who are virologically suppressed on a stable antiretroviral regimen that is administered monthly (Q1M) or every 2 months (Q2M). As an alternative regimen to lifelong daily oral antiretroviral therapy, Q1M or Q2M dosing schedules are associated with increased patient satisfaction and treatment preference. In addition, it may address challenges associated with daily oral dosing, including fear of treatment disclosure or stigma, anxiety related to oral dosing adherence, and the daily reminder of HIV disease status. Cabotegravir + RPV LA is administered by clinical staff as two intramuscular injections dosed Q1M or Q2M. In this review, we share practical dosing guidance for CAB+RPV LA injectable therapy, including how to initiate therapy, schedule injection visits, manage dosing interruptions due to missed or delayed injection visits, manage errors in dosing, and transition to alternative antiretroviral therapy after discontinuation. Practical guidance on the clinical management of CAB+RPV LA dosing, including a detailed discussion using case-based scenarios that may be encountered in clinical practice, is provided. The clinician-administered CAB+RPV LA regimen has dosing management considerations that are flexible and considerate of the patient and has the potential to provide a highly desirable and efficacious alternative to daily oral antiretroviral therapy for many people with HIV-1.

Pregnancy outcomes and pharmacokinetics in pregnant women living with HIV exposed to long‐acting cabotegravir and rilpivirine in clinical trials

BACKGROUND

Limited data exist on pregnant women living with HIV exposed to cabotegravir + rilpivirine (CAB + RPV). Outcomes in pregnant participants exposed to CAB + RPV, and pharmacokinetic washout data in those exposed to CAB + RPV long-acting (LA) with live births, are presented.

METHODS

Women exposed to one or more doses of CAB + RPV (oral/LA) from ViiV Healthcare-sponsored phase 2b/3/3b clinical trials and the compassionate use programme who became pregnant were included. Upon pregnancy in the trial programme, CAB + RPV was discontinued, an alternative antiretroviral regimen was initiated, and quarterly pharmacokinetic sampling for 52 weeks post-last injection was obtained. CAB + RPV continuation or alternative antiretroviral regimen initiation was decided by pregnant compassionate use programme participants and their treating physicians.

RESULTS

As of 31 March 2021, 25 pregnancies following CAB + RPV exposure at conception were reported (five oral, 20 LA), including four who conceived during pharmacokinetic washout following treatment discontinuation. There were eight elective abortions, six miscarriages (five in first trimester), one ectopic pregnancy, and 10 live births (one oral, nine LA), including one infant born with congenital ptosis. Among participants exposed to CAB + RPV LA at conception with live births, plasma CAB and RPV washout concentrations during pregnancy were within the range of those observed in non-pregnant women.

CONCLUSION

In this first analysis of pregnancy outcomes following CAB + RPV exposure at conception, 10 live births, including one with congenital anomaly, were reported. Plasma CAB and RPV washout concentrations during pregnancy were within the range of those in non-pregnant women. Pregnancy surveillance within ViiV Healthcare-sponsored clinical trials is ongoing, with dedicated pregnancy studies planned.

Population pharmacokinetics of cabotegravir following administration of oral tablet and long-acting intramuscular injection in adult HIV-1-infected and uninfected subjects

AIM

To characterize cabotegravir population pharmacokinetics using data from phase 1, 2 and 3 studies and evaluate the association of intrinsic and extrinsic factors with pharmacokinetic variability.

METHODS

Analyses were implemented in NONMEM and R. Concentrations below the quantitation limit were modelled with likelihood-based approaches. Covariate relationships were evaluated using forward addition (P < .01) and backward elimination (P < .001) approaches. The impact of each covariate on trough and peak concentrations was evaluated through simulations. External validation was performed using prediction-corrected visual predictive checks.

RESULTS

The model-building dataset included 23 926 plasma concentrations from 1647 adult HIV-1-infected (72%) and uninfected (28%) subjects in 16 studies at seven dose levels (oral 10-60 mg, long-acting [LA] intramuscular injection 200-800 mg). A two-compartment model with first-order oral and LA absorption and elimination adequately described the data. Clearances and volumes were scaled to body weight. Estimated relative bioavailability of oral to LA was 75.6%. Race and age were not significant covariates. LA absorption rate constant (KALA ) was 50.9% lower in females and 47.8% higher if the LA dose was given as two split injections. KALA decreased with increasing BMI and decreasing needle length. Clearance was 17.4% higher in current smokers. The impact of any covariate was ≤32% on trough and peak concentrations following LA administration. The final model adequately predicted 5097 plasma concentrations from 647 subjects who were not included in the model-building dataset.

CONCLUSIONS

A cabotegravir population pharmacokinetic model was developed that can be used to inform dosing strategies and future study design. No dose adjustment based on subject covariates is recommended.

Week 96 extension results of a Phase 3 study evaluating long-acting cabotegravir with rilpivirine for HIV-1 treatment

BACKGROUND

ATLAS (NCT02951052), a phase 3, multicenter, open-label study, demonstrated that switching to injectable cabotegravir (CAB) with rilpivirine (RPV) long-acting dosed every 4 weeks was noninferior at week (W) 48 to continuing three-drug daily oral current antiretroviral therapy (CAR). Results from the W 96 analysis are presented.

METHODS AND DESIGN

Participants completing W 52 of ATLAS were given the option to withdraw, transition to ATLAS-2M (NCT03299049), or enter an Extension Phase to continue long-acting therapy (Long-acting arm) or switch from CAR to long-acting therapy (Switch arm). Endpoints assessed at W 96 included proportion of participants with plasma HIV-1 RNA less than 50 copies/ml, incidence of confirmed virologic failure (CVF; two consecutive HIV-1 RNA ≥200 copies/ml), safety and tolerability, pharmacokinetics, and patient-reported outcomes.

RESULTS

Most participants completing the Maintenance Phase transitioned to ATLAS-2M (88%, n = 502/572). Overall, 52 participants were included in the W 96 analysis of ATLAS; of these, 100% (n = 23/23) and 97% (n = 28/29) in the Long-acting and Switch arms had plasma HIV-1 RNA less than 50 copies/ml at W 96, respectively. One participant had plasma HIV-1 RNA 50 copies/ml or higher in the Switch arm (173 copies/ml). No participants met the CVF criterion during the Extension Phase. No new safety signals were identified. All Switch arm participants surveyed preferred long-acting therapy to their previous daily oral regimen (100%, n = 27/27).

CONCLUSION

In this subgroup of ATLAS, 98% (n = 51/52) of participants at the Extension Phase W 96 analysis maintained virologic suppression with long-acting therapy. Safety, efficacy, and participant preference results support the therapeutic potential of long-acting CAB+RPV treatment for virologically suppressed people living with HIV-1.

833. Efficacy and Safety of Long-Acting Cabotegravir + Rilpivirine in Participants with HIV/HCV Co-infection: ATLAS-2M 48-Week Results

Background

The phase IIIb ATLAS-2M study demonstrated non-inferiority of long-acting (LA) cabotegravir (CAB) + rilpivirine (RPV) dosed every 8 weeks (Q8W) compared with every 4 weeks (Q4W) for maintenance of virologic suppression. Hepatitis C virus (HCV) co-infection occurs in ~6% of people with HIV due to shared modes of transmission. We report efficacy and safety of CAB + RPV LA in participants with HIV/HCV co-infection in ATLAS-2M.

Methods

Participants with HIV-1 RNA &lt; 50 c/mL receiving CAB + RPV LA Q4W (transitioned from ATLAS [NCT02951052]) or oral comparator ART were randomized 1:1 to receive CAB + RPV LA Q4W or Q8W. Baseline HCV RNA was assessed by polymerase chain reaction. Participants with symptomatic chronic HCV infection requiring treatment within 12 months or liver enzymes not meeting entry criteria were excluded. Week 48 assessments included proportion with HIV-1 RNA ≥50 and &lt; 50 c/mL (Snapshot algorithm), general and hepatic safety, and pharmacokinetics.

Results

HIV/HCV co-infection was present in 10 (1%) of 1045 participants, 60% of whom were female at birth. At Week 48, 9/10 (90%) and 972/1035 (94%) participants with HIV/HCV co-infection and HIV mono-infection, respectively, had HIV-1 RNA &lt; 50 c/mL (adjusted difference, 4.1; 95% CI, −14.5 to 22.6). No participants with HIV/HCV co-infection had HIV-1 RNA ≥50 c/mL (vs 14/1035 [1%] with HIV mono-infection) or confirmed virologic failure through Week 48 (vs 10 [1%] with HIV mono-infection); 1/10 (10%) discontinued for reasons other than adverse events (AEs). Excluding injection site reactions (ISRs), AEs and serious AEs were reported in 4 (40%) and 0 participants with HIV/HCV co-infection, respectively; the only AE reported in &gt;1 participant was injection site pain (n=5; 50%). In participants with HIV/HCV co-infection, all ISRs were grade 1/2; none led to withdrawal. No hepatic laboratory abnormalities were reported in participants with HIV/HCV co-infection through Week 48; rates were low in those with HIV mono-infection (Table). Plasma CAB and RPV concentrations were similar between groups.

Conclusion

CAB + RPV LA was effective and well tolerated in this small cohort of participants with HIV and asymptomatic HCV co-infection.

Disclosures

Ronald D’Amico, DO, MSc, GlaxoSmithKline (Shareholder)ViiV Healthcare (Employee) Paul Benn, MB ChB FRCP, ViiV Healthcare (Employee) Shanker Thiagarajah, MB ChB, GlaxoSmithKline (Employee, Shareholder) Susan L. Ford, PharmD, GlaxoSmithKline (Shareholder)ViiV Healthcare (Employee) Eileen Birmingham, MD, MPH, Janssen Research and Development (Employee, Shareholder) Ojesh R. Upadhyay, MPH, MBA, GlaxoSmithKline (Employee) Louise Garside, PhD, GlaxoSmithKline (Employee) Rodica Van Solingen-Ristea, MD, Janssen Research and Development (Employee)ViiV Healthcare (Employee) Kati Vandermeulen, M.SC., Janssen Research and Development (Employee) William Spreen, PharmD, GlaxoSmithKline (Shareholder)ViiV Healthcare (Employee)

885. Pregnancy Outcomes and Pharmacokinetics in Pregnant Women Living with HIV Exposed to Long-Acting Cabotegravir and Rilpivirine in Clinical Trials

Background

Limited data exist among women living with HIV who become pregnant while exposed to long-acting (LA) cabotegravir (CAB) and rilpivirine (RPV). We report outcomes in pregnant participants and LA pharmacokinetic (PK) tail data in pregnant women exposed to CAB+RPV with live births.

Methods

Women of reproductive potential exposed to ≥ 1 dose of CAB+RPV (oral/LA) from ViiV-sponsored Phase 2/3/3b clinical treatment studies and the compassionate use program were included in this analysis and pregnancies identified. Per protocol, upon identification of pregnancy, CAB+RPV was discontinued and an alternative regimen initiated, with continued quarterly PK sampling for 52 weeks post last injection during long-term safety follow-up (LTFU). Descriptive characteristics of pregnant women and birth outcomes and available CAB and RPV PK during pregnancy for those with live births are summarized.

Results

As of March 31, 2021, 26/325 women of reproductive potential (age 18–49 years) became pregnant while exposed to CAB+RPV (5 oral, 21 LA [including 3 following LA discontinuation]). There were 11 live births (1 oral, 10 LA), of which 10 had no reported congenital abnormalities and 1 had reported congenital ptosis, in a pre-term infant with intrauterine growth restriction. There were 9 elective terminations and 6 miscarriages (5 in first 9 weeks of gestation). Ten women exposed to intramuscular CAB+RPV LA became pregnant with subsequent live birth outcomes, including 3 infants conceived during the PK tail in LTFU. All women were virologically suppressed at time of pregnancy identification. In women becoming pregnant on LA dosing, plasma CAB and RPV concentrations during pregnancy were within the range of expected concentrations in non-pregnant women. Two of 10 women with live births exposed to CAB+RPV LA continued LA therapy during pregnancy (compassionate use program participants).

Conclusion

Pregnancy outcomes in women exposed to CAB+RPV at conception are consistent with earlier findings. There was 1 reported congenital anomaly among 11 live births. CAB and RPV PK tail in pregnancy was within the expected range for non-pregnant women. Ongoing monitoring of birth defects within the antiretroviral pregnancy registry and pregnancy surveillance within the treatment program continues.

Disclosures

Parul Patel, PharmD, GlaxoSmithKline (Shareholder)ViiV Healthcare (Employee) Susan L. Ford, PharmD, GlaxoSmithKline (Shareholder)ViiV Healthcare (Employee) Mark Baker, PhD, GlaxoSmithKline (Shareholder)ViiV Healthcare (Employee) Claudia Meyer, MBChB, MRCP, MSc, FRCPath, DTM&H, GlaxoSmithKline (Employee, Shareholder) Louise Garside, PhD, GlaxoSmithKline (Employee) Ronald D’Amico, DO, MSc, GlaxoSmithKline (Shareholder)ViiV Healthcare (Employee) Rodica Van Solingen-Ristea, MD, Janssen Research and Development (Employee)ViiV Healthcare (Employee) Herta Crauwels, PhD, Janssen (Employee) Joseph Polli, PhD, FAAPS, GlaxoSmithKline (Shareholder)ViiV Healthcare (Employee) Ciara Seal, BS, GlaxoSmithKline (Employee, Shareholder) Shanker Thiagarajah, MB ChB, GlaxoSmithKline (Employee, Shareholder) Eileen Birmingham, MD, MPH, Janssen Research and Development (Employee, Shareholder) William Spreen, PharmD, GlaxoSmithKline (Shareholder)ViiV Healthcare (Employee) Bryan Baugh, MD, Janssen, Johnson & Johnson (Employee, Shareholder) Matthew Bosse, DO, GlaxoSmithKline (Shareholder)ViiV Healthcare (Employee) Vani Vannappagari, MBBS, MPH, PhD, ViiV Healthcare Limited (Employee)

Long-acting cabotegravir and rilpivirine dosed every 2 months in adults with HIV-1 infection (ATLAS-2M), 96-week results: a randomised, multicentre, open-label, phase 3b, non-inferiority study

BACKGROUND

Long-acting cabotegravir and rilpivirine administered monthly or every 2 months might address the challenges associated with daily oral antiretroviral therapy. The ATLAS-2M week 48 results showed non-inferiority of long-acting cabotegravir and rilpivirine administered every 8 weeks compared with that of every 4 weeks. In this study, we report the efficacy, safety, and tolerability results from the week 96 analysis.

METHODS

ATLAS-2M is a randomised, multicentre, open-label, phase 3b, non-inferiority trial conducted in 13 countries, evaluating the safety and efficacy of maintenance treatment with intramuscular injections of long-acting cabotegravir and rilpivirine, administered every 8 weeks versus every 4 weeks, to people living with HIV-1. Virologically suppressed adults with HIV-1, either already receiving intramuscular long-acting cabotegravir and rilpivirine every 4 weeks (ie, ATLAS study rollover participants) or oral standard of care, were randomly assigned (1:1), in an unblinded fashion, to receive either intramuscular long-acting cabotegravir (600 mg) and rilpivirine (900 mg) every 8 weeks (ie, the every 8-week dosing group) or intramuscular long-acting cabotegravir (400 mg) and rilpivirine (600 mg) every 4 weeks (ie, the every 4-week dosing group). Randomisation was generated using the GlaxoSmithKline-validated randomisation software RANDALL NG (version 1.3.3). The primary endpoint at week 48 was the proportion of participants with plasma HIV-1 RNA measurements of 50 copies per mL or more (ie, the US Food and Drug Administration [FDA] Snapshot algorithm), which has been published previously. Here, we present the week 96 results: the proportion of participants with plasma HIV-1 RNA measurements of less than 50 copies per mL (FDA Snapshot algorithm), with a non-inferiority margin of -10%; the proportion of participants with plasma HIV-1 RNA measurements of 50 copies per mL or more (FDA Snapshot algorithm), with a non-inferiority margin of 4%; the proportion of participants with protocol-defined confirmed virological failure (ie, two consecutive plasma HIV-1 RNA measurements ≥200 copies per mL); safety; pharmacokinetics; and tolerability. This study is registered with ClinicalTrials.gov, number NCT03299049, and is currently ongoing.

FINDINGS

Between Oct 27, 2017, and May 31, 2018, a total of 1149 participants were screened; of whom, 1049 (91%) were randomly assigned and 1045 (91%) initiated treatment (522 in the every 8-week dosing group and 523 in the every 4-week dosing group). The median age was 42 years (IQR 34-50). 280 (27%) of 1045 participants were assigned female at birth and 764 (73%) were white. At week 96 (FDA Snapshot algorithm), 11 (2%) of 522 participants in the every 8-week dosing group and six (1%) of 523 in the every 4-week dosing group had an HIV-1 RNA measurement of 50 copies per mL or more, with an adjusted treatment difference of 1·0 (95% CI -0·6 to 2·5), meeting the prespecified non-inferiority threshold of 4%; 475 (91%) of 522 participants in the every 8-week dosing group and 472 (90%) of 523 in the every 4-week dosing group maintained an HIV-1 RNA measurement of less than 50 copies per mL, with an adjusted treatment difference of 0·8 (95% CI -2·8 to 4·3), which met the prespecified non-inferiority threshold of -10%. One participant in the every 8-week dosing group met the confirmed virological failure criterion since the week 48 analysis at week 88, resulting in a total of nine participants in the every 8-week dosing group and two in the every 4-week dosing group having confirmed virological failure. No new safety signals were identified, and no treatment-related deaths occurred. Injection site reactions were the most common adverse event, occurring in 412 (79%) of 522 participants in the every 8-week dosing group and 400 (76%) of 523 in the every 4-week dosing group. Most injection site reactions were grade 1 or 2 (7453 [99%] of 7557 in both groups), with a median duration of 3 days (IQR 2-5).

INTERPRETATION

Long-acting cabotegravir and rilpivirine dosed every 8 weeks had non-inferior efficacy compared with that of every 4 weeks through the 96-week analysis, with both regimens maintaining high levels of virological suppression. These results show the durable safety, efficacy, and acceptability of dosing long-acting cabotegravir and rilpivirine monthly and every 2 months as maintenance therapy for people living with HIV-1.

FUNDING

ViiV Healthcare and Janssen Research & Development.

Exploring predictors of HIV-1 virologic failure to long-acting cabotegravir and rilpivirine: a multivariable analysis

OBJECTIVE

Efficacy and safety of long-acting cabotegravir (CAB) and rilpivirine (RPV) dosed intramuscularly every 4 or 8 weeks has been demonstrated in three Phase 3 trials. Here, factors associated with virologic failure at Week 48 were evaluated post hoc.

DESIGN AND METHODS

Data from 1039 adults naive to long-acting CAB+RPV were pooled in a multivariable analysis to examine the influence of baseline viral and participant factors, dosing regimen and drug concentrations on confirmed virologic failure (CVF) occurrence using a logistic regression model. In a separate model, baseline factors statistically associated with CVF were further evaluated to understand CVF risk when present alone or in combination.

RESULTS

Overall, 1.25% (n = 13/1039) of participants experienced CVF. Proviral RPV resistance-associated mutations (RAMs), HIV-1 subtype A6/A1, higher BMI (associated with Week 8 CAB trough concentration) and lower Week 8 RPV trough concentrations were significantly associated (P < 0.05) with increased odds of CVF (all except RPV trough are knowable at baseline). Few participants (0.4%) with zero or one baseline factor had CVF. Only a combination of at least two baseline factors (observed in 3.4%; n = 35/1039) was associated with increased CVF risk (25.7%, n = 9/35).

CONCLUSION

CVF is an infrequent multifactorial event, with a rate of approximately 1% in the long-acting CAB+RPV arms across Phase 3 studies (FLAIR, ATLAS and ATLAS-2M) through Week 48. Presence of at least two of proviral RPV RAMs, HIV-1 subtype A6/A1 and/or BMI at least 30 kg/m2 was associated with increased CVF risk. These findings support the use of long-acting CAB+RPV in routine clinical practice.

Multicompartmental pharmacokinetic evaluation of long-acting cabotegravir in healthy adults for HIV preexposure prophylaxis

Aims

Cabotegravir is an integrase strand transfer inhibitor in clinical development as long‐acting (LA) injectable HIV preexposure prophylaxis.

Methods

This phase I study assessed pharmacokinetics of cabotegravir in plasma and anatomical sites associated with sexual HIV‐1 transmission after repeated oral and single intramuscular (IM) LA dosing in healthy adults. Following a 28‐day oral lead‐in period of cabotegravir 30 mg and a washout period of 14–42 days, participants were administered a single ultrasound‐guided gluteal IM cabotegravir LA 600‐mg injection. The study objective was to characterize cabotegravir concentrations in plasma, cervical, vaginal and rectal tissues, and cervicovaginal and rectal fluids and up to Week 12 after IM injection.

Results

Nineteen participants enrolled and 16 completed the study through Week 52. Cabotegravir was detected in plasma and all tissues and fluids. Median plasma cabotegravir concentrations exceeded the in vitro protein‐adjusted 90% maximal inhibitory concentration through Week 12. Median tissue‐ and fluid‐to‐plasma cabotegravir concentration ratios across all visits were 0.32 for rectal fluid and 0.08–0.16 for other tissues and fluids. Adjusted R² coefficients between cabotegravir concentrations in plasma and cervical, vaginal and rectal tissues were 0.78, 0.79 and 0.90, respectively. Injection‐site reactions were common (88% of participants) and were mostly grade 1 in intensity (82%). Two participants reported 11 non–drug‐related serious adverse events.

Conclusion

Concentrations of cabotegravir in tissues and fluids were proportional to plasma over time, with strong correlations between tissue and plasma concentrations. Cabotegravir LA tissue‐to‐plasma ratios may be important for understanding its use as preexposure prophylaxis.

Long-acting cabotegravir plus rilpivirine for treatment in adults with HIV-1 infection: 96-week results of the randomised, open-label, phase 3 FLAIR study

BACKGROUND

There is a need for more convenient, less frequent treatment to help address challenges associated with daily oral HIV treatment in people living with HIV, including stigma, pill burden, drug-food interactions, and adherence. The phase 3 ATLAS and FLAIR studies showed non-inferiority of long-acting cabotegravir and rilpivirine dosed every 4 weeks compared with standard oral therapy for the maintenance of virological suppression in adults with HIV-1 over 48 weeks. We present the 96-week findings.

METHODS

FLAIR is a randomised, phase 3, open-label, multicentre study done in 11 countries investigating whether switching to long-acting cabotegravir and rilpivirine is non-inferior to daily dolutegravir, abacavir, and lamivudine in virologically suppressed adults living with HIV-1. Antiretroviral therapy (ART)-naive participants received induction therapy with daily oral dolutegravir (50 mg), abacavir (600 mg), and lamivudine (300 mg) for 20 weeks. After 16 weeks, participants with less than 50 HIV-1 RNA copies per mL were randomly assigned (1:1) to continue the standard of care regimen (standard care group) or switch to receive daily oral cabotegravir 30 mg and rilpivirine 25 mg for at least 4 weeks followed by long-acting cabotegravir 400 mg and rilpivirine 600 mg, administered as two 2 mL intramuscular injections, every 4 weeks for at least 96 weeks (long-acting group). Randomisation was stratified by baseline (preinduction) HIV-1 RNA (<100 000 or ≥100 000 copies per mL) and sex at birth and used GlaxoSmithKline-verified randomisation software (RandAll NG, version 1.3.3) for treatment assignment. The primary endpoint was the proportion of participants with plasma HIV-1 RNA of 50 copies per mL or more assessed as per the US Food and Drug Administration (FDA) Snapshot algorithm at week 48, which has been reported previously. Here, we report the proportion of participants with 50 or more HIV-1 RNA copies per mL using the FDA Snapshot algorithm at week 96 (intention-to-treat population; non-inferiority margin 6%). The trial is registered with ClinicalTrials.gov, NCT02938520.

FINDINGS

Between Oct 27, 2016, and March 24, 2017, 809 participants were screened. 631 (78%) participants entered the induction phase and 566 (70%) were randomly assigned to either the standard care group (283 [50%] participants) or the long-acting group (283 [50%]). Median age was 34 years (IQR 29 to 43), 62 (11%) were 50 years or older, 127 (22%) were women (sex at birth), and 419 (74%) were white. At week 96, nine (3%) participants in each arm had 50 or more HIV-1 RNA copies per mL, with an adjusted difference of 0·0 (95% CI -2·9 to 2·9), consistent with non-inferiority established at week 48. Across both treatment groups, adverse events leading to withdrawal were infrequent (14 [5%] participants in the long-acting group and four [1%] in the standard care group). Injection site reactions were the most common adverse event, reported by 245 (88%) participants in the long-acting group; their frequency decreased over time. Median injection site reaction duration was 3 days (IQR 2 to 4), and 3082 (99%) of 3100 reactions were grade 1 or 2. No deaths occurred during the maintenance phase.

INTERPRETATION

The 96-week results reaffirm the 48-week results, showing long-acting cabotegravir and rilpivirine continued to be non-inferior compared with continuing a standard care regimen in adults with HIV-1 for the maintenance of viral suppression. These results support the durability of long-acting cabotegravir and rilpivirine, over an almost 2-year-long period, as a therapeutic option for virally suppressed adults with HIV-1.

FUNDING

ViiV Healthcare and Janssen Research and Development.

Effect of rifabutin on the pharmacokinetics of oral cabotegravir in healthy subjects

BACKGROUND

Cabotegravir (CAB) is an integrase strand transfer inhibitor in development as a long-acting injectable formulation, with an oral formulation used during a safety lead-in period. Tuberculosis (TB)-HIV coinfection is common, often requiring simultaneous treatment. Rifabutin (RBT) is an alternative antimycobacterial agent for TB and a moderate inducer of cytochrome P450 and UDP-glucuronosyltransferase isoenzymes. This study evaluated the impact of RBT on the pharmacokinetics (PK) of oral CAB.

METHODS

In this Phase I, single-centre, open-label, two-period, fixed-sequence, drug interaction study, subjects received oral CAB 30 mg once daily for 14 days in period 1, and oral CAB plus RBT 300 mg once daily for 14 days in period 2. Serial PK sampling was performed on days 14 and 28. Geometric least squares (GLS) mean ratios with associated 90% CIs were calculated to compare CAB noncompartmental PK parameters following CAB+RBT versus CAB alone. Safety was also assessed.

RESULTS

A total of 15 male subjects were enrolled and 12 completed all treatments. Comparing CAB+RBT with CAB alone, the GLS mean ratios (90% CIs) for CAB area under the concentration-time curve from time zero to the end of the dosing interval (AUC_0-τ), maximum observed plasma concentration (C_max) and concentration at the end of the dosing interval (C_τ) were 0.79 (0.74, 0.83), 0.83 (0.76, 0.90) and 0.74 (0.70, 0.78), respectively. 11 subjects reported 24 adverse events (AEs); 22 were reported with CAB+RBT (3 drug-related) and 2 with CAB alone (not drug-related). All AEs resolved by study end.

CONCLUSIONS

RBT had a modest impact on plasma CAB exposure following oral coadministration, resulting in overall plasma CAB trough exposures above the 10 mg oral dose shown to maintain viral suppression in HIV-1-infected subjects. Oral CAB can be coadministered with RBT without dosage adjustment.

Long-Acting Cabotegravir and Rilpivirine after Oral Induction for HIV-1 Infection

BACKGROUND

Long-acting injectable regimens may simplify therapy for patients with human immunodeficiency virus type 1 (HIV-1) infection.

METHODS

We conducted a phase 3, randomized, open-label trial in which adults with HIV-1 infection who had not previously received antiretroviral therapy were given 20 weeks of daily oral induction therapy with dolutegravir-abacavir-lamivudine. Participants who had an HIV-1 RNA level of less than 50 copies per milliliter after 16 weeks were randomly assigned (1:1) to continue the current oral therapy or switch to oral cabotegravir plus rilpivirine for 1 month followed by monthly injections of long-acting cabotegravir plus rilpivirine. The primary end point was the percentage of participants who had an HIV-1 RNA level of 50 copies per milliliter or higher at week 48 (Food and Drug Administration snapshot algorithm).

RESULTS

At week 48, an HIV-1 RNA level of 50 copies per milliliter or higher was found in 6 of 283 participants (2.1%) who received long-acting therapy and in 7 of 283 (2.5%) who received oral therapy (adjusted difference, -0.4 percentage points; 95% confidence interval [CI], -2.8 to 2.1), a result that met the criterion for noninferiority for the primary end point (margin, 6 percentage points). An HIV-1 RNA level of less than 50 copies per milliliter at week 48 was found in 93.6% who received long-acting therapy and in 93.3% who received oral therapy (adjusted difference, 0.4 percentage points; 95% CI, -3.7 to 4.5), a result that met the criterion for noninferiority for this end point (margin, -10 percentage points). Of the participants who received long-acting therapy, 86% reported injection-site reactions (median duration, 3 days; mild or moderate severity, 99% of cases); 4 participants withdrew from the trial for injection-related reasons. Grade 3 or higher adverse events and events that met liver-related stopping criteria occurred in 11% and 2%, respectively, who received long-acting therapy and in 4% and 1% who received oral therapy. Treatment satisfaction increased after participants switched to long-acting therapy; 91% preferred long-acting therapy at week 48.

CONCLUSIONS

Therapy with long-acting cabotegravir plus rilpivirine was noninferior to oral therapy with dolutegravir-abacavir-lamivudine with regard to maintaining HIV-1 suppression. Injection-site reactions were common. (Funded by ViiV Healthcare and Janssen; FLAIR ClinicalTrials.gov number, NCT02938520.).

Long-Acting Cabotegravir and Rilpivirine for Maintenance of HIV-1 Suppression

BACKGROUND

Simplified regimens for the treatment of human immunodeficiency virus type 1 (HIV-1) infection may increase patient satisfaction and facilitate adherence.

METHODS

In this phase 3, open-label, multicenter, noninferiority trial involving patients who had had plasma HIV-1 RNA levels of less than 50 copies per milliliter for at least 6 months while taking standard oral antiretroviral therapy, we randomly assigned participants (1:1) to either continue their oral therapy or switch to monthly intramuscular injections of long-acting cabotegravir, an HIV-1 integrase strand-transfer inhibitor, and long-acting rilpivirine, a nonnucleoside reverse-transcriptase inhibitor. The primary end point was the percentage of participants with an HIV-1 RNA level of 50 copies per milliliter or higher at week 48, determined with the use of the Food and Drug Administration snapshot algorithm.

RESULTS

Treatment was initiated in 308 participants per group. At week 48, HIV-1 RNA levels of 50 copies per milliliter or higher were found in 5 participants (1.6%) receiving long-acting therapy and in 3 (1.0%) receiving oral therapy (adjusted difference, 0.6 percentage points; 95% confidence interval [CI], -1.2 to 2.5), a result that met the criterion for noninferiority for the primary end point (noninferiority margin, 6 percentage points). An HIV-1 RNA level of less than 50 copies per milliliter at week 48 was found in 92.5% of participants receiving long-acting therapy and in 95.5% of those receiving oral therapy (adjusted difference, -3.0 percentage points; 95% CI, -6.7 to 0.7), a result that met the criterion for noninferiority for this end point (noninferiority margin, -10 percentage points). Virologic failure was confirmed in 3 participants who received long-acting therapy and 4 participants who received oral therapy. Adverse events were more common in the long-acting-therapy group and included injection-site pain, which occurred in 231 recipients (75%) of long-acting therapy and was mild or moderate in most cases; 1% withdrew because of this event. Serious adverse events were reported in no more than 5% of participants in each group.

CONCLUSIONS

Monthly injections of long-acting cabotegravir and rilpivirine were noninferior to standard oral therapy for maintaining HIV-1 suppression. Injection-related adverse events were common but only infrequently led to medication withdrawal. (Funded by ViiV Healthcare and Janssen; ATLAS ClinicalTrials.gov number, NCT02951052.).

2495. Pharmacokinetics of Cabotegravir (CAB) and Rilpivirine (RPV) Long-Acting (LA) Injectables in HIV-infected Individuals through 48 Weeks in the FLAIR and ATLAS Phase 3 Studies

Background

Monthly injectable CAB LA + RPV LA was noninferior to daily oral 3-drug antiretroviral therapy in HIV-1 virologically suppressed adults. CAB and RPV pharmacokinetics (PK) were assessed during the 48 Week maintenance period of the ATLAS and FLAIR Phase 3 studies.

Methods

Patients received oral CAB 30 mg + RPV 25 mg once daily for 4 weeks to assess individual tolerability prior to intramuscular (IM) injections of CAB LA 600 mg + RPV LA 900 mg followed by CAB LA 400 mg + RPV LA 600 mg every 4 weeks. Plasma CAB and RPV concentrations were measured pre-and post-dose at select visits using validated analytical methods.

Results

Baseline demographics for the pooled randomized ATLAS and FLAIR population (n = 591, LA arms) were: median age 38 years, 27% female, 18% African American, median BMI 25 kg/m² (range: 15 – 51). CAB and RPV plasma concentrations at select visits are summarized in the table. After initial IM doses, mean CAB and RPV troughs were well above their respective in vitro PA-IC90 values (CAB, 0.166 μg/mL; RPV 12 ng/mL). At Week 48, mean CAB troughs were 17x PA-IC90 and between oral CAB 10–30 mg exposures. Similarly, mean RPV troughs were 7x PA-IC90 and remained within the exposure range following oral RPV 25 mg once daily. 80% of RPV steady-state was achieved by Week 48 and 100% for CAB by Week 44. Initial CAB concentrations in females and those with BMI ≥30 kg/m² were lower due to slower absorption but this difference resolved by Week 48. For RPV, there was no absorption difference by gender or BMI.

Conclusion

CAB and RPV PK were consistent between studies achieving therapeutic concentrations within the first dosing interval that steadily increased over time through Week 48, for both males and females and irrespective of BMI. CAB LA + RPV LA provided compatible PK profiles following monthly IM dosing in a diverse patient population through 48 weeks.

Disclosures

All authors: No reported disclosures.

1532. Population Pharmacokinetic (PPK) Modeling and Simulation of Long-Acting (LA) Cabotegravir (CAB) to Inform Strategies Following Dosing Interruptions in HIV-1-Infected Subjects

Background

CAB is an integrase strand transfer inhibitor under investigation as an injectable LA formulation for the treatment and prevention of HIV, and as a tablet formulation as an oral lead-in (OLI) and bridging treatment for dose interruptions. The monthly injection regimen of CAB LA and rilpivirine (RPV) LA was noninferior to standard oral therapy in maintaining HIV-1 suppression in Phase 3 trials. PPK modeling and simulation was used to inform strategies for managing dosing interruptions.

Methods

A 2-compartment model with first-order oral and LA absorption and elimination adequately described the data from 1,647 healthy (28%) and HIV-infected (72%) adult subjects in 16 studies. Gender was a significant covariate on LA absorption; therefore, simulations of 5,000 virtual subjects were performed using a 4:1 male:female ratio to ensure 1,000 representative females and covariate sampling with replacement from the analysis dataset. One- to 12-week delays in dosing of the second, third, and fourth injection were simulated, and predicted troughs were compared with the 5th percentile (0.65 μg/mL) of trough concentrations following the first injection in Phase 3. Simulations of 1–2 months of oral bridging with CAB 30 mg once daily from time of a missed injection until CAB LA dosing resumed were performed, with the median Cmax (13.1 μg/mL) observed following oral CAB 60mg once daily in Phase 2b as an upper reference.

Results

Proportions of subjects predicted to achieve target plasma CAB trough concentrations are shown by length of delay and injection visit in Table 1. Oral bridging with CAB 30mg once daily starting at the time of a planned missed injection is predicted to provide exposures within ranges observed in clinical studies (Figure 1).

Conclusion

Dosing delays of up to one week appear to have minimal impact, but the effect is more likely to become problematic with longer delays, particularly in the first few months of dosing. Oral bridging provides therapeutic and safe exposures for planned interruptions in LA dosing. Regardless of use of oral bridging, simulations support resuming CAB LA dosing for interruptions <1 month (<2 months between injections) and reinitiating CAB LA with a loading dose and subsequent monthly injections for interruptions ≥ 1 month (≥ 2 months between injections).

Disclosures

All authors: No reported disclosures.

A Phase 1 Study to Evaluate the Pharmacokinetics and Safety of Cabotegravir in Patients With Hepatic Impairment and Healthy Matched Controls

Cabotegravir is an investigational integrase inhibitor in development for the treatment and pre-exposure prophylaxis of HIV-1 infection. Liver disease is a major cause of morbidity and mortality in HIV-infected individuals and can impact the pharmacokinetics (PK) of HIV medications. This phase 1 study evaluated the PK of cabotegravir in individuals with moderate hepatic impairment (n = 8) versus healthy controls (n = 8). Participants received a single oral cabotegravir 30-mg tablet and underwent PK sampling to determine total and unbound plasma cabotegravir concentrations. Calculated geometric least-squares mean ratios (90% confidence intervals) for individuals with hepatic impairment versus healthy controls were 0.73 (0.50-1.06) for AUC_0-∞ , 0.69 (0.51-0.93) for C_max , 1.40 (0.80-2.46) for unbound concentration (CU) 2 hours postdose, 1.55 (0.82-2.94) for CU at 24 hours, 2.14 (1.57-2.90) for unbound fraction (FU) at 2 hours, and 1.90 (1.14-3.18) for FU at 24 hours. Adverse events (AEs) occurred in 2 individuals with hepatic impairment and 3 healthy controls and were grade 1/2 in severity. No participant discontinued because of AEs. Increased FU resulted in a modest decrease in total plasma exposure not considered clinically relevant. We conclude that cabotegravir may be administered without dose adjustment in patients with mild to moderate hepatic impairment.

A Phase I Study to Evaluate the Pharmacokinetics and Safety of Cabotegravir in Adults With Severe Renal Impairment and Healthy Matched Control Participants

This study investigates the impact of severe renal impairment on the pharmacokinetics of cabotegravir, an investigational HIV-1 integrase inhibitor. This was a phase I, open-label, parallel-group, multicenter study conducted in 8 participants with severe renal impairment (creatinine clearance <30 mL/min; no renal replacement therapy) and 8 healthy participants (creatinine clearance >90 mL/min; 2 women/group; 6 men/group) matched for sex, age (±10 years), and body mass index (±25%). Participants received a single 30-mg oral cabotegravir tablet to determine total and unbound plasma cabotegravir concentrations. Arithmetic and geometric least squares means were calculated, and cabotegravir noncompartmental pharmacokinetic parameters were compared using geometric least squares mean ratios with 90% confidence intervals. Safety was assessed throughout the study. Geometric least squares mean ratios (90% confidence intervals) were 0.97 (0.84-1.14) for area under the plasma concentration-time curve extrapolated to infinity, 1.01 (0.87-1.17) for maximum observed plasma concentration, 1.31 (0.84-2.03) for unbound cabotegravir 2 hours after dosing, and 1.51 (1.19-1.92) for unbound cabotegravir 24 hours after dosing. All adverse events were grade 1, except grade 3 lipase elevation in a participant with renal impairment. Severe renal impairment did not impact plasma cabotegravir exposure, and cabotegravir may be administered without dose adjustment in renal impairment among patients not receiving renal replacement.

552. Evaluation of Relationships Between UGT1A1 Genotypes and Cabotegravir Long-Acting Injection Pharmacokinetics Among HIV-Infected Subjects in the LATTE-2 Study

Background

Cabotegravir (CAB), an HIV integrase inhibitor primarily metabolized by UGT1A1, is in development as an oral tablet and long-acting (LA) intramuscular (IM) injection for the treatment and prevention of HIV infection. CAB LA has a prolonged absorption phase, typical of flip-flop PK, which yields prolonged drug exposure compared with oral administration. Genetic variation in UGT1A1 affects enzymatic activity, impacting drug exposure. A previous analysis in healthy and HIV-infected subjects demonstrated that UGT1A1 genotypes conferring poor metabolizer status were significantly associated with steady-state oral CAB PK parameters, with ~1.5-, 1.4-, and 1.3-fold increases in mean Cτ, AUC, and Cmax, respectively, in subjects with low vs. normal genetically predicted UGT1A1 activity. These increases are not considered clinically relevant. This analysis evaluated the impact of UGT1A1 genotypes on CAB PK in subjects who received both oral CAB and CAB LA in the LATTE-2 study.

Methods

DNA was genotyped for UGT1A1 in 215 HIV-infected subjects with PGx consent who received CAB LA every 4 or 8 weeks in LATTE-2. UGT1A1 variants (*6, *28, *36 and *37) were used to classify subjects with genetically predicted UGT1A1 low (n = 33), reduced (n = 100), or normal (n = 82) enzyme activity. Genetically predicted enzyme activity was assessed for association with CAB LA PK parameters at study Weeks 32 and 48. Covariates of age, weight, treatment regimen, BMI, and gender were considered, and linear regression models were applied with adjustment for significant covariates. The impact of UGT1A1 genotypes on oral and LA plasma CAB concentrations was descriptively analyzed.

Results

Genetically predicted UGT1A1 activity was statistically associated with CAB LA Cτ, AUC(0-τ), and Cmax (P < 0.05) at study Weeks 32 and 48. Mean LA PK parameters increased ~1.2-fold in subjects with low vs. normal genetically predicted UGT1A1 activity. The impact of UGT1A1 genotypes was smaller than observed for oral CAB.

Conclusion

UGT1A1 reduced function polymorphisms as anticipated had less impact on CAB PK following LA IM administration vs. oral CAB in HIV-infected patients with no requirement for CAB dose adjustment for either formulation due to UGT1A1 polymorphisms.

Disclosures

All authors: No reported disclosures.

Satisfaction and acceptability of cabotegravir long-acting injectable suspension for prevention of HIV: Patient perspectives from the ECLAIR trial

BACKGROUND

Cabotegravir (GSK1265744) is an integrase strand transfer inhibitor in development as a long-acting (LA) intramuscular injectable suspension for HIV-1 pre-exposure prophylaxis (PrEP).

OBJECTIVE

We report participant outcomes from the phase IIa ECLAIR study related to tolerability, acceptability, and satisfaction of cabotegravir LA.

METHODS

The ECLAIR study (ClinicalTrials.gov identifier, NCT02076178) was a randomized, placebo-controlled study in healthy men not at high risk of acquiring HIV-1. Participants were randomized (5:1) to once-daily oral cabotegravir 30 mg or placebo tablets for 4 weeks, followed by gluteal intramuscular injections of cabotegravir LA 800 mg or saline placebo every 12 weeks. The primary objective was to evaluate the safety of cabotegravir LA over three injection cycles (to Week 41). Secondary objectives assessed the tolerability, satisfaction, and acceptability of cabotegravir LA.

RESULTS

Among 115 participants who received injections in the cabotegravir (n = 94) and placebo (n = 21) groups, 93% (n = 87) and 95% (n = 20) completed the injection phase, respectively. Injection intolerability led to withdrawal in 4 participants (4%) receiving cabotegravir LA. The most frequently reported Grade ≥2 adverse event was injection-site pain. Most participants (74% [n = 67]) receiving consecutive injections favored cabotegravir LA vs oral cabotegravir. Most participants were satisfied with cabotegravir LA (75% [n = 64]), were willing to continue (79% [n = 68]), and would recommend (87% [n = 75]) the therapy.

CONCLUSIONS

While Grade ≥2 injection-site pain was common, most participants reported overall satisfaction with and preference for cabotegravir LA, with few discontinuations due to injection intolerance. These findings support investigation of cabotegravir LA as an alternative to daily oral PrEP regimens.

Effect of a High-Fat Meal on the Pharmacokinetics of the HIV Integrase Inhibitor Cabotegravir

Cabotegravir is an integrase inhibitor in clinical development for the treatment and prevention of HIV infection using oral tablets for short‐term, lead‐in use before subsequent administration of a long‐acting injectable formulation. This phase 1, single‐center, randomized, 2 × 2 crossover study evaluated the effect of a high‐fat meal on the pharmacokinetics (PK) of oral cabotegravir. Healthy adults received oral cabotegravir 30 mg as a single dose on 2 separate occasions, either after fasting or following a high‐fat meal (∼53% fat, ∼870 kcal). Safety evaluations and serial PK samples were collected, and a mixed‐effects model was used to determine within‐participant treatment comparison of noncompartmental PK parameters. Twenty‐four patients were enrolled and had a mean body mass index of 25.6 kg/m²; 67% were male. Compared with the fasting state, coadministration of cabotegravir with a high‐fat meal increased plasma cabotegravir area under the concentration‐time curve and maximal drug concentration, each by 14%. The slight 14% to 17% increase in exposure associated with a high‐fat, high‐calorie meal was not considered clinically significant. No grade 3/4 adverse events (AEs), drug‐related AEs, or AEs leading to discontinuation were reported.

Long-acting intramuscular cabotegravir and rilpivirine in adults with HIV-1 infection (LATTE-2): 96-week results of a randomised, open-label, phase 2b, non-inferiority trial

BACKGROUND

Cabotegravir and rilpivirine are antiretroviral drugs in development as long-acting injectable formulations. The LATTE-2 study evaluated long-acting cabotegravir plus rilpivirine for maintenance of HIV-1 viral suppression through 96 weeks.

METHODS

In this randomised, phase 2b, open-label study, treatment-naive adults infected with HIV-1 initially received oral cabotegravir 30 mg plus abacavir-lamivudine 600-300 mg once daily. The objective of this study was to select an intramuscular dosing regimen based on a comparison of the antiviral activity, tolerability, and safety of the two intramuscular dosing regimens relative to oral cabotegravir plus abacavir-lamivudine. After a 20-week induction period on oral cabotegravir plus abacavir-lamivudine, patients with viral suppression (plasma HIV-1 RNA <50 copies per mL) were randomly assigned (2:2:1) to intramuscular long-acting cabotegravir plus rilpivirine at 4-week intervals (long-acting cabotegravir 400 mg plus rilpivirine 600 mg; two 2 mL injections) or 8-week intervals (long-acting cabotegravir 600 mg plus rilpivirine 900 mg; two 3 mL injections) or continued oral cabotegravir plus abacavir-lamivudine. Randomisation was computer-generated with stratification by HIV-1 RNA (<50 copies per mL, yes or no) during the first 12 weeks of the induction period. The primary endpoints were the proportion of patients with viral suppression at week 32 (as defined by the US Food and Drug Administration snapshot algorithm), protocol-defined virological failures, and safety events through 96 weeks. All randomly assigned patients who received at least one dose of study drug during the maintenance period were included in the primary efficacy and safety analyses. The primary analysis used a Bayesian approach to evaluate the hypothesis that the proportion with viral suppression for each long-acting regimen is not worse than the oral regimen proportion by more than 10% (denoted comparable) according to a prespecified decision rule (ie, posterior probability for comparability >90%). Difference in proportions and associated 95% CIs were supportive to the primary analysis. The trial is registered at ClinicalTrials.gov, number NCT02120352.

FINDINGS

Among 309 enrolled patients, 286 were randomly assigned to the maintenance period (115 to each of the 4-week and 8-week groups and 56 to the oral treatment group). This study is currently ongoing. At 32 weeks following randomisation, both long-acting regimens met primary criteria for comparability in viral suppression relative to the oral comparator group. Viral suppression was maintained at 32 weeks in 51 (91%) of 56 patients in the oral treatment group, 108 (94%) of 115 patients in the 4-week group (difference 2·8% [95% CI -5·8 to 11·5] vs oral treatment), and 109 (95%) of 115 patients in the 8-week group (difference 3·7% [-4·8 to 12·2] vs oral treatment). At week 96, viral suppression was maintained in 47 (84%) of 56 patients receiving oral treatment, 100 (87%) of 115 patients in the 4-week group, and 108 (94%) of 115 patients in the 8-week group. Three patients (1%) experienced protocol-defined virological failure (two in the 8-week group; one in the oral treatment group). Injection-site reactions were mild (3648 [84%] of 4360 injections) or moderate (673 [15%] of 4360 injections) in intensity and rarely resulted in discontinuation (two [<1%] of 230 patients); injection-site pain was reported most frequently. Serious adverse events during maintenance were reported in 22 (10%) of 230 patients in the intramuscular groups (4-week and 8-week groups) and seven (13%) of 56 patients in the oral treatment group; none were drug related.

INTERPRETATION

The two-drug combination of all-injectable, long-acting cabotegravir plus rilpivirine every 4 weeks or every 8 weeks was as effective as daily three-drug oral therapy at maintaining HIV-1 viral suppression through 96 weeks and was well accepted and tolerated.

FUNDING

ViiV Healthcare and Janssen R&D.

Safety and tolerability of long-acting cabotegravir injections in HIV-uninfected men (ECLAIR): a multicentre, double-blind, randomised, placebo-controlled, phase 2a trial

BACKGROUND

Cabotegravir (GSK1265744) is an HIV-1 integrase strand transfer inhibitor with potent antiviral activity and a long half-life when administered by injection that prevented simian-HIV infection upon repeat intrarectal challenge in male macaques. We aimed to assess the safety, tolerability, and pharmacokinetics of long-acting cabotegravir injections in healthy men not at high risk of HIV-1 infection.

METHODS

We did this multicentre, double-blind, randomised, placebo-controlled, phase 2a trial at ten sites in the USA. Healthy men (aged 18-65 years) deemed not at high risk of acquiring HIV-1 at screening were randomly assigned (5:1), via computer-generated central randomisation schedules, to receive cabotegravir or placebo. Participants received oral cabotegravir 30 mg tablets or matching placebo once daily during a 4 week oral lead-in phase, followed by a 1 week washout period and, after safety assessment, three intramuscular injections of long-acting cabotegravir 800 mg or saline placebo at 12 week intervals. Study site staff and participants were masked to treatment assignment from enrolment through week 41 (time of the last injection). The primary endpoint was safety and tolerability from the first injection (week 5) to 12 weeks after the last injection. We did analysis in the safety population, defined as all individuals enrolled in the study who received at least one dose of the study drug. This study is registered with ClinicalTrials.gov identifier, NCT02076178.

FINDINGS

Between March 27, 2014, and Feb 23, 2016, we randomly assigned 127 participants to receive cabotegravir (n=106) or placebo (n=21); 126 (99%) participants comprised the safety population. Most participants were men who have sex with men (MSM; n=106 [83%]) and white (n=71 [56%]). 87 (82%) participants in the cabotegravir group and 20 (95%) participants in the placebo group completed the injection phase. Adverse events (n=7 [7%]) and injection intolerability (n=4 [4%]) were the main reasons for withdrawal in the cabotegravir group. The frequency of grade 2 or higher adverse events was higher in participants in the long-acting cabotegravir group (n=75 [80%]) than in those in the placebo group (n=10 [48%]; p=0·0049), mostly due to injection-site pain (n=55 [59%]). No significant differences were noted in concomitant medications, laboratory abnormalities, electrocardiogram, and vital sign assessments. Geometric mean trough plasma concentrations were 0·302 μg/mL (95% CI 0·237-0·385), 0·331 μg/mL (0·253-0·435), and 0·387 μg/mL (0·296-0·505) for injections one, two, and three, respectively, indicating lower than predicted exposure. The geometric mean apparent terminal phase half-life estimated after the third injection was 40 days. Two (2%) MSM acquired HIV-1 infection, one in the placebo group during the injection phase and one in the cabotegravir group 24 weeks after the final injection when cabotegravir exposure was well below the protein-binding-adjusted 90% inhibitory concentration.

INTERPRETATION

Despite high incidence of transient, mild-to-moderate injection-site reactions, long-acting cabotegravir was well tolerated with an acceptable safety profile. Pharmacokinetic data suggest that 800 mg administered every 12 weeks is a suboptimal regimen; alternative dosing strategies are being investigated. Our findings support further investigation of long-acting injectable cabotegravir as an alternative to orally administered pre-exposure prophylaxis regimens.

FUNDING

ViiV Healthcare.

Lack of effect of oral cabotegravir on the pharmacokinetics of a levonorgestrel/ethinyl oestradiol-containing oral contraceptive in healthy adult women

AIMS

This study aimed to investigate whether cabotegravir (CAB), an integrase inhibitor in development for treatment and prevention of human immunodeficiency virus-1, influences the pharmacokinetics (PK) of a levonorgestrel (LNG) and ethinyl oestradiol (EO)-containing oral contraceptive (OC) in healthy women.

METHODS

In this open-label, fixed-sequence crossover study, healthy female subjects received LNG 0.15 mg/EO 0.03 mg tablet once daily Days 1-10 alone and with oral CAB 30 mg once daily Days 11-21. At the end of each treatment period, subjects underwent predose sampling for concentrations of follicle-stimulating hormone, luteinizing hormone, and progesterone and serial PK sampling for plasma LNG, EO, and CAB concentrations.

RESULTS

Twenty women were enrolled, and 19 completed the study. One subject was withdrawn due to an adverse event unrelated to study medications. Geometric least squares mean ratios (90% confidence interval) of LNG + CAB vs. LNG alone for LNG area under the plasma concentration-time curve over the dosing interval of duration τ and maximum observed plasma concentration were 1.12 (1.07-1.18) and 1.05 (0.96-1.15), respectively. Geometric least squares mean ratio (90% confidence interval) of EO + CAB vs. EO alone for EO area under the plasma concentration-time curve over the dosing interval of duration τ and maximum observed plasma concentration were 1.02 (0.97-1.08) and 0.92 (0.83-1.03), respectively. Steady-state CAB PK parameters were comparable to historical values. There was no apparent difference in mean luteinizing hormone, follicle-stimulating hormone, and progesterone concentrations between periods. No clinically significant trends in laboratory values, vital signs, or electrocardiography values were observed.

CONCLUSIONS

Repeat doses of oral CAB had no significant effect on LNG/EO PK or pharmacodynamics, which supports CAB coadministration with LNG/EO OCs in clinical practice.

Effect of Cabotegravir on Cardiac Repolarization in Healthy Subjects

A randomized, partial‐blind, repeat‐dose, 3‐period crossover study (NCT02027454) assessed the effect of cabotegravir on QT interval in healthy subjects. To achieve a supratherapeutic dose, each subject received cabotegravir 150 mg (30 mg × 5 tablets) every 12 hours for a total of 3 doses over 2 days, matching placebo (every 12 hours) over 2 days, or a single open‐label 400‐mg dose of the positive control moxifloxacin, with a 21‐day washout between treatments. Blood samples for pharmacokinetic analyses were collected up to 24 hours after the third dose on day 2. QT interval data were obtained by continuous Holter monitoring for approximately 24 hours at baseline (day ‐1) and from 2 hours before to 24 hours after the third dose on day 2. Plasma cabotegravir exposure was approximately 3‐fold above clinically relevant doses. After 3 doses of 150 mg of cabotegravir administered every 12 hours, all upper limits of 2‐sided 90% confidence intervals for ΔΔQTcF (difference in time‐matched change from baseline for QTcF between cabotegravir and placebo) were <10 milliseconds. There was no relationship between cabotegravir plasma concentrations and ΔΔQTcF. No subject receiving cabotegravir had a QTcF value > 450 milliseconds. There were no serious or grade 3 or 4 adverse events or clinically significant changes in laboratory values, vital signs, or electrocardiogram results. These data demonstrate that cabotegravir at a supratherapeutic dose had no effect on cardiac repolarization.

Drug interaction profile of the HIV integrase inhibitor cabotegravir: assessment from in vitro studies and a clinical investigation with midazolam

1. Cabotegravir (CAB; GSK1265744) is a potent HIV integrase inhibitor in clinical development as an oral lead-in tablet and long-acting injectable for the treatment and prevention of HIV infection. 2. This work investigated if CAB was a substrate for efflux transporters, the potential for CAB to interact with drug-metabolizing enzymes and transporters to cause clinical drug interactions, and the effect of CAB on the pharmacokinetics of midazolam, a CYP3A4 probe substrate, in humans. 3. CAB is a substrate for Pgp and BCRP; however, its high intrinsic membrane permeability limits the impact of these transporters on its intestinal absorption. 4. At clinically relevant concentrations, CAB did not inhibit or induce any of the CYP or UGT enzymes evaluated in vitro and had no effect on the clinical pharmacokinetics of midazolam. 5. CAB is an inhibitor of OAT1 (IC50 0.81 µM) and OAT3 (IC50 0.41 µM) but did not or only weakly inhibited Pgp, BCRP, MRP2, MRP4, MATE1, MATE2-K, OATP1B1, OATP1B3, OCT1, OCT2 or BSEP. 6. Based on regulatory guidelines and quantitative extrapolations, CAB has a low propensity to cause clinically significant drug interactions, except for coadministration with OAT1 or OAT3 substrates.

Disposition and metabolism of cabotegravir: a comparison of biotransformation and excretion between different species and routes of administration in humans

1.  Cabotegravir [(3S,11aR)-N-[(2,4-difluorophenyl)methyl]-6-hydroxy-3-methyl-5,7-dioxo-2,3,5,7,11,11a-hexahydro[1,3]oxazolo[3,2-a]pyrido[1,2-d]pyrazine-8-carboxamide] is an HIV-1 integrase inhibitor under development as a tablet for both oral lead-in therapy and long-acting (LA) injectable for intramuscular dosing. 2. Metabolism, pharmacokinetics and excretion were investigated in healthy human subjects who received either a single oral dose (28.2 mg) of [(14)C]cabotegravir in a mass balance study, or LA formulations of unlabeled cabotegravir (200-800 mg), intramuscularly or subcutaneously, in a separate study. Metabolism, distribution and excretion of [(14)C]cabotegravir were also investigated in mice, rats and monkeys. 3. Recovery of radioactivity in humans represented a mean total of 85.3% of the dose, including 26.8% in the urine. The mean apparent terminal phase half-life was similar for both cabotegravir and radioactivity, 39 h compared to 41 h. 4. Following oral, intramuscular and subcutaneous administration, cabotegravir was the major component in plasma and the glucuronic acid conjugate (M1) represented the predominant component in urine. Cabotegravir was present in bile along with its major metabolite (M1). 5. The primary metabolite of [(14)C]cabotegravir in mouse, rat and monkey was the same as that in human. In vitro phenotyping experiments demonstrated that cabotegravir was metabolized by UDP-glucuronosyltransferase (UGT) 1A1 and UGT1A9.

Pharmacokinetics, safety, and monotherapy antiviral activity of GSK1265744, an HIV integrase strand transfer inhibitor

BACKGROUND

GSK1265744 is an HIV integrase strand transfer inhibitor selected for clinical development.

OBJECTIVE

This first-time-in-human and phase IIa investigation assessed GSK1265744 antiviral activity, pharmacokinetics, safety, and tolerability in healthy and HIV-1-infected subjects.

METHODS

This double-blind, placebo-controlled study consisted of a dose escalation of single (part A) and multiple (part B) oral doses in 48 healthy subjects and an oral dose (part C) in 11 HIV-1-infected subjects. In part A, 2 cohorts of 9 subjects received either 5 and 25 mg or 10 and 50 mg. In part B, 3 cohorts of 10 subjects received 5, 10, or 25 mg once daily for 14 days. In part C and the phase IIa study, subjects received 5 or 30 mg once daily for 10 days.

RESULTS

Dose-proportional increases in drug exposure were observed in healthy and HIV-1-infected subjects. In healthy subjects, pharmacokinetic variability was low following single or repeat dosing (coefficient of variation, 13%-34% and 15%-23%, respectively). Mean plasma half-life was 31.5 hours. GSK1265744 monotherapy significantly reduced plasma HIV-1 RNA from baseline to day 11 in HIV-1-infected subjects receiving 5 or 30 mg versus placebo (P < .001); mean decrease was 2.2 to 2.3 log10 copies/mL, respectively. Study drug was generally well tolerated with no clinically relevant trends in laboratory values, vital signs, or electrocardiograms.

CONCLUSIONS

GSK1265744 was well tolerated in healthy and HIV-1-infected subjects. Results demonstrate once-daily doses of 5 or 30 mg exceeded minimum target therapeutic concentrations and produced a significant reduction in plasma HIV-1 RNA viral load.

Steady-state pharmacokinetics, cord blood concentrations, and safety of ritonavir-boosted fosamprenavir in pregnancy

Steady-state pharmacokinetics in pregnant women prescribed ritonavir-boosted fosamprenavir (FPV) to prevent HIV transmission were assessed in the second trimester, third trimester, and postpartum. Compared with postpartum, geometric mean amprenavir (APV, FPVs active metabolite) area under the plasma concentration-time curves were 35% lower in the second trimester and 25% lower in the third trimester. Maternal APV concentrations were 9- to 15-fold above the mean APV protein-adjusted 50% inhibitory concentration for wild-type HIV. Median ratio of cord blood/maternal APV levels was 0.27, and all infants were HIV negative. FPV/ritonavir during pregnancy was well tolerated and led to virologic suppression.

Safety and pharmacokinetics of brecanavir, a novel human immunodeficiency virus type 1 protease inhibitor, following repeat administration with and without ritonavir in healthy adult subjects

Brecanavir (BCV) is a novel, potent protease inhibitor in development for the treatment of human immunodeficiency virus (HIV-1) infection with low nM in vitro 50% inhibitory concentrations (IC50s) against many multiprotease inhibitor resistant viruses. This study was a double-blind, randomized, placebo-controlled repeat-dose escalation to evaluate the safety, tolerability, and pharmacokinetics of BCV, with or without ritonavir (RTV), in 68 healthy subjects. Seven sequential cohorts (n=10) received BCV (50 to 600 mg) in combination with 100 mg RTV (every 12 h [q12h] or q24h) or alone at 800 mg q12h for 15 days. BCV alone or in combination with RTV was well tolerated, with no serious adverse events reported. The most common drug-related adverse event was headache. BCV was readily absorbed with median time to maximum concentration of drug in serum values ranging from 2.5 to 5.0 h postdose following single- and repeat-dose administration of BCV alone and BCV with RTV 100 mg. Geometric mean BCV accumulation ratios ranged from 1.4 to 1.56 following BCV-RTV q24h regimens and from 1.84 to 4.93 following BCV q12h regimens. BCV steady state was generally achieved by day 13 in all groups. All day 15 BCV-RTV trough concentration values in q12h regimens reached or surpassed the estimated protein-binding corrected in vitro IC50 target BCV concentration of 28 ng/ml for highly resistant isolates. The pharmacokinetic and safety profile of BCV-RTV supports continued investigation in HIV-1-infected subjects.

Single-dose safety and pharmacokinetics of brecanavir, a novel human immunodeficiency virus protease inhibitor

Brecanavir (BCV, 640385) is a novel, potent protease inhibitor (PI) with low nanomolar 50% inhibitory concentrations against PI-resistant human immunodeficiency virus (HIV) in vitro. This phase I, double-blind, randomized, placebo-controlled, two-part single-dose study (first time with humans) was conducted to determine the safety, tolerability, and pharmacokinetics of BCV administered at 10 mg/ml in a tocopherol-polyethylene glycol succinate-polyethylene glycol 400-ethanol 50:40:10 solution. In part 1 of the study, single oral doses of BCV ranged from 25 mg to 800 mg. In part 2, single oral doses of BCV ranged from 10 mg to 300 mg and were coadministered with 100-mg oral ritonavir (RTV) soft gel capsules. Single doses of BCV and BCV/RTV were generally well tolerated. There were no severe adverse events (SAEs), and no subject was withdrawn due to BCV. The most commonly reported drug-related AEs during both parts of the study combined were gastrointestinal disturbances (similar to placebo) and headache. BCV was readily absorbed following oral administration with mean times to maximum concentration from >1 h to 2.5 h in part 1 and from 1.5 h to 3 h in part 2. Administration of BCV without RTV resulted in BCV exposures predicted to be insufficient to inhibit PI-resistant virus based on in vitro data. Coadministration of 300 mg BCV with 100 mg RTV, however, significantly increased the plasma BCV area under the concentration-time curve and maximum concentration 26-fold and 11-fold, respectively, achieving BCV concentrations predicted to inhibit PI-resistant HIV.

Coadministration of esomeprazole with fosamprenavir has no impact on steady-state plasma amprenavir pharmacokinetics

OBJECTIVES

To evaluate the drug interaction between fosamprenavir (FPV) and esomeprazole (ESO) after repeated doses in healthy adults.

METHODS

Subjects received ESO 20 mg once daily (qd) for 7 days followed by either ESO 20 mg qd + FPV 1400 mg twice daily (bid) or ESO 20 mg qd + FPV 700 mg bid + ritonavir (RTV) 100 mg bid for 14 days in arms 1 and 2, respectively. After a 21- to 28-day washout, subjects received either FPV 1400 mg bid for 14 days (arm 1) or FPV 700 mg bid + RTV 100 mg bid for 14 days (arm 2). Pharmacokinetic sampling was conducted on the last day of each treatment.

RESULTS

Simultaneous coadministration of ESO 20 mg qd with either FPV 1400 mg bid or FPV 700 mg bid + RTV 100 mg bid had no effect on steady-state amprenavir pharmacokinetics. The only effect on plasma ESO exposure was a 55% increase in area under the plasma concentration-time curve during a dosing interval, tau[AUC0-tau], after coadministration of ESO 20 mg qd with FPV 1400 mg bid.

CONCLUSIONS

FPV 1400 mg bid or FPV 700 mg bid + RTV 100 mg bid may be coadministered simultaneously with ESO without dose adjustment. However, the impact of staggered administration of proton pump inhibitors (PPI) on plasma amprenavir exposure is unknown at present.

Effect of antacids and ranitidine on the single-dose pharmacokinetics of fosamprenavir

Single doses of MAALOX TC and ranitidine were administered separately with 1,400 mg of fosamprenavir (FPV). MAALOX TC decreased the area under the concentration-time curve from 0 to 24 h (AUC(0-24)) for plasma amprenavir (APV) by 18% and the maximum concentration of drug in serum (C(max)) by 35%; the plasma APV concentration at 12 h (C(12)) increased by 14%. Ranitidine at 300 mg decreased the AUC(0-24) for plasma APV by 30% and C(max) by 51%; C(12) was unchanged. FPV may be coadministered with antacids without concern and without separation in dosing; however, caution is recommended when FPV is coadministered with histamine(2)- receptor antagonists or proton pump inhibitors.

Dragon's Blood incense: misbranded as a drug of abuse?

An unknown red substance was being sold and used with other drugs of abuse in Virginia (often being used in conjunction with marihuana). The red substance was identified as Dragon's Blood incense from Daemonorops draco. In bioassays, Dragon's Blood incense exhibited a low, but measurable cytotoxicity in in vitro cell lines. Dragon's Blood incense or Volatilized Dragon's Blood had no adverse effect on mouse motor performance based on the inclined screen and rotorod tests. delta(9)-Tetrahydrocannibinol (THC) produced a dose-related decline in mouse performance on the rotorod test. The combination of Dragon's Blood incense or Volatilized Dragon's Blood with delta(9)-THC did not contribute further to the impairment of the mice on the rotorod. This data suggests that the abuse potential for Dragon's Blood incense alone or in combination with marihuana is minimal.

Hypercalcemia in a dog: a challenging case

An 18-month-old, spayed female, mixed-breed dog was referred for investigation of persistent hypercalcemia. After extensive diagnostic evaluation, a tentative diagnosis of occult lymphosarcoma (LSA) was made and the dog was euthanized. At necropsy, infection with Heterobilharzia americana was diagnosed. In endemic areas, schistosomiasis should be included in the differential diagnosis of hypercalcemia, and a fecal examination should be performed in every dog with a hypercalcemia of unknown origin.

Pregnenolone synthesis in immature rat Sertoli cells

It has been reported that testicular Sertoli cells can be induced to synthesize the steroidogenic acute regulatory (StAR) protein. StAR mediates the rate-limiting step of steroidogenesis, which is the transfer of cholesterol to the inner mitochondrial membrane. Since Sertoli cells are thought to be unable to utilize cholesterol for the synthesis of steroids the role of StAR in these cells was questioned. In the present studies we have corroborated the induction of StAR protein in immature cultured Sertoli cells in response to either trophic hormone or cAMP analog stimulation. Further, we have shown that long term stimulation of Sertoli cells with cAMP analog results in the induction of P450scc enzyme and increased pregnenolone production. In this manner, the Sertoli cell may resemble its ovarian homolog, the granulosa cell, more closely than previously thought with regards to its steroidogenic capacity. Thus, StAR may play the same role in Sertoli cells as it does in other steroidogenic tissues.

Transient clinical diabetes mellitus in cats: 10 cases (1989-1991)

Medical records of 10 cats with transient clinical diabetes mellitus were reviewed. At the time diabetes was diagnosed, clinical signs included polyuria and polydipsia (10 cats), weight loss (8 cats), polyphagia (3 cats), lethargy (2 cats), and inappetence (1 cat). Mean (+/- SD) fasting blood glucose concentration was 454 +/- 121 mg/dL, mean blood glucose concentration during an 8-hour period (MBG/8 hours) was 378 +/- 72 mg/dL, and glycosuria and trace ketonuria were identified in 10 and 5 cats, respectively. Baseline serum insulin concentration was undetectable (6 cats) or within the reference range (4 cats) and serum insulin concentration did not increase after i.v. glucagon administration in any cat. Insulin-antagonistic drugs were being administered to 5 cats and concurrent disorders were identified in all cats. Management of diabetes included administration of glipizide (6 cats), insulin (3 cats), or both (1 cat), discontinuation of insulin-antagonistic drugs, and treatment of concurrent disorders. Insulin and glipizide treatment was discontinued 4-16 weeks (mean, 7 weeks) after the initial diagnosis of diabetes was confirmed. At the time treatment for diabetes was discontinued, clinical signs had resolved, mean fasting blood glucose concentration was 102 +/- 48 mg/dL, MBG/ 8 hours was 96 +/- 32 mg/dL, glycosuria and ketonuria were not identified in any cat, and concurrent disorders (except mild renal insufficiency in 1 cat) had resolved. Significant (P < .05) increases occurred in postglucagon serum insulin concentrations, insulin peak response, and total insulin secretion, compared with values obtained when clinical diabetes was diagnosed. Histologic abnormalities were identified in pancreatic islets of 5 cats in which pancreatic biopsies were obtained and included decreased number of islets (4 cats), islet amyloidosis (3 cats), and vacuolar degeneration of islet cells (3 cats). Mean beta cell density was significantly (P < .001) decreased in diabetic cats compared with control cats (1.4 +/- 0.7 versus 2.6 +/- 0.5%, respectively). Cells within islets stained positive for insulin, however, the number of insulin-staining cells per islet and the intensity of insulin staining were decreased in 5 and 2 cats, respectively. Clinical diabetes had not recurred in 1 cat after 6 years, in 4 cats lost to follow-up after 1.5, 1.5, 2.0, and 2.5 years, and in 2 cats that died 6 months and 5.5 years after clinical diabetes resolved. Clinical diabetes recurred in 3 cats after 6 months, 14 months, and 3.4 years, respectively. These findings suggest that cats with transient clinical diabetes have pancreatic islet pathology, including decreased beta cell density, and that treatment of diabetes and concurrent disorders results in improved beta cell function, reestablishment of euglycemia, and a transition from a clinical to subclinical diabetic state.

Ethane dimethane sulfonate and NNN'N'-tetrakis-(2-pyridylmethyl)ethylenediamine inhibit steroidogenic acute regulatory (StAR) protein expression in MA-10 Leydig cells and rat Sertoli cells

Apoptosis inhibits steroid biosynthesis, but it is not clear how the Steroidogenic Acute Regulatory (StAR) protein, is affected. To characterize StAR expression during apoptosis, mouse MA-10 Leydig tumor cells were treated with ethane dimethane sulfonate (EDS), an inducer of apoptosis, and the metal ion chelator NNN'N'-tetrakis-(2-pyridylmethyl)ethylenediamine (TPEN), an inducer of cell death. Both chemicals induced cell death and similarly inhibited dbcAMP-stimulated steroidogenesis and accumulation of the 30 kDa form of StAR. Utilizing the dye JC-1, it was found that TPEN and EDS also impaired the mitochondrial electrochemical potential (delta psi). In Sertoli cells, which also express StAR, EDS induced cell death and attenuated StAR expression. We conclude 1) steroidogenesis and accumulation of mature StAR protein are inhibited as a consequence of the induction of apoptosis; 2) reduced levels of StAR may be partially attributed to inhibition of import because of the loss of delta psi; 3) loss of steroidogenesis is probably due to loss of StAR synthesis and disruption of delta psi.

Warfarin resistance in a patient with short bowel syndrome

Drug therapy in short bowel syndrome can be complicated by inadequate or incomplete absorption of drugs in the small intestine. Many case reports claim that warfarin absorption is not affected by the syndrome. We treated a patient with oral warfarin for recurring deep vein thrombosis; up to 20 mg/day was administered with no increase in the international normalized ratio. Drug-drug interactions that may prevent absorption, increase metabolism, or antagonize the effects of warfarin were ruled out. Intravenous lipid administration, which is anecdotally reported to precipitate warfarin resistance, may have contributed to the condition, but dosing was less frequent than in published reports. The most probable explanation of warfarin resistance is the reduced surface area for drug absorption secondary to surgical removal of the patient's duodenum and gastrojejunostomy.

Effect of dietary insoluble fiber on control of glycemia in dogs with naturally acquired diabetes mellitus

OBJECTIVE

To evaluate the effect of a high insoluble-fiber (HF) diet containing 12% cellulose in dry matter and a low insoluble-fiber (LF) diet on control of glycemia in dogs with naturally acquired insulin-dependent diabetes mellitus.

DESIGN

Prospective randomized crossover controlled trial.

ANIMALS

11 dogs with naturally acquired diabetes mellitus.

PROCEDURE

Dogs were fed HF and LF diets for 8 months each in 1 of 2 randomly assigned diet sequences. Caloric intake and insulin treatment were adjusted as needed to maintain stable body weight and control of glycemia, respectively. After a 2-month adaptation period, control of glycemia was evaluated every 6 weeks for 6 months. Variables assessed included serum glucose concentration measured during the preprandial state, blood glycosylated hemoglobin concentration, serum glucose concentration measured every 2 hours for 24 hours beginning at the time of the morning insulin injection, 24-hour mean serum glucose concentration, mean serum glucose concentration fluctuation from the 24-hour mean serum glucose concentration, and 24-hour urinary excretion of glucose.

RESULTS

Significant differences in mean daily caloric intake, body weight, or daily insulin dosage among dogs fed HF and LF diets were not found. Mean preprandial serum glucose concentration, most postprandial serum glucose concentrations, 24-hour mean serum glucose concentration, and 24-hour urinary excretion of glucose were significantly lower in dogs fed the HF diet, compared with the LF diet.

CLINICAL IMPLICATIONS

Results of this study support feeding of commercially available insoluble fiber diets to dogs with naturally acquired diabetes mellitus.

Electrical permeabilization of rat luteal cells: in situ phosphorylation of endogenous protein

Progesterone synthesis in the corpus luteum is regulated primarily by luteinizing hormone which acts via the adenylate cyclase/cyclic AMP/protein kinase A signalling cascade. Protein phosphorylation therefore plays a key role in the regulation of steroidogenesis, but there are relatively few studies of the in situ phosphorylation of luteal cell substrates. This may in part reflect the difficulties inherent in measuring changes in protein phosphorylation in intact cells preloaded with 32P and difficulties in interpreting data obtained using broken cell preparations. We have now applied a method of stable permeabilization of luteal cell plasma membranes by exposure of cell populations to a high intensity electric field. Under optimum conditions (5 kV/cm, six discharges) electrical permeabilization reproducibly produced populations of luteal cells in which 70-80% of the cells were permeabilized, as assessed by Trypan blue exclusion and [14C] sucrose space measurements. Pores were stable for at least 1 h, and there were no ultrastructural changes to the cells that could be detected by transmission electron microscopy. Permeabilized cells showed rapid cyclic AMP-induced changes in phosphorylation of endogenous proteins when provided with [gamma - 32 P] ATP. Our results demonstrate that the electricity permeabilized luteal cell offers a useful model for studying intracellular events in steroidogenic stimulus-response coupling cascades.

Role of phosphoprotein phosphatases in the corpus luteum: II control of progesterone secretion by isolated rat luteal cells

The key role of protein kinases and protein phosphorylation in the regulation of luteal steroidogenesis is well documented. However the role of phosphoprotein phosphatases (PP) and dephosphorylation in the regulation of luteal cell progesterone secretion is as yet unknown. We have recently demonstrated the presence and activity of PP1 and PP2A in rat luteal cells and the present study was undertaken to determine the consequences of inhibiting PP activity in terms of progesterone secretion. Three structurally dissimilar inhibitors of PP1/2A, okadaic acid, calyculin A and cantharidin each caused a dose-dependent inhibition of LH-induced progesterone secretion without affecting cyclic AMP accumulation. The less potent derivative of okadaic acid, norokadaone, had no effect on either parameter, suggesting that the inhibitory actions on progesterone secretion are due to their specific actions on PP activity and that this inhibition occurs principally at a locus which is distal to the generation of cyclic AMP. In contrast to the inhibitory effects of PP1/2A inhibitors on progesterone biosynthesis, a PP2B inhibitor, cypermethrin, had no effect on LH-stimulated steroidogenesis. The three PP1/2A inhibitors also caused a concentration-dependent inhibition of dibutyryl cyclic AMP-stimulated progesterone secretion. However, none of the inhibitors affected 22R-hydroxycholesterol-supported steroidogenesis, clearly demonstrating that the inhibitors did not interfere with the activity of steroidogenic enzymes. These results suggest that cycles of phosphorylation/dephosphorylation of specific proteins are required for the sustained production of progesterone. Whilst the precise location and function of putative PP substrates is uncertain, the present results indicate that they are involved in regulating the availability of free cholesterol to steroidogenic enzymes within mitochondria.