Model-Based Dose Selection of Fostemsavir for Pediatric Populations With Multidrug-Resistant HIV-1 and Relative Bioavailability Assessment in Healthy Adults

Fostemsavir, a prodrug of the first-in-class HIV-1 attachment inhibitor temsavir, is approved for the treatment of multidrug-resistant HIV-1 in adults; its use in pediatric populations is currently being studied. Population pharmacokinetic modeling across pediatric weight bands was used to guide pediatric fostemsavir dose selection. Dosing simulations demonstrated that twice-daily fostemsavir 600-mg (adult dose) and 400-mg doses met safety and efficacy criteria for 35 kg or greater and 20 or greater to less than 35 kg pediatric weight bands, respectively. Temsavir relative bioavailability of 2 low-dose fostemsavir extended-release formulations (3 × 200 mg; formulations A and B) and reference formulation (600 mg extended release) was assessed in a 2-part, open-label, randomized, crossover study in healthy adults. Part 1 (N = 32) compared single-dose temsavir relative bioavailability, and Part 2 (N = 16) evaluated the impact of fed versus fasted conditions using the selected low-dose formulation. Temsavir geometric mean ratios for the area under the plasma concentration-time curve from time zero to infinity and maximum concentration for formulation B were bioequivalent to the reference formulation. Temsavir maximum concentration for formulation B was similar in fed and fasted states, but area under the plasma concentration-time curve from time zero to infinity geometric mean ratio was increased under fed conditions, consistent with previous results in adults. These analyses demonstrated efficient pediatric dose selection using a model-based approach.

Week 240 Efficacy and Safety of Fostemsavir Plus Optimized Background Therapy in Heavily Treatment-Experienced Adults with HIV-1

INTRODUCTION

Efficacy and safety of the attachment inhibitor fostemsavir + optimized background therapy (OBT) were evaluated through 48 and 96 weeks in the phase 3 BRIGHTE trial in heavily treatment-experienced (HTE) adults failing their current antiretroviral regimen. Here, we report 240-week efficacy and safety of fostemsavir + OBT in adults with multidrug-resistant human immunodeficiency virus (HIV)-1 in BRIGHTE.

METHODS

Heavily treatment-experienced adults failing their current regimen entered the randomized cohort (RC; 1-2 fully active antiretrovirals available) or non-randomized cohort (NRC; no fully active antiretrovirals available) and received open-label fostemsavir + OBT (starting Day 8 in RC and Day 1 in NRC). Endpoints included proportion with virologic response (HIV-1 RNA < 40 copies/mL, Snapshot), immunologic efficacy, and safety.

RESULTS

At Week 240, 45% and 22% of the RC and NRC, respectively, had virologic response (Snapshot); 7% of the RC and 5% of the NRC had missing data due to coronavirus disease 2019 (COVID-19)-impacted visits. In the observed analysis, 82% of the RC and 66% of the NRC had virologic response. At Week 240, mean change from baseline in CD4+ T-cell count was 296 cells/mm3 (RC) and 240 cells/mm3 (NRC); mean CD4+/CD8+ ratio increased between Weeks 96 and 240 (RC 0.44 to 0.60; NRC 0.23 to 0.32). Between Weeks 96 and 240, four participants discontinued for adverse events, one additional participant experienced a drug-related serious adverse event, and six deaths occurred (median last available CD4+ T-cell count, 3 cells/mm3). COVID-19-related events occurred in 25 out of 371 participants; all resolved without incident.

CONCLUSION

Through ~5 years, fostemsavir + OBT demonstrated durable virologic and immunologic responses with no new safety concerns between Weeks 96 and 240, supporting this regimen as a key therapeutic option for HTE people with multidrug-resistant HIV-1.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02362503.

A Phase 1 randomized study of GSK3732394, an investigational long-acting biologic treatment regimen for HIV-1 infection

Background

The GSK3732394 multivalent protein was developed as a novel, long-acting, antiretroviral biologic treatment regimen with three independent, non–cross-resistant mechanisms for inhibiting HIV-1 entry.

Methods

A single-centre, Phase 1, double-blind, randomized, placebo-controlled study was conducted in healthy volunteers, using a 2-part adaptive study design: in Part 1, participants were randomized to receive subcutaneous injection of GSK3732394 or placebo (3:1) as single ascending doses (10-mg starting dose); in Part 2, participants were intended to receive multiple ascending doses. Primary and secondary objectives included safety, pharmacokinetics (PK) and pharmacodynamics (PD; cluster of differentiation four receptor occupancy [CD4 RO]) of GSK3732394 in healthy adults; PK/PD results in healthy volunteers were used to project HIV-1 treatment success.

Results

The most frequently reported adverse event was injection site reactions (ISRs; 8/18 [44%]). Most ISRs were mild (Grade 1–2; n = 7); one participant experienced a Grade 3 ISR (erythema ≥10 cm). All ISRs were delayed in onset (after Day 10). GSK3732394 demonstrated linear PK across all cohorts. Clearance was faster than expected, and PK/PD results were lower than expected, with the maximum dose investigated (80 mg) achieving mean trough CD4 RO of ∼25% on Day 7. The study was terminated as the PK/PD model linking PK and CD4 RO indicated that the maximum planned doses would not achieve the desired therapeutic profile.

Conclusions

This study demonstrated successful deployment of PK/PD dose relationships in the design and conduct of clinical trials by leveraging the findings toward predicting probability of success, resulting in appropriate early termination ( ClinicalTrials.gov , NCT03984812).

Week 96 Genotypic and Phenotypic Results of the Fostemsavir Phase 3 BRIGHTE Study in Heavily Treatment-Experienced Adults Living with Multidrug-Resistant HIV-1

In the phase 3 BRIGHTE study in heavily treatment-experienced adults with multidrug-resistant HIV-1, fostemsavir plus optimized background therapy (OBT) resulted in sustained rates of virologic suppression through 96 weeks. HIV-1 RNA <40 copies/mL was achieved in 163/272 (60%) Randomized Cohort (RC) participants (with 1 or 2 remaining approved fully active antiretrovirals) and 37/99 (37%) Non-randomized Cohort (NRC) participants (with 0 fully active antiretrovirals). Here we report genotypic and phenotypic analyses of HIV-1 samples from 63/272 (23%) RC participants and 49/99 (49%) NRC participants who met protocol-defined virologic failure (PDVF) criteria through Week 96. The incidence of PDVF was as expected in this difficult-to-treat patient population and, among RC participants, was comparable regardless of the presence of predefined gp120 amino acid substitutions that potentially influence phenotypic susceptibility to temsavir (S375H/I/M/N/T, M426L, M434I, M475I) or baseline temsavir 50% inhibitory concentration fold change (IC₅₀ FC). The incidence of PDVF was lower among participants with higher overall susceptibility score to newly used antiretrovirals (OSS-new), indicating that OSS-new may be a preferred predictor of virologic outcome in heavily treatment-experienced individuals. Predefined gp120 substitutions, most commonly M426L or S375N, were emergent on treatment in 24/50 (48%) RC and 33/44 (75%) NRC participants with PDVF, with related increases in temsavir IC₅₀ FC. In BRIGHTE, PDVF was not consistently associated with treatment-emergent genotypic or phenotypic changes in susceptibility to temsavir or to antiretrovirals in the initial OBT. Further research will be needed to identify which factors are most likely to contribute to virologic failure in this heavily treatment-experienced population (ClinicalTrials.gov, NCT02362503).

834. Characterization of Heavily Treatment Experienced HIV-1 Infected Clinical Trial Participants Infected with SARS-CoV-2 COVID 19: Fostemsavir BRIGHTE Phase 3 Clinical Trial

Background

BRIGHTE is an ongoing global study evaluating the gp120 attachment inhibitor fostemsavir (FTR) in heavily treatment-experienced (HTE) adults with multidrug resistant (MDR) HIV-1 unable to form a viable antiretroviral (ARV) regimen. An estimated 2 million people living with HIV-1 have been infected with SARS-CoV-2. Those with HIV viremia and/or low CD4+ counts are at increased risk of serious adverse outcome. We describe the reported COVID cases in a clinical trial population of people living with MDR HIV and immune suppression.

Methods

At the start of the COVID pandemic, all ongoing BRIGHTE subjects had achieved ≥ 192 weeks on FTR and optimized background ARVs; results through Week 96 were presented previously. Investigators used WHO guidelines for COVID diagnosis and reported exposure, testing results and symptom presence.

Figure 1. BRIGHTE Study Design

Results

371 subjects [272 Randomized Cohort (RC), 99 Non-Randomized Cohort (NC)] were enrolled; 44% were ≥ 50 years of age and 86% had an AIDS history. Median CD4+ count at study start of was 80 cells/mm³ (IQR 11–202); 30% with ≤ 20 cells/mm³. 250 subjects remained in BRIGHTE at pandemic start. By April 2021, 17 subjects (14 RC, 3 NC) had confirmed COVID infection (positive PCR test). Severity was Grade 1-3, all cases resolved with no deaths. Six subjects were hospitalized (Table 1); most recent CD4+ count prior to COVID were 293-1641 cells/mm³ and 5/6 subjects were virologically suppressed. Treatments often included prophylactic anticoagulants and supplemental oxygen; no cART changes were made. The remaining 11/17 confirmed cases were managed outpatient. Five more subjects had suspect COVID not confirmed by PCR and 2 subjects had negative PCR tests.

Table 1. Characterization of Participants with Serious AEs of Confirmed COVID-19 Infections – All Hospitalizations

Conclusion

A total of 22/250 COVID-19 cases (17 confirmed, 5 unconfirmed) have been reported in BRIGHTE. Outcomes were reassuring with no deaths or known persistent sequelae, despite having advanced HIV and comorbid diseases at baseline associated with poorer COVID outcomes. Outcomes may have benefitted from immunologic improvement during the trial.

Disclosures

Shiven Chabria, MD, Viiv Healthcare (Employee) Stephane De Wit, MD, Gilead (Grant/Research Support)Janssen (Grant/Research Support)Merck Sharpe & Dohme (Grant/Research Support)ViiV Healthcare (Grant/Research Support) Amy Pierce, BS, GlaxoSmithKline (Shareholder)ViiV Healthcare (Employee) Bronagh M. Shepherd, PhD, GlaxoSmithKline (Employee, Shareholder) Michael Warwick-Sanders, BM BSc DPM MFPM, GSK (Employee) Marcia Wang, PhD, GlaxoSmithKline (Employee, Shareholder) Andrew Clark, MD, GlaxoSmithKline (Shareholder)ViiV Healthcare (Employee) Peter Ackerman, MD, GSK/ViiV Healthcare (Employee, Shareholder)

Steroid-exacerbated HIV-associated cutaneous Kaposi's sarcoma immune reconstitution inflammatory syndrome: 'Where a good intention turns bad'

A 51-year-old man with head and neck skin lesions was diagnosed with Kaposi's sarcoma (KS) as his initial presentation of acquired immunodeficiency syndrome. Following initiation of antiretroviral therapy and subsequent full virologic suppression, his facial lesions worsened, consistent with immune reconstitution inflammatory syndrome (IRIS). He was started on glucocorticoids in an attempt to ameliorate the KS-IRIS but experienced paradoxical worsening of the KS lesions. Steroids were subsequently discontinued and he required chemotherapy for severe and cosmetically disfiguring skin lesions. This article describes the potential for worsening of KS lesions in individuals started on glucocorticoids for KS-IRIS as this has been reported rarely in published literature. The mechanisms underlying this phenomenon remain poorly understood but potential explanations are offered in the case discussion. This article aims to raise clinician awareness on the harms of steroid use in patients with KS-IRIS.

Fatal multiple deer tick-borne infections in an elderly patient with advanced liver disease

We present a case of a 66-year-old woman with decompensated alcoholic liver cirrhosis and poorly controlled non-insulin-dependent diabetes mellitus who was admitted with a 1 day history of altered mental status, high-grade fevers, worsening jaundice and generalised malaise with subsequent development of hypotension requiring intensive care. She was diagnosed with severe babesiosis with high-grade parasitaemia. She was also found to have Lyme disease coinfection. Despite aggressive therapeutic measures including appropriate antibiotics and multiple exchange blood transfusions, she developed septic shock and fulminant multiple organ failure with eventual demise. In this article, we highlight multiple tick-borne illnesses in a vulnerable host, in this case an elderly patient with liver cirrhosis, as risk factors for severe morbidity and potentially fatal outcomes.