Effects of Temsavir, Active Moiety of Antiretroviral Agent Fostemsavir, on QT Interval: Results From a Phase I Study and an Exposure-Response Analysis

No dose adjustment of metformin or substrates of organic cation transporters (OCT)1 and OCT2 and multidrug and toxin extrusion protein (MATE)1/2K with fostemsavir coadministration based on modeling approaches

Fostemsavir is an approved gp120-directed attachment inhibitor and prodrug for the treatment of human immunodeficiency virus type 1 infection in combination with other antiretrovirals (ARVs) in heavily treatment-experienced adults with multi-drug resistance, intolerance, or safety concerns with their current ARV regimen. Initial in vitro studies indicated that temsavir, the active moiety of fostemsavir, and its metabolites, inhibited organic cation transporter (OCT)1, OCT2, and multidrug and toxin extrusion transporters (MATEs) at tested concentration of 100 uM, although risk assessment based on the current Food and Drug Administration in vitro drug-drug interaction (DDI) guidance using the mechanistic static model did not reveal any clinically relevant inhibition on OCTs and MATEs. However, a DDI risk was flagged with EMA static model predictions. Hence, a physiologically based pharmacokinetic (PBPK) model of fostemsavir/temsavir was developed to further assess the DDI risk potential of OCT and MATEs inhibition by temsavir and predict changes in metformin (a sensitive OCT and MATEs substrate) exposure. No clinically relevant impact on metformin concentrations across a wide range of temsavir concentrations was predicted; therefore, no dose adjustment is recommended for metformin when co-administered with fostemsavir.

An update on drug-drug interactions in older adults living with human immunodeficiency virus (HIV)

INTRODUCTION

People with HIV are living longer due to advances in antiretroviral therapy. With improved life expectancy comes an increased lifetime risk of comorbid conditions - such as cardiovascular disease and cancer - and polypharmacy. Older adults, particularly those living with HIV, are more vulnerable to drug interactions and adverse effects, resulting in negative health outcomes.

AREA COVERED

Antiretrovirals are involved in many potential drug interactions with medications used to treat common comorbidities and geriatric conditions in an aging population of people with HIV. We review the mechanisms and management of significant drug-drug interactions involving antiretroviral medications and non-antiretroviral medications commonly used among older people living with HIV. The management of these interactions may require dose adjustments, medication switches to alternatives, enhanced monitoring, and considerations of patient- and disease-specific factors.

EXPERT OPINION

Clinicians managing comorbid conditions among older people with HIV must be particularly vigilant to side effect profiles, drug-drug interactions, pill burden, and cost when optimizing treatment. To support healthier aging among people living with HIV, there is a growing need for antiretroviral stewardship, multidisciplinary care models, and advances that promote insight into the correlations between an individual, their conditions, and their medications.

Long-term safety and impact of immune recovery in heavily treatment-experienced adults receiving fostemsavir for up to 5 years in the phase 3 BRIGHTE study

Introduction

Fostemsavir is a gp120-directed attachment inhibitor approved for heavily treatment-experienced (HTE) adults with multidrug-resistant HIV-1. We provide detailed week 240 safety results from the BRIGHTE study and evaluate the impact of immune recovery on safety outcomes.

Methods

The phase 3 BRIGHTE trial is ongoing; data for this analysis were collected from the first participant's first visit (February 23, 2015) through the last participant's last visit for week 240 (March 22, 2021). Safety endpoints were assessed in participants who received fostemsavir + optimized background therapy. In participants with baseline CD4+ T-cell count <200 cells/mm3, exposure-adjusted adverse event (AE) rates were assessed among subgroups with or without CD4+ T-cell count ≥200 cells/mm3 at any time during 48-week analysis periods through week 192.

Results

Through a median of 258 weeks (range, 0.14-319) of treatment, discontinuations due to AEs occurred in 30/371 (8%) participants. Serious AEs were reported in 177/371 (48%) participants, including 16 drug-related events in 13 (4%) participants. Thirty-five (9%) deaths occurred, primarily related to AIDS or acute infections. COVID-19-related events occurred in 25 (7%) participants; all resolved without sequelae. Among participants with baseline CD4+ T-cell count <200 cells/mm3, 122/162 (75%) achieved CD4+ T-cell count ≥200 cells/mm3 at week 192. Exposure-adjusted AE rates were markedly lower among participants achieving CD4+ T-cell count ≥200 cells/mm3 at any time vs those sustaining <200 cells/mm3. No new AIDS-defining events were reported after week 48 in participants with CD4+ T-cell count ≥200 cells/mm3.

Conclusions

Cumulative safety findings through the BRIGHTE 240-week interim analysis are consistent with other trials in HTE participants with advanced HIV-1 and comorbid disease. Reduced rates of AIDS-defining events and AEs were observed in participants with immunologic recovery on fostemsavir-based treatment.

Clinical trial number

NCT02362503, https://clinicaltrials.gov/study/NCT02362503.

Consensus recommendations for the use of novel antiretrovirals in persons with HIV who are heavily treatment-experienced and/or have multidrug-resistant HIV-1: Endorsed by the American Academy of HIV Medicine, American College of Clinical Pharmacy

Treatment options are currently limited for persons with HIV-1 (PWH) who are heavily treatment-experienced and/or have multidrug-resistant HIV-1. Three agents have been approved by the U.S. Food and Drug Administration (FDA) since 2018, representing a significant advancement for this population: ibalizumab, fostemsavir, and lenacapavir. However, there is a paucity of recommendations endorsed by national and international guidelines describing the optimal use (e.g., selection and monitoring after initiation) of these novel antiretrovirals in this population. To address this gap, a modified Delphi technique was used to develop these consensus recommendations that establish a framework for initiating and managing ibalizumab, fostemsavir, or lenacapavir in PWH who are heavily treatment-experienced and/or have multidrug-resistant HIV-1. In addition, future areas of research are also identified and discussed.

Mechanism of action, resistance, interaction, pharmacokinetics, pharmacodynamics, and safety of fostemsavir

The Food and Drug Administration (FDA) has licensed many antiretroviral medications to treat human immunodeficiency virus type 1 (HIV-1), however, treatment options for people with multi-drug resistant HIV remain limited. Medication resistance, undesirable effects, prior tolerance, and previous interlacement incapacity to deliver new drug classes all lead to the requirement for new medication classes and drug combination therapy. Fostemsavir (FTR) is a new CD-4 attachment inhibitor medicine that was recently authorized by the United States FDA to treat HIV-1. In individuals with multidrug-resistant (MDR) HIV-1, FTR is well tolerated and virologically active. According to recent investigations, drug combination therapy can positively affect MDR-HIV. The mechanism of action, resistance, interaction, pharmacokinetics, pharmacodynamics, and safety of FTR has been highlighted in this review.

Effects of the HIV-1 maturation inhibitor GSK3640254 on QT interval in healthy participants

GSK3640254 (GSK'254) is a novel HIV-1 maturation inhibitor with pharmacokinetics supporting once-daily (QD) therapy for HIV-1 treatment. This thorough QT/corrected QT (QTc) study evaluated the effect of GSK'254 on cardiac repolarization. In this two-part, randomized study, healthy participants received GSK'254 or placebo QD for 7 days (part 1) to determine safety and pharmacokinetics of a 500-mg supratherapeutic dose. Four sequential treatment periods composed the main QTc study (part 2): GSK'254 100 mg, GSK'254 500 mg, placebo QD for 7 days, or placebo QD for 6 days with a 400-mg moxifloxacin dose on Day 7 (all with a moderate-fat meal). Concentration-QTc analyses modeled the relationship between GSK'254 plasma concentrations and placebo-adjusted change from baseline in QT interval corrected with Fridericia's formula (ΔΔQTcF). Of 50 participants enrolled, 48 completed the study (part 1, 8/8; part 2, 40/42). Least-squares (LS) mean change from baseline in QTcF for GSK'254 100 mg followed the placebo pattern across time points (maximum LS mean ΔΔQTcF, 1.7 ms); the upper bound of the 90% CI remained <10 ms. Maximum LS mean ΔΔQTcF for GSK'254 500 mg exceeded the 10-ms threshold: 10.6 ms (90% CI 7.75-13.38). Neither GSK'254 dose had clinically relevant effects on heart rate or cardiac conduction. By concentration-QTc analysis, no effect on ΔΔQTcF >10 ms is expected up to GSK'254 concentrations of ~3070 ng mL-1 . No clinically relevant effects on cardiac parameters were seen in healthy participants with GSK'254 at the 100-mg dose.

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.

Efficacy and Safety of Two-Drug Regimens That Are Approved from 2018 to 2022 for the Treatment of Human Immunodeficiency Virus (HIV) Disease and Its Opportunistic Infections

The human immunodeficiency virus (HIV) is a type of virus that targets the body's immune cells. HIV infection can be divided into three phases: acute HIV infection, chronic HIV infection, and acquired immunodeficiency syndrome (AIDS). HIV-infected people are immunosuppressed and at risk of developing opportunistic infections such as pneumonia, tuberculosis, candidiasis, toxoplasmosis, and Salmonella infection. The two types of HIV are known as HIV-1 and HIV-2. HIV-1 is the predominant and more common cause of AIDS worldwide, with an estimated 38 million people living with HIV-1 while an estimated 1 to 2 million people live with HIV-2. No effective cures are currently available for HIV infection. Current treatments emphasise the drug's safety and tolerability, as lifelong management is needed to manage HIV infection. The goal of this review is to study the efficacy and safety of newly approved drugs from 2018 to 2022 for the treatment of HIV by the United States Food and Drug Administration (US-FDA). The drugs included Cabotegravir and Rilpivirine, Fostemsavir, Doravirine, and Ibalizumab. From the review, switching to doravirine/lamivudine/tenofovir disoproxil fumarate (DOR/3TC/TDF) was shown to be noninferior to the continuation of the previous regimen, efavirenz/emtricitabine/tenofovir disoproxil fumarate (EFV/FTC/TDF) in virologically suppressed adults with HIV-1. However, DOR/3TC/TDF had shown a preferable safety profile with lower discontinuations due to adverse events (AEs), lower neuropsychiatric AEs, and a preferable lipid profile. Ibalizumab was also safe, well tolerated, and had been proven effective against multiple drug-resistant strains of viruses.

Validation of an LC-MS/MS method for quantitation of fostemsavir in plasma

BACKGROUND

A novel, sensitive and specific LC-MS/MS technique was developed and validated for the quantification of fostemsavir in human plasma and its pharmacokinetic application in rabbits.

METHODS

Chromatographic separation of the fostemsavir and fosamprenavir (internal standard) were achieved on Zorbax C18 (50 mm × 2 mm × 5 μm) column with 0.80 mL/min flow rate and coupled with API6000 triple quadrupole MS in multi reaction monitoring mode by applying mass transitions m/z 584.16/105.03 for fostemsavir and m/z 586.19/57.07 for the internal standard.

RESULTS

The calibration curve exhibited linearity in concentration range of 58.5-2340.0 ng/mL for fostemsavir. The LLOQ was 58.5 ng/mL. The validated LC-MS/MS process was effectively applied for the analysis of plasma in healthy rabbits for determinations of Fostemsavir. From the pharmacokinetic data, the mean of C_max and T_max were 198.19 ± 5.85 ng/mL and 2.42 ± 0.13, respectively. Plasma concentration reduced with t_1/2 of 7.02 ± 0.14. AUC_0→Last value obtained was 2374.87 ± 29.75 ng. h/ml, respectively.

CONCLUSION

In summary, the developed method has been successfully validated and pharmacokinetic parameters were demonstrated after oral administration of Fostemsavir to healthy rabbits.

Investigational drugs for HIV: trends, opportunities and key players

INTRODUCTION

Since the first antiretroviral drug was described, the field of HIV treatment and prevention has undergone two drug-based revolutions: the first one, enabled by the virtually concomitant discovery of non-nucleoside reverse transcriptase and protease inhibitors, was the inception of combined antiretroviral therapy. The second followed the creation of integrase strand-transfer inhibitors with improved safety, potency, and resistance profiles. Long-acting antiretroviral drugs, including broadly neutralizing antibodies, now offer the opportunity for a third transformational change in HIV management.

AREAS COVERED

Our review focused on HIV treatment and prevention with investigational drugs that offer the potential for infrequent dosing, including drugs not yet approved for clinical use. We also discussed approved drugs for which administration modalities or formulations are being optimized. We performed a literature search in published manuscripts, conference communications, and registered clinical trials.

EXPERT OPINION

While the field focuses on extending dosing intervals, we identify drug tissue penetration as an understudied opportunity to improve HIV care. We repeat that self-administration remains an essential milestone to reach the full potential of long-acting drugs. Treatments and prevention strategies based on broadly neutralizing antibodies require a deeper understanding of their antiretroviral properties.

Temsavir Treatment of HIV-1-Infected Cells Decreases Envelope Glycoprotein Recognition by Broadly Neutralizing Antibodies

The heavily glycosylated HIV-1 envelope glycoprotein (Env) is the sole viral antigen present at the surface of virions and infected cells, representing the main target for antibody responses. The FDA-approved small molecule temsavir acts as an HIV-1 attachment inhibitor by preventing Env-CD4 interaction. This molecule also stabilizes Env in a prefusion "closed" conformation that is preferentially targeted by several broadly neutralizing antibodies (bNAbs). A recent study showed that an analog of temsavir (BMS-377806) affects the cleavage and addition of complex glycans on Env. In this study, we investigated the impact of temsavir on the overall glycosylation, proteolytic cleavage, cell surface expression, and antigenicity of Env. We found that temsavir impacts Env glycosylation and processing at physiological concentrations. This significantly alters the capacity of several bNAbs to recognize Env present on virions and HIV-1-infected cells. Temsavir treatment also reduces the capacity of bNAbs to eliminate HIV-1-infected cells by antibody-dependent cellular cytotoxicity (ADCC). Consequently, the impact of temsavir on Env glycosylation and antigenicity should be considered for the development of new antibody-based approaches in temsavir-treated individuals. IMPORTANCE FDA-approved fostemsavir, the prodrug for the active moiety small molecule temsavir (GSK 2616713 [formally BMS-626529]), acts as an attachment inhibitor by targeting the HIV-1 envelope (Env) and preventing CD4 interaction. Temsavir also stabilizes Env in its "closed," functional state 1 conformation, which represents an ideal target for broadly neutralizing antibodies (bNAbs). Since these antibodies recognize conformation-dependent epitopes composed of or adjacent to glycans, we evaluated the impact of temsavir treatment on overall Env glycosylation and its influence on bNAb recognition. Our results showed an alteration of Env glycosylation and cleavage by temsavir at physiological concentrations. This significantly modifies the overall antigenicity of Env and therefore reduces the capacity of bNAbs to recognize and eliminate HIV-1-infected cells by ADCC. These findings provide important information for the design of immunotherapies aimed at targeting the viral reservoir in temsavir-treated individuals.

Therapeutic potential of indole derivatives as anti-HIV agents: A mini-review

Acquired immunodeficiency syndrome (AIDS), caused by human immunodeficiency virus (HIV), is one of the leading causes of human deaths. The advent of different anti-HIV drugs over different disease progress has made AIDS/HIV from a deadly infection to chronic and manageable disease. However, the development of multidrug-resistant viruses, together with the severe side effects of anti-HIV agents, compromised their efficacy and limited the treatment options. Indoles, the most common frameworks in the bioactive molecules, represent attractive scaffolds for the design and development of novel drugs. Indole derivatives are potential inhibitors of HIV enzymes such as reverse transcriptase, integrase and protease, and some indole-based agents like Delavirdine have already been applied in clinics or under clinical evaluations for the treatment of AIDS/HIV, revealing that indole moiety is a useful template for the development of anti-HIV agents. This review focuses on the recent advancement of indole derivatives including indole alkaloids, hybrids, and dimers with anti-HIV potential, covering articles published between 2010 and 2020. The chemical structures, structure-activity relationship and mechanisms of action are also discussed.

Effect of Renal and Hepatic Impairment on the Pharmacokinetics of Temsavir, the Active Moiety of Fostemsavir

The oral prodrug fostemsavir (GSK3684394, formerly BMS-663068) is an antiretroviral treatment for HIV-1. Fostemsavir is metabolized to its active moiety, temsavir, a first-in-class HIV-1 attachment inhibitor that binds to the viral envelope glycoprotein 120. Long-term antiretroviral therapy, the resulting longer life expectancy, and/or certain coinfections can increase the risk of chronic liver and kidney disease in HIV-1-infected individuals. Two studies were conducted to collectively evaluate the impact of renal and hepatic impairment on temsavir pharmacokinetics (PK) and safety following a single dose of a 600-mg extended-release fostemsavir tablet. There was no clinically meaningful effect of renal or hepatic impairment on temsavir PK, although renal clearance decreased with increasing renal impairment from moderate to severe, and exposure (maximum concentration and area under the plasma concentration-time curve from time 0 to infinity) tended to increase with increasing severity of hepatic impairment. No clinically meaningful effect of hemodialysis on temsavir PK parameters was observed. Fostemsavir was generally safe and well tolerated by treated subjects. Most adverse events (AEs) were mild, with the exception of 1 patient in the renal impairment study who discontinued due to 2 serious AEs unrelated to the study drug. No other treatment-emergent serious AEs occurred, and no other AEs leading to discontinuation were reported. Overall, these results suggest that fostemsavir can be used without dose modification in subjects with mild to severe renal impairment, including those with end-stage renal disease on hemodialysis, and in subjects with mild to severe hepatic impairment.

BMS Derivatives C7-Linked to β-Cyclodextrin and Hyperbranched Polyglycerol Retain Activity against R5-HIV-1NLAD8 Isolates and Can Be Deemed Potential Microbicides

Amides from indole-3-glyoxylic acid and 4-benzoyl-2-methylpiperazine, which are related to entry inhibitors developed by Bristol-Myers Squibb (BMS), have been synthesized with aliphatic chains located at the C7 position of the indole ring. These spacers contain an azido group suitable for the well-known Cu(I)-catalyzed (3+2)-cycloaddition or an activated triple bond for the nucleophilic addition of thiols under physiological conditions. Reaction with polyols (β-cyclodextrin and hyperbranched polyglycerol) decorated with complementary click partners has afforded polyol-BMS-like conjugates that are not cytotoxic (TZM.bl cells) and retain the activity against R5-HIV-1_NLAD8 isolates. Thus, potential vaginal microbicides based on entry inhibitors, which can be called of 4^th generation, are reported here for the first time.

Fostemsavir: The first oral attachment inhibitor for treatment of HIV-1 infection

PURPOSE

The pharmacology, pharmacokinetics, and role in therapy of fostemsavir in management of HIV-1 infection are reviewed, with an emphasis on clinical efficacy and safety data from phase 2 and phase 3 clinical trials.

SUMMARY

Fostemsavir (Rukobia, ViiV Healthcare), is a prodrug of temsavir, a novel pyridine compound with potent activity against HIV-1. Fostemsavir, the first oral attachment inhibitor, was approved and granted the breakthrough therapy designation by the Food and Drug Administration for use in combination with other antiretroviral agents for the treatment of HIV-1 infection in heavily treatment-experienced adults. As absorption of temsavir is not altered with increased gastric pH, patients may take acid suppressive agents such as famotidine during fostemsavir therapy.Temsavir is primarily metabolized through hydrolysis but also via cytochrome P-450 (CYP) oxidation; therefore, coadministration of fostemsavir with strong CYP3A inducers such as rifampin, carbamazepine, phenytoin, mitotane, enzalutamide, or St John's wort is contraindicated because it may result in significantly lower temsavir exposure, which can ultimately impair virologic response. The most common adverse reactions associated with fostemsavir use include nausea, diarrhea, headache, abdominal pain, dyspepsia, fatigue, rash, and sleep disturbance.

CONCLUSION

Fostemsavir may be an effective option for heavily treatment-experienced adults with multidrug-resistant HIV-1 infection. Fostemsavir is a particularly attractive treatment option for patients who are no longer able to achieve viral suppression with use of currently available antiretroviral therapies and who are able to adhere to a twice-daily oral regimen.

Fostemsavir: A Novel Attachment Inhibitor for Patients With Multidrug-Resistant HIV-1 Infection

Objective

To review the efficacy and safety of fostemsavir (FTR) for the treatment of multidrug-resistant HIV-1 infection in heavily treatment-experienced adults who are failing their current antiretroviral regimen.

Data Sources

Clinical trials and review articles were obtained through PubMed (2015 to July 2020) using the search terms fostemsavir, BMS-663068, and GSK3684934.

Study Selection and Data Extraction

All relevant articles, trials, and abstracts in the English language were included.

Data Synthesis

FTR demonstrates a novel mechanism of action, preventing virus attachment to the host CD4 receptor. FTR extended-release 600-mg tablets every 12 hours orally has proven beneficial in obtaining viral suppression for heavily treatment-experienced patients with multidrug-resistant infection refractory to other agents, as indicated in phase 3 trials. Treatment courses were evaluated to 96 weeks with significant viral load reductions noted within the first 24 weeks. Adverse events commonly reported include nausea, vomiting, diarrhea, fatigue, and headache. Serious events and fatality were not attributed to FTR and occurred because of advancement of HIV or other acute infection.

Relevance to Patient Care and Clinical Practice

FTR presents a new treatment option for patients with multidrug resistance and intolerability to other medications. The favorable adverse effect profile of FTR alongside the limited drug interaction profile makes it a viable option in a salvage regimen.

Conclusions

FTR provides an alternative agent when composing a regimen for patients with multidrug-resistant HIV-1 infection. It is generally well tolerated, with few significant interactions, and neither renal nor hepatic dose adjustments are required.