Modelling organophosphate intoxication in C. elegans highlights nicotinic acetylcholine receptor determinants that mitigate poisoning.

Organophosphate intoxication via acetylcholinesterase inhibition executes neurotoxicity via hyper stimulation of acetylcholine receptors. Here, we use the organophosphate paraoxon-ethyl to treat C. elegans and use its impact on pharyngeal pumping as a bio-assay to model poisoning through these neurotoxins. This assay provides a tractable measure of acetylcholine receptor mediated contraction of body wall muscle. Investigation of the time dependence of organophosphate treatment and the genetic determinants of the drug-induced inhibition of pumping highlight mitigating modulation of the effects of paraoxon-ethyl. We identified mutants that reduce acetylcholine receptor function protect against the consequence of intoxication by organophosphates. Data suggests that reorganization of cholinergic signalling is associated with organophosphate poisoning. This reinforces the under investigated potential of using therapeutic approaches which target a modulation of nicotinic acetylcholine receptor function to treat the poisoning effects of this important class of neurotoxins.

Effect of alcohol exposure on the efficacy and safety of tenofovir alafenamide fumarate, a major medicine against human immunodeficiency virus.

Human immunodeficiency virus (HIV) continues to be a major health concern. AIDS-related deaths (acquired immunodeficiency syndrome) have decreased recently, but chronic liver disease is now a major cause of mortality among HIV patients. Widespread alcohol use is recognized to be a major contributing factor. Tenofovir alafenamide fumarate (TAF), one of the most used HIV drugs, requires hydrolysis followed by phosphorylation to produce tenofovir diphosphate, the ultimate anti-HIV metabolite. Carboxylesterase-1 (CES1), established to hydrolyze TAF, is known to catalyze transesterification in the presence of ethanol. The aim of the study was to test the hypothesis that metabolism-based interactions between TAF and ethanol negatively impact both efficacy and safety of TAF. To test this hypothesis, the metabolism of TAF was determined in human primary hepatocytes and with a large number of human liver samples (S9 fractions) in the presence or absence of ethanol. The metabolism was monitored by LC-MS/MS (liquid chromatography with tandem mass spectrometry) and the level of CES1 or CES2 was determined by Western blotting. Consistent with the hypothesis, TAF underwent transesterification in the presence of ethanol accompanied by decreased hydrolysis. The formation of tenofovir diphosphate (the therapeutically active metabolite) was significantly decreased. In addition, TAF but not its hydrolytic metabolite, was found to increase intracellular lipid retention, and the increase was enhanced by ethanol. These findings conclude that alcohol consumption, beyond commonly accepted poor adherence to HIV medications, directly impacts the efficacy and safety of TAF.

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).

Structural insights into sphingosine-1-phosphate receptor activation.

As a critical sphingolipid metabolite, sphingosine-1-phosphate (S1P) plays an essential role in immune and vascular systems. There are five S1P receptors, designated as S1PR1 to S1PR5, encoded in the human genome, and their activities are governed by endogenous S1P, lipid-like S1P mimics, or nonlipid-like therapeutic molecules. Among S1PRs, S1PR1 stands out due to its nonredundant functions, such as the egress of T and B cells from the thymus and secondary lymphoid tissues, making it a potential therapeutic target. However, the structural basis of S1PR1 activation and regulation by various agonists remains unclear. Here, we report four atomic resolution cryo-electron microscopy (cryo-EM) structures of Gi-coupled human S1PR1 complexes: bound to endogenous agonist d18:1 S1P, benchmark lipid-like S1P mimic phosphorylated Fingolimod [(S)-FTY720-P], or nonlipid-like therapeutic molecule CBP-307 in two binding modes. Our results revealed the similarities and differences of activation of S1PR1 through distinct ligands binding to the amphiphilic orthosteric pocket. We also proposed a two-step "shallow to deep" transition process of CBP-307 for S1PR1 activation. Both binding modes of CBP-307 could activate S1PR1, but from shallow to deep transition may trigger the rotation of the N-terminal helix of Gαi and further stabilize the complex by increasing the Gαi interaction with the cell membrane. We combine with extensive biochemical analysis and molecular dynamic simulations to suggest key steps of S1P binding and receptor activation. The above results decipher the common feature of the S1PR1 agonist recognition and activation mechanism and will firmly promote the development of therapeutics targeting S1PRs.

Study of Organophosphorus Compound Poisoning in a Tertiary Care Hospital and the Role of Peradeniya Organophosphorus Poisoning Scale as a Prognostic Marker of the Outcome.

Organophosphate compounds (OPC) cause most selfpoisoning deaths in India due to their easy availability and lack of stringent laws. AIM: To evaluate the clinical profile and outcome of the patients presenting with OPC poisoning and to study the prognostic value of Peradeniya Organophosphorus Poisoning Scale (POPS) in predicting the clinical outcomes. MATERIAL: This was a prospective study involving 100 patients of OPC poisoning admitted to Tata Main Hospital from June 2018 to May 2020 based on the inclusion criteria. Demographic profile, clinical features, treatment details, and need for ventilatory support were noted. POPS was applied on admission, and the patients were followed up for the outcome in terms of morbidity and mortality. OBSERVATION: Of the 100 patients, most patients were between 20 and 29 years with male to female ratio being 1.2:1. Vomiting (94%), followed by excessive secretions (84%) were the most common symptoms. Overall mortality was 22%. On grading of severity as per the POP scale, 27% of the patients had mild poisoning, 37% patients had moderate, whereas 36% had severe poisoning. Only 11.11% of the patients with POPS 0-3 required ventilator support, whereas 16.2% of the patients with POPS 4-7, and 100% of patients with POPS 8-11 required ventilator assistance (P < 0.0001). Similarly, the total dose of atropine required (P < 0.0001), length of intensive care unit (ICU) stay, complications, and mortality (P < 0.0001) were significantly associated with higher POPS. CONCLUSION: POPS at admission, correlated well with the need for ventilator support, the total dose of atropine required, length of stay in the ICU, complications, and mortality. It can thus be used for prognostication and risk stratification of patients with OPC poisoning.

The Genesis and Future Prospects of Small Molecule HIV-1 Attachment Inhibitors.

Gp120 is a critical viral proteins required for HIV-1 entry and infection. It facilitates HIV-1 binding to target cells, human-to-human transmission, relocation of virus from mucosa to lymph nodes, cell-cell infection and syncytium formation, and the bystander effect that kills uninfected CD4+ T-cells and other human cells. Molecules that bind to gp120 can inhibit its function by stabilizing conformations of the protein, leading to the inability to infect cells, and resulting in non-permissive. Small molecule-mediated stabilization of certain conformations of gp120 may also enhance recognition of HIV-1 infected cells by neutralizing antibodies and make the virus more susceptible to effector functions such as ADCC, which could potentially be part of future cure regimens. Additionally, HIV attachment inhibitors can complex with free gp120 and potentially repress both cytopathic effects from membrane-bound or soluble gp120. Fostemsavir (RukobiaTM), a phosphate prodrug of an HIV-1 attachment inhibitor that was recently approved for use in highly treatment experienced (HTE) patients with multidrug resistant HIV-1 is a first-in-class drug with a favorable safety profile that provides an additional treatment option for treatment in this population of patients with a high medical need.

Efficacy and Safety Profile of Fostemsavir for the Treatment of People with Human Immunodeficiency Virus-1 (HIV-1): Current Evidence and Place in Therapy.

Heavily-treatment-experienced people living with human immunodeficiency virus (HTE-PLWH) represent a population with limited therapeutic options and at high-risk of clinical progression, morbidity, and mortality. The development of new drugs and new drug classes for the treatment of HIV-1 infection in HTE-PLWH is critical to successfully suppress HIV-1 replication, restore the immune system, and improve quality of life. Fostemsavir is the first attachment inhibitor approved by Food and Drug Administration and European Medicines Agency for the treatment of HIV-1 infection. It is approved in combination with other antiretrovirals, for HTE-PLWH with multi-drug resistant HIV-1 after failing their current antiretroviral regimen due to resistance, intolerance, or safety considerations. In this review, we present and discuss the mechanism of action, the pharmacodynamic and pharmacokinetic properties, and the efficacy and safety of fostemsavir as an antiretroviral agent for the treatment of HIV-1 infection.

Pharmacokinetics and Pharmacodynamics of Tedizolid.

Tedizolid is an oxazolidinone antibiotic with high potency against Gram-positive bacteria and currently prescribed in bacterial skin and skin-structure infections. The aim of the review was to summarize and critically review the key pharmacokinetic and pharmacodynamic aspects of tedizolid. Tedizolid displays linear pharmacokinetics with good tissue penetration. In in vitro susceptibility studies, tedizolid exhibits activity against the majority of Gram-positive bacteria (minimal inhibitory concentration [MIC] of ≤ 0.5 mg/L), is four-fold more potent than linezolid, and has the potential to treat pathogens being less susceptible to linezolid. Area under the unbound concentration-time curve (fAUC) related to MIC (fAUC/MIC) was best correlated with efficacy. In neutropenic mice, fAUC/MIC of ~ 50 and ~ 20 induced bacteriostasis in thigh and pulmonary infection models, respectively, at 24 h. The presence of granulocytes augmented its antibacterial effect. Hence, tedizolid is currently not recommended for immunocompromised patients. Clinical investigations with daily doses of 200 mg for 6 days showed non-inferiority to twice-daily dosing of linezolid 600 mg for 10 days in patients with acute bacterial skin and skin-structure infections. In addition to its use in skin and skin-structure infections, the high pulmonary penetration makes it an attractive option for respiratory infections including Mycobacterium tuberculosis. Resistance against tedizolid is rare yet effective antimicrobial surveillance and defining pharmacokinetic/pharmacodynamic targets for resistance suppression are needed to guide dosing strategies to suppress resistance development.

Tedizolid: new data and experiences for clinical practice.

The most relevant information on the clinical uses of tedizolid from studies published in the last 18 months is presented in this brief review. The most important data indicate better tolerance and safety profile of long-term therapeutic regimes in off-label indications, such as osteoarticular infections and those caused by mycobacteria. Its lower risk of hazardous interactions compared to linezolid should be emphasized. Furthermore, tedizolid in its combination with rifampicin shows a more favourable way of acting as demonstrated in vitro and in vivo studies. A recent trial also opens the door for its potential use in nosocomial pneumonia caused by Gram-positive bacteria.

Targeted Enrichment of Enzyme-Instructed Assemblies in Cancer Cell Lysosomes Turns Immunologically Cold Tumors Hot.

Lysosome-relevant cell death induced by lysosomal membrane permeabilization (LMP) has recently attracted increasing attention. However, nearly no studies show that currently available LMP inducers can evoke immunogenic cell death (ICD) or convert immunologically cold tumors to hot. Herein, we report a LMP inducer named TPE-Py-pYK(TPP)pY, which can respond to alkaline phosphatase (ALP), leading to formation of nanoassembies along with fluorescence and singlet oxygen turn-on. TPE-Py-pYK(TPP)pY tends to accumulate in ALP-overexpressed cancer cell lysosomes as well as induce LMP and rupture of lysosomal membranes to massively evoke ICD. Such LMP-induced ICD effectively converts immunologically cold tumors to hot as evidenced by abundant CD8+ and CD4+ T cells infiltration into the cold tumors. Exposure of ALP-catalyzed nanoassemblies in cancer cell lysosomes to light further intensifies the processes of LMP, ICD and cold-to-hot tumor conversion. This work thus builds a new bridge between lysosome-relevant cell death and cancer immunotherapy.

New Drugs 2021, Part 2.

ABSTRACT: The second of a two-part series, this article describes eight recently approved drugs, including the first drug approved for the treatment of SARS-CoV-2, a first-in-class HIV attachment inhibitor, and a new intravenous injection indicated for the treatment of acute pain in adults for whom other treatments are ineffective.

PrEP uptake, persistence, adherence, and effect of retrospective drug level feedback on PrEP adherence among young women in southern Africa: Results from HPTN 082, a randomized controlled trial.

BACKGROUND: Pre-exposure prophylaxis (PrEP) is highly effective and an important prevention tool for African adolescent girls and young women (AGYW), but adherence and persistence are challenging. PrEP adherence support strategies for African AGYW were studied in an implementation study. METHODS AND FINDINGS: HIV Prevention Trials Network (HPTN) 082 was conducted in Cape Town, Johannesburg (South Africa) and Harare (Zimbabwe) from October 2016 to October 2018 to evaluate PrEP uptake, persistence, and the effect of drug level feedback on adherence. Sexually active HIV-negative women ages 16-25 were offered PrEP and followed for 12 months; women who accepted PrEP were randomized to standard adherence support (counseling, 2-way SMS, and adherence clubs) or enhanced adherence support with adherence feedback from intracellular tenofovir-diphosphate (TFV-DP) levels in dried blood spots (DBS). PrEP uptake, persistence through 12 months (no PrEP hold or missed visits), and adherence were assessed. The primary outcome was high adherence (TFV-DP ≥700 fmol/punch) at 6 months, compared by study arm. Of 451 women enrolled, median age was 21 years, and 39% had curable sexually transmitted infections (STIs). Most (95%) started PrEP, of whom 55% had uninterrupted PrEP refills through 12 months. Of those with DBS, 84% had detectable TFV-DP levels at month 3, 57% at month 6, and 31% at month 12. At 6 months, 36/179 (21%) of AGYW in the enhanced arm had high adherence and 40/184 (22%) in the standard adherence support arm (adjusted odds ratio [OR] of 0.92; 95% confidence interval [CI] 0.55, 1.34; p = 0.76). Four women acquired HIV (incidence 1.0/100 person-years), with low or undetectable TFV-DP levels at or prior to seroconversion, and none of whom had tenofovir or emtricitabine resistance mutations. The study had limited power to detect a modest effect of drug level feedback on adherence, and there was limited awareness of PrEP at the time the study was conducted. CONCLUSIONS: In this study, PrEP initiation was high, over half of study participants persisted with PrEP through month 12, and the majority of young African women had detectable TFV-DP levels through month 6 with one-fifth having high adherence. Drug level feedback in the first 3 months of PrEP use did not increase the proportion with high adherence at month 6. HIV incidence was 1% in this cohort with 39% prevalence of curable STIs and moderate PrEP adherence. Strategies to support PrEP use and less adherence-dependent formulations are needed for this population. TRIAL REGISTRATION: ClinicalTrials.gov NCT02732730.

Evaluating fostemsavir as a therapeutic option for patients with HIV.

ABSTRACIntroduction: Despite the unquestionable success of antiretroviral therapy achieved in recent years, there are still cases of heavily treated patients who do not achieve or struggle to maintain undetectable HIV-RNA due to drug resistance. New antiretroviral options are needed to address this issue.Area covered: The authors first provide an overview of fostemsavir and its role in the treatment of HTE PLWH. Data from pre-clinical and clinical studies are reviewed and the pharmacokinetic and farmacodynamic properties are highlited. Drug-drug interactions and safety data from available clinical studies are also discussed.Expert opinion: Fostemsavir is a promising antiretroviral belonging to the class of entry inhibitors; its novel mechanism of action represents a very important innovation. Its use will be limited to the heavy-treatment-experienced patient population. This use will have to be monitored to avoid abuse and waste of a molecule that for some patients may represent a life-saving drug.

A comparison of covariate selection techniques applied to pre-exposure prophylaxis (PrEP) drug concentration data in men and transgender women at risk for HIV.

Pre-exposure prophylaxis (PrEP) containing antiretrovirals tenofovir disoproxil fumarate (TDF) or tenofovir alafenamide (TAF) can reduce the risk of acquiring HIV. Concentrations of intracellular tenofovir-diphosphate (TFV-DP) measured in dried blood spots (DBS) have been used to quantify PrEP adherence; although even under directly observed dosing, unexplained between-subject variation remains. Here, we wish to identify patient-specific factors associated with TFV-DP levels. Data from the iPrEX Open Label Extension (OLE) study were used to compare multiple covariate selection methods for determining demographic and clinical covariates most important for drug concentration estimation. To allow for the possibility of non-linear relationships between drug concentration and explanatory variables, the component selection and smoothing operator (COSSO) was implemented. We compared COSSO to LASSO, a commonly used machine learning approach, and traditional forward and backward selection. Training (N = 387) and test (N = 166) datasets were utilized to compare prediction accuracy across methods. LASSO and COSSO had the best predictive ability for the test data. Both predicted increased drug concentration with increases in age and self-reported adherence, the latter with a steeper trajectory among Asians. TFV-DP reductions were associated with increasing eGFR, hemoglobin and transgender status. COSSO also predicted lower TFV-DP with increasing weight and South American countries. COSSO identified non-linear relationships between log(TFV-DP) and adherence, weight and eGFR, with differing trajectories for some races. COSSO identified non-linear log(TFV-DP) trajectories with a subset of covariates, which may better explain variation and enhance prediction. Future research is needed to examine differences identified in trajectories by race and country.

The Kv7 Modulator, Retigabine, is an Efficacious Antiseizure Drug for Delayed Treatment of Organophosphate-induced Status Epilepticus.

Benzodiazepines are the primary treatment option for organophosphate (OP)-induced status epilepticus (SE), but these antiseizure drugs (ASDs) lose efficacy as treatment is delayed. In the event of a mass civilian or military exposure, significant treatment delays are likely. New ASDs that combat benzodiazepine-resistant, OP-induced SE are critically needed, particularly if they can be efficacious after a long treatment delay. This study evaluated the efficacy of the Kv7 channel modulator, retigabine, as a novel therapy for OP-induced SE. Adult, male rats were exposed to soman or diisopropyl fluorophosphate (DFP) to elicit SE and monitored by electroencephalogram (EEG) recording. Retigabine was administered alone or adjunctive to midazolam (MDZ) at delays of 20- or 40-min in the soman model, and 60-min in the DFP model. Following EEG recordings, rats were euthanized and brain tissue was collected for Fluoro-Jade B (FJB) staining to quantify neuronal death. In the DFP model, MDZ + 15 mg/kg retigabine suppressed seizure activity and was neuroprotective. In the soman model, MDZ + 30 mg/kg retigabine suppressed seizures at 20- and 40-min delays. Without MDZ, 15 mg/kg retigabine provided partial antiseizure and neuroprotectant efficacy in the DFP model, while 30 mg/kg without MDZ failed to attenuate soman-induced SE. At 60 mg/kg, retigabine without MDZ strongly reduced seizure activity and neuronal degeneration against soman-induce SE. This study demonstrates the antiseizure and neuroprotective efficacy of retigabine against OP-induced SE. Our data suggest retigabine could be a useful adjunct to standard-of-care and has potential for use in the absence of MDZ.

Experiences of oral pre-exposure prophylaxis (PrEP) use disclosure among South African adolescent girls and young women and its perceived impact on adherence.

INTRODUCTION: There is limited understanding of how social dynamics impact pre-exposure prophylaxis (PrEP) adherence among adolescent girls and young women (AGYW) in generalized HIV-epidemic settings. We examined experiences of oral PrEP use disclosure to various social groups with the goal of identifying supportive relationships that can be leveraged to promote adherence. METHODS: We used qualitative methods to explore experiences disclosing PrEP use and the perceived impact of disclosure on adherence among 22 South African AGYW (16-25 years) taking daily oral PrEP. Serial in-depth-interviews (IDIs) were conducted 1-, 3-, and 12-months post-PrEP initiation. Respondents also self-reported their disclosures separately for various social groups and adherence was assessed using intracellular tenofovir-diphosphate levels. RESULTS: Qualitative respondents had a median age of 20.5 years and reported disclosing their PrEP use to friends (n = 36 total disclosures), partners, siblings, other family members (n = 24 disclosures each), and parents (n = 19 disclosures). IDI data revealed that parents and partners provided the most support to respondents and a lack of support from these groups was most often perceived as negatively affecting PrEP use. AGYW described difficulties explaining PrEP to their mothers, who believed PrEP was HIV treatment or would lead to HIV infection. Disclosure to household members was notably meaningful for AGYW (both positively and negatively). Respondents reported leveraging supportive relationships for pill reminders. For respondents who perceived a household member would be unsupportive, however, non-disclosure was less feasible and PrEP use was often stigmatized. To avoid stigma, several respondents hid or discontinued PrEP. CONCLUSIONS: While supportive relationships may facilitate PrEP use, disclosure can also lead to stigma. Counselors should support AGYW in disclosing to key people in their social networks and provide AGYW with materials that lend credibility to explanations of PrEP. Community education is necessary to alleviate PrEP-related stigma and facilitate disclosure.

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.

Susceptibility of global HIV-1 clinical isolates to fostemsavir using the PhenoSense® Entry assay.

BACKGROUND: Fostemsavir is a prodrug of a first-in-class HIV-1 attachment inhibitor, temsavir, that binds to gp120 and blocks attachment to the host-cell CD4 receptor, preventing entry and infection of the target cell. Previous studies using a limited number of clinical isolates showed that there was intrinsic variability in their susceptibility to temsavir. OBJECTIVES: Here, an analysis was performed using all clinical isolates analysed in the Monogram Biosciences PhenoSense® Entry assay as part of the development programme. METHODS: In total, 1337 individual envelopes encompassing 20 different HIV-1 subtypes were examined for their susceptibility to temsavir. However, only seven subtypes (B, C, F1, A, [B, F1], BF and A1) were present more than five times, with subtype B (881 isolates) and subtype C (156 isolates) having the largest numbers. RESULTS: As expected, variability in susceptibility was observed within all subtypes. However, for the great majority of these viruses, temsavir was highly potent, with most viruses exhibiting IC50s <10 nM. One exception was CRF01_AE viruses, where all five isolates exhibited IC50s >100 nM. For the 607 isolates where tropism data were available, geometric mean temsavir IC50 values were remarkably similar for CCR5-, CXCR4- and dual mixed-tropic envelopes from infected individuals. CONCLUSIONS: These data show that HIV-1 viruses from most subtypes are highly susceptible to temsavir and that temsavir susceptibility is independent of tropism.

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.