Development of a HPLC fluorometric method for the quantification of enfuvirtide following in vitro releasing studies on thermosensitive in situ forming gel

Due to the presence of peptidase and protease in the gastrointestinal tract, peptides are subjected to digestion and inactivation when administrated orally. To avoid degradation and maintain the desired efficacy of peptide drugs, there is a demand to develop transdermal and intradermal delivery systems. This requires efficient and specific analytical methods to separate and quantify the peptide drugs from the formulation and the skin matrix in the early stages of pharmaceutical development. A high-performance liquid chromatography (HPLC) system equipped with a fluorometric detector was used to quantify enfuvirtide, which is the first fusion inhibitor for HIV treatment. The HPLC method was developed and validated according to the ICH Q2(R1) guidelines. The viability of the method was demonstrated during in vitro studies, where samples were analysed following intradermal administration of a thermosensitive in situ forming gel. Compared with previously reported methods, this assay proved efficient, sensitive and accurate, with a detection limit of 0.74 μg/mL and a run time of 9 min, mitigating the use of any internal standards and detergents. The addition of an organic solvent to the samples successfully solved the problem of low recovery caused by the adsorption of the drug to the plastic consumables in the sample treatment process. The amount of enfuvirtide releasing from the in situ gel through skin after 7 hours was 16.25 ± 7.08 μg, which was significantly lower than the reconstituted FUZEON^® itself (26.68 ± 10.45 μg), showing a longer release profile. The results may be beneficial as a constructive input for future enfuvirtide quantification within a preclinical setting through in vitro release studies across the skin.

Enfuvirtide, an HIV-1 fusion inhibitor peptide, can act as a potent SARS-CoV-2 fusion inhibitor: an in silico drug repurposing study

Regarding the urgency of therapeutic measures for coronavirus disease 2019 (COVID-19) pandemic, the use of available drugs with FDA approval is preferred because of the less time and cost required for their development. In silico drug repurposing is an accurate way to speed up the screening of the existing FDA-approved drugs to find a therapeutic option for COVID-19. The similarity in SARS-CoV-2 and HIV-1 fusion mechanism to host cells can be a key point for Inhibit SARS-CoV-2 entry into host cells by HIV fusion inhibitors. Accordingly, in this study, an HIV-1 fusion inhibitor called Enfuvirtide (Enf) was selected. The affinity and essential residues involving in the Enf binding to the S2 protein of SARS-CoV-2, HIV-1 gp41 protein and angiotensin-converting enzyme 2 (ACE-2) as a negative control, was evaluated using molecular docking. Eventually, Enf-S2 and Enf-gp41 protein complexes were simulated by molecular dynamics (MD) in terms of binding affinity and stability. Based on the most important criteria such as docking score, cluster size, energy and dissociation constant, the strongest interaction was observed between Enf with the S2 protein. In addition, MD results confirmed that Enf-S2 protein interaction was remarkably stable and caused the S2 protein residues to undergo the fewest fluctuations. In conclusion, it can be stated that Enf can act as a strong SARS-CoV-2 fusion inhibitor and demonstrates the potential to enter the clinical trial phase of COVID-19.

Communicated by Ramaswamy H. Sarma

HIV-1 gp41 genetic diversity and enfuvirtide resistance-associated mutations among enfuvirtide-naïve patients in southern China

BACKGROUND

Human immunodeficiency virus (HIV) increasing molecular diversity and emergence of drug resistant mutants remain a major concern in China. Enfuvirtide (ENF/T-20) is the first entry inhibitor used in patients failing highly active antiretroviral therapy (HAART). However, data on HIV-1 gp41genetic diversity and primary ENF resistance-associated mutations among treatment-naïve patients in China is limited. The objective was to identify molecular diversity and ENF resistance patterns of HIV-1 in southern China, using envelope (env) gp41 sequences and bioinformatics tools, which may help optimize antiretroviral therapy.

METHODS

From November 2018 to January 2019, 439 blood plasma samples from ENF-naïve patients were collected from Shenzhen, Wuhan and Chongqing, of which 396 HIV env regions were sequenced and subtyped, and were performed the analysis of drug resistance-associated mutations (DRMs).

RESULTS

The main subtypes were circulating recombinant form (CRF) 01_AE (30.6 %) and CRF07_BC (48.7 %). CRF55_01B had been the fourth subtype in the study, and many rare CRFs were observed. Notably, CRF02_AG and CRF_BF strains typically found in Africa and US respectively were identified amongst Chinese patients. Known DRMs were detected in 27.5 % (109/396) of ENF treatment-naïve patients. One major DRM (L44 M), many secondary DRMs (including N126 K, E137 K, S138A), and lots of polymorphisms were found in the study, which have been proved to elevate resistance to ENF.

CONCLUSIONS

HIV-1 molecular diversity was observed in the study, which indicating that HIV-1 variability is becoming increasingly complex in southern China. A diverse set of primary DRMs discovered in this study described the serious threat to ART, which reminds us the urgent need of timely surveillance of HIV-1 viral diversity and drug resistance in China.

A 30 kDa polyethylene glycol-enfuvirtide complex enhances the exposure of enfuvirtide in lymphatic viral reservoirs in rats

HIV therapy with anti-retroviral drugs is limited by the poor exposure of viral reservoirs, such as lymphoid tissue, to these small molecule drugs. We therefore investigated the effect of PEGylation on the anti-retroviral activity and subcutaneous lymphatic pharmacokinetics of the peptide-based fusion inhibitor enfuvirtide in thoracic lymph duct cannulated rats. Both the peptide and the PEG were quantified in plasma and lymph via ELISA. Conjugation to a single 5 kDa linear PEG decreased anti-HIV activity three-fold compared to enfuvirtide. Whilst plasma and lymphatic exposure to peptide mass was moderately increased, the loss of anti-viral activity led to an overall decrease in exposure to enfuvirtide activity. A 20 kDa 4-arm branched PEG conjugated with an average of two enfuvirtide peptides decreased peptide activity by six-fold. Plasma and lymph exposure to enfuvirtide, however, increased significantly such that anti-viral activity was increased two- and six-fold respectively. The results suggest that a multi-enfuvirtide-PEG complex may optimally enhance the anti-retroviral activity of the peptide in plasma and lymph.

Transdermal Delivery of Enfuvirtide in a Porcine Model Using a Low-Frequency, Low-Power Ultrasound Transducer Patch

Ultrasound-mediated transdermal delivery is a promising parenteral administration method for large-molecule or unstable medications. This study evaluated skin health and systemic delivery when administering enfuvirtide, an injectable anti-retroviral medication, over a 1-mo period in a porcine model using a low-frequency cymbal transducer. Three groups received twice-daily treatments: (i) enfuvirtide injection control (n = 12); (ii) saline ultrasound control (n = 6); and (iii) enfuvirtide ultrasound treatment (n = 13). Ultrasound parameters were as follows: 30-min exposure, 90 mW/cm², 24-26 kHz and 15% duty cycle. No statistical difference in trans-epidermal water loss, a measure of skin health and function, was seen between ultrasound-treated and control skin sites for either saline (p = 0.50) or enfuvirtide (p = 0.29) groups. Average trough plasma concentrations of enfuvirtide were 0.6 ± 0.2 and 2.8 ± 0.8 μg/mL for ultrasound and injection, respectively. Tolerability and efficacy results indicate that chronic, low-frequency ultrasound exposure can be a practical means for transdermal delivery of medications such as enfuvirtide.

Lanthipeptides: chemical synthesis versus in vivo biosynthesis as tools for pharmaceutical production

Lanthipeptides (also called lantibiotics for those with antibacterial activities) are ribosomally synthesized post-translationally modified peptides having thioether cross-linked amino acids, lanthionines, as a structural element. Lanthipeptides have conceivable potentials to be used as therapeutics, however, the lack of stable, high-yield, well-characterized processes for their sustainable production limit their availability for clinical studies and further pharmaceutical commercialization. Though many reviews have discussed the various techniques that are currently employed to produce lanthipeptides, a direct comparison between these methods to assess industrial applicability has not yet been described. In this review we provide a synoptic comparison of research efforts on total synthesis and in vivo biosynthesis aimed at fostering lanthipeptides production. We further examine current applications and propose measures to enhance product yields. Owing to their elaborate chemical structures, chemical synthesis of these biomolecules is economically less feasible for large-scale applications, and hence biological production seems to be the only realistic alternative.

Continuous intravenous infusion of enfuvirtide in a patient with a multidrug-resistant HIV strain

Case description To evaluate whether continuous intravenous (i.v.) administration of enfuvirtide (T20) could be a suitable alternative to subcutaneous (s.c.) administration of T20 in a patient with extensively drug-resistant HIV experiencing difficulties administering T20 subcutaneously. T20 was administered to a patient through 100 mL cassettes once daily via a CADD. Plasma samples were drawn and the pharmacokinetic profile compared to that of s.c. twice daily administration of T20. Also, viral replication and CD4+ count were monitored over a period of 9 months for this study. Continuous i.v. administration of T20 resulted in significantly higher T20 plasma levels compared to s.c. administration, continued viral suppression, a rise in CD4+ count and strong patient preference over s.c. administration. Conclusion This method of T20 administration may be a suitable alternative for selected patients who are not able to tolerate it when given subcutaneously. It may even be considered a priori in selected patients with extensive viral resistance who are unable or unwilling to inject T20 subcutaneously.

Enfuvirtide-PEG conjugate: A potent HIV fusion inhibitor with improved pharmacokinetic properties

Enfuvirtide (ENF) is a clinically used peptide drug for the treatment of HIV infections, but its poor pharmacokinetic profile (T1/2 = 1.5 h in rats) and low aqueous solubility make the therapy expensive and inconvenience. In this study, we present a simple and practical strategy to address these problems by conjugating ENF with polyethylene glycol (PEG). Site-specific attachment of a 2 kDa PEG at the N-terminus of ENF resulted in an ENF-PEG (EP) conjugate with high solubility (≥3 mg/mL) and long half-life in rats (T1/2 = 16.1 h). This conjugate showed similar antiviral activity to ENF against various primary HIV-1 isolates (EC50 = 6-91 nM). Mechanistic studies suggested the sources of the antiviral potency. The conjugate bound to a functional domain of the HIV gp41 protein in a helical conformation with high affinity (Kd = 307 nM), thereby inhibiting the gp41-mediated fusion of viral and host-cell membranes. As PEG conjugation has advanced many bioactive proteins and peptides into clinical applications, the EP conjugate described here represents a potential new treatment for HIV infections that may address the unmet medical needs associated with the current ENF therapy.

Nanoformulation of antiretroviral drugs enhances their penetration across the blood brain barrier in mice

Eradication of virus by sanctuary sites is a main goal in HIV management. The central nervous system (CNS) is a classic model of sanctuary where viral replication occurs despite a complete viral suppression in peripheral blood. In recent years, nanotechnologies have provided a great promise in the eradication of HIV from the CNS. We hereby demonstrate for the first time that the structurally complex antiretroviral drug enfuvirtide (Enf), which normally is unable to penetrate the cerebrospinal fluid, is allowed to cross the blood brain barrier (BBB) in mice by conjugation with a nanoconstruct. Iron oxide nanoparticles coated with an amphiphilic polymer increase Enf translocation across the BBB in both in vitro and in vivo models. The mechanism involves the uptake of nanoconjugated-Enf in the endothelial cells, the nanocomplex dissociation and the release of the peptide, which is eventually excreted by the cells in the brain parenchyma.

FROM THE CLINICAL EDITOR

Despite the success of cocktail therapy of antiretroviral drugs, the complete eradication of HIV remains elusive, due to existence of viral sanctuary sites. The authors showed in this study that an antiretroviral drug complexed with iron oxide nanoparticles and coated with PMA amphiphilic polymer crosses the blood brain barrier. Furthermore, there was significant anti-viral activity. The results would aid further drug designs to eradicate HIV.

Effectiveness of enfuvirtide in a cohort of highly antiretroviral-experienced HIV-1-infected patients in Mexico

Background

Treatments in patients with multidrug resistance often involve the use of multiple agents with partial antiviral activity and overlapping metabolic toxicities. Enfuvirtide is therefore a welcome addition to the antiretroviral management of patients with multiclass resistant virus, given the low risk of systemic toxicities and novel mechanism of action relative to existing drug classes.

The aim of this study was to evaluate the effectiveness of ENF plus optimized background regimen (OBR) in a Mexican cohort of highly HIV-1 ARV-experienced patients.

Methods

Prospective cohort of treatment-experienced HIV-1-infected adults with virological failure who started therapy with an ENF-containing regimen. The effectiveness of ENF treatment was evaluated with percentages of undetectable HIV-1 RNA viral load after 24 and 48 weeks of treatment, and changes in CD4+ cell counts.

Results

Forty patients >18 years were included. After 24 weeks of treatment, 91% of patients had HIV-1 RNA viral load <400 copies/mL and 65.8% had <50 copies/mL. At week 48 of treatment, 81.4% of the patients had HIV-1 RNA <400 copies/mL and 55.5% had <50 copies/mL; in both cases p <0.0001 compared to baseline. Increase CD4+ cells were also statistically significant at weeks 24 and 48 with respect to the baseline. Pain at the site of injection was the main adverse event in 100% of patients.

Conclusion

Our study provides clinically important evidence of the effectiveness and safety of ENF in highly ARV-experienced HIV-1-infected patients. These findings strengthen the results of previous randomized controlled trials with this agent.

Recombinant approach for the production of HIV fusion inhibitor Enfuvirtide using Escherichia coli

The use of antiretroviral drugs is gaining importance in the recent past for the treatment of human immunodeficiency virus infection. Enfuvirtide (T20) is one of the fusion inhibitors, inhibits the fusion between the virus and healthy target CD4 cells. The treatment with T20 involves very high therapeutic dose. In addition to its high dose, production of T20 by synthetic methods is expensive and cumbersome. We report an alternative recombinant approach for the production of the T20 peptide through a novel short fusion-tag expression system. This expression system consists of the hydrophobic region of growth hormone (GH) as the fusion tag, a factor Xa cleavage site upstream to the T20. The fusion protein was expressed in Escherichia coli as inclusion bodies. We also report here, a simple and an efficient down-stream strategy for the purification of recombinant T20 peptide (rT20). Our study is the first to demonstrate a novel approach using GH fusion tag, ensured the peptide stability, for the production of rT20 which yields more than 250mg/L with 98% purity. The biological activity of the rT20 is comparable to its synthetic counterpart. Thus, this novel approach could be an alternate method of choice for production of therapeutically important small peptides.

Patient care and support measures overcome reluctance to initiate new regimen containing enfuvirtide

Patients can be resistant to initiation of enfuvirtide therapy because of concerns about self-injection and related issues. Because the introduction of a new drug class can substantially enhance the efficacy of an antiretroviral regimen, supporting the patient in the introduction of enfuvirtide, a safe and efficacious agent in a new class, offers therapeutic benefits. In the present patient, who showed resistance to all three of the major antiretroviral drug classes, enfuvirtide was successfully introduced with clinic and peer support group assistance. The patient's acceptance was enhanced by the use of a needle-free injection system (Biojector), with minimal side effects and significantly improved virological and immunological control.

The clinical cost of delays in switching therapy

Management of the HIV patient with treatment experience continues to improve and evolve. New guidelines suggest that the goal of therapy should be maximal virological suppression. This is best achieved by using combinations of agents to which the virus is most likely to have some susceptibility and, where possible, by using agents within a new therapeutic class. The cases discussed demonstrate how the use of a potent regimen as salvage therapy can have good clinical, immunological and virological outcomes. However, if the salvage regimen selected is not potent enough to achieve these goals, the durability of the response is limited. The key lesson is that these strategies should be built on potency and agents should not be held back in case the strategy fails.