A Blast From the Past: Abdominal Wall Amyloidosis Due to Enfuvirtide Injections.

Enfuvirtide was the first marketed fusion inhibitor that worked by binding to glycoprotein 41 of the HIV envelope, preventing the conformational changes required for HIV fusion with CD4+ T cells. Due to its novel mechanisms of action, it was frequently used in the past as part of regimens for the indication of multi-class-resistant HIV until newer oral agents emerged. Here, we describe the case of a 40-year-old man who used enfuvirtide injections from 2012 to 2017 inclusive for multi-class-resistant HIV until he presented in 2021 with an abscess overlying a right lower quadrant mass requiring drainage via pigtail. Congo red stain of the tissue showed positive apple green birefringence on amorphous material after polarization, enabling the diagnosis of enfuvirtide-induced amyloidosis. The patient experienced significant improvement following surgical excision of the cysts and nodules. This case demonstrates that sequelae of injection site reactions can persist for many years following the cessation of enfuvirtide injections.

Modulation of the Fibrillation Kinetics and Morphology of a Therapeutic Peptide by Cucurbit[7]uril.

Fibrillation is a challenge commonly encountered in the formulation and development of therapeutic peptides. Cucurbit[7]urils (CB[7]), a group of water soluble macrocycles, have been reported to suppress fibrillation in insulin and human calcitonin through association with Phe and Tyr residues which drive fibril formation. Here, we report the effect of CB[7] on the fibrillation behavior of the HIV fusion inhibitor enfuvirtide (ENF) that contains N-terminal Tyr and C-terminal Phe residues. Thioflavin T fluorescence, CD spectroscopy, and transmission electron microscopy were used to monitor fibrillation behavior. Fibrillation onset showed a strong pH dependency, with pH 6.5 identified as the condition most suitable to monitor the effects of CB[7]. Binding of CB[7] to wild-type ENF was measured by isothermal titration calorimetry and was consistent with a single site (Ka = 2.4 × 105 M-1). A weaker interaction (Ka = 2.8 × 103 M-1) was observed for an ENF mutant with the C-terminal Phe substituted for Ala (ENFm), suggesting that Phe was the specific site for CB[7] recognition. The onset of ENF fibrillation onset was delayed, rather than fully suppressed, in the presence of CB[7]. The ENFm mutant showed a greater delay in fibrillation onset but with no observable effect on fibrillation kinetics in the presence of CB[7]. Interestingly, ENF/CB[7] and ENFm fibrils exhibited comparable morphologies, differing from those observed for ENF alone. The results indicate that CB[7] is capable of modulating fibrillation onset and the resulting ENF fibrils by specifically binding to the C-terminal Phe residue. The work reinforces the potential of CB[7] as an inhibitor of fibrillation and highlights its role in determining fibril morphologies.

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.

Action of enfuvirtide on the pregnancy of albino rats ( Rattus norvegicus albinus, Rodentia, Mammalia ): biological assay and functional and histological analyses of exposed maternal-fetal organs

ABSTRACT Objective To assess the effects of enfuvirtide on pregnancy in albino rats and their fetuses. Methods Forty pregnant EPM 1 Wistar rats were randomly allocated into four groups: control (E) (distilled water twice/day), G1 (4mg/kg/day enfuvirtide), G2 (12mg/kg/day enfuvirtide), and G3 (36mg/kg/day enfuvirtide) groups. On the 20th day of gestation, the rats were anesthetized and subjected to cesarean section. Their blood was collected for laboratory analysis, and they were sacrificed. The offspring's fragments of their kidneys, liver, and placentas and the maternal rats' fragments of their lungs, kidneys, and liver were separated in the immediate postpartum period for light microscopy analysis. Results No maternal deaths occurred. In the second week at the end of pregnancy, the mean weight of the G3 Group was significantly lower than that of the G2 Group (p=0.029 and p=0.028, respectively). Analyzing blood laboratory parameters, the G1 Group had the lowest mean amylase level, and the G2 Group had the lowest mean hemoglobin level and the highest mean platelet count. In the morphological analysis, there were no changes in organs, such as the kidneys and liver, in both the maternal rats and offspring. Three maternal rats in the G3 Group had pulmonary inflammation in the lungs. Conclusion Enfuvirtide has no significant adverse effects on pregnancy, conceptual products, or functional alterations in maternal rats.

The Glu143 Residue Might Play a Significant Role in T20 Peptide Binding to HIV-1 Receptor gp41: An In Silico Study.

Despite the enormous efforts made to develop other fusion inhibitors for HIV, the enfuvirtide (known as T20) peptide is the only approved HIV-1 inhibitory drug so far. Investigating the role of potential residues of the T20 peptide's conformational dynamics could help us to understand the role of potential residues of the T20 peptide. We investigated T20 peptide conformation and binding interactions with the HIV-1 receptor (i.e., gp41) using MD simulations and docking techniques, respectively. Although the mutation of E143 into alanine decreased the flexibility of the E143A mutant, the conformational compactness of the mutant was increased. This suggests a potential role of E143 in the T20 peptide's conformation. Interestingly, the free energy landscape showed a significant change in the wild-type T20 minimum, as the E143A mutant produced two observed minima. Finally, the docking results of T20 to the gp41 receptor showed a different binding interaction in comparison to the E143A mutant. This suggests that E143 residue can influence the binding interaction with the gp41 receptor. Overall, the E143 residue showed a significant role in conformation and binding to the HIV-1 receptor. These findings can be helpful in optimizing and developing HIV-1 inhibitor peptides.

Chimeric Human Papillomavirus-16 Virus-like Particles Presenting P18I10 and T20 Peptides from HIV-1 Envelope Induce HPV16 and HIV-1-Specific Humoral and T Cell-Mediated Immunity in BALB/c Mice.

In this study, the HIV-1 P18I10 CTL peptide derived from the V3 loop of HIV-1 gp120 and the T20 anti-fusion peptide of HIV-1 gp41 were inserted into the HPV16 L1 capsid protein to construct chimeric HPV:HIV (L1:P18I10 and L1:T20) VLPs by using the mammalian cell expression system. The HPV:HIV VLPs were purified by chromatography. We demonstrated that the insertion of P18I10 or T20 peptides into the DE loop of HPV16 L1 capsid proteins did not affect in vitro stability, self-assembly and morphology of chimeric HPV:HIV VLPs. Importantly, it did not interfere either with the HIV-1 antibody reactivity targeting sequential and conformational P18I10 and T20 peptides presented on chimeric HPV:HIV VLPs or with the induction of HPV16 L1-specific antibodies in vivo. We observed that chimeric L1:P18I10/L1:T20 VLPs vaccines could induce HPV16- but weak HIV-1-specific antibody responses and elicited HPV16- and HIV-1-specific T-cell responses in BALB/c mice. Moreover, could be a potential booster to increase HIV-specific cellular responses in the heterologous immunization after priming with rBCG.HIVA vaccine. This research work would contribute a step towards the development of the novel chimeric HPV:HIV VLP-based vaccine platform for controlling HPV16 and HIV-1 infection, which is urgently needed in developing and industrialized countries.

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.

Peptide-based Fusion Inhibitors for Preventing the Six-helix Bundle Formation of Class I Fusion Proteins: HIV and Beyond.

A number of different viral families have developed convergent methods to infect cells. Class I fusion proteins are commonly used by members of Arenaviridae, Coronaviridae, Filovirdae, Orthomyxoviridae, Paramyxoviridae, and Retroviridae. Class I viral fusion proteins are trimers that are involved in recognizing the cellular receptor, with a region that is responsible for fusing the viral and target cell membranes. During the fusion process, the fusion region folds into a six-helix bundle (6 HB) which approximates the two membranes leading to fusion. For Human Immunodeficiency Virus (HIV), the gp41 subunit is responsible for the formation of this 6 HB. The fusion inhibitor drug enfuvirtide, or T20, is the only US Food and Drug Administration and European Medicines Agency approved drug which targets this crucial step and has been widely used in combination regimens for the treatment of HIV since March 2003. In this review, we describe the current state of peptide-based fusion inhibitors in the treatment of HIV, and review how the field of HIV research is driving advances in the development of similar therapeutics in other viral systems, including the Severe Acute Respiratory Syndrome (SARS) coronaviruses.

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.

HIVfird: A Tool for Detection of Resistance to Fusion Inhibitor Drugs in HIV-1 Sequences.

Fusion inhibitors are antiretroviral (ARV) drugs that prevent HIV-1 entry into host cells. Enfuvirtide (ENF) is the only ARV drug marketed in this class and, like other HIV drugs, it has been associated with the emergence and selection of therapeutic-resistant HIV-1 strains. The aims of this work were to develop a computational tool capable of identifying and classifying mutations associated with resistance to Enfuvirtide and to evaluate the prevalence of these mutations among the HIV-1 sequences deposited in public databases. The HIVfird (HIV-1 fusion inhibitor resistance detector) was developed using the PHP programming language, using 30 DNA bases obtained from the HIV-1 HXB2 gp41 protein as a reference. To assess the level of resistance in HIV-1 populations, sequences were retrieved from the Los Alamos National Laboratory (LANL) database. The HIVfird is hosted at www.hivfird.ics.ufba.br, fully functional and available for public use. Twenty-five amino acid substitutions and 15 combinations were found to be associated with some level of resistance to ENF. These mutations are located at positions 36-45 of gp41, with 36, 38, 43, and 44 having the greatest diversity and frequency of variations associated with drug resistance. Resistance mutations were found in 3.16% and 4.67% of the circulating HIV-1 isolates in the world and Brazil, respectively. Subtype B showed a significantly higher ENF resistance rate (4.9%) compared to other genetic forms, while subtype C presented the lowest rate (0.9%). We present here HIVfird, an online tool that might assist in the therapeutic management of HIV-1 patients with multiple drug failure and in population-based analysis of drug resistance.

Massively Parallel Profiling of HIV-1 Resistance to the Fusion Inhibitor Enfuvirtide.

Identifying drug resistance mutations is important for the clinical use of antivirals and can help define both a drug's mechanism of action and the mechanistic basis of resistance. Resistance mutations are often identified one-at-a-time by studying viral evolution within treated patients or during viral growth in the presence of a drug in cell culture. Such approaches have previously mapped resistance to enfuvirtide, the only clinically approved HIV-1 fusion inhibitor, to enfuvirtide's binding site in the N-terminal heptad repeat (NHR) of the Envelope (Env) transmembrane domain as well as a limited number of allosteric sites. Here, we sought to better delineate the genotypic determinants of resistance throughout Env. We used deep mutational scanning to quantify the effect of all single-amino-acid mutations to the subtype A BG505 Env on resistance to enfuvirtide. We identified both previously characterized and numerous novel resistance mutations in the NHR. Additional resistance mutations clustered in other regions of Env conformational intermediates, suggesting they may act during different fusion steps by altering fusion kinetics and/or exposure of the enfuvirtide binding site. This complete map of resistance sheds light on the diverse mechanisms of enfuvirtide resistance and highlights the utility of using deep mutational scanning to comprehensively map potential drug resistance mutations.

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.

Assessment of Antibody Interference of Enfuvirtide (T20) Function Shows Assay Dependent Variability.

BACKGROUND: During HIV infection, fusion of the viral and cellular membranes is dependent on folding of the gp41 trimer into a six-helix bundle. Fusion inhibitors, such as the antiretroviral Enfuvirtide (T20), interfere with the formation of the gp41 six-helix bundle. Recent in vitro studies reveal that the gp41 immunodominant region one targeting antibody 3D6 can block T20 interference, but the clinical and pathophysiologic significance of this finding is unclear. OBJECTIVE/METHOD: We have previously characterized a number of antibodies that target conformational epitopes on gp41and herein characterized their ability to interfere with T20 in multiple assays and assess their prevalence in HIV infected subjects. RESULTS: The T20 interference by antibody 3D6 was confirmed in a CHO-HXB2 envelope/ HeLaT4+ cell culture assay. Antibodies that target an immunodominant region one epitope, as well as a gp41 discontinuous epitope, also interfered in this assay, however, not all antibodies that targeted these epitopes showed T20 interference. This response was not due to the direct binding of T20 by the antibodies and could not be replicated utilizing TZM-bl and HL2/3 cells. Notably, serum competition studies on a panel of HIV subjects demonstrate that these conformational targeting antibodies are common in the HIV population. CONCLUSION: The relatively common nature of antibodies targeting these epitopes, the disparate in vitro results, and lack of reported clinical failures ascribed to such antibodies leads us to conclude that antibody interference of T20 is likely not clinically relevant. However, this warrants continued consideration with the advancement of other fusion inhibitors.

Immunization with HIV-1 envelope T20-encoding DNA vaccines elicits cross-clade neutralizing antibody responses.

BACKGROUND: Genetic immunization is expected to induce the expression of antigens in a native form. The encoded peptide epitopes are presented on endogenous MHC molecules, mimicking antigen presentation during a viral infection. We have explored the potential of enfuvirtide (T20), a short HIV peptide with antiviral properties, to enhance immune response to HIV antigens. To generate an expression vector, the T20 sequence was cloned into a conventional plasmid, the novel minicircle construct, and a replicon plasmid. In addition, 3 conventional plasmids that express the envelope of HIV-1 subtypes A, B and C and contain T20 in their gp41 sequences were also tested. RESULTS: All combinations induced HIV-specific antibodies and cellular responses. The addition of T20 as a peptide and as an expression cassette in the 3 DNA vectors enhanced antibody responses. The highest anti-HIV-1 Env titers were obtained by the replicon T20 construct. This demonstrates that besides its known antiviral activity, T20 promotes immune responses. We also confirm that the combination of slightly divergent antigens improves immune responses. CONCLUSIONS: The antiretroviral T20 HIV-1 sequence can be used as an immunogen to elicit binding and neutralizing antibodies against HIV-1. These, or similarly modified gp41 genes/peptides, can be used as priming or boosting components for induction of broadly neutralizing anti-HIV antibodies. Future comparative studies will reveal the optimal mode of T20 administration.

Current Status of the Pharmacokinetics and Pharmacodynamics of HIV-1 Entry Inhibitors and HIV Therapy.

BACKGROUND: Human Immunodeficiency Virus (HIV) entry inhibitors target the first step of the HIV life cycle and efficiently inhibit HIV from infecting the immune cells which is a key prerequisite for viral spread. Because of their unique mechanism of action on cell-cell transmission, they may provide a promising perspective for the treatment of AIDS. METHOD: Maraviroc (MVC) and Enfuvirtide (ENF) have been approved by the FDA for the treatment of HIV-1 infection. Attachment inhibitors (BMS-663068 and TNX-355) and co-receptor inhibitors (PRO-140 and cenicriviroc (CVC)) have reached phase II or III clinical trials. These entry inhibitors show beneficial pharmacokinetics and substantial reductions of plasma HIV-1 RNA load in HIV infected patients. RESULTS: Most entry inhibitors are generally safe, without serious Adverse Event (AE) or AE leading to discontinuation. The pharmacokinetics of MVC, CVC and BMS-663068 was affected by CYP3A4 inhibitors or inducers. The FDA has proposed that the dosage of MVC (300 mg, BID, orally) be adjusted to half or two-fold for patients if it is combined with a major CYP3A4 inhibitor or inducer, respectively. Researchers suggested that the dosage of CVC (50-75 mg, QD, orally) may also need adjustment but the dosage of BMS-663068 (600 mg, BID, orally) does not. CONCLUSION: The standard, recommended ENF dosage is 90 mg BID, injected subcutaneously for adults, and 2 mg/kg BID, up to a maximum dose of 90 mg, injected subcutaneously for pediatric patients. TNX-355 (10-15 mg/kg, BID, intravenously) and PRO-140(5-10 mg/kg, BID, intravenously; 324 mg, biweekly, subcutaneously) are administered by intravenous infusion or subcutaneous injection.

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.

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.

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.