Clinical Relevance of Pre-Existing and Treatment-Induced Anti-Poly(Ethylene Glycol) Antibodies

Novel peptide and hyaluronic acid coated biomimetic liposomes for targeting bacterial infections and sepsis

Sepsis is a life-threatening syndrome resulting from an imbalanced immune response to severe infections. Despite advances in nanomedicines, effective treatments for sepsis are still lacking. Herein, vancomycin free base (VCM)-loaded dual functionalized biomimetic liposomes based on a novel TLR4-targeting peptide (P3) and hyaluronic acid (HA) (HA-P3-Lipo) were developed to enhance sepsis therapy. The nanocarrier revealed appropriate physicochemical parameters, good stability, and biocompatibility. The release of VCM from HA-P3-Lipo was found to be sustained with 76 % VCM released in 48 h. The biomimicry was elucidated by in silico tools and MST and results confirmed strong binding between the system and TLR4. Furthermore, HA-P3-Lipo revealed 2-fold enhanced antibacterial activity against S. aureus, sustained antibacterial activity against MRSA over 72 h and 5-fold better MRSA biofilm inhibition compared to bare VCM. Bacterial-killing kinetics and flow cytometry confirmed the superiority of HA-P3-Lipo in eliminating MRSA faster than VCM. The in vivo potential of the nanocarrier was elucidated in an MRSA-induced sepsis mice model, and the results confirmed the superiority of HA-P3-Lipo compared to free VCM in eliminating bacteria and down-regulating the proinflammatory markers. Therefore, HA-P3-Lipo exhibits potential as a promising novel multi-functional nanosystem against sepsis and could significantly contribute to the transformation of sepsis therapy.

Lipid Nanoparticles for Nucleic Acid Delivery Beyond the Liver

Lipid nanoparticles (LNPs) are the most clinically advanced drug delivery system for nucleic acid therapeutics, exemplified by the success of the COVID-19 mRNA vaccines. However, their clinical use is currently limited to hepatic diseases and vaccines due to their tendency to accumulate in the liver upon intravenous administration. To fully leverage their potential, it is essential to understand and address their liver tropism, while also developing strategies to enhance delivery to tissues beyond the liver. Ensuring that these therapeutics reach their target cells while avoiding off-target cells is essential for both their efficacy and safety. There are three potential targeting strategies-passive, active, and endogenous-which can be used individually or in combination to target nonhepatic tissues. In this review, we delve into the recent advancements in LNP engineering for delivering nucleic acid beyond the liver.

Polyethylene glycol and immunology: aspects of allergic reactions and their mechanisms, as well as ways to prevent them in clinical practice

In modern medical practice, where polyethylene glycol is widely used as a component of various drugs, such as vaccines, chemotherapy drugs, and antibiotics, including vaccines, the issue of allergic reactions to this substance is becoming increasingly important. The purpose of this study is to review and systematise data on various aspects of allergic reactions to polyethylene glycol with the aim of better understanding their pathogenesis, clinical manifestations, diagnostic methods, and possible treatment approaches. The study analysed literature data in modern databases, such as MEDLINE, PubMed, and Scopus, on allergic reactions to polyethylene glycol, using the keywords: "PEG", "polyethylene glycol", "allergy", "side effect". The main aspects of allergy to this substance were highlighted, including mechanisms of development, diagnostic methods, and possible treatment strategies. The analysis found that allergic reactions to polyethylene glycol can manifest in a variety of ways, including anaphylaxis and systemic reactions. A possible role for the immune response has been identified, including the production of IgE and IgM antibodies, complement activation, and accelerated clearance in response to polyethylene glycol, in blood plasma. Data are also provided on how to diagnose an increased risk of an allergic reaction in patients who have previously received drugs with this type of drug transporter and in patients receiving high molecular weight types of polyethylene glycol. The results of this review contribute to a better understanding of allergic reactions to polyethylene glycol and provide information for the development of more effective diagnostic and treatment methods.

Striving for Uniformity: A Review on Advances and Challenges To Achieve Uniform Polyethylene Glycol

Poly(ethylene glycol) (PEG) is the polymer of choice in drug delivery systems due to its biocompatibility and hydrophilicity. For over 20 years, this polymer has been widely used in the drug delivery of small drugs, proteins, oligonucleotides, and liposomes, improving the stability and pharmacokinetics of many drugs. However, despite the extensive clinical experience with PEG, concerns have emerged related to its use. These include hypersensitivity, purity, and nonbiodegradability. Moreover, conventional PEG is a mixture of polymers that can complicate drug synthesis and purification leading to unwanted immunogenic reactions. Studies have shown that uniform PEGylated drugs may be more effective than conventional PEGylated drugs as they can overcome issues related to molecular heterogeneity and immunogenicity. This has led to significant research efforts to develop synthetic procedures to produce uniform PEGs (monodisperse PEGs). As a result, iterative step-by-step controlled synthesis methods have been created over time and have shown promising results. Nonetheless, these procedures have presented numerous challenges due to their iterative nature and the requirement for multiple purification steps, resulting in increased costs and time consumption. Despite these challenges, the synthetic procedures went through several improvements. This review summarizes and discusses recent advances in the synthesis of uniform PEGs and its derivatives with a focus on overall yields, scalability, and purity of the polymers. Additionally, the available characterization methods for assessing polymer monodispersity are discussed as well as uniform PEG applications, side effects, and possible alternative polymers that can overcome the drawbacks.

Impact of Anti-PEG IgM Induced via the Topical Application of a Cosmetic Product Containing PEG Derivatives on the Antitumor Effects of PEGylated Liposomal Antitumor Drug Formulations in Mice

Poly(ethylene glycol) (PEG) is used in many common products, such as cosmetics. PEG, however, is also used to covalently conjugate drug molecules, proteins, or nanocarriers, which is termed PEGylation, to serve as a shield against the natural immune system of the human body. Repeated administration of some PEGylated products, however, is known to induce anti-PEG antibodies. In addition, preexisting anti-PEG antibodies are now being detected in healthy individuals who have never received PEGylated therapeutics. Both treatment-induced and preexisting anti-PEG antibodies alter the pharmacokinetic properties, which can result in a subsequent reduction in the therapeutic efficacy of administered PEGylated therapeutics through the so-called accelerated blood clearance (ABC) phenomenon. Moreover, these anti-PEG antibodies are widely reported to be related to severe hypersensitivity reactions following the administration of PEGylated therapeutics, including COVID-19 vaccines. We recently reported that the topical application of a cosmetic product containing PEG derivatives induced anti-PEG immunoglobulin M (IgM) in a mouse model. Our finding indicates that the PEG derivatives in cosmetic products could be a major cause of the preexistence of anti-PEG antibodies in healthy individuals. In this study, therefore, the pharmacokinetics and therapeutic effects of Doxil (doxorubicin hydrochloride-loaded PEGylated liposomes) and oxaliplatin-loaded PEGylated liposomes (Liposomal l-OHP) were studied in mice. The anti-PEG IgM antibodies induced by the topical application of cosmetic products obviously accelerated the blood clearance of both PEGylated liposomal formulations. Moreover, in C26 tumor-bearing mice, the tumor growth suppressive effects of both Doxil and Liposomal l-OHP were significantly attenuated in the presence of anti-PEG IgM antibodies induced by the topical application of cosmetic products. These results confirm that the topical application of a cosmetic product containing PEG derivatives could produce preexisting anti-PEG antibodies that then affect the therapeutic efficacy of subsequent doses of PEGylated therapeutics.

Development of anti-PEG IgG/IgM/IgE ELISA assays for profiling anti-PEG immunoglobulin response in PEG-sensitized individuals and patients with alpha-gal allergy

Polyethylene glycol (PEG) is frequently used in various protein and nanomedicine therapeutics. However, various studies have shown that select PEGylated therapeutics can induce production of anti-PEG antibodies (APA), potentially culminating in rapid clearance from the systemic circulation, loss of efficacy and possibly increased risks of allergic reactions. Although IgE is a frequent cause of immediate hypersensitivity reactions (IHR), the role of IgE APA in PEG-related IHR is not well understood, due in part to a lack of standardized assays for measuring IgE APA. Here, we developed a rigorous competitive ELISA method to measure the concentrations of various APA isotypes, including IgE, with picomolar sensitivities. In a small number of serum samples from patients with known PEG allergy, the assay allowed us to detect a strong correlation between IgG and IgE APA in individuals with history of allergic reactions to PEG or PEGylated drugs, but not between IgM and IgE APA. We detected appreciable levels of IgG and IgM APA in individuals with history of alpha-gal allergy, however, they were not elevated relative to those detected in other healthy controls, and we found no pre-existing IgE APA. While preliminary and should be further investigated, these results suggest that differences in the route and mechanism of PEG exposure may drive variability in APA response.

Anti-PEG antibodies enriched in the protein corona of PEGylated nanocarriers impact the cell uptake

Poly(ethylene glycol) (PEG) is the gold standard used to reduce unspecific protein adsorption and prolong nanocarrier circulation time. However, this stealth effect could be counteracted by the increasing prevalence of anti-PEG antibodies in the bloodstream. Up to now, the presence of anti-PEG antibodies in the protein corona and their effect on cell uptake has not been investigated yet. Our results showed a high concentration and prevalence of anti-PEG antibodies in the German population. PEGylated nanocarriers exhibited a higher level of anti-PEG antibodies in the protein corona compared to non-PEGylated, which lead to higher uptake in macrophages. Consequently, the anti-PEG antibodies in the protein corona could mitigate the stealth effect of PEG, leading to accelerated blood clearance and unwanted side effects.

The interplay between PEGylated nanoparticles and blood immune system

During the last two decades, an increasing number of reports have pointed out that the immunogenicity of polyethylene glycol (PEG) may trigger accelerated blood clearance (ABC) and hypersensitivity reaction (HSR) to PEGylated nanoparticles, which could make PEG modification counterproductive. These phenomena would be detrimental to the efficacy of the load and even life-threatening to patients. Consequently, further elucidation of the interplay between PEGylated nanoparticles and the blood immune system will be beneficial to developing and applying related formulations. Many groups have worked to unveil the relevance of structural factors, dosing schedule, and other factors to the ABC phenomenon and hypersensitivity reaction. Interestingly, the results of some reports seem to be difficult to interpret or contradict with other reports. In this review, we summarize the physiological mechanisms of PEG-specific immune response. Moreover, we speculate on the potential relationship between the induction phase and the effectuation phase to explain the divergent results in published reports. In addition, the role of nanoparticle-associated factors is discussed based on the classification of the action phase. This review may help researchers to develop PEGylated nanoparticles to avoid unfavorable immune responses based on the underlying mechanism.

Thermoresponsive Polypeptide Fused L-Asparaginase with Mitigated Immunogenicity and Enhanced Efficacy in Treating Hematologic Malignancies

L-Asparaginase (ASP) is well-known for its excellent efficacy in treating hematological malignancies. Unfortunately, the intrinsic shortcomings of ASP, namely high immunogenicity, severe toxicity, short half-life, and poor stability, restrict its clinical usage. Poly(ethylene glycol) conjugation (PEGylation) of ASP is an effective strategy to address these issues, but it is not ideal in clinical applications due to complex chemical synthesis procedures, reduced ASP activity after conjugation, and pre-existing anti-PEG antibodies in humans. Herein, the authors genetically engineered an elastin-like polypeptide (ELP)-fused ASP (ASP-ELP), a core-shell structured tetramer predicted by AlphaFold2, to overcome the limitations of ASP and PEG-ASP. Notably, the unique thermosensitivity of ASP-ELP enables the in situ formation of a sustained-release depot post-injection with zero-order release kinetics over a long time. The in vitro and in vivo studies reveal that ASP-ELP possesses increased activity retention, improved stability, extended half-life, mitigated immunogenicity, reduced toxicity, and enhanced efficacy compared to ASP and PEG-ASP. Indeed, ASP-ELP treatment in leukemia or lymphoma mouse models of cell line-derived xenograft (CDX) shows potent anti-cancer effects with significantly prolonged survival. The findings also indicate that artificial intelligence (AI)-assisted genetic engineering is instructive in designing protein-polypeptide conjugates and may pave the way to develop next-generation biologics to enhance cancer treatment.

Clinical Impact of Antipolyethylene Glycol (PEG) Antibody in Hematological Patients Administered PEGylated-Granulocyte Colony-Stimulating Factor

Polyethylene glycol (PEG) is a polymer covalently attached to proteins to improve their half-life and efficacy. We previously reported that the PEGylated granulocyte colony-stimulating factor (PEG-G-CSF) is immunogenic, which could adversely impact drug efficacy and safety in animal models. Here, we analyzed the relationship between anti-PEG antibody titers and the clinical impact of PEG-G-CSF in 19 hematological patients. A gradual decrease of anti-PEG antibody titers from baseline was observed after PEG-G-CSF administration. Of the 19 participants, 10 were assessed for noninfectious fever after the first administration of PEG-G-CSF and three experienced this reaction. The receiver operating characteristic curve revealed that the cut-off values of pretreated anti-PEG IgM and IgG titers for noninfectious fever were set at 5.0 and 96.6 U/mL, respectively. All patients who experienced noninfectious fever had anti-PEG antibody titers above this cut-off value (P = .033). An enzyme-linked immunosorbent assay revealed that some anti-PEG antibodies in patients with anti-PEG antibody titers above the cut-off value reacted with the PEGylated liposome. These results indicate the reactivity of the anti-PEG antibodies to PEGylated therapeutics observed in hematologic patients and the possibility of the relationship between high titers of anti-PEG antibodies and the development of adverse events after PEG-G-CSF administration.

Cleavable-Branched Polymer-Modified Liposomes Reduce Accelerated Blood Clearance and Enhance Photothermal Therapy

In recent years, cationic liposomes have been successfully used as delivery platforms for mRNA vaccines. Poly(ethylene glycol) (PEG)-lipid derivatives are widely used to enhance the stability and reduce the toxicity of cationic liposomes. However, these derivatives are often immunogenic, triggering the rise of anti-PEG antibodies. Understanding the role and impact of PEG-lipid derivatives on PEGylated cationic liposomes is key to solving the PEG dilemma. In this study, we designed linear, branched, and cleavable-branched cationic liposomes modified with PEG-lipid derivatives and investigated the effect of the liposome-induced accelerated blood clearance (ABC) phenomenon on photothermal therapy. Our study indicated that the linear PEG-lipid derivatives mediated the effect of photothermal therapy by stimulating splenic marginal zone (MZ) B cells to secrete anti-PEG antibodies and increasing the level of IgM expression in the follicular region of the spleen. However, the cleavable-branched and branched PEG-lipid derivatives did not activate the complement system and avoided the ABC phenomenon by inducing noticeably lower levels of anti-PEG antibodies. The cleavable-branched PEGylated cationic liposomes improved the effect of photothermal therapy by reversing the charge on the liposome surface. This detailed study of PEG-lipid derivatives contributes to the further development and clinical application of PEGylated cationic liposomes.

Studying how administration route and dose regulates antibody generation against LNPs for mRNA delivery with single-particle resolution

Following the recent approval of both siRNA- and mRNA-based therapeutics, nucleic acid therapies are considered a game changer in medicine. Their envisioned widespread use for many therapeutic applications with an array of cellular target sites means that various administration routes will be employed. Concerns exist regarding adverse reactions against the lipid nanoparticles (LNPs) used for mRNA delivery, as PEG coatings on nanoparticles can induce severe antibody-mediated immune reactions, potentially being boosted by the inherently immunogenic nucleic acid cargo. While exhaustive information is available on how physicochemical features of nanoparticles affects immunogenicity, it remains unexplored how the fundamental choice of administration route regulates anti-particle immunity. Here, we directly compared antibody generation against PEGylated mRNA-carrying LNPs administered by the intravenous, intramuscular, or subcutaneous route, using a novel sophisticated assay capable of measuring antibody binding to authentic LNP surfaces with single-particle resolution. Intramuscular injections in mice were found to generate overall low and dose-independent levels of anti-LNP antibodies, while both intravenous and subcutaneous LNP injections generated substantial and highly dose-dependent levels. These findings demonstrate that before LNP-based mRNA medicines can be safely applied to new therapeutic applications, it will be crucial to carefully consider the choice of administration route.

Strategic Approaches to Improvise Peptide Drugs as Next Generation Therapeutics

In recent years, the occurrence of a wide variety of drug-resistant diseases has led to an increase in interest in alternate therapies. Peptide-based drugs as an alternate therapy hold researchers' attention in various therapeutic fields such as neurology, dermatology, oncology, metabolic diseases, etc. Previously, they had been overlooked by pharmaceutical companies due to certain limitations such as proteolytic degradation, poor membrane permeability, low oral bioavailability, shorter half-life, and poor target specificity. Over the last two decades, these limitations have been countered by introducing various modification strategies such as backbone and side-chain modifications, amino acid substitution, etc. which improve their functionality. This has led to a substantial interest of researchers and pharmaceutical companies, moving the next generation of these therapeutics from fundamental research to the market. Various chemical and computational approaches are aiding the production of more stable and long-lasting peptides guiding the formulation of novel and advanced therapeutic agents. However, there is not a single article that talks about various peptide design approaches i.e., in-silico and in-vitro along with their applications and strategies to improve their efficacy. In this review, we try to bring different aspects of peptide-based therapeutics under one article with a clear focus to cover the missing links in the literature. This review draws emphasis on various in-silico approaches and modification-based peptide design strategies. It also highlights the recent progress made in peptide delivery methods important for their enhanced clinical efficacy. The article would provide a bird's-eye view to researchers aiming to develop peptides with therapeutic applications.

Graphical Abstract

PEGylated Lipid Nanoparticle Formulations: Immunological Safety and Efficiency Perspective

Lipid nanoparticles (LNPs) have been recognized as efficient vehicles to transport a large variety of therapeutics. Currently in the spotlight as important constituents of the COVID-19 mRNA vaccines, LNPs play a significant role in protecting and transporting mRNA to cells. As one of their key constituents, polyethylene glycol (PEG)-lipid conjugates are important in defining LNP physicochemical characteristics and biological activity. PEGylation has proven particularly efficient in conferring longer systemic circulation of LNPs, thus greatly improving their pharmacokinetics and efficiency. Along with revealing the benefits of PEG conjugates, studies have revealed unexpected immune reactions against PEGylated nanocarriers such as accelerated blood clearance (ABC), involving the production of anti-PEG antibodies at initial injection, which initiates accelerated blood clearance upon subsequent injections, as well as a hypersensitivity reaction referred to as complement activation-related pseudoallergy (CARPA). Further, data have been accumulated indicating consistent yet sometimes controversial correlations between various structural parameters of the PEG-lipids, the properties of the PEGylated LNPs, and the magnitude of the observed adverse effects. Detailed knowledge and comprehension of such correlations are of foremost importance in the efforts to diminish and eliminate the undesirable immune reactions and improve the safety and efficiency of the PEGylated medicines. Here, we present an overview based on analysis of data from the CAS Content Collection regarding the PEGylated LNP immunogenicity and overall safety concerns. A comprehensive summary has been compiled outlining how various structural parameters of the PEG-lipids affect the immune responses and activities of the LNPs, with regards to their efficiency in drug delivery. This Review is thus intended to serve as a helpful resource in understanding the current knowledge in the field, in an effort to further solve the remaining challenges and to achieve full potential.

Advances in engineering and delivery strategies for cytokine immunotherapy

INTRODUCTION

Cytokine immunotherapy is a growing field for the treatment of cancer, infectious disease, autoimmunity, and other ailments. Therapeutic cytokines are a class of secreted, small proteins that play a pivotal role in regulating the innate and adaptive immune system by provoking or mitigating immune responses. In the clinic, cytokines are frequently combined with other treatments, such as small molecules and monoclonal antibodies. However, the clinical translation of cytokine therapies is hindered by their short half-life, pleiotropic nature, and off-target effects, which cause diminished efficacy and severe systemic toxicity. Such toxicity limits dosage, thus resulting in suboptimal doses. Accordingly, numerous efforts have been devoted to exploring strategies to promote cytokine therapies by improving their tissue specificity and pharmacokinetics.

AREAS COVERED

Preclinical and clinical research into bioengineering and delivery strategies for cytokines, consisting of bioconjugation, fusion proteins, nanoparticles, and scaffold-based systems.

EXPERT OPINION

These approaches pave the way for the development of next-generation cytokine treatments with greater clinical benefit and reduced toxicity, circumventing such issues currently associated with cytokine therapy.

Expanding opportunities to engineer mucosal vaccination with biomaterials

Mucosal vaccines are receiving increasing interest both for protecting against infectious diseases and for inducing therapeutic immune responses to treat non-infectious diseases. However, the mucosal barriers of the lungs, gastrointestinal tract, genitourinary tract, nasal, and oral tissues each present unique challenges for constructing efficacious vaccines. Vaccination through each of these mucosae requires transport through the mucus and across specialized epithelia to reach tissue-specific immune cells and lymphoid structures, necessitating finely tuned and multifunctional strategies. Serving as inspiration for mucosal vaccine design, pathogens have evolved elaborate, diverse, and multipronged approaches to penetrate and infect mucosae. This review is focused on biomaterials-based strategies, many inspired by pathogens, for designing mucosal vaccine platforms. Passive and active technologies are discussed, along with the microbial processes that they seek to mimic.

Anti-PEG antibodies before and after a first dose of Comirnaty® (mRNA-LNP-based SARS-CoV-2 vaccine)

The early and massive vaccination campaign in Israel with the mRNA-LNP Comirnaty® (Pfizer-BioNTech) vaccine against the SARS-CoV-2 virus made available large amounts of data regarding the efficacy and safety of this vaccine. Adverse reactions to mRNA-based SARS-CoV-2 vaccines are rare events, but due to large mediatic coverage they became feared and acted as a potential source of delay for the vaccination of the Israeli population. The experience with the reactogenicity of the polyethylene glycol (PEG) moiety of PEGylated liposomes, PEGylated proteins and other PEGylated drugs raised the fear that similar adverse effects can be associated with the PEG lipid which is an essential component of currently used mRNA-LNP vaccines against COVID-19. In this study we quantified the levels of anti-PEG IgG, IgM and IgE present in the blood of 79 volunteers immediately before and 3 weeks after receiving a first dose of Comirnaty® vaccine. Our in vitro results show that different humanized anti-PEG antibodies bind the PEGylated nano-liposomes in a concentration-dependent manner, but they bind with a lower affinity to the Comirnaty vaccine, despite it having a high mole% of neutral PEG₂₀₀₀-lipid on its surface. We found an increase in IgG concentration in the blood 3 weeks after the first vaccine administration, but no increase in IgM or IgE. In addition, no severe signs of adverse reactions to the Comirnaty vaccine were observed in the population studied despite the significant pre-existing high titers of IgG before the first dose of vaccine in 2 donors.

Enhanced Cytotoxic Activity of PEGylated Curcumin Derivatives: Synthesis, Structure-Activity Evaluation, and Biological Activity

Curcumin has been modified in various ways to broaden its application in medicine and address its limitations. In this study, we present a series of curcumin-based derivatives obtained by replacing the hydroxy groups in the feruloyl moiety with polyethylene glycol (PEG) chains and the addition of the BF₂ moiety to the carbonyl groups. Tested compounds were screened for their cytotoxic activity toward two bladder cancer cell lines, 5637 and SCaBER, and a noncancerous cell line derived from lung fibroblasts (MRC-5). Cell viability was analyzed under normoxic and hypoxic conditions (1% oxygen). Structure-activity relationships (SARs) are discussed, and curcumin derivatives equipped within feruloyl moieties with 3-methoxy and 4-{2-[2-(2-methoxyethoxy)ethoxy]ethoxy} substituents (5) were selected for further analysis. Compound 5 did not affect the viability of MRC-5 cells and exerted a stronger cytotoxic effect under hypoxic conditions. However, the flow cytometry studies showed that PEGylation did not improve cellular uptake. Another observation was that the lack of serum proteins limits the intracellular uptake of curcumin derivative 5. The preliminary mechanism of action studies indicated that compound 5 under hypoxic conditions induced G2/M arrest in a dose-dependent manner and increased the expression of stress-related proteins such as p21/CIP1, phosphorylated HSP27, ADAMTS-1, and phosphorylated JNK. In summary, the results of the studies indicated that PEGylated curcumin is a more potent compound against bladder cancer cell lines than the parent compound, and derivative 5 is worthy of further investigation to clarify its mechanism of anticancer action under hypoxic conditions.

Anti-PEG Antibodies Boosted in Humans by SARS-CoV-2 Lipid Nanoparticle mRNA Vaccine

Humans commonly have low level antibodies to poly(ethylene) glycol (PEG) due to environmental exposure. Lipid nanoparticle (LNP) mRNA vaccines for SARS-CoV-2 contain small amounts of PEG, but it is not known whether PEG antibodies are enhanced by vaccination and what their impact is on particle-immune cell interactions in human blood. We studied plasma from 130 adults receiving either the BNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna) mRNA vaccines or no SARS-CoV-2 vaccine for PEG-specific antibodies. Anti-PEG IgG was commonly detected prior to vaccination and was significantly boosted a mean of 13.1-fold (range 1.0-70.9) following mRNA-1273 vaccination and a mean of 1.78-fold (range 0.68-16.6) following BNT162b2 vaccination. Anti-PEG IgM increased 68.5-fold (range 0.9-377.1) and 2.64-fold (0.76-12.84) following mRNA-1273 and BNT162b2 vaccination, respectively. The rise in PEG-specific antibodies following mRNA-1273 vaccination was associated with a significant increase in the association of clinically relevant PEGylated LNPs with blood phagocytes ex vivo. PEG antibodies did not impact the SARS-CoV-2 specific neutralizing antibody response to vaccination. However, the elevated levels of vaccine-induced anti-PEG antibodies correlated with increased systemic reactogenicity following two doses of vaccination. We conclude that PEG-specific antibodies can be boosted by LNP mRNA vaccination and that the rise in PEG-specific antibodies is associated with systemic reactogenicity and an increase of PEG particle-leukocyte association in human blood. The longer-term clinical impact of the increase in PEG-specific antibodies induced by lipid nanoparticle mRNA vaccines should be monitored. It may be useful to identify suitable alternatives to PEG for developing next-generation LNP vaccines to overcome PEG immunogenicity in the future.

Evaluation of PEG-L-asparaginase in asparagine suppression and anti-drug antibody development in healthy Beagle dogs: A multi-phase preclinical study

L-asparaginase is a frequently used drug in the treatment of canine malignant lymphoma. Since production and availability of native E. coli-derived L-asparaginase are limited, PEG-L-asparaginase (PEG-ASP) is an alternative. However, recommended doses and dosing intervals are mainly empirically determined. A multi-phase clinical dose-finding study with seven healthy Beagle dogs was conducted to find the minimum effective dose and, potentially, a dosing interval for PEG-ASP in dogs. Plasma concentrations of amino acids and PEG-ASP activity were measured at various time points after administration of different doses of PEG-ASP. Anti-PEG and anti-asparaginase antibody titres were measured. Administration of 10 IU/kg PEG-ASP resulted in asparagine depletion in all dogs, albeit for various durations: for 9 days in all dogs, 15 days in five dogs, 21 days in three dogs and 29 days in one dog. Asparagine suppression occurred at PEG-ASP plasma concentrations < 25 IU/L. Subsequent administrations of a second and third dose of 20 IU/kg and 40 IU/kg PEG-ASP resulted in asparagine suppression at < 9 days in five dogs, accompanied by the development of antibodies against PEG and L-asparaginase. Two dogs with prolonged asparagine suppression after the second and third administration did not develop antibodies. Marked individual variation in the mechanism and duration of response to PEG-ASP was noted. Antibody formation against PEG-ASP was frequently observed and sometimes occurred after one injection. This study suggests that PEG-ASP doses as high as the currently used dose of 40 IU/kg might not be needed in treatment of canine malignant lymphoma.

PEG-Free Polyion Complex Nanocarriers for Brain-Derived Neurotrophic Factor

Many therapeutic formulations incorporate poly(ethylene glycol) (PEG) as a stealth component to minimize early clearance. However, PEG is immunogenic and susceptible to accelerated clearance after multiple administrations. Here, we present two novel reformulations of a polyion complex (PIC), originally composed of poly(ethylene glycol)₁₁₃-b-poly(glutamic acid)₅₀ (PEG-PLE) and brain-derived neurotrophic factor (BDNF), termed Nano-BDNF (Nano-BDNF PEG-PLE). We replace the PEG based block copolymer with two new polymers, poly(sarcosine)₁₂₇-b-poly(glutamic acid)₅₀ (PSR-PLE) and poly(methyl-2-oxazolines)₃₈-b-poly(oxazolepropanoic acid)₂₇-b-poly(methyl-2-oxazoline)₃₈ (PMeOx-PPaOx-PMeOx), which are driven to association with BDNF via electrostatic interactions and hydrogen bonding to form a PIC. Formulation using a microfluidic mixer yields small and narrowly disperse nanoparticles which associate following similar principles. Additionally, we demonstrate that encapsulation does not inhibit access by the receptor kinase, which affects BDNF’s physiologic benefits. Finally, we investigate the formation of nascent nanoparticles through a series of characterization experiments and isothermal titration experiments which show the effects of pH in the context of particle self-assembly. Our findings indicate that thoughtful reformulation of PEG based, therapeutic PICs with non-PEG alternatives can be accomplished without compromising the self-assembly of the PIC.

Protein precoating modulates biomolecular coronas and nanocapsule-immune cell interactions in human blood

The biomolecular corona that forms on particles upon contact with blood plays a key role in the fate and utility of nanomedicines. Recent studies have shown that precoating nanoparticles with serum proteins can improve the biocompatibility and stealth properties of nanoparticles. However, it is not fully clear how precoating influences biomolecular corona formation and downstream biological responses. Herein, we systematically examine three precoating strategies by coating bovine serum albumin (single protein), fetal bovine serum (FBS, mixed proteins without immunoglobulins), or bovine serum (mixed proteins) on three nanoparticle systems, namely supramolecular template nanoparticles, metal-phenolic network (MPN)-coated template (core-shell) nanoparticles, and MPN nanocapsules (obtained after template removal). The effect of protein precoating on biomolecular corona compositions and particle-immune cell interactions in human blood was characterized. In the absence of a pre-coating, the MPN nanocapsules displayed lower leukocyte association, which correlated to the lower amount (by 2-3 fold) of adsorbed proteins and substantially fewer immunoglobulins (more than 100 times) in the biomolecular corona relative to the template and core-shell nanoparticles. Among the three coating strategies, FBS precoating demonstrated the most significant reduction in leukocyte association (up to 97% of all three nanoparticles). A correlation analysis highlights that immunoglobulins and apolipoproteins may regulate leukocyte recognition. This study demonstrates the impact of different precoating strategies on nanoparticle-immune cell association and the role of immunoglobulins in bio-nano interactions.

Polymer-Modified Liposomes for Drug Delivery: From Fundamentals to Applications

Liposomes are highly advantageous platforms for drug delivery. To improve the colloidal stability and avoid rapid uptake by the mononuclear phagocytic system of conventional liposomes while controlling the release of encapsulated agents, modification of liposomes with well-designed polymers to modulate the physiological, particularly the interfacial properties of the drug carriers, has been intensively investigated. Briefly, polymers are incorporated into liposomes mainly using “grafting” or “coating”, defined according to the configuration of polymers at the surface. Polymer-modified liposomes preserve the advantages of liposomes as drug-delivery carriers and possess specific functionality from the polymers, such as long circulation, precise targeting, and stimulus-responsiveness, thereby resulting in improved pharmacokinetics, biodistribution, toxicity, and therapeutic efficacy. In this review, we summarize the progress in polymer-modified liposomes for drug delivery, focusing on the change in physiological properties of liposomes and factors influencing the overall therapeutic efficacy.

Leveraging self-assembled nanobiomaterials for improved cancer immunotherapy

Nanomaterials and targeted drug delivery vehicles improve the therapeutic index of drugs and permit greater control over their pharmacokinetics, biodistribution, and bioavailability. Here, nanotechnologies applied to cancer immunotherapy are discussed with a focus on current and next generation self-assembling drug delivery systems composed of lipids and/or polymers. Topics covered include the fundamental design, suitability, and inherent properties of nanomaterials that induce anti-tumor immune responses and support anti-cancer vaccination. Established active and passive targeting strategies as well as newer "indirect" methods are presented together with insights into how nanocarrier structure and surface chemistry can be leveraged for controlled delivery to the tumor microenvironment while minimizing off-target effects.

Therapeutic approaches to preserve the musculature in Duchenne Muscular Dystrophy: The importance of the secondary therapies

Muscular dystrophies (MDs) are heterogeneous diseases, characterized by primary wasting of skeletal muscle, which in severe cases, such as Duchenne Muscular Dystrophy (DMD), leads to wheelchair dependency, respiratory failure, and premature death. Research is ongoing to develop efficacious therapies, particularly for DMD. Most of the efforts, currently focusing on correcting or restoring the primary defect of MDs, are based on gene-addition, exon-skipping, stop codon read-through, and genome-editing. Although promising, most of them revealed several practical limitations. Shared knowledge in the field is that, in order to be really successful, any therapeutic approach has to rely on spared functional muscle tissue, restricting the number of patients eligible for clinical trials to the youngest and less compromised individuals. In line with this, many therapeutic strategies aim to preserve muscle tissue and function. This Review outlines the most interesting and recent studies addressing the secondary outcomes of DMD and how to better deliver the therapeutic agents. In the future, the effective treatment of DMD will likely require combinations of therapies addressing both the primary genetic defect and its consequences.

Interpolyelectrolyte Complexes as an Emerging Technology for Pharmaceutical Delivery of Polypeptides

Polyelectrolyte complexes and the derivatives thereof comprise some of the most promising vehicles for the encapsulation and delivery of macromolecular therapeutics. In particular, protein therapeutics, which present a host of special considerations, can often be effectively packaged and delivered using interpolyelectrolyte complexes. While the technologies are still in the developmental phase, there are numerous examples of complexes where control is exerted over spacial and temporal delivery of a model protein cargo or candidate protein therapeutic agent. Here we provide a historical and practical background to promote a deeper understanding of interpolyelectrolyte complexes and the derivative technologies. Additionally, we review the physical principles underlying the association of polyelectrolyte complexes and the application of those principles to novel strategies and technologies driving interpolyelectrolyte complexation. Then, the application of polyelectrolyte complex technology to protein therapeutics is discussed in detail including discussions of several types of protein cargo with a special emphasis on Brain-Derived Neurotrophic Factor. Finally, we focus on the use of stealth polymers in block ionomer complexes, specifically PEG; its benefits, flaws, and possible alternatives. Comprehensive understanding of the field may promote the continued development of derivative technologies for the delivery of particularly intransigent protein therapeutics, much as has been accomplished for small molecule drugs. We also aim to link current advances to the historical developments which inaugurated the field. With consideration to the field, industrial and academic researchers can utilize the discussed technologies and continue to elucidate novel modalities for a myriad of therapeutic and commercial applications.

In vivo biocompatibility evaluation of in situ-forming polyethylene glycol-collagen hydrogels in corneal defects

The available treatment options include corneal transplantation for significant corneal defects and opacity. However, shortage of donor corneas and safety issues in performing corneal transplantation are the main limitations. Accordingly, we adopted the injectable in situ-forming hydrogels of collagen type I crosslinked via multifunctional polyethylene glycol (PEG)-N-hydroxysuccinimide (NHS) for treatment and evaluated in vivo biocompatibility. The New Zealand White rabbits (N = 20) were randomly grouped into the keratectomy-only and keratectomy with PEG-collagen hydrogel-treated groups. Samples were processed for immunohistochemical evaluation. In both clinical and histologic observations, epithelial cells were able to migrate and form multilayers over the PEG-collagen hydrogels at the site of the corneal stromal defect. There was no evidence of inflammatory or immunological reactions or increased IOP for PEG-collagen hydrogel-treated corneas during the four weeks of observation. Immunohistochemistry revealed the presence of α-smooth muscle actin (α-SMA) in the superior corneal stroma of the keratectomy-only group (indicative of fibrotic healing), whereas low stromal α-SMA expression was detected in the keratectomy with PEG-collagen hydrogel-treated group. Taken together, we suggest that PEG-collagen may be used as a safe and effective alternative in treating corneal defect in clinical setting.

Multi-targeted 1H/19F MRI unmasks specific danger patterns for emerging cardiovascular disorders

Prediction of the transition from stable to acute coronary syndromes driven by vascular inflammation, thrombosis with subsequent microembolization, and vessel occlusion leading to irreversible myocardial damage is still an unsolved problem. Here, we introduce a multi-targeted and multi-color nanotracer platform technology that simultaneously visualizes evolving danger patterns in the development of progressive coronary inflammation and atherothrombosis prior to spontaneous myocardial infarction in mice. Individual ligand-equipped perfluorocarbon nanoemulsions are used as targeting agents and are differentiated by their specific spectral signatures via implementation of multi chemical shift selective 19F MRI. Thereby, we are able to identify areas at high risk of and predictive for consecutive development of myocardial infarction, at a time when no conventional parameter indicates any imminent danger. The principle of this multi-targeted approach can easily be adapted to monitor also a variety of other disease entities and constitutes a technology with disease-predictive potential.

Sialic Acid-Modified Nanoparticles-New Approaches in the Glioma Management-Perspective Review

The cell surface is covered by a dense and complex network of glycans attached to the membrane proteins and lipids. In gliomas, the aberrant sialylation, as the final stage of glycosylation, is an important regulatory mechanism of malignant cell behavior and correlates with worse prognosis. Better understanding of the role of sialylation in cellular and molecular processes opens a new way in the development of therapeutic tools for human brain tumors. According to the recent clinical observation, the cellular heterogeneity, activity of brain cancer stem cells (BCSCs), immune evasion, and function of the blood–brain barrier (BBB) are attractive targets for new therapeutic strategies. In this review, we summarize the importance of sialic acid-modified nanoparticles in brain tumor progression.