Anti-PEG antibodies: Properties, formation, testing and role in adverse immune reactions to PEGylated nano-biopharmaceuticals

Challenges and material innovations in drug delivery to central nervous system tumors

Central nervous system (CNS) tumors, encompassing a diverse array of neoplasms in the brain and spinal cord, pose significant therapeutic challenges due to their intricate anatomy and the protective presence of the blood-brain barrier (BBB). The primary treatment obstacle is the effective delivery of therapeutics to the tumor site, which is hindered by multiple physiological, biological, and technical barriers, including the BBB. This comprehensive review highlights recent advancements in material science and nanotechnology aimed at surmounting these delivery challenges, with a focus on the development and application of nanomaterials. Nanomaterials emerge as potent tools in designing innovative drug delivery systems that demonstrate the potential to overcome the limitations posed by CNS tumors. The review delves into various strategies, including the use of lipid nanoparticles, polymeric nanoparticles, and inorganic nanoparticles, all of which are engineered to enhance drug stability, BBB penetration, and targeted tumor delivery. Additionally, this review highlights the burgeoning role of theranostic nanoparticles, integrating therapeutic and diagnostic functionalities to optimize treatment efficacy. The exploration extends to biocompatible materials like biodegradable polymers, liposomes, and advanced material-integrated delivery systems such as implantable drug-eluting devices and microfabricated devices. Despite promising preclinical results, the translation of these material-based strategies into clinical practice necessitates further research and optimization.

Advanced nanoparticle engineering for precision therapeutics of brain diseases

Despite the increasing global prevalence of neurological disorders, the development of nanoparticle (NP) technologies for brain-targeted therapies confronts considerable challenges. One of the key obstacles in treating brain diseases is the blood-brain barrier (BBB), which restricts the penetration of NP-based therapies into the brain. To address this issue, NPs can be installed with specific ligands or bioengineered to boost their precision and efficacy in targeting brain-diseased cells by navigating across the BBB, ultimately improving patient treatment outcomes. At the outset of this review, we highlighted the critical role of ligand-functionalized or bioengineered NPs in treating brain diseases from a clinical perspective. We then identified the key obstacles and challenges NPs encounter during brain delivery, including immune clearance, capture by the reticuloendothelial system (RES), the BBB, and the complex post-BBB microenvironment. Following this, we overviewed the recent progress in NPs engineering, focusing on ligand-functionalization or bionic designs to enable active BBB transcytosis and targeted delivery to brain-diseased cells. Lastly, we summarized the critical challenges hindering clinical translation, including scalability issues and off-target effects, while outlining future opportunities for designing cutting-edge brain delivery technologies.

Core-shell hybrid liposomes: Transforming imaging diagnostics and therapeutic strategies

For the last few years, researchers and industry have intensified efforts to develop a diverse array of diagnostic and therapeutic approaches to fight diseases such as cancer, diabetes, and viral infections. Among the emerging technologies, hybrid liposomes (HLs) stand out for their ability to address key limitations of conventional liposomes and deliver multifunctional solutions more effectively. While several novel nanosystems, including polymerlipid conjugates and inorganic nanoparticles (NPs), have shown great potential in the preclinical and clinical phases for the diagnosis and treatment of diseases, particularly cancer, HLs can integrate the best of both worlds, combining drug delivery properties with imaging capabilities. HLs, particularly those with core-shell structures, can surpass conventional liposomes by offering improved physicochemical properties, multifunctionality, and the capacity to overcome critical delivery challenges. The integration of natural and synthetic polymers has rapidly emerged as a preferred strategy in the development of HLs, providing significant advantages, such as enhanced stability, stimuli-responsive drug release, prolonged circulation, and improved therapeutic efficacy. Additionally, the customizable structure of HLs allows the incorporation of diverse materials, such as metals, ligands, and functional lipids, improving diagnosis and enhancing targeted delivery and cellular uptake far beyond what conventional liposomes offer. This review provides a critical and updated analysis of core-shell structure exhibiting HLs, with a focus on their preparation, characterization, and functional enhancements. We also examine in vitro/in vivo outcomes in imaging diagnosis and drug delivery while addressing the current barriers to clinical translation and future prospects for these versatile nanoplatforms.

Investigating the stability of RNA-lipid nanoparticles in biological fluids: Unveiling its crucial role for understanding LNP performance

Lipid nanoparticles (LNPs) are the most established and clinically advanced platform for RNA delivery. While significant efforts have been made to improve RNA delivery efficiency for improved protein production, the interplay between physiological stability, target specificity, and therapeutic efficacy of RNA-LNPs remains largely unexplored. This review highlights the crucial, yet often overlooked, impact of in vivo stability or instability of RNA-LNPs in contact with biological fluids on delivery performance. We discuss the various factors, including lipid composition, particle surface properties and interactions with proteins in physiological conditions, and provide an overview of the current methods for assessing RNA-LNP stability in biological fluids, such as dynamic laser light scattering, liquid chromatography, and fluorescent and radiolabeled techniques. In the final part, we propose strategies for enhancing stability, with a focus on shielding lipids. Therefore, this work highlights the importance of investigating and understanding the balance between stability and instability of LNPs in the biological context to achieve a more meaningful correlation between formulation properties and in vivo performance.

A homogeneous immunoassay technology based on liposomes and the complement system enables one-step, no-wash, rapid diagnostics directly in serum

Liposomes are a well-established carrier and controlled release system in medicine and bioanalysis. Their biomimetic capabilities are harnessed for the development of a reliable homogeneous assay platform technology that lends itself to high-throughput screening and point-of-care applications since no wash or separation steps are needed. It was developed for fluorescent, chemiluminescent, and electrochemical detection strategies and applied to antibodies directed against small or polymeric molecules and peptides as model analytes. The simplicity of the approach is achieved as mere binding of analytes or analyte-associated entities to the liposome surface leads to the activation of the complement system, which in turn lyses the liposomes. Released encapsulated marker molecules are quantified and directly correlated to the analytes. Control over the liposome chemistry, including cholesterol content, surface chemistry, and encapsulants, was identified to be key to ensure their general serum and storage stability (more than 40 months at 4 °C and up to 4 weeks at 37 °C) and their efficient and specific response to complement activity. Additional assay conditions of relevance included the concentration of liposomes and their ratio to serum proteins, the amount of complement trigger per liposome, and the activity of complement proteins. Understanding and being able to control the liposomes enable various analysis strategies including the quantification of analytes, determination of complement activity, and evaluation of the therapeutic application potential of antibodies. A time-resolved version of the assay even allows the study of the complex actions of the complement system.

Zwitterionic polymer-coated magnetic nanoparticle induced chemotherapy and ferroptosis for triple-negative breast cancer therapy

Triple-negative breast cancer (TNBC), an aggressive cancer with a high risk of metastasis and recurrence, is resistant to conventional chemotherapy. Ferroptosis, a non-apoptotic form of cell death, is primarily caused by excessive accumulation of lipid peroxides, and is closely associated with the occurrence and development of various diseases. Mounting evidence indicates that ferroptosis is becoming a promising treatment for TNBC based on its inherent characteristics. Herein, zwitterionic polymer poly (N-(3-sulfopropyl)-N-methacryloxyethyl-N,N-dimethylammonium betaine) (PSBMA)-coated gambogenic acid (GNA)-loaded magnetic composite nanoparticles (Fe3O4@PSBMA-GNA) were fabricated for chemotherapy combined with ferroptosis therapy for TNBC. Fe3O4@PSBMA-GNA achieved significant cytotoxicity against TNBC cell lines and contributed to the disruption of intracellular redox homeostasis. Furthermore, Fe3O4@PSBMA-GNA could induce apoptosis through the inhibition of Bcl-2 and trigger ferroptosis by inhibiting the PI3K/AKT/mTOR/GPX4 pathway in MDA-MB-231 cells simultaneously. Given the excellent blood circulation performance, Fe3O4@PSBMA-GNA enhanced tumor accumulation and showed a satisfactory tumor suppression effect on MDA-MB-231 tumor-bearing mice. This strategy of chemotherapy combined with ferroptosis therapy is expected to be a feasible treatment for refractory TNBC.

Trojan Horse-Like Vehicles for CRISPR-Cas Delivery: Engineering Extracellular Vesicles and Virus-Like Particles for Precision Gene Editing in Cystic Fibrosis

The advent of genome editing has kindled the hope to cure previously uncurable, life-threatening genetic diseases. However, whether this promise can be ultimately fulfilled depends on how efficiently gene editing agents can be delivered to therapeutically relevant cells. Over time, viruses have evolved into sophisticated, versatile, and biocompatible nanomachines that can be engineered to shuttle payloads to specific cell types. Despite the advances in safety and selectivity, the long-term expression of gene editing agents sustained by viral vectors remains a cause for concern. Cell-derived vesicles (CDVs) are gaining traction as elegant alternatives. CDVs encompass extracellular vesicles (EVs), a diverse set of intrinsically biocompatible and low-immunogenic membranous nanoparticles, and virus-like particles (VLPs), bioparticles with virus-like scaffold and envelope structures, but devoid of genetic material. Both EVs and VLPs can efficiently deliver ribonucleoprotein cargo to the target cell cytoplasm, ensuring that the editing machinery is only transiently active in the cell and thereby increasing its safety. In this review, we explore the natural diversity of CDVs and their potential as delivery vectors for the clustered regularly interspaced short palindromic repeats (CRISPR) machinery. We illustrate different strategies for the optimization of CDV cargo loading and retargeting, highlighting the versatility and tunability of these vehicles. Nonetheless, the lack of robust and standardized protocols for CDV production, purification, and quality assessment still hinders their widespread adoption to further CRISPR-based therapies as advanced "living drugs." We believe that a collective, multifaceted effort is urgently needed to address these critical issues and unlock the full potential of genome-editing technologies to yield safe, easy-to-manufacture, and pharmacologically well-defined therapies. Finally, we discuss the current clinical landscape of lung-directed gene therapies for cystic fibrosis and explore how CDVs could drive significant breakthroughs in in vivo gene editing for this disease.

Slow intravenous infusion reduces the accelerated blood clearance of PEGylated liposomes by removing anti-PEG antibodies

Anti-PEG antibodies exist in many individuals and accelerate the clearance of PEGylated liposomes. Herein, we reported that the slow intravenous infusion of PEGylated liposomes significantly reduced their accelerated blood clearance (ABC) phenomenon in rats. This was mainly because the PEGylated liposomes that first entered the bloodstream were sufficient to clear anti-PEG antibodies, thus reducing the clearance of subsequently injected liposomes. In contrast, the rapid intravenous injection of PEGylated liposomes resulted in a uniform binding of anti-PEG antibodies, leading to rapid clearance of PEGylated liposomes from blood circulation. Pretreating PEG-immunized plasma with a low concentration of PEGylated liposomes significantly reduced complement activation-induced drug release. However, the clearance of anti-PEG antibodies did not entirely inhibit the ABC phenomenon of PEGylated liposomes. This might be due to the continuous entry of anti-PEG antibodies into the bloodstream, accelerating the clearance of existing PEGylated liposomes. Our results highlight that the slow infusion of PEGylated liposomes can effectively reduce the ABC phenomenon, which explains why the ABC phenomenon is infrequently observed in clinical applications of DOXIL.

Synthesis, Characterization, and Self-Assembly Behavior of Block Copolymers of N-Vinyl Pyrrolidone with n-Alkyl Methacrylates

Novel amphiphilic block copolymers of N-vinyl pyrrolidone (NVP) and either n-hexyl methacrylate (HMA, PNVP-b-PHMA) or stearyl methacrylate (SMA, PNVP-b-PSMA) were prepared by RAFT polymerization techniques and the sequential addition of monomers starting from the polymerization of NVP and using two different Chain Transfer Agents, CTAs. PNVP-b-PHMA are amorphous block copolymers containing constituent blocks with both high and low Tg values, whereas PNVP-b-PSMA are amorphous-semi-crystalline copolymers. Samples with different molecular weights and compositions were obtained. The copolymers were microphase-separated, but partial mixing was also observed. The presence of the amorphous PNVP block reduced the crystallinity of the PSMA blocks in the PNVP-b-PSMA copolymers. The thermal stability of the blocks was influenced by both constituents. The self-assembly behavior in THF, which is a selective solvent for polymethacrylate blocks, and in aqueous solutions, where PNVP was soluble, was examined. Unimolecular or low-aggregation-number micelles were obtained in THF for both types of samples. On the contrary, high-aggregation-number, spherical, and compact micelles were revealed in aqueous solutions. The increase in the steric hindrance of the side ester group of the polymethacrylate chain led to slightly lower degrees of association. The hydrophobic compound curcumin was efficiently encapsulated within the micellar core of the supramolecular structures in aqueous solutions. Micelles with higher aggregation numbers were more efficient in the encapsulation of curcumin. The results of this study were compared with those obtained from other block copolymers based on PNVP.

Toward Quantitative End-Group Fidelity in the Synthesis of High Molecular Weight Polysarcosine

Polymers applied in pharmaceutical applications need to meet stringent quality standards to ensure reproducibility of product properties, such as efficacy and safety of therapeutics. End-group fidelity is a crucial quality feature that ensures functional integrity, reproducible synthesis, and robust therapeutic performance. The contemporary production of poly(ethylene glycol) (PEG) exemplifies this requirement, which has consolidated its position as a gold standard in pharmaceutical applications. However, modest to severe immune responses toward PEG in patients generate the need for alternative polymers in the development of pharmaceuticals or cosmetics. Among such alternatives, polysarcosine (pSar) displays PEG-like stealth properties in vivo while displaying improved immunogenicity and toxicity profiles, generating the need for heterotelechelic pSar polymers of the highest end-group integrity. Here, we compared current synthetic methods for the controlled synthesis of pSar over a broad molecular weight range and assessed the end-group fidelity by ion exchange chromatography. Subsequent isolation allowed the identification of impurities via mass spectrometry, thus yielding mechanistic insights into the N-substituted N-carboxyanhydride ring-opening polymerization (ROP). Our results reveal a nuanced role of organocatalysts in the ROP, highlighting opportunities for better catalysts. Finally, this work showcases a scalable purification method to obtain high molecular weight pSar with quantitative end-group fidelity.

Albumin Corona-Coated Nanoscale Metal-Organic Framework for Enzyme-Mediated Cascade Metabolization of Uric Acid in Hyperuricemia

Hyperuricemia, characterized by elevated uric acid levels, is the primary cause of gout. Recombinant uricase is one of the last-resort therapies but generates unwanted pro-inflammatory H2O2 and anti-uricase antibodies. In this work, we developed an albumin corona-coated enzyme-loaded zeolitic imidazolate framework (UCZIF) to sustainably maintain low blood uric acid level without producing H2O2. The corona coating not only preserves loaded enzymes but also reduces macrophage phagocytosis by 73.4% compared to free uricase. In addition, the uptake level of UCZIF by dendritic cells is reduced by 74.1%, and the maturation of dendritic cells is inhibited by 35.4% compared to free uricase. Animal experiments demonstrate that albumin corona-coated UCZIF effectively lowers blood uric acid level in both acute and diet-induced chronic hyperuricemia models with significantly increasing the half-life of uricase. Furthermore, compared to the generation of anti-uricase antibodies during standalone uricase treatment, the levels of anti-uricase immunoglobulins are significantly reduced by 65.5% (immunoglobulin M) and 76.3% (immunoglobulin G) with repeated administration of albumin corona-coated UCZIF. Overall, this albumin corona-coated nanoscale metal-organic framework offers a promising approach to minimize the immunogenicity induced by exogenous enzymes and further safely reduce uric acid levels in the treatment of hyperuricemia.

Intracellular Proteins Targeting with Bi-Functionalized Magnetic Nanoparticles Following their Endosomal Escape

The specific targeting of intracellular proteins or organelles by magnetic nanoparticles (MNPs) is a major challenge in nanomedicine, as most MNPs are internalized by cells through endocytosis and remain trapped inside small intracellular vesicles, limiting their ability to reach intracellular components. Furthermore, this phenomenon limits their heating capacity in magnetic hyperthermia, and therefore their potential for cancer treatment. This study presents a strategy based on an original double functionalization of MNPs, with polyhistidine peptides (PHPs) triggering endosomal escape and antibodies targeting specific cytosolic proteins. Negatively charged γ-Fe2O3@SiO2 MNPs with diameter smaller than 50 nm are functionalized with zwitterionic and thiol groups at their surface. These sulfhydryl groups are used to graft PHPs through a labile link, allowing the peptide to be released from the MNPs' surface once in the cytosolic reductive environment. This severing avoids any interaction between these peptides and intracellular components, which can hinder MNPs' intracellular mobility. The second MNPs' surface functionalization is performed through a non-labile link with antibodies targeting specific cytosolic proteins, namely HSP27 thermosensitive proteins, for this inaugural proof of concept. Bi-functionalized MNPs are able to successfully target the intracellular protein of interest, opening the door to promising biomedical applications of MNPs, in cellular engineering and magnetic hyperthermia.

Autonomic lysosomal escape via sialic acid modification enhances mRNA lipid nanoparticles to eradicate tumors and build humoral immune memory

Lysosomes present a major barrier to efficient mRNA delivery. Existing strategies primarily depend on lysosomal disruption, which is inefficient and carries a risk of cytolysis. We propose an Autonomic Lysosomal Escape (ALE) strategy, in which sialic acid (SA) modification enables over 90 % of LNPs to successfully escape from lysosomes by inducing cells to spontaneously reduce lysosome generation. The SA modification enhances the transfection efficiency of LNPs administered via intravenous injection, intramuscular injection, and inhalation, demonstrating the broad applicability. The structure of cleavable PEG-lipids was optimized using a newly developed method, termed Systematic Evaluation of LNPs' Efficiency by Cumulative Tests (SELECT). The results showed that polyethylene glycol 2000-cholesterol hemisuccinate (Ps) is the optimal candidate for co-modification with SA. The resulting LNPs co-modified with SA and Ps (SAPs@LNPs) completely eradicated TC-1 tumors and induced humoral immune memory. Combining SA-modified doxorubicin liposomes (DOX-SL) further accelerates tumor elimination, while licensed PEGylated liposomal doxorubicin (Caelyx) impairs the efficacy of mRNA vaccines. This difference stems from DOX-SL's selective depletion of tumor-associated immune cells (TAICs) and the nonspecific cytotoxicity of Caelyx. These findings suggest that combining Caelyx with mRNA vaccines should be approached with caution. Our study also highlights the key roles of humoral immune memory and natural killer cell-driven antibody-dependent cellular cytotoxicity (ADCC) in tumor eradication, and incorporating them into the cancer immune cycle further refines this theory.

Development of a UPLC-MS/MS assay for determination of PA-PEG8-PA polymers in rat plasma coupled with [M - H]- to enhance sensitivity

Propionic acid-polyethylene glycol-propionic acid (PA-PEG-PA) is a commonly used biocompatible polymer in drug delivery systems. Unraveling the in vivo pharmacokinetic behavior of PA-PEG-PA polymer is important for the safety evaluation of PA-PEG-PA related drug delivery systems. In this research, a highly sensitive ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) assay was developed for detection of PA-PEG8-PA polymers in complex biological matrices. Methoxy-polyethylene glycol propionic acid polymers with 6 subunits (mPEG6-PA) were used as the internal standard (IS). The multiple reaction monitoring (MRM) transitions at m/z 513.4 ([M - H]- precursor ions) → 441.2 (fragment ions) and m/z 367.3 ([M - H]- precursor ions) → 118.8 (fragment ions) were chosen to determine PA-PEG8-PA and mPEG6-PA, respectively. The analysis time was only 5 min for each sample. Numerous parameters like specificity, sensitivity, accuracy, precision, recoveries, matrix effects and dilution effect were validated for the developed assay. The UPLC-MS/MS assay showed excellent linearity over the range of 30-1500 ng mL-1(r > 0.995). The assay was successfully applied to quantify the concentration of PA-PEG8-PA polymers in rat plasma.

SYL3C Aptamer-DNA Tetrahedra Conjugates Enable Near-Infrared Fluorescent Imaging of Colorectal Cancer

Purpose

SYL3C is an optimized DNA aptamer with high selectivity and affinity for the epithelial cell adhesion molecule (EpCAM), an overexpressed tumor antigen in colorectal cancer (CRC). While its cellular affinity has been validated, in vivo studies are lacking.

Methods

This study modifies SYL3C with the fluorescent motif Cy7 to evaluate its metabolism and diagnostic potential in EpCAM-positive HT-29 xenograft mice using near-infrared fluorescence (NIRF). We also employ DNA Tetrahedra (DTN) to load the Cy7-DTN-SYL3C probe and assess whether this strategy improves circulation and tumor uptake of SYL3C.

Results

Cy7-SYL3C is primarily metabolized by the kidneys and enables targeted imaging of HT-29 tumors, outperforming untargeted Cy7-DTN. The DTN coupling strategy prolongs SYL3C metabolism and enhances tumor probe uptake about twice higher than Cy7-SYL3C over 24 hours.

Conclusion

This study presents preliminary evidence for the SYL3C aptamer's potential in vivo imaging of EpCAM-positive CRC. The DTN conjugation strategy may extend the aptamer's metabolic stability and improve tumor uptake, expanding its applications in CRC diagnosis and treatment.

Strategies to Enhance Protein Delivery

Therapeutic proteins play a crucial role in modern healthcare. However, the rapid clearance of proteins in the circulation system poses a significant threat to their therapeutic efficacy. The generation of anti-drug antibodies expedites drug clearance, resulting in another challenge to overcome in protein delivery. Several methods to increase the circulation half-lives of these proteins and to minimize their immunogenicity have been developed. This Review discusses the causes of protein clearance in the body, evaluates the FDA-approved strategies to prolong protein circulation, and highlights recent progress in the field. Additionally, the strengths and drawbacks of these methods and our perspectives for advancing protein delivery are provided.

Mast cell activators as adjuvants for intranasal mucosal vaccines

Mast cells have roles in immune regulation, allergy, and host response to pathogens. Compounds that activate mast cells (MCAs) can serve as vaccine adjuvants, potentially outperforming current FDA-approved options, especially for mucosal vaccines. While most vaccines are administered intramuscularly, intranasal and needle-free formulations offer benefits like improved compliance and accessibility. However, the lack of effective adjuvants limits mucosal vaccine development. This review explores MCAs as promising alternatives to traditional adjuvants, aiming to enhance mucosal vaccine efficacy. We summarize the nascent work of formulating MCAs like compound 48/80 into nanoparticles, with excipients such as chitosan and chitosan/alginate. Other MCAs like the peptide mastoparan 7 complexed with CpG have formed nanoparticle complexes that illustrate protective mucosal immunity in a model of influenza. The small molecule MCA ST101036, when encapsulated in acetalated dextran particles, has demonstrated enhanced immune responses and protection in a West Nile Virus model of infection. This review highlights the potential of MCAs as potent vaccine adjuvants, particularly for mucosal vaccines, and summarizes, recent advancements in formulating these activators into nanoparticles to enhance immune responses and protection.

Imaging of Thromboinflammation by Multispectral 19F MRI

The close interplay between thrombotic and immunologic processes plays an important physiological role in the immune defence after tissue injury and has the aim to reduce damage and to prevent the spread of invading pathogens. However, the uncontrolled or exaggerated activation of these processes can lead to pathological thromboinflammation. Thromboinflammation has been shown to worsen the outcome of cardiovascular, autoinflammatory, or even infectious diseases. Imaging of thromboinflammation is difficult because many clinically relevant imaging techniques can only visualize either inflammatory or thrombotic processes. One interesting option for the noninvasive imaging of thromboinflammation is multispectral 19F magnetic resonance imaging (MRI). Due to the large chemical shift range of the 19F atoms, it is possible to simultaneously visualize immune cells as well as thrombus components with specific 19F tracer that have individual spectral 19F signatures. Of note, the 19F signal can be easily quantified and a merging of the 19F datasets with the anatomical 1H MRI images enables precise anatomical localization. In this review, we briefly summarize the background of 19F MRI for inflammation imaging, active targeting approaches to visualize thrombi and specific immune cells, introduce studies about multispectral 19F MRI, and summarize one study that imaged thromboinflammation by multispectral 19F MRI.

Sequential pH/GSH-responsive stealth nanoparticles for co-delivery of anti-PD-1 antibody and paclitaxel to enhance chemoimmunotherapy of lung cancer

Intravenously administered nanoparticles (NPs) often bind with plasma proteins, forming the protein corona that promotes rapid systemic clearance, a primary challenge in nanomedicine. In this study, we developed a pH- and GSH-sensitive "stealth" nanodelivery system, PTX@NPs-aPD1-IL, for sequential drug release. By using a biocompatible choline-based ionic liquid (IL) as the coating for NPs, the interaction and adsorption of NPs with serum proteins were reduced, achieving targeted delivery to the lung organ and increasing drug accumulation. In the weakly acidic extracellular tumor microenvironment (pH 6.5), the anti-PD-1 antibody (aPD-1) was first released to block the PD-1/PD-L1 pathway and restore the immunocidal function of T cells. In the highly reductive intracellular environment of tumor cells, the disulfide bonds were cleaved, causing NPs to rupture and release paclitaxel (PTX). It induced tumor cell apoptosis and triggered immunogenic cell death (ICD), promoted dendritic cells (DCs) maturation and activated T cells for chemo-immunotherapy. In the mouse orthotopic lung cancer model, PTX@NPs-aPD1-IL exhibited superior efficacy to other treatment groups at the same dose. This was due to the significantly increase in the release of immune factors, including TNF-α and IFN-γ, and the promotion of CD8+ T cells recruitment, which induced a stronger immune response, and thus enhanced the anti-lung cancer effect. In summary, PTX@NPs-aPD1-IL provided a promising strategy for effective chemo-immunotherapy for lung cancer through sequential release profile.

Using Immunoliposomes as Carriers to Enhance the Therapeutic Effectiveness of Macamide N-3-Methoxybenzyl-Linoleamide

BACKGROUND/OBJECTIVES

Epilepsy is one of the most common chronic neurological disorders, characterized by alterations in neuronal electrical activity that result in recurrent seizures and involuntary body movements. Anticonvulsants are the primary treatment for this condition, helping patients improve their quality of life. However, the development of new drugs with fewer side effects and greater economic accessibility remains a key focus in nanomedicine. Macamides, secondary metabolites derived from Maca (Lepidium meyenii), represent a promising class of novel drugs with diverse therapeutic applications, particularly in the treatment of neurological disorders.

METHODS

In this study, we optimized the potential of the macamide N-3-methoxybenzyl-linoleamide (3-MBL) as an anticonvulsant agent through its encapsulation in PEGylated liposomes conjugated with OX26 F(ab')2 fragments.

RESULTS

These immunoliposomes exhibited a size of 120.52 ± 9.46 nm and a zeta potential of -8.57 ± 0.80 mV. Furthermore, in vivo tests using a pilocarpine-induced status epilepticus model revealed that the immunoliposomes provided greater efficacy against epileptic seizures compared to the free form of N-3-methoxybenzyl-linoleamide at the same dose. Notably, the observed anticonvulsant effect was comparable to that of carbamazepine, a traditional FDA-approved antiepileptic drug.

CONCLUSIONS

This pioneering work employs liposomal nanocarriers to deliver macamides to the brain, aiming to set a new standard for the use of modified liposomes in anticonvulsant epilepsy treatment.

Effect of polymer architecture on the properties and in vitro cytotoxicity of drug formulation: A case study with mono- and di-gradient amphiphilic poly(2-Oxazoline)s

Due to the straightforward single-step synthesis, amphiphilic gradient copoly(2-oxazoline)s are becoming more popular alternative to their block analogue for the development of next-generation drug delivery systems. Here, we investigated the influence of polymer architecture on the physiochemical and biological assessment of nanoformulations formed by the self-assembly of gradient copoly(2-oxazoline)s. Two different architectures were synthesized: hydrophilic-grad-hydrophobic (mono-gradient) and hydrophobic-grad-hydrophilic-grad-hydrophobic (di-gradient) which contained a hydrophilic monomer, 2-ethyl-2-oxazoline (EtOx) and a hydrophobic monomer, 2-phenyl-2-oxazoline (PhOx). Di-gradient copolymers self-assembled in the presence of a hydrophobic model drug, curcumin and formed monodispersed or slightly polydispersed nanoparticle solution. On the other hand, mono-gradient copolymers formed polydispersed nanoparticle solutions. Di-gradient copolymer was slightly more efficient to solubilize curcumin. Mono-gradient copolymer nanoparticle showed faster monomer chain exchange kinetics and comparatively less stability in the presence of serum albumin. At longer incubation times, faster drug release was observed from the mono-gradient copolymer nanoformulations. Cytotoxicity of free curcumin and curcumin loaded nanoparticles in cancer cell of U87 MG (human glioblastoma cell) was dose and time-dependent, whereby the significant cell death occurred after 48 h. Curcumin-loaded mono-gradient copolymer nanoparticles inhibited U87MG cancel cell growth to a large extent compared to the di-gradient copolymer nanoparticles.

Leveraging nature's nanocarriers: Translating insights from extracellular vesicles to biomimetic synthetic vesicles for biomedical applications

Naturally occurring extracellular vesicles (EVs) and synthetic nanoparticles like liposomes have revolutionized precision diagnostics and medicine. EVs excel in biocompatibility and cell targeting, while liposomes offer enhanced drug loading capacity and scalability. The clinical translation of EVs is hindered by challenges including low yield and heterogeneity, whereas liposomes face rapid immune clearance and limited targeting efficiency. To bridge these gaps, biomimetic synthetic vesicles (SVs) have emerged as innovative platforms, combining the advantageous properties of EVs and liposomes. This review emphasizes critical aspects of EV biology, such as mechanisms of EV-cell interaction and source-dependent functionalities in targeting, immune modulation, and tissue regeneration, informing biomimetic SV engineering. We reviewed a broad array of biomimetic SVs, with a focus on lipid bilayered vesicles functionalized with proteins. These include cell-derived nanovesicles, protein-functionalized liposomes, and hybrid vesicles. By addressing current challenges and highlighting opportunities, this review aims to advance biomimetic SVs for transformative biomedical applications.

Emerging strategies against accelerated blood clearance phenomenon of nanocarrier drug delivery systems

Nanocarrier drug delivery systems (NDDS) have gained momentum in the field of anticancer or nucleic acid drug delivery due to their capacity to aggrandize the targeting efficacy and therapeutic outcomes of encapsulated drugs. A disadvantage of NDDS is that repeated administrations often encounter an obstacle known as the "accelerated blood clearance (ABC) phenomenon". This phenomenon results in the rapid clearance of the secondary dose from the bloodstream and markedly augmented liver accumulation, which substantially undermines the accurate delivery of drugs and the therapeutic effect of NDDS. Nevertheless, the underlying mechanism of this phenomenon has not been elucidated and there is currently no effective method for its eradication. In light of the above, the aim of this review is to provide a comprehensive summary of the underlying mechanism and potential countermeasures of the ABC phenomenon, with a view to rejuvenating both the slow-release property and expectation of NDDS in the clinic. In this paper, we innovatively introduce the pharmacokinetic mechanism of ABC phenomenon to further elucidate its occurrence mechanism after discussing its immunological mechanism, which provides a new direction for expanding the mechanistic study of ABC phenomenon. Whereafter, we conducted a critical conclusion of potential strategies for the suppression or prevention of the ABC phenomenon in terms of the physical and structural properties, PEG-lipid derivatives, dosage regimen and encapsulated substances of nanoformulations, particularly covering some novel high-performance nanomaterials and mixed modification methods. Alternatively, we innovatively propose a promising strategy of applying the characteristics of ABC phenomenon, as the significantly elevated hepatic accumulation and activated CYP3A1 profile associated with the ABC phenomenon are proved to be conducive to enhancing the efficacy of NDDS in the treatment of hepatocellular carcinoma. Collectively, this review is instructive for surmounting or wielding the ABC phenomenon and advancing the clinical applications and translations of NDDS.

Rational design and analytical characterization of self-assembling poly(N‑isopropylacrylamide) and poly(2‑alkyl‑2‑oxazoline) hyaluronic acid copolymers

In this study, we applied a systematic approach to establish an iterative workflow and to drive the chemical design of thermosensitive, in situ forming injectables as a function of the intended target product profile. Self-assembly, mechanical properties, physical state, and thermal transition behavior were assessed via nuclear magnetic resonance, oscillatory rheology, turbidimetry and visual inspection techniques. Thus, poly(N-isopropylacrylamide) (PNIPAM) and poly(2-alkyl-2-oxazoline)s (PAOx)s with LCSTs below body temperature were studied before and after grafting them onto azido-substituted hyaluronic acid (HA) via strain-promoted azide-alkyne cycloaddition (SPAAC). Ultimately, we identified critical material attributes able to guide the pharmaceutical development of in situ gelling thermosensitive polymers.

An anionic and proline-rich peptide prolonged blood circulation of liposomes and evaded accelerated blood clearance after repeated administration

In recent years, polypeptides have been standing out as excellent candidates to replace polyethylene glycol (PEG) with adequate biocompatibility and biodegradability. In this study, we found that (VELPPP)3, an anionic γ-zein-based proline-rich peptide with a polyproline-II helical structure, was able to impart liposomes with considerable stability and significantly prolonged blood circulation in vivo. Furthermore, we have shown that (VELPPP)3-modified liposomes induced negligible anti-peptide IgM production, and no noticeable accelerated blood clearance after repeated or multi-dose administration. The biodistribution study suggested that compared to PEGylated liposomes, (VELPPP)3-modified liposomes showed a slight inclination of accumulation in livers, and a decreased entrapment in most of the other organs over long hours. In conclusion, (VELPPP)3 has shown considerable capacity in establishing stealth nanocarriers, providing inspiring insights into developing alternatives for PEGylation.

Recent advances in zeolitic imidazolate frameworks as drug delivery systems for cancer therapy

Biological nanotechnologies based on functional nanoplatforms have synergistically catalyzed the emergence of cancer therapies. As a subtype of metal-organic frameworks (MOFs), zeolitic imidazolate frameworks (ZIFs) have exploded in popularity in the field of biomaterials as excellent protective materials with the advantages of conformational flexibility, thermal and chemical stability, and functional controllability. With these superior properties, the applications of ZIF-based materials in combination with various therapies for cancer treatment have grown rapidly in recent years, showing remarkable achievements and great potential. This review elucidates the recent advancements in the use of ZIFs as drug delivery agents for cancer therapy. The structures, synthesis methods, properties, and various modifiers of ZIFs used in oncotherapy are presented. Recent advances in the application of ZIF-based nanoparticles as single or combination tumor treatments are reviewed. Furthermore, the future prospects, potential limitations, and challenges of the application of ZIF-based nanomaterials in cancer treatment are discussed. We except to fully explore the potential of ZIF-based materials to present a clear outline for their application as an effective cancer treatment to help them achieve early clinical application.

Surface modification of extracellular vesicles with polyoxazolines to enhance their plasma stability and tumor accumulation

Extracellular vesicles (EVs) are future promising therapeutics, but their instability in vivo after administration remains an important barrier to their further development. Many groups evaluated EV surface modification strategies to add a targeting group with the aim of controlling EV biodistribution. Conversely, fewer groups focused on their stabilization to obtain "stealth" allogenic EVs. Modulating their stabilization and biodistribution is an essential prerequisite for their development as nano-therapeutics. Here, we explored polyoxazolines with lipid anchors association to the EV membrane (POxylation as an alternative to PEGylation) to stabilize EVs in plasma and control their biodistribution, while preserving their native properties. We found that this modification maintained and seemed to potentiate the immunomodulatory properties of EVs derived from mesenchymal stem/stromal cells (MSC). Using a radiolabeling protocol to track EVs at a therapeutically relevant concentration in vivo, we demonstrated that POxylation is a promising option to stabilize EVs in plasma because it increased EV half-life by 6 fold at 6 h post-injection. Moreover, EV accumulation in tumors was higher after POxylation than after PEGylation.

Applications of liposomes and lipid nanoparticles in cancer therapy: current advances and prospects

Liposomes and lipid nanoparticles are common lipid-based drug delivery systems and play important roles in cancer treatment and vaccine manufacture. Although significant progress has been made with these lipid-based nanocarriers in recent years, efficient clinical translation of active targeted liposomal nanocarriers remains extremely challenging. In this review, we focus on targeted liposomes, stimuli-responsive strategy and combined therapy in cancer treatment. We also summarize advances of liposome and lipid nanoparticle applications in nucleic acid delivery and tumor vaccination. In addition, we discuss limitations and challenges in the clinical translation of these lipid nanomaterials and make recommendations for the future research in cancer therapy.

Polymeric nanoparticles in radiopharmaceutical delivery strategies

The potential applications of polymer nanoparticles (NPs) in the biomedical field have been the subject of extensive research. Radiopharmaceuticals that combine radionuclides and drugs using polymer nanoparticles (NPs) as carriers can be externally labelled, internally labelled or interfacially labelled with radionuclides at different sites. Consequently, they can be employed as delivery agents for a range of diseases. Currently, polymeric nanoparticles can deliver isotopes via active targeting, passive targeting and stimuli-responsive release systems. The objective is to deliver drugs and nuclides to the target site in an efficient manner, thereby maximizing efficacy and minimizing side effects. The development of drug release systems has the potential to address the growing social and economic challenges currently facing modern healthcare. This paper presents a detailed synthesis of the methods used to create polymer nanoparticles (NPs) and strategies for the targeted delivery of radiopharmaceuticals with radionuclides labelled at different locations. Additionally, the paper outlines the current progress of polymer NPs for use in imaging and therapeutic applications, as well as the future challenges that lie ahead in this field.

Enhanced effect of the immunosuppressive soluble HLA-G2 homodimer by site-specific PEGylation

Human leukocyte antigen (HLA)-G is a nonclassical HLA class I molecule that has an immunosuppressive effect mediated by binding to immune inhibitory leukocyte immunoglobulin-like receptors (LILR) B1 and LILRB2. A conventional HLA-G isoform, HLA-G1, forms a heterotrimeric complex composed of a heavy chain (α1-α3 domains), β2-microglobulin (β2m) and a cognate peptide. One of the other isoforms, HLA-G2, lacks a α2 domain or β2m to form a nondisulfide-linked homodimer, and its ectodomain specifically binds to LILRB2 expressed in human monocytes, macrophages, and dendritic cells. The administration of the ectodomain of HLA-G2, designated the soluble HLA-G2 homodimer, showed significant immunosuppressive effects in mouse models of rheumatoid arthritis and systemic lupus erythematosus, presumably by binding to a mouse ortholog of LILRB2, paired immunoglobulin-like receptor B. However, the refolded soluble HLA-G2 homodimer used in these studies tends to aggregate and degrade; thus, its stability for clinical use has been a concern. In the present study, we improved the stability of the refolded soluble HLA-G2 homodimer via a site-directed PEGylation method. PEGylation at an original free cysteine residue, Cys42, resulted in increased lyophilization and thermal and serum stability. Furthermore, the PEGylated soluble HLA-G2 homodimer could better suppress atopic symptoms in mice than the non-PEGylated homodimer. These results suggest that PEGylated soluble HLA-G2 homodimers could be candidates for immunosuppressive biologics that specifically target LILRB2-positive myelomonocytic antigen-presenting cells.

Dual-responsive nanoparticles for enhanced drug delivery in breast Cancer chemotherapy

Drug delivery efficiency often affects chemotherapy outcome due to dense collagen barrier in tumor environment. Here, we report a nanoparticle capable of pH and glutathione dual-responsive drug delivery to enhance the efficacy of breast cancer chemotherapy. Maleiminated polyethylene glycol and polylactide block copolymer were synthesized as a core material, doxorubicin was encapsulated into the nanoparticle by self-assembly. Thiocollagenase and maleimide were connected on the nanoparticle surface by click chemistry, and further coated with chondroitin sulfate as a protective layer to form dual-responsive doxorubicin nanoparticle. The results showed that the nanoparticle had the ability to penetrate deep tumor tissue, to target on CD44 of cancer cell, and to release doxorubicin in cancer cell in response to pH and glutathione signals, demonstrating superior anticancer efficacy in breast cancer-bearing mice. In conclusion, the dual-responsive nanoparticle could be used as a drug carrier to enhance drug delivery in breast cancer chemotherapy.

Tuning Helical Peptide Nanofibers as a Sublingual Vaccine Platform for a Variety of Peptide Epitopes

Mucosal immune responses to vaccination are essential for achieving full protection against pathogens entering their host at mucosal sites. However, traditional parenteral immunization routes commonly fail to raise significant mucosal immunity. Sublingual immunization is a promising alternative delivery route to raise robust immune responses both systemically and at mucosal sites, and nanomaterial-based subunit vaccine platforms offer opportunities for raising epitope-specific responses. Here, sublingual immunization is reported using the Coil29 platform of coiled-coil self-assembling peptide nanofibers. The successful immunization with epitopes of varying physicochemical properties by including mucus-modulating components - namely sequences of proline, alanine, and serine (PAS) is demonstrated. PASylation is shown to decrease mucin complexation and increase epithelial penetration in vitro, enabling sublingual immunization against a variety of selected peptide epitopes in vivo. Coil29 fibers are also readily formed into tablets for solid-state dosing formulations and maintain their immunogenicity in this state. Previous sublingual peptide nanofiber immunotherapies have been based on different structures, such as highly stable β-sheets. The present work demonstrates that alternatively folded structures such as α-helical nanofibers can also be rendered sublingually immunogenic, enabling immunization with a variety of peptide epitopes and offering additional ways to specify mucus interactions, delivery state, dosing, and formulation.

Neutralizing antibodies to interferon alfa arising during peginterferon therapy of chronic hepatitis B in children and adults: Results from the HBRN Trials

BACKGROUND AIMS

Pegylated interferon-α (PegIFNα) is of limited utility during immunotolerant or immune active phases of chronic hepatitis B infection but is being explored as part of new cure regimens. Low/absent levels of IFNα found in some patients receiving treatment are associated with limited/no virological responses. The study aimed to determine if sera from participants inhibit IFNα activity and/or contain therapy-induced anti-IFNα antibodies.

APPROACH RESULTS

Pre-treatment, on-treatment, and post-treatment sera from 61 immunotolerant trial participants on PegIFNα/entecavir therapy and 88 immune active trial participants on PegIFNα/tenofovir therapy were screened for anti-IFNα antibodies by indirect ELISA. The neutralization capacity of antibodies was measured by preincubation of sera±recombinant human IFNα added to Huh7 cells with the measurement of interferon-stimulated gene (ISG)-induction by qPCR. Correlations between serum-induced ISG inhibition, presence, and titer of anti-IFNα antibodies and virological responses were evaluated. Preincubation of on-treatment serum from 26 immunotolerant (43%) and 13 immune active (15%) participants with recombinant-human IFNα markedly blunted ISG-induction in Huh7 cells. The degree of ISG inhibition correlated with IFNα antibody titer ( p < 0.0001; r = 0.87). On-treatment development of anti-IFNα neutralizing antibodies (nAbs) was associated with reduced quantitative HBsAg and qHBeAg declines ( p < 0.05) and inhibited IFNα bioactivity to 240 weeks after PegIFNα cessation. Children developed anti-IFNα nAbs more frequently than adults ( p = 0.004) but nAbs in children had less impact on virological responses.

CONCLUSIONS

The development of anti-IFNα nAbs during PegIFNα treatment diminishes responses to antiviral therapy. Understanding how and why anti-IFNα antibodies develop may allow for the optimization of IFN-based therapy, which is critical given its renewed use in HBV-cure strategies.

Development of a validated novel bead extraction method for the detection of anti-PEG antibodies in human serum

AIMS

Polyethylene glycol (PEG) is used in many applications including drug development. Due to exposure to environmental products, there is a high prevalence of preexisting anti-PEG antibodies in the global human population. The presence of anti-PEG antibodies is a concern for potentially reducing the efficacy of therapeutics after administration and represents a risk of safety events after exposure to PEGylated drug products. We developed and validated a creative and sensitive method for the detection of anti-PEG antibodies in human serum to support clinical programs for PEGylated drugs.

METHODS

In this method, biotin-PEG streptavidin beads were used to extract anti-PEG antibodies from human serum for analysis in an anti-PEG ELISA assay. The same serum sample was analyzed in an anti-drug antibody assay.

RESULTS

The anti-PEG antibody assay was validated with a screening cut point of 1.41 normalized signal, confirmatory cut point of 32.2% inhibition, sensitivity of 7.81 ng/mL and sufficient reproducibility, selectivity, and drug tolerance in accordance with the FDA 2019 Immunogenicity guidance.

CONCLUSION

This method of removal of anti-PEG antibodies enables the use of a single sample to detect anti-drug and anti-PEG antibodies to support drug development programs.

Peptide Aptamer-Paclitaxel Conjugates for Tumor Targeted Therapy

Background/Objectives: Traditional paclitaxel therapy often results in significant side effects due to its non-specific targeting of cancer cells. Peptide aptamer-paclitaxel conjugates present a promising alternative by covalently attaching paclitaxel to a versatile peptide aptamer via a linker. Compared to antibody-paclitaxel conjugates, peptide aptamer-paclitaxel conjugates offer several advantages, including a smaller size, lower immunogenicity, improved tissue penetration, and easier engineering. Methods: This review provides an in-depth analysis of the multifunctional peptide aptamers in these conjugates, emphasizing their structural features, therapeutic efficacy, and challenges in clinical applications. Results: This analysis highlights the potential of peptide aptamer-paclitaxel conjugates as a novel and effective approach for targeted cancer therapy. By harnessing the unique properties of peptide aptamers, these conjugates demonstrate significant promise in improving drug delivery efficiency while reducing the adverse effects associated with traditional paclitaxel therapy. Conclusions: The incorporation of peptide aptamers into paclitaxel conjugates offers a promising pathway for developing more efficient and targeted cancer therapies. However, further research and clinical studies are essential to fully unlock the therapeutic potential of these innovative conjugates and enhance patient outcomes.

Impact of Pre-existing Anti-polyethylene Glycol Antibodies on the Pharmacokinetics and Efficacy of a COVID-19 mRNA Vaccine (Comirnaty) In Vivo

The presence of anti-polyethylene glycol (anti-PEG) antibodies can hinder the therapeutic efficacy of PEGylated drugs. With the widespread use of a PEGylated coronavirus disease 2019 (COVID-19) messenger RNA vaccine (Comirnaty), the impact of pre-existing anti-PEG antibodies on vaccine potency has become a point of debate. To investigate this, we established mouse models with pre-existing anti-PEG antibodies and divided them into 3 groups: group 1 with anti-PEG immunoglobulin G + immunoglobulin M concentrations of 0.76 to 27.41 μg/ml, group 2 with concentrations of 31.27 to 99.52 μg/ml, and a naïve group with no detectable anti-PEG antibodies. Results indicated that anti-spike antibody concentrations significantly decreased in group 1 and group 2 after the 2nd vaccine dose compared to those in the naïve group. Spearman's rank correlation analysis demonstrated a negative relationship between anti-spike antibody production and anti-PEG antibody levels at both the 2nd and 3rd doses (2nd dose: ρ = -0.5296, P = 0.0031; 3rd dose: ρ = -0.387, P = 0.0381). Additionally, spike protein concentrations were 31.4-fold and 46.6-fold lower in group 1 and group 2, respectively, compared to those in the naïve group at 8 h postvaccination. The concentration of complement C3a in group 2 was significantly higher than that in the naïve group after the 3rd dose. These findings confirm that pre-existing anti-PEG antibodies diminish vaccine efficacy, alter pharmacokinetics, and elevate complement activation. Therefore, detecting pre-existing anti-PEG antibodies is crucial for optimizing vaccine efficacy, ensuring patient safety, and developing improved therapeutic strategies.

Site-Selective Zwitterionic Poly(caprolactone-carboxybetaine)-Growth Hormone Receptor Antagonist Conjugate: Synthesis and Biological Evaluation

Zwitterionic polymers have been found to be biocompatible alternatives to poly(ethylene glycol) (PEG) for conjugation to proteins. This work reports the site-selective conjugation of poly(caprolactone-carboxybetaine) (pCLZ) to human growth hormone receptor antagonist (GHA) B2036-alkyne and investigation of safety, activity, and pharmacokinetics. Azide-end-functionalized pCLZs were synthesized and conjugated to GHA B2036-alkyne via copper-catalyzed click reaction. The resulting inhibitory bioactivity concentration responses in Ba/F3-GHR cells were compared to those of PEGylated GHA B2036. IgG and IgM antibody production was tested in mice, and no measurable antibody or cytokine production was detected for the pCLZ conjugate. Using 18F-labeled PET/CT imaging, the pCLZ conjugate showed an increase in circulation time compared to that of GHA B2036. Acute toxicity of the polymer was investigated in vivo and found to be nontoxic. Ex vivo degradation of the polymer on the conjugate was investigated. The results suggest that pCLZ-GHA is a potentially safe alternative to PEG-GHA.

Nanoparticle-mediated universal CAR-T therapy

In recent years, chimeric antigen receptor (CAR)-T cell therapy has been highly successful in treating hematological malignancies, leading to significant advancements in the cancer immunotherapy field. However, the typical CAR-T therapy necessitates the enrichment of patients' own leukocytes for ex vivo production of CAR-T cells, this customized pattern requires a complicated and time-consuming manufacturing procedure, making it costly and less accessible. The off-the-shelf universal CAR-T strategy could reduce manufacturing costs and realize timely drug administration, presenting as an ideal substitute for typical CAR-T therapy. Utilizing nanocarriers for targeted gene delivery is one of the approaches for the realization of universal CAR-T therapy, as biocompatible and versatile nanoparticles could deliver CAR genes to generate CAR-T cells in vivo. Nanoparticle-mediated in situ generation of CAR-T cells possesses multiple advantages, including lowered cost, simplified manufacturing procedure, and shortened administration time, this strategy is anticipated to provide a potentially cost-effective alternative to current autologous CAR-T cell manufacturing, thus facilitating the prevalence and improvement of CAR-T therapy.

Charge-Stabilized Nanodiscs as a New Class of Lipid Nanoparticles

Nanoparticles have the potential to improve disease treatment and diagnosis due to their ability to incorporate drugs, alter pharmacokinetics, and enable tissue targeting. While considerable effort is placed on developing spherical lipid-based nanocarriers, recent evidence suggests that high aspect ratio lipid nanocarriers can exhibit enhanced disease site targeting and altered cellular interactions. However, the assembly of lipid-based nanoparticles into non-spherical morphologies has typically required incorporating additional agents such as synthetic polymers, proteins, lipid-polymer conjugates, or detergents. Here, charged lipid headgroups are used to generate stable discoidal lipid nanoparticles from mixed micelles, which are termed charge-stabilized nanodiscs (CNDs). The ability to generate CNDs in buffers with physiological ionic strength is restricted to lipids with more than one anionic group, whereas monovalent lipids only generate small nanoliposomal assemblies. In mice, the smaller size and anisotropic shape of CNDs promote higher accumulation in subcutaneous tumors than spherical liposomes. Further, the surface chemistry of CNDs can be modified via layer-by-layer (LbL) assembly to improve their tumor-targeting properties over state-of-the-art LbL-liposomes when tested using a metastatic model of ovarian cancer. The application of charge-mediated anisotropy in lipid-based assemblies can aid in the future design of biomaterials and cell-membrane mimetic structures.

Recent advances in liposomes and peptide-based therapeutics for glioblastoma treatment

In the context of glioblastoma treatment, the penetration of drugs is drastically limited by the blood-brain-barrier (BBB). Emerging therapies have focused on the field of therapeutic peptides for their excellent BBB targeting properties that promote a deep tumor penetration. Peptide-based strategies are also renowned for their abilities of driving cargo such as liposomal system allowing an active targeting of receptors overexpressed on GBM cells. This review provides a detailed description of the internalization mechanisms of specific GBM homing and penetrating peptides as well as the latest in vitro/in vivo studies of liposomes functionalized with them. The purpose of this review is to summarize a selection of promising pre-clinical results that demonstrate the advantages of this nanosystem, including an increase of tumor cell targeting, triggering drug accumulation and thus a strong antitumor effect. Aware of the early stage of these studies, many challenges need to be overcome to promote peptide-directed liposome at clinical level. In particular, the lack of suitable production, the difficulty to characterize the nanosystem and therapeutic competition leaded by antibodies.

Generating Immunological Memory Against Cancer by Camouflaging Gold-Based Photothermal Nanoparticles in NIR-II Biowindow for Mimicking T-Cells

Photothermal therapy (PTT) against cancer not only directly ablates tumors but also induces tumor immunogenic cell death (ICD). However, the antitumor immune response elicited by ICD is insufficient to prevent relapse and metastasis because of the immunosuppressive tumor microenvironment (TME). A biomimetic nanoplatform (bmNP) mimicking cytotoxic lymphocytes (CTLs) for combinational photothermal-immunotherapy to effectively regulate the immunosuppressive TME is reported here. The bmNP is constructed by wrapping the T-cell membrane onto a new type of photothermal agents, spherical Au-based PNCs (sAuPNCs). Similar to T-cells, the bmNP enhanced accumulation at the tumor site by targeting the tumor via adhesion proteins on T-cell membrane. The obtained sAuPNCs have a wide absorption band in the second near-infrared (NIR-II) region with a high photothermal conversion efficiency (PCE) up to about 75% and excellent photostability. The bmNP with a smaller size is more superior compete with T-cells to bond with tumor cells via PD-1/PD-L1 interaction to effectively block the PD-1 checkpoint of T-cells for preventing T-cell exhaustion. Furthermore, in vivo studies reveal the immunological memory effect is significantly elicited in mice received bmNPs therapy. Collectively, bmNPs show great potential in photothermal-enhanced immunotherapy.

Immunogenicity assessment strategy for a chemically modified therapeutic protein in clinical development

The clinical immunogenicity assessment for complex multidomain biological drugs is challenging due to multiple factors that must be taken into consideration. Here, we describe a strategy to overcome multiple bioanalytical challenges in order to assess anti-drug antibodies (ADA) for a novel and unique chemically modified protein therapeutic. A risk-centered approach was adopted to evaluate the immunogenic response to a modified version of human growth differentiation factor 15 (GDF15) connected to an albumin-binding fatty acid via a polyethylene glycol (PEG) linker. Key steps include monitoring anti-drug antibodies (ADAs), using a standard tiered approach of screening and confirmation. To deepen our understanding of ADA response, as a third tier of immunogenicity assessment, novel extensive characterization using a set of assays was developed, validated, and used routinely in clinical sample analysis. This characterization step included performance of titration, mapping of ADA response including anti-GDF15 and anti-PEG-fatty-acid antibody characterization, and assessment of the neutralizing anti-drug antibodies (NAbs) using cell-based assays for immunogenicity in parallel. The analytical methods were applied during two clinical trials involving both healthy volunteers and overweight or obese patients. We observed low incident rates for ADA and no ADAs against the PEG linker with fatty acid conjugation. In one of the clinical studies, we identified neutralizing ADAs. The proposed novel strategy of extensive characterization proved effective for monitoring the presence of ADAs and NAbs and can be used to support clinical development of a broad range of chemically modified proteins and multidomain biotherapeutics.

Optimizing Pharmacological and Immunological Properties of Therapeutic Proteins Through PEGylation: Investigating Key Parameters and Their Impact

Protein PEGylation represents a significant technological advancement in the development of protein-based therapeutics and is widely used to reduce immunogenicity, enhance pharmacokinetics, and/or improve stability. The improved pharmacokinetic profile of PEGylated proteins compared with the native protein results in sustained versus fluctuating plasma concentrations and carries the potential of less frequent administration. However, attachment of PEG to therapeutic proteins can alter their structural conformation, which exposes new epitopes to the immune system. The design of PEGylated proteins thus needs to balance the intended benefits with the potential risks associated with the immunogenicity of the PEG moiety itself or resulting from alterations in the conformation of the therapeutic protein. In recent years, advancements in protein PEGylation chemistry have offered the capability to target PEG attachment to specific amino acids to create more stable and bioactive therapies. The biophysical and biopharmaceutical features of PEGylated proteins can vary based on polymer size, shape, density, and conjugation site, and the immunogenicity of the conjugate can be further impacted by the properties of the therapeutic protein itself and the characteristics of the patient. It is important to note that not all patients will develop an immune response toward the PEG moiety, and not all immune responses are clinically meaningful. A comprehensive understanding of the factors that influence immunogenic responses to PEGylated proteins is important to optimize their therapeutic benefits. This article reviews the design and optimization of PEGylation strategies to enhance the clinical performance of protein-based therapeutics while minimizing immunogenic responses to the PEG moiety or PEGylated proteins.

Amine headgroups in ionizable lipids drive immune responses to lipid nanoparticles by binding to the receptors TLR4 and CD1d

Lipid nanoparticles (LNPs) are the most clinically advanced delivery vehicle for RNA therapeutics, partly because of established lipid structure-activity relationships focused on formulation potency. Yet such knowledge has not extended to LNP immunogenicity. Here we show that the innate and adaptive immune responses elicited by LNPs are linked to their ionizable lipid chemistry. Specifically, we show that the amine headgroups in ionizable lipids drive LNP immunogenicity by binding to Toll-like receptor 4 and CD1d and by promoting lipid-raft formation. Immunogenic LNPs favour a type-1 T-helper-cell-biased immune response marked by increases in the immunoglobulins IgG2c and IgG1 and in the pro-inflammatory cytokines tumour necrosis factor, interferon γ and the interleukins IL-6 and IL-2. Notably, the inflammatory signals originating from these receptors inhibit the production of anti-poly(ethylene glycol) IgM antibodies, preventing the often-observed loss of efficacy in the LNP-mediated delivery of siRNA and mRNA. Moreover, we identified computational methods for the prediction of the structure-dependent innate and adaptive responses of LNPs. Our findings may help accelerate the discovery of well-tolerated ionizable lipids suitable for repeated dosing.

Exemplifying interspecies variation of liposome in vivo fate by the effects of anti-PEG antibodies

The different fate of liposomes among species has been discovered and mentioned in many studies, but the underlying mechanisms have not been explored. In the present work, we concentrated on the in vivo fate of PEGylated liposomes (sLip) in three commonly used species (mice, rats, and dogs). It was exhibited that the accelerated blood clearance (ABC) phenomenon and hypersensitivity in large animals (beagle dogs) were much more significant than that in rodents. We demonstrated that anti-PEG IgM (partially) and complement (mostly) determined the elimination of sLip and linked the distinct interspecies performances with the diverse complement capacity among species. Based on the data from animals and clinical patients, it was revealed that the fate of sLip in large animals was closer to that in humans, for the sufficient complement capacity could expose the potential adverse reactions caused by anti-PEG antibodies. Our results suggested that the distinctive interspecies performances of sLip were highly related to the physiological variabilities among species, which should not be overlooked in the innovation and translation of nanomedicines.

Acid-degradable lipid nanoparticles enhance the delivery of mRNA

Lipid nanoparticle (LNP)-mRNA complexes are transforming medicine. However, the medical applications of LNPs are limited by their low endosomal disruption rates, high toxicity and long tissue persistence times. LNPs that rapidly hydrolyse in endosomes (RD-LNPs) could solve the problems limiting LNP-based therapeutics and dramatically expand their applications but have been challenging to synthesize. Here we present an acid-degradable linker termed 'azido-acetal' that hydrolyses in endosomes within minutes and enables the production of RD-LNPs. Acid-degradable lipids composed of polyethylene glycol lipids, anionic lipids and cationic lipids were synthesized with the azido-acetal linker and used to generate RD-LNPs, which significantly improved the performance of LNP-mRNA complexes in vitro and in vivo. Collectively, RD-LNPs delivered mRNA more efficiently to the liver, lung, spleen and brains of mice and to haematopoietic stem and progenitor cells in vitro than conventional LNPs. These experiments demonstrate that engineering LNP hydrolysis rates in vivo has great potential for expanding the medical applications of LNPs.

Mechanisms of extracellular vesicle uptake and implications for the design of cancer therapeutics

The translation of pre-clinical anti-cancer therapies to regulatory approval has been promising, but slower than hoped. While innovative and effective treatments continue to achieve or seek approval, setbacks are often attributed to a lack of efficacy, failure to achieve clinical endpoints, and dose-limiting toxicities. Successful efforts have been characterized by the development of therapeutics designed to specifically deliver optimal and effective dosing to tumour cells while minimizing off-target toxicity. Much effort has been devoted to the rational design and application of synthetic nanoparticles to serve as targeted therapeutic delivery vehicles. Several challenges to the successful application of this modality as delivery vehicles include the induction of a protracted immune response that results in their rapid systemic clearance, manufacturing cost, lack of stability, and their biocompatibility. Extracellular vesicles (EVs) are a heterogeneous class of endogenous biologically produced lipid bilayer nanoparticles that mediate intercellular communication by carrying bioactive macromolecules capable of modifying cellular phenotypes to local and distant cells. By genetic, chemical, or metabolic methods, extracellular vesicles (EVs) can be engineered to display targeting moieties on their surface while transporting specific cargo to modulate pathological processes following uptake by target cell populations. This review will survey the types of EVs, their composition and cargoes, strategies employed to increase their targeting, uptake, and cargo release, and their potential as targeted anti-cancer therapeutic delivery vehicles.

A biomimetic solution, albumin-doxorubicin molecular complex, targeting tumor and tumor-draining lymph nodes

Chemotherapy-induced immunologic cell death is haunted by the non-specific distribution of chemotherapeutic drugs and insignificant immune activation effects, which render efforts to inhibit the distant metastasis of tumors frustrated. Given the pivotal role that lymph nodes play in tumor metastasis, it is of vital importance whether the drug delivery to tumor-draining lymph nodes (TDLNs) succeeds. In the current study, we developed a doxorubicin-albumin complex (DOX-HSA) solution with the specific ability to simultaneously target the primary tumor and the TDLNs. DOX-HSA could effectively activate and amplify the immunogenic cell death (ICD) effect in both the tumor tissues and the TDLNs, resulting in increased release of damage-associated molecular patterns (DAMPs), which further promoted phagocytosis and maturation of dendritic cells (DCs), stimulated activation of CD8+T cells, and then significantly enhanced the therapeutic effects of doxorubicin on orthotopic 4T1 tumor-bearing model mice. Therefore, the DOX-HSA solution demonstrated a more prominent ability to control cancer cells and curb metastasis, as well as improved security by reducing cardiotoxicity and myelosuppression toxicity of doxorubicin itself. This DOX-HSA strengthened the synergistic anti-tumor effects based on the ICD effect in combination with traditional chemotherapy, thus providing promising prospects for clinical application.

Enhancing bevacizumab efficacy in a colorectal tumor mice model using dextran-coated albumin nanoparticles

Bevacizumab is a monoclonal antibody (mAb) that prevents the growth of new blood vessels and is currently employed in the treatment of colorectal cancer (CRC). However, like other mAb, bevacizumab shows a limited penetration in the tumors, hampering their effectiveness and inducing adverse reactions. The aim of this work was to design and evaluate albumin-based nanoparticles, coated with dextran, as carriers for bevacizumab in order to promote its accumulation in the tumor and, thus, improve its antiangiogenic activity. These nanoparticles (B-NP-DEX50) displayed a mean size of about 250 nm and a payload of about 110 µg/mg. In a CRC mice model, these nanoparticles significantly reduced tumor growth and increased tumor doubling time, tumor necrosis and apoptosis more effectively than free bevacizumab. At the end of study, bevacizumab plasma levels were higher in the free drug group, while tumor levels were higher in the B-NP-DEX50 group (2.5-time higher). In line with this, the biodistribution study revealed that nanoparticles accumulated in the tumor core, potentially improving therapeutic efficacy while reducing systemic exposure. In summary, B-NP-DEX can be an adequate alternative to improve the therapeutic efficiency of biologically active molecules, offering a more specific biodistribution to the site of action.

Polysorbate 80-containing ionizable lipid nanoparticles for mRNA delivery

Ionizable lipid nanoparticles have demonstrated remarkable success as mRNA vaccine carriers and represent one of the most promising gene drug delivery vehicles. However, polyethylene glycol (PEG), one of the major components, can cause immunogenic reactions, anaphylaxis and increased blood clearance, leading to toxic side effects and reduced efficacy. In this study, we utilize polysorbate 80 (PS80) as a PEG alternative in formulating eGFP mRNA-loaded ionizable lipid nanoparticles (PS80-iLNPs), aiming to enhance stealth properties, uptake efficiency, and biosafety. Our findings revealed that PS80-iLNPs enhanced the stealthiness and resistance to serum interference. Compared to PEG-containing ionizable lipid nanoparticles (PEG-iLNPs), PS80-iLNPs showed a 1.14-fold increase in stealthiness. Moreover, at a total lipid concentration of 50 μg mL-1, PS80-iLNPs exhibited 1.12 times higher cell viability compared to PEG-iLNPs. Notably, under serum interference, PEG-iLNPs showed a 44.97% uptake reduction, whereas PS80-iLNPs exhibited a modest 30.55% decrease, underscoring its superior serum resistance. This work demonstrated that PS80 could serve as a suitable substitute for PEG, thus signifying an excellent basis for the development of PEG-free ionizable lipid nanoparticles.