Protein PEGylation for cancer therapy: bench to bedside

LDLR-targeted orlistat therapeutic nanoparticles: Peptide selection, assembly, characterization, and cell-uptake in breast cancer cell lines

MOTIVATION

Many cancers overexpress low-density lipoprotein receptors (LDLR), facilitating cholesterol metabolism for tumour growth. Targeting LDLR offers a promising strategy for selective drug delivery. Orlistat, a fatty acid synthase (FAS) inhibitor, has shown anti-cancer potential, particularly in tumours with high FAS expression. This study introduces an LDLR-Orlistat Targeted Nanoparticles (LDLR-OTNs) to enhance cancer cell uptake via LDLR-mediated endocytosis. The objectives include synthesizing lipid-based orlistat nanoparticles, functionalizing them with an 11-mer LDLR-binding peptide, assessing uptake and cytotoxicity in three LDLR- and FAS-expressing breast cancer cell lines (BT-474, MDA MB 453, MCF-7), and comparing uptake kinetics with non-targeted nanoparticles.

METHODS

Orlistat nanoparticles (ONs) were synthesised via rapid solvent exchange, producing uncoated ONs, POPC-coated ONs (POPC-ONs), and LDLR-targeted ONs (LDLR-OTNs). Targeting was achieved by conjugating an 11-mer binding peptide (RLTRKRGLKLA) to DSPE-PEG5000 maleimide via click chemistry, confirmed by Ellman's test. Nanoparticles were characterised using DLS and TEM. Cellular uptake over 24 hours was assessed using fluorescence-labelled POPC-ONs and LDLR-OTNs, and uptake kinetics were analysed. Suramin-blocking studies were used to confirm LDLR-mediated uptake. A 48-hour cytotoxicity assay quantified IC50 values in the aforementioned cell lines.

RESULTS

TEM data showed that LDLR-OTNs (33 nm) were smaller than untargeted POPC-ONs (58 nm) and uncoated ONs (67 nm). Ellman's test confirmed > 99.2% peptide conjugation. Cellular uptake of LDLR-OTNs was rapid, with significant fluorescence by 1 hour and a kinetic plateau at 24-48 hours, with data fitting to a modified exponential model, while that of untargeted POPC-ONs had lower initial uptake, following a logistic model. Suramin blocking reduced LDLR-OTN uptake, confirming receptor-mediated entry. Cytotoxicity assays yielded IC50 values of 23.8 µM (BT-474), 25.8 µM (MDA MB 453), and 8.2 µM (MCF-7), with maximal inhibition at 48 h.

CONCLUSIONS

LDLR-OTNs demonstrated receptor-mediated uptake and potent cytotoxicity in LDLR- and FAS- overexpressing breast cancer cells. These findings support LDLR-targeted nanoparticles as a promising approach for delivering FAS inhibitors to LDLR-rich tumours, meriting further investigation in targeted cancer therapy development.

Physical characterization of PEGylated exosome constructs: Size, charge, and morphology changes in non-specific alkylating N-terminal reactions

Small extracellular vesicles, commonly referred to as exosomes, withhold a promising future in the pharmaceutical industry as carriers for targeted drug delivery due to their high specificity and bioavailability when compared to synthetic-based vectors. They, however, present some limitations for systematic administration because of natural organism defenses and their high-water solubility, ultimately making it difficult for them to reach the intended target. To improve the delivery capacity of these nanoparticles, the possibility for the construction of PEGylated versions was explored in this work. This process was performed, analyzed, and characterized using N-terminal specific PEGylation reactions targeted to the protein contents in the exosomal membrane. For this, two different mono-methoxy polyethylene glycols (mPEG) of 5 and 20 kDa were reacted with exosomes under alkylating conditions. The resulting 5k and 20k PEGylated exosome constructs were characterized and compared with unmodified exosomes, using size, morphology, and zeta potential as comparison parameters. Results after analysis showed an absorbance reduction of approximately 65% and 34% (for the 5 and 20 kDa conjugates respectively), a reduction of 10 to 20% in peak resolution, particle size increase corresponding to the polymer sizes used, and a slight reduction in electric distribution of about 2 to 3 mV less than the unmodified vesicles. The data obtained may provide insights for the optimization of exosome PEGylation strategies for therapeutic use.

Peptide-based drugs in immunotherapy: current advances and future prospects

In immunotherapy, peptide-based medications are showing great promise as a new class of therapies that can be used to treat autoimmune diseases, cancer, and other immune-related conditions. Peptides are being created for use in immunotherapy as vaccines, immunological modulators, and adjuvants because of their capacity to precisely alter immune responses. They can imitate endogenous signals or interact with immune cells, improving the body's capacity to identify and combat malignancies or reestablishing immunological tolerance in autoimmune disorders. Notably, peptide-based treatments have demonstrated promise in promoting tumor-specific immune responses and improving the effectiveness of already available immunotherapies, such as immune checkpoint inhibitors. Notwithstanding its potential, peptide-based medications' clinical translation is fraught with difficulties, such as those pertaining to immunogenicity, bioavailability, and peptide stability. Overcoming these obstacles has been made possible by developments in peptide engineering, including pharmacokinetic optimization, receptor-binding affinity enhancement, and the creation of innovative delivery systems. The targeted distribution and effectiveness of peptide medications can be improved by using liposomes, nanoparticles, and other delivery methods, increasing their therapeutic utility. With an emphasis on recent scientific developments, mechanisms of action, and therapeutic uses, this review examines the present status of peptide-based medications in immunotherapy. We also look at the obstacles that still need to be overcome in order to get peptide-based treatments from the lab to the clinic and offer suggestions for future research initiatives. By tackling these important problems, we hope to demonstrate how peptide-based medications have the ability to revolutionize immunotherapeutic treatment approaches.

Cysteine-selective [188Re]Re(v) radiolabelling of a Nanobody® for targeted radionuclide therapy using a "chelate-then-click" approach

In this study, we present the first reported use of bioorthogonal click chemistry with rhenium-188 for radiolabelling of an anti-c-Met VHH Nanobody®. We employed a "chelate-then-click" strategy, wherein a bifunctional chelator was designed in two parts, which were subsequently joined post-labelling and post-conjugation via the strain-promoted azide-alkyne cycloaddition (SPAAC) reaction. Cysteine-selective conjugation of the VHH was achieved through thiol-Michael addition, forming a VHH-DBCO construct. Radiolabelling of the azide-functionalised chelator with [188Re]Re(v) was optimised to achieve a radiochemical conversion of ∼70%, despite challenges associated with maintaining the azide functionality under reducing conditions. The final product, [188Re]Re-VHH, demonstrated high radiochemical purity and good in vitro stability over 48 h. In vitro cell-binding studies against U87MG and BxPC3 cell lines proved the retention of c-Met binding post-labelling. In vivo biodistribution studies on mice bearing BxPC3 tumour xenografts, however, exhibited suboptimal tumour uptake, likely a result of the low molar activity (1.4-3.3 MBq nmol-1) of the radioconjugate. This work illustrates the potential of bioorthogonal click chemistry for radiolabelling biomolecules with 188Re, although further optimisation or alternative radiolabelling strategies to enhance the molar activity are necessary to improve pharmacokinetics.

Artificial blood-hope and the challenges to combat tumor hypoxia for anti-cancer therapy

The blood plays a vital role in the human body and serves as an intermediary between various physiological systems and organs. White blood cells, which are a part of the immune system, defend against infections and regulate the body temperature and pH balance. Blood platelets play a crucial role in clotting, the prevention of excessive bleeding, and the promotion of healing. Blood also serves as a courier system that transports hormones to facilitate communication and synchronization between different organs and systems in the body. The circulatory system, comprised of arteries, veins, and capillaries, plays a crucial role in the efficient transportation and connection of vital nutrients and oxygen. Despite the importance of natural blood, there are often supply shortages, compatibility issues, and medical conditions, which make alternatives such as artificial blood necessary. This is particularly relevant in cancer treatment, which was the focus of our study. In this study, we investigated the potential of artificial blood in cancer therapy, specifically to address tumor hypoxia. We also examined the potential of red blood cell substitutes such as hemoglobin-based oxygen carriers and perfluorocarbons. Additionally, we examined the production of hemoglobin using E. coli and the role of hemoglobin in oncogenesis. Furthermore, we explored the potential use of artificial platelets for cancer treatment. Our study emphasizes the significance of artificial blood in improving cancer treatment outcomes.

Functionalization of polymeric nanomicelles and mixed nanomicelles for targeted retinal delivery in the management of retinoblastoma

The current research discusses polymer conjugation, formulation development, and evaluation of sorafenib-loaded polymeric nanomicelles of conjugated soluplus (solu-tin) and polymeric mixed nanomicelles of conjugated soluplus (solu-tin) with conjugated poloxamer 188 (polo-tin) for site-specific posterior segment delivery to the retina in managing retinoblastoma. Firstly, the soluplus and poloxamer 188 were conjugated with biotin by Fischer esterification reaction and evaluated by FTIR and 1H NMR for confirmation of covalent bond formation involving the carboxyl group of biotin and hydroxyl group of polymers. Secondly, the sorafenib-loaded solu-tin nanomicelles and mixed nanomicelles of solu-tin with polo-tin were formulated by the thin film hydration method. Thereafter, these nanomicelles were evaluated and displayed suitable outcomes for particle size (78.53 nm and 73.17 nm), PDI (0.089 and 0.074), zeta potential (-3.65 mV and -4.17 mv), entrapment efficiency (99.23 % and 99.83 %), in vitro drug release (4 h and 8 h), solid-state analysis, osmolality (290 mOsm/kg and 293 mOsm/kg), pH (7.4 and 7.4), TEM (spherical) and residual solvent analysis (287.90 ppm and 363.49 ppm). The ex vivo transcleral permeation at 8 h was found to be 548.45 ng/cm2 and 281.61 ng/cm2, respectively. Both the drug-loaded nanomicelles displayed a dose-dependent anticancer effect on Y-79 cells at all time points i.e. 6, 12, 18, and 24 h, and were non-toxic to normal retinal pigmented epithelial cell line (ARPE-19) when incubated for 24 h. Furthermore, the formulations were non-irritant (HET-CAM) and stable for 6 months. Hence, the developed technology is safe and efficacious for targeting the retina in managing retinoblastoma.

l-Asparaginase Immobilized on Nanographene Oxide as an Efficient Nanobiocatalytic Tool for Asparagine Depletion in Leukemia Cells

l-Asparaginase (l-ASNase) catalyzes the hydrolysis of l-asparagine, leading to its depletion and subsequent effects on the cellular proliferation and survival. In contrast to normal cells, malignant cells that lack asparagine synthase are extremely susceptible to asparagine deficiency. l-ASNase has been successfully employed in treating pediatric leukemias and non-Hodgkin lymphomas; however, its usage in adult patients and other types of cancer is limited due to significant side effects and drug resistance. Recent research has explored alternative formulations and delivery methods to enhance its efficacy and minimize adverse effects. One promising approach involves the immobilization of l-ASNase onto nanostructured materials, offering improved enzymatic activity and biocompatibility of the support. We harnessed an E. coli l-ASNase type II preparation to develop a novel strategy of enzyme immobilization on graphene oxide (GO)-based support. We compared GO and nanographene oxide (nGO) in terms of their biocompatibility and influence on enzyme parameters. The obtained l-ASNase on the nGO nanobiocatalyst maintains enzymatic activity and increases its stability, selectively acting on K562 leukemia cells without cytotoxic influence on normal endothelial cells. In the case of treated K562 cells, we confirmed enlargement in the cell and nucleus size, disturbance in the cell cycle (interphase and metaphase), and increased apoptosis rate. The potential therapeutic possibilities of immobilized l-ASNase on leukemia cell damage are also discussed, highlighting the importance of further research in this area for advancing cancer therapy.

Dendrimer-Mediated Molecular Sieving on Avidin

Decoration of proteins and enzymes with well-defined polymeric structures allows precise decoration of protein surfaces, enabling controlled modulation of activity. Here, the impact of dendronization on the interaction between avidin and biotin was investigated. A series of generation 3-7 bis(2,2-hydroxymethyl)propionic acid (bis-MPA) dendrons were coupled to either biotin or avidin to yield a library of dendronized avidin and biotin structures. The thermodynamics of binding each biotinylated generation to a library of avidin conjugates was probed with isothermal titration calorimetry (ITC). Dissociation constants of high-generation biotin-dendrons (G5 and G6) with higher-generation avidin-dendron conjugates (Av-G6) increased from ∼10-15 M (for the native structures) to ∼10-6 M, and binding was found to be weaker than that of the Avidin-HABA complex. Avidin-G5 and Avidin-G6 were highly size-selective for biotinylated ligands; both prevented the binding of aprotinin (6.9 kDa), bovine serum albumin (BSA), and PEG3400 while forming fractional complexes with smaller biotinylated dendrons.

Development of a peptide-based tumor-activated checkpoint inhibitor for cancer immunotherapy

Antibody-based checkpoint inhibitors have achieved great success in cancer immunotherapy, but their uncontrollable immune-related adverse events remain a major challenge. In this study, we developed a tumor-activated nanoparticle that is specifically active in tumors but not in normal tissues. We discovered a short anti-PD-L1 peptide that blocks the PD-1/PD-L1 interaction. The peptide was modified with a PEG chain through a novel matrix metalloproteinase-2 (MMP-2)-specific cleavage linker. The modified TR3 peptide self-assembles into a micelle-like nanoparticle (TR3-M-NP), which remains inactive and unable to block the PD-1/PD-L1 interaction in its native form. However, upon cleavage by MMP-2 in tumors, it releases the active peptide. The TR3-M-NP5k nanoparticle was specifically activated in tumors through enzyme-mediated cleavage, leading to the inhibition of tumor growth and extended survival compared to control groups. In summary, TR3-M-NP shows great potential as a tumor-responsive immunotherapy agent with reduced toxicities. STATEMENT OF SIGNIFICANCE: In this study, we developed a bioactive peptide-based checkpoint inhibitor that is active only in tumors and not in normal tissues, thereby potentially avoiding immune-related adverse effects. We discovered a short anti-PD-L1 peptide, TR3, that blocks the PD-1/PD-L1 interaction. We chemically modified the TR3 peptide to self-assemble into a micelle-like nanoparticle (TR3-M-NP), which itself cannot block the PD-1/PD-L1 interaction but releases the active TR3 peptide in tumors upon cleavage by MMP-2. In contrast, the nanoparticle is randomly degraded in normal tissues into peptides fragments that cannot block the PD-1/PD-L1 interaction. Upon intraperitoneal injection, TR3-M-NP5k was activated specifically in tumors through enzyme cleavage, leading to the inhibition of tumor growth and extended survival compared to the control groups. In summary, TR3-M-NP holds significant promise as a tumor-responsive immunotherapy agent with reduced toxicities. The bioactive platform has the potential to be used for other types of checkpoint inhibitor.

Innovative Strategies in Oncology: Bacterial Membrane Vesicle-Based Drug Delivery Systems for Cancer Diagnosis and Therapy

Outer membrane vesicles (OMVs) are double-layered structures of nanoscale lipids released by gram-negative bacteria. They have the same membrane composition and characteristics as primitive cells, which enables them to penetrate cells and tissues efficiently. These OMVs exhibit excellent membrane stability, immunogenicity, safety, and permeability (which makes it easier for them to penetrate into tumour tissue), making them suitable for developing cancer vaccines and drug delivery systems. Recent studies have focused on engineering OMVs to enhance tumour-targeting capabilities, reduce toxicity, and extend circulation time in vivo. This article reviews the latest progress in OMV engineering for tumour treatment and discusses the challenges associated with the use of OMV-based antitumour therapy in clinical practice.

Unravelling the Role of Tyrosine and Tyrosine Hydroxylase in Parkinson's Disease: Exploring Nanoparticle-based Gene Therapies

Parkinson's disease (PD) is a neurodegenerative disorder that results from the progressive loss of neurons in the brain followed by symptoms such as slowness and rigidity in movement, sleep disorders, dementia and many more. The different mechanisms due to which the neuronal degeneration occurs have been discussed, such as mutation in PD related genes, formation of Lewy bodies, oxidation of dopamine. This review discusses current surgical treatment and gene therapies with novel developments proposed for PD. Gene therapy based on novel approaches will possess more potential advantages over the conventional methods. Currently, gene therapy for such disorders is still under the process of clinical trials and approval. The pathogenesis comes from the breakdown of dopaminergic neurons within substantia nigra (SN) by the action of tyrosinase enzyme and subsequent accumulation of α-synuclein within the neurons. These dopaminergic neurons are the main source of dopamine, the decline of which is responsible for the symptoms. So, gene therapy can possibly provide more stable supplementation and regulate the expression of tyrosinase enzyme, providing better symptomatic relief and lesser side effects. Dopamine replacement therapy is a wellstudied gene therapy method for PD. Another approach involves introducing functional genes for enzymes such as tyrosine hydroxylase, cyclohydrolases, and decarboxylases with the help of engineered vectors such as AAV and LV. Further, the potential application of nanoparticles in gene therapy as an efficient gene delivery and imaging system has been discussed. Among these, lipidbased nanoparticles such as PILs offer important benefits in terms of enhanced bioavailability, permeability to the cells, and solubility. So, this review paper summarizes some of the advanced gene therapy approaches for PD and the current status of clinical research in the development of gene therapy using nanoparticles.

Pseudomonas aeruginosa Recombinant L-asparaginase: PEGylation with Low Molecular Weight Polyethylene Glycol, Molecular Dynamics Simulation, In vitro and In vivo Serum half-life and Biochemical Characterization

BACKGROUND

Microbial L-asparaginase (L-ASNase, EC 3.5.1.1) is a pivotal biopharmaceutical drug-protein that catalyzes the hydrolysis of the non-essential amino acid L-asparagine (L-Asn) into L-aspartic acid (L-Asp) and ammonia , resulting in deplenishing the cellular L-Asn pool, which leads to the ultimate death of the L-asparagine synthetase (L-ASNS) deficient cancerous cells.

OBJECTIVE

This study aimed to investigate the impact of conjugating low molecular weight polyethylene glycol to recombinant P. aeruginosa L-ASNase by examining the pharmacokinetic properties, affinity towards the substrate, and enzyme stability prior to and following the reaction.

METHODS

The recombinant P. aeruginosa L-ASNase was affinity purified and then PEGylated by attaching polyethylene glycol (MW= 330 Da) site-specifically to the protein's N-terminus end. After which, the PEGylated L-ASNase was examined by SDS-PAGE (15%), FTIR, and UV/Vis spectrophotometry and subsequently biochemically characterized.

RESULTS

The Km and Vmax values of free P. aeruginosa rL-ASNase were determined to be 0.318 ±1.76 mM and 2915 μmol min-1 and following the PEGylation, they were found to be 0.396 ±1.736 mM and 3193 μmol min-1, respectively. Polyethylene glycol (330 Da) has markedly enhanced LASNase thermostability at 37, 45, 50, and 55°C, as opposed to the free enzyme, which retained 19.5% after 1 h of incubation at 37°C. The PEGylated L-ASNase was found to be stable upon incubation with human serum for 28 h, in contrast to the sharp decline in the residual bioactivity of the free rL-ASNase after 4 h incubation. Accordingly, an in vivo study was used for validation, and it demonstrated that PEGylated rL-ASNase exhibited longer bioactivity for 24 h, while the free form's activity vanished entirely from the rats' blood sera after 8 h. Molecular dynamics simulation indicated that PEG (330 Da) has affected the hydrodynamic volume of L-ASNase and increased its structural stability. Docking analysis has explored the position of PEG with respect to binding sites and predicted a similar binding affinity to that of the free enzyme.

CONCLUSION

For the first time, recombinant L-ASNase was modified by covalently attaching PEG (330 Da). The resultant novel proposed PEGylated rL-ASNase with remarkably increased stability and prolonged in vivo half-life duration, could be considered an alternative to mitigate the high molecular weight of PEGylation's drawbacks.

A Noncationic Biocatalytic Nanobiohybrid Platform for Cytosolic Protein Delivery Through Controlled Perturbation of Intracellular Redox Homeostasis

Intracellular delivery of proteins has largely been relying on cationic nanoparticles to induce efficient endosome escape, which, however, poses serious concerns on the inflammatory and cytotoxic effects. Herein, a versatile noncationic nano biohybrid platform is introduced for efficient cytosolic protein delivery by utilizing a nano-confined biocatalytic reaction. This platform is constructed by co-immobilizing glucose oxidase (GOx) and the target protein into nanoscale hydrogen-bonded organic frameworks (HOFs). The biocatalytic reaction of nano-confined GOx is leveraged to induce controlled perturbation of intracellular redox homeostasis by sustained hydrogen peroxide (H2O2) production and diminishing the flux of the pentose phosphate pathway (PPP). This in turn induces the endosome escape of nanobiohybrids. Concomitantly, GOx-mediated hypoxia leads to overexpression of azo reductase that initiated the materials' self-destruction for releasing target proteins. These biological effects collectively induce highly efficient cytosolic protein delivery. The versatility of this delivery platform is further demonstrated for various types of proteins, different protein loading approaches (in situ immobilization or post-adsorption), and in multiple cell lines. Finally, the protein delivery efficiency and biosafety are demonstrated in a tumor-bearing mouse model. This nanohybrid system opens up new avenues for intracellular protein delivery and is expected to be extensively applicable for a broad range of biomolecuels.

Exactly defined molecular weight poly(ethylene glycol) allows for facile identification of PEGylation sites on proteins

PEGylation (the covalent attachment of one or more poly(ethylene glycol) (PEG) units to a therapeutic) is a well-established technique in the pharmaceutical industry to increase blood-residence time and decrease immunogenicity. A challenging aspect of PEGylation is the dispersity of PEGylation agents, which results in batch-to-batch variations and analytical limitations. Herein, we present an approach to overcome these limitations by manufacturing a defined molecular weight (dispersity-free) PEGylation agent. We synthesise a defined molecular weight (Mw), linear 5 kDa methoxy-PEG (mPEG) active ester in an efficient and scalable manner using an iterative liquid-phase approach based on Nanostar Sieving. We then perform a comparative study on the random PEGylation and subsequent characterisation of the protein bovine serum albumin (BSA), using both the defined Mw, dispersity-free mPEG active ester, and a commercially available disperse 5 kDa mPEG active ester. We demonstrate that the defined Mw PEG both allows for facile monitoring of chemical modification reactions during the synthesis of the PEGylation agents, and facilitates straightforward identification of the PEGylated fragments within a PEGylated protein via a simple peptide mapping approach using UPLC-MS.

Enhanced anti-cancer efficacy of arginine deaminase expressed by tumor-seeking Salmonella Gallinarum

Amino acid deprivation, particularly of nonessential amino acids that can be synthesized by normal cells but not by cancer cells with specific defects in the biosynthesis pathway, has emerged as a potential strategy in cancer therapeutics. In normal cells, arginine is synthesized from citrulline in two steps via two enzymes: argininosuccinate synthetase (ASS1) and argininosuccinate lyase. Several cancer cells exhibit arginine auxotrophy due to the loss or down-regulation of ASS1. These cells undergo starvation-induced cell death in the presence of arginine-degrading enzymes such as arginine deaminase (ADI). Thus, ADI has emerged as a potential therapeutic in cancer therapy. However, the use of ADI has two major disadvantages: ADI of bacterial origin is strongly antigenic in mammals, and ADI has a short circulation half-life (∼5 h). In this study, we engineered tumor-targeting Salmonella Gallinarum to express and secrete ADI and deployed this strain into mice implanted with ASS1-defective mouse colorectal cancer (CT26) through an intravenous route. A notable antitumor effect was observed, suggesting that the disadvantages were overcome as ADI was expressed constitutively by tumor-targeting bacteria. A combination with chloroquine, which inhibits the induction of autophagy, further enhanced the effect. Anti-cancer effect of Salmonella Gallinarum expressing an arginine deiminase (ADI) on arginine-dependent tumors in situ.

Adverse Impacts of PEGylated Protein Therapeutics: A Targeted Literature Review

The beneficial effects of polyethylene glycol (PEG)-conjugated therapeutics, such as increased half-life, solubility, stability, and decreased immunogenicity, have been well described. There have been concerns, however, about adverse outcomes with their use, but understanding of those adverse outcomes is still relatively limited. The present study aimed to characterize adverse outcomes associated with PEGylation of protein-based therapeutics on immunogenicity, pharmacologic properties, and safety. A targeted review of English language articles published from 1990 to September 29, 2023, was conducted. Of the 29 studies included in this review, 18 reported adverse safety outcomes such as hematologic complications, hepatic toxicity, injection site reactions, arthralgia, nausea, infections, grade 3 or 4 adverse events (AEs), and AE-related discontinuations and dose modifications. Fifteen studies reported immunogenicity-related outcomes, such as the prevalence of pre-existing antibodies to PEG, treatment-emergent antibody response, and hypersensitivity reactions to PEGylated drugs. Seven studies reported pharmacological outcomes such as increased clearance and reduced activity in response to PEGylated drugs. This review aims to contribute to a balanced view of PEGylated therapies by summarizing the adverse outcomes or lack of benefit associated with PEGylated therapeutics reported in the literature. We identified several studies characterizing adverse outcomes, pharmacological effects, and immunogenicity associated with the use of PEGylated therapeutics. Our findings suggest that using PEGylated therapeutics may require careful monitoring for adverse safety outcomes, including screening and monitoring for pre-existing antibodies and those induced in response to PEGylated therapy, as well as monitoring and adjusting the dosing of PEGylated therapeutics.

Whole-body fluorescence cryotomography identifies a fast-acting, high-contrast, durable contrast agent for fluorescence-guided surgery

Imaging of tumor-specific fluorescent contrast agents to guide tumor removal has been shown to improve outcomes and is now standard practice for some neurosurgical procedures. However, many agents require administration hours before surgery, a practical challenge, and may exhibit inconsistent concordance with contrast-enhanced MRI (CE-MRI), the current standard for diagnosing and guiding glioma removal. A fluorescent agent that accurately marks tumor shortly after administration and is otherwise similar to CE-MRI would help overcome these shortcomings. Methods: We used whole-body 3-D fluorescence cryo-imaging and co-registered CE-MRI volumes to evaluate several fluorescent contrast agent candidates for diagnostic performance and concordance with CE-MRI. Mice with brain tumors were administered a cocktail of fluorescent agent candidates and a MRI contrast agent, and then imaged with MRI and fluorescence cryo-imaging at several timepoints after administration. The high-resolution 3-D cryo-imaging volumes of the fluorescent agents were used to determine diagnostic performance metrics and correlation with CE-MRI. Results: While all agents showed positive metrics, one agent, tetramethylrhodamine conjugated to a small polyethylene glycol chain (TMR-PEG1k), outperformed the others, exhibiting minimal normal brain signal, high tumor-to-background-ratio, diagnostic accuracy, and cross-correlation to CE-MRI at all post-administration timepoints (10-90 min) and tumor lines examined. Conclusion: These favorable properties establish TMR-PEG1k as a promising candidate for surgical guidance.

Targeted radiopharmaceuticals: an underexplored strategy for ovarian cancer

Ovarian cancer is the most common gynecological malignancy worldwide with the highest mortality. This low survival rate can be attributed to the fact that symptoms arise only at an advanced disease stage, characterized by a (micro)metastatic spread across the peritoneal cavity. Radiopharmaceuticals, composed of a targeting moiety coupled with either a diagnostic or therapeutic radionuclide, constitute a relatively underexplored theranostic approach that may improve the current standard of care. Efficient patient stratification, follow-up and treatment are several caveats that could be addressed with theranostics to improve patient outcomes. So far, the bulk of research is situated and often halted at the preclinical level, employing murine models of primary and metastatic peritoneal disease that do not necessarily provide an accurate representation of the disease heterogeneity, (intrinsic) drug resistance or the complex physiological interactions with the tumor microenvironment. Radioimmunoconjugates with therapeutic α- and electron-emitting radionuclides have been the prevailing standard, targeting a myriad of cell-membrane markers that are expressed in the various heterogeneous histological subtypes of ovarian cancer. Evidently, several hurdles exist within preclinical research that are potentially withholding these agents from advancing into clinical practice. On the other hand, the field of nuclear medicine has also seen significant innovation to address shortcomings related to target/ligand identification, preclinical research models, radiochemistry, radiopharmacy and dosimetry, as outlined in this review. Altogether, theranostics hold great promise to answer an unmet medical need for ovarian cancer.

PEGylated Pemetrexed and PolyNIPAM Decorated Gold Nanoparticles: A Biocompatible and Highly Stable CT Contrast Agent for Cancer Imaging

This study describes a multifunctional nanoparticle platform for targeted CT imaging and therapy of cancers. Pemetrexed (conjugated with polyethylene glycol, MW 2000 Da) and polyNIPAM (PEGylated) were designed for targeted delivery to folate receptors and thermally ablated tumors, respectively. These moieties were coated on gold nanoparticles (7 and 30 nm), and the prepared compounds were characterized using 1H NMR, FT-IR, CHNS, DLS, TEM, TGA, and UV-vis. The resulting agents exhibited 2-4 times higher X-ray attenuation compared to Visipaque and demonstrated specific accumulation in tumor tissue (4T1 xenograft model) 90 min after injection in mice. The nanoparticles displayed anticancer activity against 4T1 and MDA-MB-231 breast cancer cells (IC50: 182.87 and 206.18 μg/mL) and good biocompatibility. Importantly, the platform showed excellent stability over a year and at pH 2-12 and temperature range of -78 to 40 °C, and a water-dichloromethane extraction method was optimized for efficient purification, facilitating large-scale production.

Evaluation of ABD-Linked RM26 Conjugates for GRPR-Targeted Drug Delivery

Targeting the gastrin-releasing peptide receptor (GRPR) with the bombesin analogue RM26, a 9 aa peptide, has been a promising strategy for cancer theranostics, with recent success in radionuclide imaging of prostate cancer. However, therapeutic application of the short peptide RM26 would require a longer half-life to prevent fast clearance from the circulation. Conjugation to an albumin-binding domain (ABD) is a viable strategy to extend the in vivo half-life of peptides and proteins. We previously reported an ABD-fused RM26 peptide targeting GRPR (ABD-RM26 Gen 1) that showed prolonged and stable tumor uptake over 144 h; however, the observed high kidney uptake indicated that the conjugate's binding to albumin was reduced and that this could be an obstacle for its use as a delivery system for targeted therapy, especially for radiotherapy. Here, we have designed, produced, and preclinically evaluated a series of novel ABD-RM26 conjugates with the aim of improving the conjugate's binding to albumin and decreasing the kidney uptake. We developed three second-generation constructs with varying formats, differing in the relative positions of the targeting moieties and the radionuclide chelator. The produced conjugates were radiolabeled with indium-111 and evaluated in vitro and in vivo. All constructs displayed improved biophysical characteristics, biodistribution, and lower kidney uptake compared to previously reported first-generation molecules. The ABD-RM26 Gen 2A conjugate showed the best biodistribution profile with a nearly 6-fold reduction in kidney uptake. However, the ABD-RM26 Gen 2A conjugate's binding to GRPR was compromised. This conjugate's assembly of albumin- and GRPR-binding moieties might be used for further development of drug conjugates for targeted therapy/radiotherapy of GRPR-expressing cancers.

The JAK-STAT pathway: from structural biology to cytokine engineering

The Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway serves as a paradigm for signal transduction from the extracellular environment to the nucleus. It plays a pivotal role in physiological functions, such as hematopoiesis, immune balance, tissue homeostasis, and surveillance against tumors. Dysregulation of this pathway may lead to various disease conditions such as immune deficiencies, autoimmune diseases, hematologic disorders, and cancer. Due to its critical role in maintaining human health and involvement in disease, extensive studies have been conducted on this pathway, ranging from basic research to medical applications. Advances in the structural biology of this pathway have enabled us to gain insights into how the signaling cascade operates at the molecular level, laying the groundwork for therapeutic development targeting this pathway. Various strategies have been developed to restore its normal function, with promising therapeutic potential. Enhanced comprehension of these molecular mechanisms, combined with advances in protein engineering methodologies, has allowed us to engineer cytokines with tailored properties for targeted therapeutic applications, thereby enhancing their efficiency and safety. In this review, we outline the structural basis that governs key nodes in this pathway, offering a comprehensive overview of the signal transduction process. Furthermore, we explore recent advances in cytokine engineering for therapeutic development in this pathway.

Controlled release of therapeutic antibody using hydrolytically degradable microgels

Monoclonal antibodies have gained significant interest as potential therapeutics for treating various diseases. However, these therapies are not always effective due to poor treatment compliance associated with multiple administrations and drug resistance. Thus, there is a growing interest in developing advanced monoclonal antibody delivery systems that can customize pharmacokinetics to enhance therapeutic outcomes. This work aimed to engineer hydrolytic 4-arm PEG maleimide (PEG-4MAL) microgels for the controlled delivery of therapeutic antibodies, specifically anti-angiogenic bevacizumab, to overcome the limitations of current monoclonal antibody therapies. Through a PEGylation reaction with a thiol-terminated PEG linker, the antibody was covalently conjugated to the macromer backbone before microgel synthesis. The PEGylation reaction was simple, effective, and did not affect antibody bioactivity. Antibody release kinetics was tuned by changing the concentration of the hydrolytic linker (0-2 mM) and/or PEG-4MAL:protein molar ratio (1000:1, 2000:1, and 5000:1) in the macromer precursor solution during microgel fabrication. The bioactivity of the released antibody was assessed on human umbilical endothelial vascular cells (HUVEC), demonstrating that extracts from hydrolytic microgels reduced cell proliferation over time. Collectively, this study demonstrates the development of highly tunable delivery platform based on degradable PEG-4MAL microgels that can be adapted for therapeutic antibody-controlled release.

A Facile Approach to Producing Liposomal J-Aggregates of Indocyanine Green with Diagnostic and Therapeutic Potential

Liposomal J-Aggregates of Indocyanine Green (L-JA) can serve as a biocompatible and biodegradable nanoparticle for photoacoustic imaging and photothermal therapy. When compared to monomeric IcG, L-JA are characterized by longer circulation, improved photostability, elevated absorption at longer wavelengths, and increased photoacoustic signal generation. However, the documented methods for production of L-JA vary widely. We developed an approach to efficiently form IcG J-aggregates (IcG-JA) directly in liposomes at elevated temperatures. Aggregating within fully formed liposomes ensures particle uniformity and allows for control of J-aggregate size. L-JA have unique properties compared to IcG. L-JA provide significant contrast enhancement in photoacoustic images for up to 24 hours after injection, while IcG and unencapsulated IcG-JA are cleared within an hour. L-JA allow for more accurate photoacoustic-based sO2 estimation and particle tracking compared to IcG. Furthermore, photothermal heating of L-JA with an 852nm laser is demonstrated to be more effective at lower laser powers than conventional 808nm lasers for the first time. The presented technique offers an avenue for formulating a multi-faceted contrast agent for photoacoustic imaging and photothermal therapy that offers significant advantages over other conventional agents.

Controlling rates and reversibilities of elimination reactions of hydroxybenzylammoniums by tuning dearomatization energies

Hydroxybenzylammonium compounds can undergo a reversible 1,4- or 1,6-elimination to afford quinone methide intermediates after release of the amine. These molecules are useful for the reversible conjugation of payloads to amines. We hypothesized that aromaticity could be used to alter the rate of reversibility as a distinct thermodynamic driving force. We describe the use of density functional theory (DFT) calculations to determine the effect of aromaticity on the rate of release of the amine from hydroxybenzylammonium compounds. Namely, the aromatic scaffold affects the dearomatization reaction to reduce the kinetic barrier and prevent the reversibility of the amine elimination. We consequently synthesized a small library of polycyclic hydroxybenzylammoniums, which resulted in a range of release half-lives from 18 minutes to 350 hours. The novel mechanistic insight provided herein significantly expands the range of release rates amenable to hydroxybenzylammonium-containing compounds. This work provides another way to affect the rate of payload release in hydroxybenzylammoniums.

Peptide-functionalized, -assembled and -loaded nanoparticles in cancer therapy

The combination of peptides and nanoparticles in cancer therapy has shown synergistic results. Nanoparticle functionalization with peptides can increase their targeting ability towards tumor cells. In some cases, the peptides can develop self-assembled nanoparticles, in combination with drugs, for targeted cancer therapy. The peptides can be loaded into nanoparticles and can be delivered by other drugs for synergistic cancer removal. Multifunctional types of peptide-based nanoparticles, including pH- and redox-sensitive classes, have been introduced in cancer therapy. The tumor microenvironment remolds, and the acceleration of immunotherapy and vaccines can be provided by peptide nanoparticles. Moreover, the bioimaging and labeling of cancers can be mediated by peptide nanoparticles. Therefore, peptides can functionalize nanoparticles in targeted cancer therapy.

Polymer-drug and polymer-protein conjugated nanocarriers: Design, drug delivery, imaging, therapy, and clinical applications

Polymer-drug conjugates and polymer-protein conjugates have been pivotal in the realm of drug delivery systems for over half a century. These polymeric drugs are characterized by the conjugation of therapeutic molecules or functional moieties to polymers, enabling a range of benefits including extended circulation times, targeted delivery, controlled release, and decreased immunogenicity. This review delves into recent advancements and challenges in the clinical translations and preclinical studies of polymer-drug conjugates and polymer-protein conjugates. The design principles and functionalization strategies crucial for the development of these polymeric drugs were explored followed by the review of structural properties and characteristics of various polymer carriers. This review also identifies significant obstacles in the clinical translation of polymer-drug conjugates and provides insights into the directions for their future development. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Enzymatic depletion of circulating glutamine is immunosuppressive in cancers

Although glutamine addiction in cancer cells is extensively reported, there is controversy on the impact of glutamine metabolism on the immune cells within the tumor microenvironment (TME). To address the role of extracellular glutamine, we enzymatically depleted circulating glutamine using PEGylated Helicobacter pylori gamma-glutamyl transferase (PEG-GGT) in syngeneic mouse models of breast and colon cancers. PEG-GGT treatment inhibits growth of cancer cells in vitro, but in vivo it increases myeloid-derived suppressor cells (MDSCs) and has no significant impact on tumor growth. By deriving a glutamine depletion signature, we analyze diverse human cancers within the TCGA and illustrate that glutamine depletion is not associated with favorable clinical outcomes and correlates with accumulation of MDSC. Broadly, our results help clarify the integrated impact of glutamine depletion within the TME and advance PEG-GGT as an enzymatic tool for the systemic and selective depletion (no asparaginase activity) of circulating glutamine in live animals.

The use of proteins and peptides-based therapy in managing and preventing pathogenic viruses

Therapeutic proteins have been employed for centuries and reached approximately 50 % of all drugs investigated. By 2023, they represented one of the top 10 largest-selling pharma products ($387.03 billion) and are anticipated to reach around $653.35 billion by 2030. Growth hormones, insulin, and interferon (IFN α, γ, and β) are among the leading applied therapeutic proteins with a higher market share. Protein-based therapies have opened new opportunities to control various diseases, including metabolic disorders, tumors, and viral outbreaks. Advanced recombinant DNA biotechnology has offered the production of therapeutic proteins and peptides for vaccination, drugs, and diagnostic tools. Prokaryotic and eukaryotic expression host systems, including bacterial, fungal, animal, mammalian, and plant cells usually applied for recombinant therapeutic proteins large-scale production. However, several limitations face therapeutic protein production and applications at the commercial level, including immunogenicity, integrity concerns, protein stability, and protein degradation under different circumstances. In this regard, protein-engineering strategies such as PEGylation, glycol-engineering, Fc-fusion, albumin conjugation, and fusion, assist in increasing targeting, product purity, production yield, functionality, and the half-life of therapeutic protein circulation. Therefore, a comprehensive insight into therapeutic protein research and findings pave the way for their successful implementation, which will be discussed in the current review.

Aerosolization of poly(sulfobetaine) microparticles that encapsulate therapeutic antibodies

Pulmonary delivery of protein therapeutics poses significant challenges that have not been well addressed in the research literature or practice. In fact, there is currently only one commercial protein therapeutic that is delivered through aerosolization and inhalation. In this study, we propose a drug delivery strategy that enables a high-concentration dosage for the pulmonary delivery of antibodies as an aerosolizable solid powder with desired stability. We utilized zwitterionic polymers for their promising properties as drug delivery vehicles and synthesized swellable, biodegradable poly(sulfo-betaine) (pSB) microparticles. The microparticles were loaded with Immunoglobulin G (IgG) as a model antibody. We quantified the microparticle size and morphology, and the particles were found to have an average diameter of 1.6 μm, falling within the optimal range (~1-5 μm) for pulmonary drug delivery. In addition, we quantified the impact of the crosslinker to monomer ratio on particle morphology and drug loading capacity. The results showed that there is a trade-off between desired morphology and drug loading capacity as the crosslinker density increases. In addition, the particles were aerosolized, and our data indicated that the particles remained intact and retained their initial morphology and size after aerosolization. The combination of morphology, particle size, antibody loading capacity, low cytotoxicity, and ease of aerosolization support the potential use of these particles for pulmonary delivery of protein therapeutics.

Dimethyl sulfoxide as a gas phase charge-reducing agent for the determination of PEGylated proteins' intact mass

Determination of PEGylated proteins' intact mass by mass spectrometry is challenging due to the molecules' large size, excessive charges, and instrument limitations. Previous efforts have been reported. However, signal variability, ion coalescence, and a generally low degree of robustness have been observed. In this work, we have explored the capabilities of post-column infusion of dimethyl sulfoxide (DMSO) following reversed-phase liquid chromatography-mass spectrometry (RP-LCMS) to determine PEG-filgrastim' intact mass, and to characterize its PEG moiety. The method was optimized around reproducibility (six preparations, and three injection replicates) with an in-house prepared PEG-filgrastim standard. The method showed a mass accuracy of ≤1.2 Da. The average molecular weight (MWEO=483) was 40 147.9 Da. The number average molecular weight (Mn) and the weight average molecular weight (Mw) were observed to be 40 101.1 and 40 113.9 Da, respectively, both with an RSD of 0.03%. The molecular weight distribution of ethylene oxide (EO), the polydispersity index (PDI), was 1.0003 for all preparations with a minimum and maximum number of EO units of 448 ± 2 and 516 ± 2, respectively. The method was finally applied to commercially available Neulasta® lots where the Mn and Mw were 39 995.8 and 40 008.8 Da, respectively, both with an RSD of 0.1%. The minimum and maximum EO units across the lots were observed to be 444.5 ± 1.5 and 514 ± 3, respectively. The PDI for all Neulasta® lots was 1.0003. This study provides an insightful characterization of Neulasta® and describes a robust LC-MS methodology for the characterization of the PEGylated proteins.

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.

An organometallic swap strategy for bottlebrush polymer-protein conjugate synthesis

Polymer-protein bioconjugation offers a powerful strategy to alter the physical properties of proteins, and various synthetic polymer compositions and architectures have been investigated for this purpose. Nevertheless, conjugation of molecular bottlebrush polymers (BPs) to proteins remains an unsolved challenge due to the large size of BPs and a general lack of methods to transform the chain ends of BPs into functional groups suitable for bioconjugation. Here, we present a strategy to address this challenge in the context of BPs prepared by "graft-through" ring-opening metathesis polymerization (ROMP), one of the most powerful methods for BP synthesis. Quenching ROMP of PEGylated norbornene macromonomers with an activated enyne terminator facilitates the transformation of the BP Ru alkylidene chain ends into Pd oxidative addition complexes (OACs) for facile bioconjugation. This strategy is shown to be effective for the synthesis of two BP-protein conjugates (albumin and ERG), setting the stage for a new class of BP-protein conjugates for future therapeutic and imaging applications.

Free PEG Suppresses Anaphylaxis to PEGylated Nanomedicine in Swine

Covalent conjugation of poly(ethylene glycol) (PEG) is frequently employed to enhance the pharmacokinetics and biodistribution of various protein and nanoparticle therapeutics. Unfortunately, some PEGylated drugs can induce elevated levels of antibodies that can bind PEG, i.e., anti-PEG antibodies (APA), in some patients. APA in turn can reduce the efficacy and increase the risks of allergic reactions, including anaphylaxis. There is currently no intervention available in the clinic that specifically mitigates allergic reactions to PEGylated drugs without the use of broad immunosuppression. We previously showed that infusion of high molecular weight free PEG could safely and effectively suppress the induction of APA in mice and restore prolonged circulation of various PEGylated therapeutics. Here, we explored the effectiveness of free PEG as a prophylaxis against anaphylaxis induced by PEG-specific allergic reactions in swine. Injection of PEG-liposomes (PL) resulted in anaphylactoid shock (pseudoanaphylaxis) within 1-3 min in both naïve and PL-sensitized swine. In contrast, repeated injection of free PEG alone did not result in allergic reactions, and injection of free PEG effectively suppressed allergic reactions to PL, including in previously PL-sensitized swine. These results strongly support the further investigation of free PEG for reducing APA and allergic responses to PEGylated therapeutics.

Nothing short of a revolution: Novel extended half-life factor VIII replacement products and non-replacement agents reshape the treatment landscape in hemophilia A

Hemophilia A, an X-linked genetic disorder, is characterized by a deficiency or dysfunction of clotting Factor VIII. The treatment landscape has substantially changed by introducing novel extended half-life factor VIII (EHL-FVIII) replacement therapies such as efanesoctocog Alfa and non-factor replacement therapy such as emicizumab. These agents signal a shift from treatments requiring multiple weekly infusions to advanced therapies with long half-lives, offering superior protection against bleeding and improving patient adherence and quality of life. While EHL-FVIII treatment might lead to inhibitor development in some patients, non-factor replacement therapy carries thrombotic risks. Therefore, ongoing research and the generation of robust clinical evidence remain vital to guide the selection of optimal and cost-effective first-line therapies for hemophilia A patients.

Therapeutic synthetic and natural materials for immunoengineering

Immunoengineering is a rapidly evolving field that has been driving innovations in manipulating immune system for new treatment tools and methods. The need for materials for immunoengineering applications has gained significant attention in recent years due to the growing demand for effective therapies that can target and regulate the immune system. Biologics and biomaterials are emerging as promising tools for controlling immune responses, and a wide variety of materials, including proteins, polymers, nanoparticles, and hydrogels, are being developed for this purpose. In this review article, we explore the different types of materials used in immunoengineering applications, their properties and design principles, and highlight the latest therapeutic materials advancements. Recent works in adjuvants, vaccines, immune tolerance, immunotherapy, and tissue models for immunoengineering studies are discussed.

Recent advances in nano/micro systems for improved circulation stability, enhanced tumor targeting, penetration, and intracellular drug delivery: a review

In recent years, nanoparticles (NPs) have been extensively developed as drug carriers to overcome the limitations of cancer therapeutics. However, there are several biological barriers to nanomedicines, which include the lack of stability in circulation, limited target specificity, low penetration into tumors and insufficient cellular uptake, restricting the active targeting toward tumors of nanomedicines. To address these challenges, a variety of promising strategies were developed recently, as they can be designed to improve NP accumulation and penetration in tumor tissues, circulation stability, tumor targeting, and intracellular uptake. In this Review, we summarized nanomaterials developed in recent three years that could be utilized to improve drug delivery for cancer treatments.

Docosahexaenoic Acid Promotes Eryptosis and Haemolysis through Oxidative Stress/Calcium/Rac1 GTPase Signalling

Docosahexaenoic acid (DHA) is an omega-3 polyunsaturated fatty acid with promising anticancer potential. Anaemia is a frequent adverse effect of anticancer treatment caused in part by eryptosis and haemolysis. Thus, it is important to investigate the role of DHA in red blood cell (RBC) death. RBCs were treated with anticancer concentrations (10-100 μM) of DHA under different physiological conditions, and fluorescence-assisted cell sorting was employed to measure eryptotic markers. Cell membrane scrambling was detected by annexin-V-FITC labelling, cytoplasmic Ca2+ by Fluo4/AM, cell size by forward scatter (FSC), and oxidative stress by H2DCFDA. Haemolytic markers were also assayed by photometric methods. DHA caused significant phospholipid scrambling with Ca2+ accumulation, loss of cellular volume, and oxidative stress. These changes were associated with dacrocyte formation, as revealed by electron microscopy. Moreover, DHA exhibited a dual effect on membrane integrity: it was haemolytic under isotonic conditions and anti-haemolytic in hypotonic environments. Importantly, inhibition of Rac1 GTPase activity with NSC23766 significantly reduced DHA-mediated haemolysis, as did co-administration of either sucrose or polyethylene glycol 8,000. Conversely, the presence of 125 mM KCl and urea without extracellular Ca2+ significantly exacerbated DHA toxicity. In conclusion, this is the first report that identifies key biochemical mechanisms underlying the cytotoxic effects of DHA in RBCs, promoting further development and validation of DHA in anticancer therapy.

PEGylated therapeutics in the clinic

The covalent attachment of polyethylene glycol (PEG) to therapeutic agents, termed PEGylation, is a well-established and clinically proven drug delivery approach to improve the pharmacokinetics and pharmacodynamics of drugs. Specifically, PEGylation can improve the parent drug's solubility, extend its circulation time, and reduce its immunogenicity, with minimal undesirable properties. PEGylation technology has been applied to various therapeutic modalities including small molecules, aptamers, peptides, and proteins, leading to over 30 PEGylated drugs currently used in the clinic and many investigational PEGylated agents under clinical trials. Here, we summarize the diverse types of PEGylation strategies, the key advantages of PEGylated therapeutics over their parent drugs, and the broad applications and impacts of PEGylation in clinical settings. A particular focus has been given to the size, topology, and functionalities of PEG molecules utilized in clinically used PEGylated drugs, as well as those under clinical trials. An additional section has been dedicated to analyzing some representative PEGylated drugs that were discontinued at different stages of clinical studies. Finally, we critically discuss the current challenges faced in the development and clinical translation of PEGylated agents.

Stabilization challenges and aggregation in protein-based therapeutics in the pharmaceutical industry

Protein-based therapeutics have revolutionized the pharmaceutical industry and become vital components in the development of future therapeutics. They offer several advantages over traditional small molecule drugs, including high affinity, potency and specificity, while demonstrating low toxicity and minimal adverse effects. However, the development and manufacturing processes of protein-based therapeutics presents challenges related to protein folding, purification, stability and immunogenicity that should be addressed. These proteins, like other biological molecules, are prone to chemical and physical instabilities. The stability of protein-based drugs throughout the entire manufacturing, storage and delivery process is essential. The occurrence of structural instability resulting from misfolding, unfolding, and modifications, as well as aggregation, poses a significant risk to the efficacy of these drugs, overshadowing their promising attributes. Gaining insight into structural alterations caused by aggregation and their impact on immunogenicity is vital for the advancement and refinement of protein therapeutics. Hence, in this review, we have discussed some features of protein aggregation during production, formulation and storage as well as stabilization strategies in protein engineering and computational methods to prevent aggregation.

Revitalizing Cytokine-Based Cancer Immunotherapy through Advanced Delivery Systems

Cytokines can coordinate robust immune responses, holding great promise as therapeutics against infections, autoimmune diseases, and cancers. In cancer treatment, numerous pro-inflammatory cytokines have displayed promising efficacy in preclinical studies. However, their clinical application is hindered by poor pharmacokinetics, significant toxicity and unsatisfactory anticancer efficacy. Thus, while IFN-α and IL-2 are approved for specific cancer treatments, other cytokines still remain subject of intense investigation. To accelerate the application of cytokines as cancer immunotherapeutics, strategies need to be directed to improve their safety and anticancer performance. In this regard, delivery systems could be used to generate innovative therapies by targeting the cytokines or nucleic acids, such as DNA and mRNA, encoding the cytokines to tumor tissues. This review centers on these innovative delivery strategies for cytokines, summarizing key approaches, such as gene delivery and protein delivery, and critically examining their potential and challenges for clinical translation.

Nanomaterial surface modification toolkit: Principles, components, recipes, and applications

Surface-functionalized nanostructures are at the forefront of biotechnology, providing new opportunities for biosensors, drug delivery, therapy, and bioimaging applications. The modification of nanostructures significantly impacts the performance and success of various applications by enabling selective and precise targeting. This review elucidates widely practiced surface modification strategies, including click chemistry, cross-coupling, silanization, aldehyde linkers, active ester chemistry, maleimide chemistry, epoxy linkers, and other protein and DNA-based methodologies. We also delve into the application-focused landscape of the nano-bio interface, emphasizing four key domains: therapeutics, biosensing, environmental monitoring, and point-of-care technologies, by highlighting prominent studies. The insights presented herein pave the way for further innovations at the intersection of nanotechnology and biotechnology, providing a useful handbook for beginners and professionals. The review draws on various sources, including the latest research articles (2018-2023), to provide a comprehensive overview of the field.

PEGylation of Terminal Ligands as a Route to Decrease the Toxicity of Radiocontrast Re6-Clusters

The development of novel radiocontrast agents, mainly used for the visualization of blood vessels, is still an emerging task due to the variety of side effects of conventional X-ray contrast media. Recently, we have shown that octahedral chalcogenide rhenium clusters with phosphine ligands-Na2H14[{Re6Q8}(P(C2H4COO)3)6] (Q = S, Se)-can be considered as promising X-ray contrast agents if their relatively high toxicity related to the high charge of the complexes can be overcome. To address this issue, we propose one of the most widely used methods for tuning the properties of proteins and peptides-PEGylation (PEG is polyethylene glycol). The reaction between the clusters and PEG-400 was carried out in acidic aqueous media and resulted in the binding of up to five carboxylate groups with PEG. The study of cytotoxicity against Hep-2 cells and acute toxicity in mice showed a twofold reduction in toxicity after PEGylation, demonstrating the success of the strategy chosen. Finally, the compound obtained has been used for the visualization of blood vessels of laboratory rats by angiography and computed tomography.

Improving potential strategies for biological activities of phlorotannins derived from seaweeds

Seaweeds have garnered considerable attention due to their capacity to serve as exceptional reservoirs of numerous bioactive metabolites possessing substantial chemical and biological significance. .Phlorotannins constitute a significant class of natural polyphenols originating from brown seaweeds, featuring a broad spectrum of bioactive attributes and demonstrating potential applicability across various sectors. The potential health advantages associated with phlorotannins, particularly concerning the prevention of conditions linked to oxidative stress, such as inflammation, diabetes, and allergies, have generated substantial interest within the food and pharmaceutical industries. Nevertheless, current research remains insufficient in providing a comprehensive understanding of their absorption, as comparisons drawn with their terrestrial counterparts remain speculative. It is commonly presumed that phenolic compounds, including phlorotannins, face challenges due to their limited solubility, instability, and extensive metabolism, all of which restrict their bioavailability. In order to circumvent these limitations and amplify their utility as components of medicinal formulations or healthcare products, researchers have explored various strategies, including the encapsulation or integration of phlorotannins into nano-/micro-particles or advanced drug delivery systems. This review offers a thorough exploration of the structural and biological attributes of phlorotannins and furnishes insights into potential strategies showing promise for their effective utilization in preclinical and clinical applications.

Polypeptide-Based Systems: From Synthesis to Application in Drug Delivery

Synthetic polypeptides are biocompatible and biodegradable macromolecules whose composition and architecture can vary over a wide range. Their unique ability to form secondary structures, as well as different pathways of modification and biofunctionalization due to the diversity of amino acids, provide variation in the physicochemical and biological properties of polypeptide-containing materials. In this review article, we summarize the advances in the synthesis of polypeptides and their copolymers and the application of these systems for drug delivery in the form of (nano)particles or hydrogels. The issues, such as the diversity of polypeptide-containing (nano)particle types, the methods for their preparation and drug loading, as well as the influence of physicochemical characteristics on stability, degradability, cellular uptake, cytotoxicity, hemolysis, and immunogenicity of polypeptide-containing nanoparticles and their drug formulations, are comprehensively discussed. Finally, recent advances in the development of certain drug nanoformulations for peptides, proteins, gene delivery, cancer therapy, and antimicrobial and anti-inflammatory systems are summarized.

Surface modification strategies in translocating nano-vesicles across different barriers and the role of bio-vesicles in improving anticancer therapy

Nanovesicles and bio-vesicles (BVs) have emerged as promising tools to achieve targeted cancer therapy due to their ability to overcome many of the key challenges currently being faced with conventional chemotherapy. These challenges include the diverse and often complex pathophysiology involving the progression of cancer, as well as the various biological barriers that circumvent therapeutic molecules reaching their target site in optimum concentration. The scientific evidence suggests that surface-functionalized nanovesicles and BVs camouflaged nano-carriers (NCs) both can bypass the established biological barriers and facilitate fourth-generation targeting for the improved regimen of treatment. In this review, we intend to emphasize the role of surface-functionalized nanovesicles and BVs camouflaged NCs through various approaches that lead to an improved internalization to achieve improved and targeted oncotherapy. We have explored various strategies that have been employed to surface-functionalize and biologically modify these vesicles, including the use of biomolecule functionalized target ligands such as peptides, antibodies, and aptamers, as well as the targeting of specific receptors on cancer cells. Further, the utility of BVs, which are made from the membranes of cells such as mesenchymal stem cells (MSCs), white blood cells (WBCs), red blood cells (RBCs), platelets (PLTs) as well as cancer cells also been investigated. Lastly, we have discussed the translational challenges and limitations that these NCs can encounter and still need to be overcome in order to fully realize the potential of nanovesicles and BVs for targeted cancer therapy. The fundamental challenges that currently prevent successful cancer therapy and the necessity of novel delivery systems are in the offing.

Targeting GD2-Positive Tumor Cells by Pegylated scFv Fragment-Drug Conjugates Carrying Maytansinoids DM1 and DM4

Oligomerization of antibody fragments via modification with polyethylene glycol (pegylation) may alter their function and properties, leading to a multivalent interaction of the resulting constructs with the target antigen. In a recent study, we generated pegylated monomers and multimers of scFv fragments of GD2-specific antibodies using maleimide-thiol chemistry. Multimerization enhanced the antigen-binding properties and demonstrated a more efficient tumor uptake in a syngeneic GD2-positive mouse cancer model compared to monomeric antibody fragments, thereby providing a rationale for improving the therapeutic characteristics of GD2-specific antibody fragments. In this work, we obtained pegylated conjugates of scFv fragments of GD2-specific antibodies with maytansinoids DM1 or DM4 using tetravalent PEG-maleimide (PEG4). The protein products from the two-stage thiol-maleimide reaction resolved by gel electrophoresis indicated that pegylated scFv fragments constituted the predominant part of the protein bands, and most of the scFv formed pegylated monomers and dimers. The conjugates retained the ability to bind ganglioside GD2 comparable to that of the parental scFv fragment and to specifically interact with GD2-positive cells. Both induced significant inhibitory effects in the GD2-positive B78-D14 cell line, in contrast to the GD2-negative B16 cell line. The decrease in the B78-D14 cell viability when treated with scFv-PEG4-DM4 was more prominent than that for scFv-PEG4-DM1, and was characterized by a twofold lower half-maximal inhibitory concentration (IC50). Unlike the parental scFv fragment, the product of scFv and PEG4 conjugation (scFv-PEG4), consisting predominantly of pegylated scFv multimers and monomers, induced direct cell death in the GD2-positive B78-D14 cells. However, the potency of scFv-PEG4 was low in the selected concentration range, thus demonstrating that the cytotoxic effect of DM1 and DM4 within the antibody fragment-drug conjugates was primary. The suggested approach may contribute to development of novel configurations of antibody fragment-drug conjugates for cancer treatment.

Peptide-Based Agents for Cancer Treatment: Current Applications and Future Directions

Peptide-based strategies have received an enormous amount of attention because of their specificity and applicability. Their specificity and tumor-targeting ability are applied to diagnosis and treatment for cancer patients. In this review, we will summarize recent advancements and future perspectives on peptide-based strategies for cancer treatment. The literature search was conducted to identify relevant articles for peptide-based strategies for cancer treatment. It was performed using PubMed for articles in English until June 2023. Information on clinical trials was also obtained from ClinicalTrial.gov. Given that peptide-based strategies have several advantages such as targeted delivery to the diseased area, personalized designs, relatively small sizes, and simple production process, bioactive peptides having anti-cancer activities (anti-cancer peptides or ACPs) have been tested in pre-clinical settings and clinical trials. The capability of peptides for tumor targeting is essentially useful for peptide-drug conjugates (PDCs), diagnosis, and image-guided surgery. Immunomodulation with peptide vaccines has been extensively tested in clinical trials. Despite such advantages, FDA-approved peptide agents for solid cancer are still limited. This review will provide a detailed overview of current approaches, design strategies, routes of administration, and new technological advancements. We will highlight the success and limitations of peptide-based therapies for cancer treatment.

Molecular Sieving with PEGylated Dendron-Protein Conjugates

A series of generation 3-5 dendrons based on a bis(2,2-hydroxymethylpropionic acid) (bis-MPA) scaffold bearing three respective lengths of linear poly(ethylene glycol) at their periphery and a dibenzocyclooctyne unit at their core was prepared. These dendrons were appended to the surface of azide-decorated α-chymotrypsin (α-CT) via strain-promoted azide-alkyne cycloaddition to yield a library of dendron-protein conjugates. These conjugates were characterized by FT-IR and NMR spectroscopy and were imaged using cryo-electron microscopy. The activity of the PEGylated α-CT-dendron conjugates was investigated using a small molecule (benzoyl-l-tyrosine p-nitroanilide) as well as different proteins of different sizes and crystallinities (casein and bovine serum albumin) as substrates. It was found that the activity of the conjugates toward the small molecule was largely retained, while the activity toward the proteins was significantly diminished. Furthermore, the results indicate that for most of the conjugates the PEG length had a more pronounced impact on enzyme activity than the dendron generation. Overall, the highest sieving ratios were found for α-CT-dendron conjugates decorated with G3-PEG2000, G4-PEG2000, and G5-PEG1000, with the latter two structures offering the best combination of sieving ratio and small molecule activity.

NIR-II Nanoprobes: A Review of Components-Based Approaches to Next-Generation Bioimaging Probes

Fluorescence and photoacoustic imaging techniques offer valuable insights into cell- and tissue-level processes. However, these optical imaging modalities are limited by scattering and absorption in tissue, resulting in the low-depth penetration of imaging. Contrast-enhanced imaging in the near-infrared window improves imaging penetration by taking advantage of reduced autofluorescence and scattering effects. Current contrast agents for fluorescence and photoacoustic imaging face several limitations from photostability and targeting specificity, highlighting the need for a novel imaging probe development. This review covers a broad range of near-infrared fluorescent and photoacoustic contrast agents, including organic dyes, polymers, and metallic nanostructures, focusing on their optical properties and applications in cellular and animal imaging. Similarly, we explore encapsulation and functionalization technologies toward building targeted, nanoscale imaging probes. Bioimaging applications such as angiography, tumor imaging, and the tracking of specific cell types are discussed. This review sheds light on recent advancements in fluorescent and photoacoustic nanoprobes in the near-infrared window. It serves as a valuable resource for researchers working in fields of biomedical imaging and nanotechnology, facilitating the development of innovative nanoprobes for improved diagnostic approaches in preclinical healthcare.

Fibronectin-targeted FUD and PEGylated FUD peptides for fibrotic diseases

Tissue fibrosis is characterized by excessive deposition of extracellular matrix (ECM) molecules. Fibronectin (FN) is a glycoprotein found in the blood and tissues, a key player in the assembly of ECM through interaction with cellular and extracellular components. Functional Upstream Domain (FUD), a peptide derived from an adhesin protein of bacteria, has a high binding affinity for the N-terminal 70-kDa domain of FN that plays a crucial role in FN polymerization. In this regard, FUD peptide has been characterized as a potent inhibitor of FN matrix assembly, reducing excessive ECM accumulation. Furthermore, PEGylated FUD was developed to prevent rapid elimination of FUD and enhance its systemic exposure in vivo. Herein, we summarize the development of FUD peptide as a potential anti-fibrotic agent and its application in experimental fibrotic diseases. In addition, we discuss how modification of the FUD peptide via PEGylation impacts pharmacokinetic profiles of the FUD peptide and can potentially contribute to anti-fibrosis therapy.