Rational design of a nanoparticle platform for oral prophylactic immunotherapy to prevent immunogenicity of therapeutic proteins

Tolerization with a Novel Dual-Acting Liposomal Tim Agonist Prepares the Immune System for the Success of Gene Therapy

Gene therapy holds great promise for treating various congenital rare diseases. However, immunogenicity against viral vectors used in gene therapy remains a challenge, impacting both the safety and efficacy of gene therapy products. Neutralizing antibodies against the vector capsid proteins impact the ability to re-dose patients, which a growing body of evidence suggests might be required for some indications and certain younger patient populations. In this communication, we report a novel dual-acting liposomal formulation that induces immune tolerance toward adeno-associated virus 9null (AAV9null) capsid proteins. We present in silico data on our first- and second-generation Tim agonist molecules as well as in vitro and in vivo data supporting the generation of antigen-specific regulatory T cells (Tregs) as well as abrogation of antibody response to AAV9null capsid in our animal models. These early data are encouraging and may offer a new solution to mitigate the immunogenicity induced by gene therapy products.

Exploring the Effects of Incorporating Different Bioactive Phospholipids into Messenger Ribonucleic Acid Lipid Nanoparticle (mRNA LNP) Formulations

The current rapid advancement in ribonucleic acid (RNA) therapeutics research depends on innovations in drug delivery, especially the development of a lipid-nanoparticle (LNP)-based system. The conventional LNP formulation typically contains four components, including an ionizable cationic lipid, a phospholipid, cholesterol or a cholesterol derivative, and poly(ethylene glycol) (PEG)-lipid, with each contributing to the formulation's overall stability and effectiveness. Among these four types of lipids, the phospholipid component is often known to provide structural support for the nanoparticles but is also a class of bioactive molecules with strong cell signaling potential. This study explores the possibility of incorporating some known structurally related bioactive phospholipids as the fifth component of a conventional four-component LNP formulation and assesses the impacts of such an approach on the physicochemical properties and biological functions of the mRNA LNP formulation. We screened a library of mRNA LNP formulations containing 7 different structurally related bioactive phospholipids at molar concentrations of 5%, 15% and 30% in addition to a conventional four-component LNP formulation (base). We observed differences in physicochemical properties between the mRNA LNP formulations that could be attributed to both the types of phospholipids examined and the molar concentrations used. Cryo-EM analysis revealed structural similarity between the Base formulation and the other formulations. We also characterized the protein expression level in HeLa cells and picked up a distinct cytokine panel signature for each formulation in human peripheral blood mononuclear cells (hPBMCs). Further immunophenotyping analysis showed that most cells that were transfected were CD4+ T cells, and the addition of the different bioactive phospholipids slightly altered cellular tropism. This exploratory study illustrates how adding the bioactive phospholipid can be used to modulate the LNP function, further expanding the design space for RNA LNP formulations and potentiating LNPs for use as RNA therapeutics.

Lipid Nanoparticle (LNP) -A Vector Suitable for Evolving Therapies for Advanced Hepatocellular Carcinoma (HCC)

Hepatocellular carcinoma (HCC) stands as the predominant form of primary liver cancer, characterized by a dismal prognosis. Therapeutic options for advanced HCC remain sparse, with efficacy significantly hampered by the emergence of drug resistance. In parallel with research into novel pharmacological agents, advances in drug delivery systems represent a promising avenue for overcoming resistance. Lipid nanoparticles (LNPs) have demonstrated considerable efficacy in the delivery of nucleic acid-based therapeutics and hold potential for broader applications in drug delivery. This review describes the development of LNPs tailored for HCC treatment and consolidates recent investigations using LNPs to target HCC.

Immune regulatory adjuvant approach to mitigate subcutaneous immunogenicity of monoclonal antibodies

Introduction

Immunogenicity continues to be a challenge for development and clinical utility of monoclonal antibodies, and there are gaps in our current ability to prevent anti-drug antibody development in a safe and antigen-specific manner.

Methods

To mitigate immunogenicity of monoclonal antibodies administered subcutaneously, O-phospho-L-serine (OPLS)-the head group of the tolerance-inducing phospholipid, phosphatidylserine-was investigated as an immunoregulatory adjuvant.

Results

Formulations of adalimumab, trastuzumab or rituximab with OPLS showed reduction in relative immunogenicity in mice compared to vehicle formulations, indicated by reduced anti-drug antibody development and significant reductions in CD138+ plasma cell differentiation in bone marrow. Titer development toward recombinant human hyaluronidase, a dispersion enhancer that was co-formulated with monoclonal antibodies, was similarly reduced. Subcutaneous administration of adalimumab with OPLS resulted in a two-fold increase in expression of type 1 regulatory (Tr1) T cell subset in the spleen. This is consistent with in vitro studies where co-culturing of dendritic cells primed with ovalbumin in the presence and absence of OPLS and antigen specific T-cells induced expression of Tr1 phenotype on live CD4+ T cells.

Conclusion

This adjuvant does not impact immune competence of non-human primates and mice, and repeated administration of the adjuvant does not show renal or hepatic toxicity. Formulation of monoclonal antibodies with the immunoregulatory adjuvant, OPLS, was found to be safe and effective at mitigating immunogenicity.

Immune response to the components of lipid nanoparticles for ribonucleic acid therapeutics

Ribonucleic acid therapeutics have advantages over biologics and small molecules, including lower safety risks, cheaper costs, and extensive targeting flexibility, which is rapidly fueling the expansion of the field. This is made possible by breakthroughs in the field of drug delivery, wherein lipid nanoparticles (LNPs) are one of the most clinically advanced systems. LNP formulations that are currently approved for clinical use typically contain an ionizable cationic lipid, a phospholipid, cholesterol, and a polyethylene glycol-lipid; each contributes to the stability and/or effectiveness of LNPs. In this review, we discuss the immunomodulatory effects associated with each of the lipid components. We highlight several studies in which the components of LNPs have been implicated in cellular sensing and explore the pathways involved.

Immunogenicity of Therapeutic Biological Modalities - Lessons from Hemophilia A Therapies

The introduction and development of biologics such as therapeutic proteins, gene-, and cell-based therapy have revolutionized the scope of treatment for many diseases. However, a significant portion of the patients develop unwanted immune reactions against these novel biological modalities, referred to as immunogenicity, and no longer benefit from the treatments. In the current review, using Hemophilia A (HA) therapy as an example, we will discuss the immunogenicity issue of multiple biological modalities. Currently, the number of therapeutic modalities that are approved or recently explored to treat HA, a hereditary bleeding disorder, is increasing rapidly. These include, but are not limited to, recombinant factor VIII proteins, PEGylated FVIII, FVIII Fc fusion protein, bispecific monoclonal antibodies, gene replacement therapy, gene editing therapy, and cell-based therapy. They offer the patients a broader range of more advanced and effective treatment options, yet immunogenicity remains the most critical complication in the management of this disorder. Recent advances in strategies to manage and mitigate immunogenicity will also be reviewed.

Sequential administration of virus-like particle-based nanomedicine to elicit enhanced tumor chemotherapy

Protein cages have played a long-standing role in biomedicine applications, especially in tumor chemotherapy. Among protein cages, virus like particles (VLPs) have received attention for their potential applications in vaccine development and targeted drug delivery. However, most of the existing protein-based platform technologies are plagued with immunological problems that may limit their systemic delivery efficiency as drug carriers. Here, we show that using immune-orthogonal protein cages sequentially and modifying the dominant loop epitope can circumvent adaptive immune responses and enable effective drug delivery using repeated dosing. We genetically modified three different hepadnavirus core protein derived VLPs as delivery vectors for doxorubicin (DOX). These engineered VLPs have similar assembly characteristics, particle sizes, and immunological properties. Our results indicated that there was negligible antibody cross-reactivity in either direction between these three RGD-VLPs in mice that were previously immunized against HBc VLPs. Moreover, the sequential administration of multiple RGD-VLP-based nanomedicine (DOX@RGD-VLPs) could effectively reduce immune clearance and inhibited tumor growth. Hence, this study could provide an attractive protein cage-based platform for therapeutic drug delivery.

Phosphatidylserine-mediated oral tolerance

Phosphatidylserine (PS) is an anionic phospholipid exposed on the surface of apoptotic cells. The exposure of PS typically recruits and signals phagocytes to engulf and silently clear these dying cells to maintain tolerance via immunological ignorance. However, recent and emerging evidence has demonstrated that PS converts an "immunogen" into a "tolerogen", and PS exposure on the surface of cells or vesicles actively promotes a tolerogenic environment. This tolerogenic property depends on the biophysical characteristics of PS-containing vesicles, including PS density on the particle surface to effectively engage tolerogenic receptors, such as TIM-4, which is exclusively expressed on the surface of antigen-presenting cells. We harnessed the cellular and molecular mechanistic insight of PS-mediated immune regulation to design an effective oral tolerance approach. This immunotherapy has been shown to prevent/reduce immune response against life-saving protein-based therapies, food allergens, autoantigens, and the antigenic viral capsid peptide commonly used in gene therapy, suggesting a broad spectrum of potential clinical applications. Given the good safety profile of PS together with the ease of administration, oral tolerance achieved with PS-based nanoparticles has a very promising therapeutic impact.

Biophysical Characterization of Tolerogenic Lipid-Based Nanoparticles Containing Phosphatidylcholine and Lysophosphatidylserine

Autoimmune conditions, allergies, and immunogenicity against therapeutic proteins are initiated by the unwanted immune response against self and non-self proteins. The development of tolerance induction approaches can offer an effective treatment modality for these clinical conditions. We recently showed that oral administration of lipidic nanoparticles containing phosphatidylcholine (PC) and lysophosphatidylserine (Lyso-PS) converted an immunogen to a tolerogen and induced immunological tolerance towards several antigens. While the biophysical properties such as lamellar characteristics of this binary lipid system are critical for stability, therapeutic delivery, and mechanism of tolerance induction, such information has not been thoroughly investigated. In the current study, we evaluated the lamellar phase properties of PC/Lyso-PS system using orthogonal biophysical methods such as fluorescence (steady-state, anisotropy, PSvue, and Laurdan), dynamic light scattering, and differential scanning calorimetry. The results showed that Lyso-PS partitioned into the PC bilayers and led to changes in the particles' lamellar phase properties, lipid-packing, and lipid-water dynamics. Additionally, the biophysical characteristics of PC/Lyso-PS system are different from the well-studied PC/double-chain phosphatidylserine (PS) system. Notably, the incorporation of Lyso-PS significantly reduced the hydrodynamic diameter of PC particles. Results from the in vivo uptake study and intestinal loop assay utilizing flow cytometry analysis also indicated that the uptake of Lyso-PS-containing nanoparticles by immune cells in the gut and Peyer's patches is significantly higher than that of double-chain PS due to the differential transport through microfold cells. It was also found that the acyl chain mismatch between PC and Lyso-PS is critical for the miscibility and particle stability. Collectively, the results suggest that these biophysical characteristics likely influence the in vivo behaviors and contribute to the oral tolerance property of PC/Lyso-PS system.

Tumor-Associated Exosomes: A Potential Therapeutic Target for Restoring Anti-Tumor T Cell Responses in Human Tumor Microenvironments

Exosomes are a subset of extracellular vesicles (EVs) that are released by cells and play a variety of physiological roles including regulation of the immune system. Exosomes are heterogeneous and present in vast numbers in tumor microenvironments. A large subset of these vesicles has been demonstrated to be immunosuppressive. In this review, we focus on the suppression of T cell function by exosomes in human tumor microenvironments. We start with a brief introduction to exosomes, with emphasis on their biogenesis, isolation and characterization. Next, we discuss the immunosuppressive effect of exosomes on T cells, reviewing in vitro studies demonstrating the role of different proteins, nucleic acids and lipids known to be associated with exosome-mediated suppression of T cell function. Here, we also discuss initial proof-of-principle studies that established the potential for rescuing T cell function by blocking or targeting exosomes. In the final section, we review different in vivo models that were utilized to study as well as target exosome-mediated immunosuppression, highlighting the Xenomimetic mouse (X-mouse) model and the Omental Tumor Xenograft (OTX) model that were featured in a recent study to evaluate the efficacy of a novel phosphatidylserine-binding molecule for targeting immunosuppressive tumor-associated exosomes.