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Abstract Realizing the immense clinical potential of mRNA-based drugs will require continued development of methods to safely deliver the bioactive agents with high efficiency and without triggering side effects. In this regard, lipid nanoparticles have been successfully utilized to improve mRNA delivery and protect the cargo from extracellular degradation. Encapsulation in lipid nanoparticles was an essential factor in the successful clinical application of mRNA vaccines, which conclusively demonstrated the technology's potential to yield approved medicines. In this review, we begin by describing current advances in mRNA modifications, design of novel lipids and development of lipid nanoparticle components for mRNA-based drugs. Then, we summarize key points pertaining to preclinical and clinical development of mRNA therapeutics. Finally, we cover topics related to targeted delivery systems, including endosomal escape and targeting of immune cells, tumors and organs for use with mRNA vaccines and new treatment modalities for human diseases.

Abstract Background The COVID-19 pandemic continues to pose a significant worldwide threat to human health, as emerging SARS-CoV-2 Omicron variants exhibit resistance to therapeutic antibodies and the ability to evade vaccination-induced antibodies. Here, we aimed to identify human antibodies (hAbs) from convalescent patients that are potent and broadly neutralizing toward Omicron sublineages. Methods Using a single B-cell cloning approach, we isolated BA.5 specific human antibodies. We further examined the neutralizing activities of the most promising neutralizing hAbs toward different variants of concern (VOCs) with pseudotyped virus. Results Sixteen hAbs showed strong neutralizing activities against Omicron BA.5 with low IC50 values (IC50

Abstract The novel coronavirus disease (COVID-19) pandemic remains a global public health crisis, presenting a broad range of challenges. To help address some of the main problems, the scientific community has designed vaccines, diagnostic tools and therapeutics for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The rapid pace of technology development, especially with regard to vaccines, represents a stunning and historic scientific achievement. Nevertheless, many challenges remain to be overcome, such as improving vaccine and drug treatment efficacies for emergent mutant strains of SARS-CoV-2. Outbreaks of more infectious variants continue to diminish the utility of available vaccines and drugs. Thus, the effectiveness of vaccines and drugs against the most current variants is a primary consideration in the continual analyses of clinical data that supports updated regulatory decisions. The first two vaccines granted Emergency Use Authorizations (EUAs), BNT162b2 and mRNA-1273, still show more than 60% protection efficacy against the most widespread current SARS-CoV-2 variant, Omicron. This variant carries more than 30 mutations in the spike protein, which has largely abrogated the neutralizing effects of therapeutic antibodies. Fortunately, some neutralizing antibodies and antiviral COVID-19 drugs treatments have shown continued clinical benefits. In this review, we provide a framework for understanding the ongoing development efforts for different types of vaccines and therapeutics, including small molecule and antibody drugs. The ripple effects of newly emergent variants, including updates to vaccines and drug repurposing efforts, are summarized. In addition, we summarize the clinical trials supporting the development and distribution of vaccines, small molecule drugs, and therapeutic antibodies with broad-spectrum activity against SARS-CoV-2 strains.

The COVID-19 pandemic continues to threaten human health worldwide as new variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerge. Currently, the predominant circulating strains around the world are Omicron variants, which can evade many therapeutic antibodies. Thus, the development of new broadly neutralizing antibodies remains an urgent need. In this work, we address this need by using the mRNA-lipid nanoparticle immunization method to generate a set of Omicron-targeting monoclonal antibodies. Five of our novel K-RBD-mAbs show strong binding and neutralizing activities toward all SARS-CoV-2 variants of concern (Alpha, Beta, Gamma, Delta and Omicron). Notably, the epitopes of these five K-RBD-mAbs are overlapping and localized around Y453 and F486 of the spike protein receptor binding domain (RBD). Chimeric derivatives of the five antibodies (K-RBD-chAbs) neutralize Omicron sublineages BA.1 and BA.2 with low IC50 values ranging from 5.7 to 12.9 ng/mL. Additionally, we performed antibody humanization on broadly neutralizing chimeric antibodies to create K-RBD-hAb-60 and -62, which still retain excellent neutralizing activity against Omicron. Our results collectively suggest that these five therapeutic antibodies may effectively combat current and emerging SARS-CoV-2 variants, including Omicron BA.1 and BA.2. Therefore, the antibodies can potentially be used as universal neutralizing antibodies against SARS-CoV-2.

Abstract The coronavirus disease 2019 (COVID-19) pandemic is an exceptional public health crisis that demands the timely creation of new therapeutics and viral detection. Owing to their high specificity and reliability, monoclonal antibodies (mAbs) have emerged as powerful tools to treat and detect numerous diseases. Hence, many researchers have begun to urgently develop Ab-based kits for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and Ab drugs for use as COVID-19 therapeutic agents. The detailed structure of the SARS-CoV-2 spike protein is known, and since this protein is key for viral infection, its receptor-binding domain (RBD) has become a major target for therapeutic Ab development. Because SARS-CoV-2 is an RNA virus with a high mutation rate, especially under the selective pressure of aggressively deployed prophylactic vaccines and neutralizing Abs, the use of Ab cocktails is expected to be an important strategy for effective COVID-19 treatment. Moreover, SARS-CoV-2 infection may stimulate an overactive immune response, resulting in a cytokine storm that drives severe disease progression. Abs to combat cytokine storms have also been under intense development as treatments for COVID-19. In addition to their use as drugs, Abs are currently being utilized in SARS-CoV-2 detection tests, including antigen and immunoglobulin tests. Such Ab-based detection tests are crucial surveillance tools that can be used to prevent the spread of COVID-19. Herein, we highlight some key points regarding mAb-based detection tests and treatments for the COVID-19 pandemic.

Abstract Background Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), an RNA virus with a high mutation rate. Importantly, several currently circulating SARS-CoV-2 variants are associated with loss of efficacy for both vaccines and neutralizing antibodies. Methods We analyzed the binding activity of six highly potent antibodies to the spike proteins of SARS-CoV-2 variants, assessed their neutralizing abilities with pseudovirus and authentic SARS-CoV-2 variants and evaluate efficacy of antibody cocktail in Delta SARS-CoV-2-infected hamster models as prophylactic and post-infection treatments. Results The tested RBD-chAbs, except RBD-chAb-25, maintained binding ability to spike proteins from SARS-CoV-2 variants. However, only RBD-chAb-45 and -51 retained neutralizing activities; RBD-chAb-1, -15, -25 and -28 exhibited diminished neutralization for all SARS-CoV-2 variants. Notably, several cocktails of our antibodies showed low IC50 values (3.35–27.06 ng/ml) against the SARS-CoV-2 variant pseudoviruses including United Kingdom variant B.1.1.7 (Alpha), South Africa variant B.1.351 (Beta), Brazil variant P1 (Gamma), California variant B.1.429 (Epsilon), New York variant B.1.526 (Iota), and India variants, B.1.617.1 (Kappa) and B.1.617.2 (Delta). RBD-chAb-45, and -51 showed PRNT50 values 4.93–37.54 ng/ml when used as single treatments or in combination with RBD-chAb-15 or -28, according to plaque assays with authentic Alpha, Gamma and Delta SARS-CoV-2 variants. Furthermore, the antibody cocktail of RBD-chAb-15 and -45 exhibited potent prophylactic and therapeutic effects in Delta SARS-CoV-2 variant-infected hamsters. Conclusions The cocktail of RBD-chAbs exhibited potent neutralizing activities against SARS-CoV-2 variants. These antibody cocktails are highly promising candidate tools for controlling new SARS-CoV-2 variants, including Delta.

Abstract It has been more than three decades since the first monoclonal antibody was approved by the United States Food and Drug Administration (US FDA) in 1986, and during this time, antibody engineering has dramatically evolved. Current antibody drugs have increasingly fewer adverse effects due to their high specificity. As a result, therapeutic antibodies have become the predominant class of new drugs developed in recent years. Over the past five years, antibodies have become the best-selling drugs in the pharmaceutical market, and in 2018, eight of the top ten bestselling drugs worldwide were biologics. The global therapeutic monoclonal antibody market was valued at approximately US$115.2 billion in 2018 and is expected to generate revenue of $150 billion by the end of 2019 and $300 billion by 2025. Thus, the market for therapeutic antibody drugs has experienced explosive growth as new drugs have been approved for treating various human diseases, including many cancers, autoimmune, metabolic and infectious diseases. As of December 2019, 79 therapeutic mAbs have been approved by the US FDA, but there is still significant growth potential. This review summarizes the latest market trends and outlines the preeminent antibody engineering technologies used in the development of therapeutic antibody drugs, such as humanization of monoclonal antibodies, phage display, the human antibody mouse, single B cell antibody technology, and affinity maturation. Finally, future applications and perspectives are also discussed.

Development of effective therapeutics for mitigating the COVID-19 pandemic is a pressing global need. Neutralizing antibodies are known to be effective antivirals, as they can be rapidly deployed to prevent disease progression and can accelerate patient recovery without the need for fully developed host immunity. Here, we report the generation and characterization of a series of chimeric antibodies against the receptor-binding domain (RBD) of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein. Some of these antibodies exhibit exceptionally potent neutralization activities in vitro and in vivo, and the most potent of our antibodies target three distinct non-overlapping epitopes within the RBD. Cryo-electron microscopy analyses of two highly potent antibodies in complex with the SARS-CoV-2 spike protein suggested they may be particularly useful when combined in a cocktail therapy. The efficacy of this antibody cocktail was confirmed in SARS-CoV-2-infected mouse and hamster models as prophylactic and post-infection treatments. With the emergence of more contagious variants of SARS-CoV-2, cocktail antibody therapies hold great promise to control disease and prevent drug resistance. Author summary Effective approaches to mitigate the COVID-19 pandemic are a pressing global need. One promising strategy is to combine neutralizing antibodies that can reduce viral load to prevent disease progression and accelerate patient recovery. However, the current supply of therapeutic antibodies for COVID-19 is insufficient to fill the enormous demand, and escape mutants may compromise the utility of existing drugs. Thus, there is an urgent worldwide need to develop highly potent neutralizing antibody cocktails. We generated a series of chimeric antibodies against the receptor-binding domain (RBD) of SARS-CoV-2 spike protein, which potently neutralize authentic SARS-CoV-2 infection according to the plaque reduction neutralization test (PRNT) and pseudovirus-based inhibition assay. These antibodies can be classified into three distinct groups based on their targets within the receptor-binding motif. Cryo-electron microscopy structural analyses of two representative receptor-binding domain-chimeric antibodies in complex with the SARS-CoV-2 spike protein further revealed two sets of non-overlapping epitopes, suggesting the potential for their combination in a therapeutic antibody cocktail. The prophylactic and therapeutic effects of these antibodies and their combination were demonstrated in SARS-CoV-2-infected mouse and hamster models. Thus, our potent neutralizing antibody cocktail has strong potential for development as an effective therapeutic drug to prevent and treat SARS-CoV-2 infection.

Mitigation strategies of the coronavirus disease 2019 (COVID-19) pandemic have been greatly hindered by the continuous emergence of SARS-CoV-2 variants. New sensitive, rapid diagnostic tests for the wide-spectrum detection of viral variants are needed. We generated a panel of 41 monoclonal antibodies against the SARS-CoV-2 nucleocapsid protein (NP) by using mice hybridoma techniques. Of these mAbs, nine exhibited high binding activities and were applied in latex-based lateral flow immunoassays (LFIAs). The LFIAs utilizing NP-mAb-7 and -40 had the best sensitivity and lowest limit of detection: 8 pg for purified NP and 625 TCID50/mL for the authentic virus (hCoV-19/Taiwan/4/2020). The specificity tests showed that the NP-mAb-40/7 LFIA strips did not cross-react with five human coronavirus strains or 20 other common respiratory pathogens. Importantly, we found that 10 NP mutants, including alpha (B.1.1.7), beta (B.1.351), gamma (P.1), and delta (B.1.617.2) variants, could be detected by NP-mAb-40/7 LFIA strips. A clinical study (n = 60) of the NP-mAb-40/7 LFIA strips demonstrated a specificity of 100% and sensitivity of 90% in infected individuals with cycle threshold (Ct) values < 29.5. These anti-NP mAbs have strong potential for use in the clinical detection of SARS-CoV-2 infection, whether the virus is wild-type or a variant of concern.

Targeted delivery of drugs to tumors represents a significant advance in cancer diagnosis and therapy. Therefore, development of novel tumor-specific ligands or pharmaceutical nanocarriers is highly desirable. In this study, we utilized phage display to identify a new targeting peptide, SP90, which specifically binds to breast cancer cells, and recognizes tumor tissues from breast cancer patients. We used confocal and electron microscopy to reveal that conjugation of SP90 with liposomes enables efficient delivery of drugs into cancer cells through endocytosis. Furthermore, in vivo fluorescent imaging demonstrated that SP90-conjugated quantum dots possess tumor-targeting properties. In tumor xenograft and orthotopic models, SP90-conjugated liposomal doxorubicin was found to improve the therapeutic index of the chemotherapeutic drug by selectively increasing its accumulation in tumors. We conclude that the targeting peptide SP90 has significant potential in improving the clinical benefits of chemotherapy in the treatment and the diagnosis of breast cancer.

Lung cancer ranks among the most common malignancies, and is the leading cause of cancer-related mortality worldwide. Chemotherapy for lung cancer can be made more specific to tumor cells, and less toxic to normal tissues, through the use of ligand-mediated drug delivery systems. In this study, we investigated the targeting mechanism of the ligand-mediated drug delivery system using a peptide, SP5-2, which specifically binds to non-small cell lung cancer (NSCLC) cells. Conjugation of SP5-2 to liposomes enhanced the amount of drug delivered directly into NSCLC cells, through receptor-mediated endocytosis. Functional SP5-2 improved the therapeutic index of Lipo-Dox by enhancing therapeutic efficacy, reducing side effects, and increasing the survival rate of tumor-bearing mice in syngenic, metastatic and orthotopic animal models. Accumulation of SP5-2-conjugated liposomal doxorubicin (SP5-2-LD) in tumor tissues was 11.2-fold higher than that of free doxorubicin, and the area under the concentration-time curve (AUC0-72 hours) was increased 159.2-fold. Furthermore, the experiment of bioavailability was assessed to confirm that SP5-2 elevates the uptake of the liposomal drugs by the tumor cells in vivo. In conclusion, the use of SP5-2-conjugated liposomes enhances pharmacokinetic properties, improves efficacy and safety profiles, and allows for controlled biodistribution and drug release.

Human embryonic stem cells (hESCs) are unique pluripotent cells capable of self-renewal and differentiation into all three germ layers. To date, more cell surface markers capable of reliably identifying hESCs are needed. The epithelial cell adhesion molecule (EpCAM) is a type I transmembrane glycoprotein expressed in several progenitor cell populations and cancers. It has been used to enrich cells with tumor-initiating activity in xenograft transplantation studies. Here, we comprehensively profile the expression of EpCAM by immunofluorescence microscopy, Western blotting, and flow cytometry using an anti-EpCAM monoclonal antibody (mAb) 0C98-1. We found EpCAM to be highly and selectively expressed by undifferentiated rather than differentiated hESCs. The protein and transcript level of EpCAM rapidly diminished as soon as hESC had differentiated. This silencing was closely and exclusively associated with the radical transformation of histone modification at the EpCAM promoter. Moreover, we demonstrated that the dynamic pattern of lysine 27 trimethylation of histone 3 was conferred by the interplay of SUZ12 and JMJD3, both of which were involved in maintaining hESC pluripotency. In addition, we used chromatin immunoprecipitation analysis to elucidate the direct regulation by EpCAM of several reprogramming genes, including c-MYC, OCT-4, NANOG, SOX2, and KLF4, to help maintain the undifferentiation of hESCs. Collectively, our results suggest that EpCAM might be used as a surface marker for hESC. The expression of EpCAM may be regulated by epigenetic mechanisms, and it is strongly associated with the maintenance of the undifferentiated state of hESCs. [ABSTRACT FROM AUTHOR]

Spinal muscular atrophy (SMA) is a recessive neuromuscular disorder caused by the homozygous loss of the SMN1 gene. The human SMN2 gene has a C-to-T transition at position +6 of exon 7 and thus produces exon 7-skipping mRNAs. However, we observed an unexpectedly high level of exon 7-containing SMN2 transcripts as well as SMN protein in testis of smn-/- SMN2 transgenic mice. Using affinity chromatography, we identified several SMN RNA-associating proteins in mouse testis and human HeLa cells, including hnRNP Q. The major hnRNP Q isoform, Q1, directly bound SMN exon 7 in the vicinity of nucleotide +6. Overexpression of hnRNP Q1 promoted the inclusion of exon 7 in SMN2, probably by activating the use of its upstream 3′ splice site. However, the minor isoforms Q2/Q3 could antagonize the activity of hnRNP Q1 and induced exon 7 exclusion. Intriguingly, enhanced exon 7 inclusion was also observed upon concomitant depletion of three hnRNP Q isoforms. Thus, differential expression of hnRNP Q isoforms may result in intricate control of SMN precursor mRNA splicing. Here, we demonstrate that hnRNP Q is a splicing modulator of SMN, further underscoring the potential of hnRNP Q as a therapeutic target for SMA. [ABSTRACT FROM AUTHOR]

A growing body of evidence supports the coordination of mRNA synthesis and its subsequent processing events. Nuclear proteins harboring both WW and FF protein interaction modules bind to splicing factors as well as RNA polymerase II and may serve to link transcription with splicing. To understand how WW domains coordinate the assembly of splicing complexes, we used glutathione S-transferase fusions containing WW domains from CA150 or FBP11 in pull-down experiments with HeLa cell nuclear extract. The WW domains associate preferentially with the U2 small nuclear ribonucleoprotein and with splicing factors SF1, U2AF, and components of the SF3 complex. Accordingly, WW domain-associating factors bind to the 3' part of a pre-mRNA to form a pre-spliceosome-like complex. We performed both in vitro and in vivo splicing assays to explore the role of WW/FF domain-containing proteins in this process. However, although CA150 is associated with the spliceosome, it appears to be dispensable for splicing in vitro. Nevertheless, in vivo depletion of CA150 substantially reduced splicing efficiency of a reporter pre-mRNA. Moreover, overexpression of CA150 fragments containing both WW and FF domains activated splicing and modulated alternative exon selection, probably by facilitating 3' splice site recognition. Our results suggest an essential role of WW/FF domaincontaining factors in pre-mRNA splicing that likely occurs in concert with transcription in vivo. [ABSTRACT FROM AUTHOR]