Antibody variable region engineering for improving cancer immunotherapy

Comparison of single-chain variable fragments and monoclonal antibody against dihydroartemisinin

Immunoassay relies on antibodies, but traditional antibodies such as monoclonal antibody (mAb) require animal immunization and complex procedures. Single-chain variable fragment (scFv) becomes a potential alternative to mAb with advantages of the low cost, rapid and easy prepared. In the present study, we prepared scFvs against dihydroartemisinin (DHA) based on E. coli and HEK293T cell expression system, named MBP-scFv and scFv-Fc, respectively. Their properties were compared with the parent mAb. The calculated affinity constants of mAb, MBP-scFv and scFv-Fc were 2.1 × 108 L mol-1, 2.2 × 107 L mol-1 and 1.6 × 108 L mol-1, respectively. The half inhibitory concentration (IC50) of mAb, MBP-scFv and scFv-Fc were 1.16 ng mL-1, 2.15 ng mL-1 and 6.57 ng mL-1, respectively. Both the scFv showed less sensitive than the mAb based on the IC50. The cross-reactivities of MBP-scFv for artemisinin and artesunate exhibited similarities to the mAb, yet the cross-reactivities of scFv-Fc for these compounds exceeded those of the mAb significantly. The stability of the scFvs was ascertained to be maintained for over 5 days at room temperature, and for more than a month at both 4 °C and - 20 °C. After that, the indirect competitive enzyme-linked immunosorbent assays (icELISAs) based on the scFv from E. coli were used to detect the DHA content in eight drug samples, and the result was consistent with ultra-performance liquid chromatography simultaneously. Although scFv can be used for quantitative determination of drugs, but it still cannot completely replace mAb in immunoassay without evolution and modification.

The Potential of Single-Chain Variable Fragment Antibody: Role in Future Therapeutic and Diagnostic Biologics

The advancement of genetic engineering has revolutionized the field of immunology by allowing the utilization of intrinsic antibody structures. One of the biologics that are being produced by recombinant antibody technology is single-chain fragments variable (scFv). Genes of variable regions, the heavy and light chains that are genetically linked into a single transcript by a short flexible linker peptide, are used to generate this fragment from cellular and synthetic libraries. The specificity and affinity of these molecules are comparable to those of parental antibodies. Fusion with marker proteins and other potent molecules improves their stability, circulation half-life, activity, and efficient purification. Besides, this review comprises construction protocols, therapeutics, and diagnostic applications of scFv, as well as related challenges. Nonetheless, there are still issues with efficacy, stability, safety, intracellular administration, and production costs that need to be addressed.

Precision engineering of antibodies: A review of modification and design in the Fab region

The binding of functional groups to antibodies is crucial for disease treatment, diagnosis, and basic scientific research. Traditionally, antibody modifications have focused on the Fc region to maintain antigen-antibody binding activity. However, such modifications may impact critical antibody functions, including immune cell surface receptor activation, cytokine release, and other immune responses. In recent years, modifications targeting the antigen-binding fragment (Fab) region have garnered increasing attention. Precise modifications of the Fab region not only maximize the retention of antigen-antibody binding capacity but also enhance numerous physicochemical properties of antibodies. This paper reviews the chemical, biological, biochemical, and computer-assisted methods for modifying the Fab region of antibodies, discussing their advantages, limitations, recent advances, and future trends.

Exploring treatment options in cancer: Tumor treatment strategies

Traditional therapeutic approaches such as chemotherapy and radiation therapy have burdened cancer patients with onerous physical and psychological challenges. Encouragingly, the landscape of tumor treatment has undergone a comprehensive and remarkable transformation. Emerging as fervently pursued modalities are small molecule targeted agents, antibody-drug conjugates (ADCs), cell-based therapies, and gene therapy. These cutting-edge treatment modalities not only afford personalized and precise tumor targeting, but also provide patients with enhanced therapeutic comfort and the potential to impede disease progression. Nonetheless, it is acknowledged that these therapeutic strategies still harbour untapped potential for further advancement. Gaining a comprehensive understanding of the merits and limitations of these treatment modalities holds the promise of offering novel perspectives for clinical practice and foundational research endeavours. In this review, we discussed the different treatment modalities, including small molecule targeted drugs, peptide drugs, antibody drugs, cell therapy, and gene therapy. It will provide a detailed explanation of each method, addressing their status of development, clinical challenges, and potential solutions. The aim is to assist clinicians and researchers in gaining a deeper understanding of these diverse treatment options, enabling them to carry out effective treatment and advance their research more efficiently.

Applications of self-assembled peptide hydrogels in anti-tumor therapy

Peptides are a class of active substances composed of a variety of amino acids with special physiological functions. The rational design of peptide sequences at the molecular level enables their folding into diverse secondary structures. This property has garnered significant attention in the biomedical sphere owing to their favorable biocompatibility, adaptable mechanical traits, and exceptional loading capabilities. Concurrently with advancements in modern medicine, the diagnosis and treatment of tumors have increasingly embraced targeted and personalized approaches. This review explores recent applications of self-assembled peptides derived from natural amino acids in chemical therapy, immunotherapy, and other adjunctive treatments. We highlighted the utilization of peptide hydrogels as delivery systems for chemotherapeutic drugs and other bioactive molecules and then discussed the challenges and prospects for their future application.

Efficacy and advantage of immunotherapy for melanoma via intramuscular co-expression of plasmid-encoded PD-1 and CTLA-4 scFvs

Immunotherapy, in the shape of immune checkpoint inhibitors (ICIs), has completely changed the treatment of cancer. However, the increasing expense of treatment and the frequency of immune-related side effects, which are frequently associated with combination antibody therapies and Fc fragment of antibody, have limited the patient's ability to benefit from these treatments. Herein, we presented the therapeutic effects of the plasmid-encoded PD-1 and CTLA-4 scFvs (single-chain variable fragment) for melanoma via an optimized intramuscular gene delivery system. After a single injection, the plasmid-encoded ICI scFv in mouse sera continued to be above 150 ng/mL for 3 weeks and reached peak amounts of 600 ng/mL. Intramuscular delivery of plasmid encoding PD-1 and CTLA-4 scFvs significantly changed the tumor microenvironment, delayed tumor growth, and prolonged survival in melanoma-bearing mice. Furthermore, no significant toxicity was observed, suggesting that this approach could improve the biosafety of ICIs combination therapy. Overall, the expression of ICI scFvs in vivo using intramuscular plasmid delivery could potentially develop into a reliable, affordable, and safe immunotherapy technique, expanding the range of antibody-based gene therapy systems that are available.

Engineered bacteria in tumor immunotherapy

As the limitations of cancer immunotherapy become increasingly apparent, there is considerable anticipation regarding the utilization of biological tools to enhance treatment efficacy, particularly bacteria and their derivatives. Leveraging advances in genetic and synthetic biology technologies, engineered bacteria now play important roles far beyond those of conventional immunoregulatory agents, and they could function as tumor-targeting vehicles and in situ pharmaceutical factories. In recent years, these engineered bacteria play a role in almost every aspect of immunotherapy. It is nothing short of impressive to keep seeing different strain of bacteria modified in diverse ways for unique immunological enhancement. In this review, we have scrutinized the intricate interplay between the immune system and these engineered bacteria. These interactions generate strategies that can directly or indirectly optimize immunotherapy and even modulate the effects of combination therapies. Collectively, these engineered bacteria present a promising novel therapeutic strategy that promises to change the current landscape of immunotherapy.

Reforming solid tumor treatment: the emerging potential of smaller format antibody-drug conjugate

In recent years, substantial therapeutic efficacy of antibody-drug conjugates (ADCs) has been validated through approvals of 16 ADCs for the treatment of malignant tumors. However, realization of the maximum clinical use of ADCs requires surmounting extant challenges, mainly the limitations in tumor penetration capabilities when targeting solid tumors. To resolve the hurdle of suboptimal tumor penetration, miniaturized antibody fragments with engineered formats have been harnessed for ADC assembly. By virtue of their reduced molecular sizes, antibody fragment-drug conjugates hold considerable promise for efficacious delivery of cytotoxic agents, thus conferring superior therapeutic outcomes. This review will focus on current advancements in novel ADC development utilizing smaller antibody formats from ~6 to 80 kDa, with particular emphasis on single-domain antibodies, which have been widely applied in novel ADC design. Additionally, strategies to optimize clinical translation are discussed, including half-life extension, acceleration of internalization, and reduction of immunogenic potential.

Engineered polyspecific antibodies: A new frontier in the field of immunotherapeutics

The 21st-century beginning remarked with the huge success of monospecific MAbs, however, in the last couple of years, polyspecific MAbs (PsAbs) have been an interesting topic and show promise of being biobetter than monospecific MAbs. Polyspecificity, in which a single antibody serves multiple specific target binding, has been hypothesized to contribute to the development of a highly effective antibody repertoire for immune defence. This polyspecific MAb trend represents an explosion that is gripping the whole pharmaceutical industry. This review is concerned with the current development and quality enforcement of PsAbs. All provided literature on monospecific MAbs and polyspecific MAbs (PsAbs) were searched using various electronic databases such as PubMed, Google Scholar, Web of Science, Elsevier, Springer, ACS, Google Patent and books via the keywords Antibody engineering, Polyspecific antibody, Conventional antibody, non-conventional antibody, and Single domain antibody. In the literature, there are more than 100 different formats to construct PsAb by quadroma technology, chemical conjugation and genetic engineering. Till March 2023, nine PsAb have been approved around the world, and around 330 are in advanced developmental stages, showing the dominancy of PsAb in the growing health sector. Recent advancements in protein engineering techniques and the fusion of non-conventional antibodies have made it possible to create complex PsAbs that demonstrate higher stability and enhanced potency. This marks the most significant achievement for cancer immunotherapy, in which PsAbs have immense promise. It is worth mentioning that seven out of the nine PsAbs have been approved as anti-cancer therapy. As PsAbs continue to acquire prominence, they could pave the way for the development of novel immunotherapies for multiple diseases.

Designing Robust Monoclonal Antibody Drug Products: Pitfalls of Simplistic Approaches for Stability Prediction

Thermal stability attributes including unfolding onset (Tonset) and mid-point (Tm) are often utilized for efficient development of monoclonal antibody (mAb) products during lead selection and formulation screening workflows. An assumption of direct correlation between thermal and kinetic physical stability underpins this basic approach. While literature reports have substantiated this general approach under specific conditions, clear exceptions have been highlighted alongside. Herein, a set of mAbs formulated under diverse solution conditions to generate a broad array of thermal and kinetic stability profiles were systematically analyzed. Sequence modifications in the Fc region were purposefully engineered to generate a set of low-melting mAbs. A diverse set of excipients were subsequently utilized and shown to modulate the Tm over a wide range. While a general correlation between high Tm and low aggregation rate was observed under accelerated conditions, the predictive utility of Tm under relevant product storage conditions was inadequate at best. Critically, Tm data did not correlate with long-term aggregation rates under refrigerated or room temperature conditions. Even under accelerated conditions, Tm appeared to be a poor predictor of aggregation once it exceeded the solution storage temperature (40°C) by ∼15°C, similar to conditions routinely encountered in the development of canonical mAbs (Tm > 60°C). Pitfalls of simplistic correlative approaches are discussed in the context of practical biologics product development.

In vivo human T cell engineering with enveloped delivery vehicles

Viruses and virally derived particles have the intrinsic capacity to deliver molecules to cells, but the difficulty of readily altering cell-type selectivity has hindered their use for therapeutic delivery. Here, we show that cell surface marker recognition by antibody fragments displayed on membrane-derived particles encapsulating CRISPR-Cas9 protein and guide RNA can deliver genome editing tools to specific cells. Compared to conventional vectors like adeno-associated virus that rely on evolved capsid tropisms to deliver virally encoded cargo, these Cas9-packaging enveloped delivery vehicles (Cas9-EDVs) leverage predictable antibody-antigen interactions to transiently deliver genome editing machinery selectively to cells of interest. Antibody-targeted Cas9-EDVs preferentially confer genome editing in cognate target cells over bystander cells in mixed populations, both ex vivo and in vivo. By using multiplexed targeting molecules to direct delivery to human T cells, Cas9-EDVs enable the generation of genome-edited chimeric antigen receptor T cells in humanized mice, establishing a programmable delivery modality with the potential for widespread therapeutic utility.

Cancer therapeutic trispecific antibodies recruiting both T and natural killer cells to cancer cells

T cells and natural killer (NK) cells are major effector cells recruited by cancer therapeutic bispecific antibodies; however, differences in the populations of these cells in individual tumors limit the general use of these antibodies. In the present study, trispecific antibodies were created, namely T cell and NK cell engagers (TaKEs), that recruit both T cells and NK cells. Notably, three Fc‑fused TaKEs were designed, TaKE1‑Fc, TaKE2‑Fc and TaKE3‑Fc, using variable fragments targeting the epidermal growth factor receptor on tumor cells, CD3 on T cells, and CD16 on NK cells. Among them, TaKE1‑Fc was predicted to form a circular tetrabody‑like configuration and exhibited the highest production and greatest cancer growth inhibitory effects. TaKE1 was prepared from TaKE1‑Fc by digesting the Fc region for further functional evaluation. The resulting TaKE1 exhibited trispecificity via its ability to bind cancer cells, T cells and NK cells, as well as comparable or greater cancer growth inhibitory effects to those of two bispecific antibodies that recruit T cells and NK cells, respectively. A functional trispecific antibody with the potential to exert strong therapeutic effects independent of T cell and NK cell populations was developed.

Revolutionizing cancer immunotherapy: unleashing the potential of bispecific antibodies for targeted treatment

Recent progressions in immunotherapy have transformed cancer treatment, providing a promising strategy that activates the immune system of the patient to find and eliminate cancerous cells. Bispecific antibodies, which engage two separate antigens or one antigen with two distinct epitopes, are of tremendous concern in immunotherapy. The bi-targeting idea enabled by bispecific antibodies (BsAbs) is especially attractive from a medical standpoint since most diseases are complex, involving several receptors, ligands, and signaling pathways. Several research look into the processes in which BsAbs identify different cancer targets such angiogenesis, reproduction, metastasis, and immune regulation. By rerouting cells or altering other pathways, the bispecific proteins perform effector activities in addition to those of natural antibodies. This opens up a wide range of clinical applications and helps patients with resistant tumors respond better to medication. Yet, further study is necessary to identify the best conditions where to use these medications for treating tumor, their appropriate combination partners, and methods to reduce toxicity. In this review, we provide insights into the BsAb format classification based on their composition and symmetry, as well as the delivery mode, focus on the action mechanism of the molecule, and discuss the challenges and future perspectives in BsAb development.

MFSD2A potentiates gastric cancer response to anti-PD-1 immunotherapy by reprogramming the tumor microenvironment to activate T cell response

BACKGROUND

The efficacy of anti-programmed cell death protein 1 (PD-1) immunotherapy in various cancers, including gastric cancer (GC), needs to be potentiated by more effective targeting to enhance therapeutic efficacy or identifying accurate biomarkers to predict clinical responses. Here, we attempted to identify molecules predicting or/and promoting anti-PD-1 therapeutic response in advanced GC (AGC).

METHODS

The transcriptome of AGC tissues from patients with different clinical responses to anti-PD-1 immunotherapy and GC cells was analyzed by RNA sequencing. The protein and mRNA levels of the major facilitator superfamily domain containing 2A (MFSD2A) in GC cells were assessed via quantitative real-time polymerase chain reaction, Western blotting, and immunohistochemistry. Additionally, the regulation of anti-PD-1 response by MFSD2A was studied in tumor-bearing mice. Cytometry by Time-of-Flight, multiple immunohistochemistry, and flow cytometry assays were used to explore immunological responses. The effects of MFSD2A on lipid metabolism in mice cancer tissue and GC cells was detected by metabolomics.

RESULTS

Higher expression of MFSD2A in tumor tissues of AGC patients was associated with better response to anti-PD-1 immunotherapy. Moreover, MFSD2A expression was lower in GC tissues compared to adjacent normal tissues, and its expression was inversely correlated with GC stage. The overexpression of MFSD2A in GC cells enhanced the efficacy of anti-PD-1 immunotherapy in vivo by reprogramming the tumor microenvironment (TME), characterized by increased CD8+ T cell activation and reduced its exhaustion. MFSD2A inhibited transforming growth factor β1 (TGFβ1) release from GC cells by suppressing cyclooxygenase 2 (COX2)-prostaglandin synthesis, which consequently reprogrammed TME to promote anti-tumor T cell activation.

CONCLUSIONS

MFSD2A potentially serves as a predictive biomarker for anti-PD-1 immunotherapy response in AGC patients. MFSD2A may be a promising therapeutic target to potentiate the efficacy of anti-PD-1 immunotherapy by reprogramming the TME to promote T cells activation.

The preparation and therapeutic effects of β-glucan-specific nanobodies and nanobody-natamycin conjugates in fungal keratitis

Fungal keratitis (FK) is a severe infectious corneal disease. Since traditional eye drops exhibit poor dissolution and high corneal toxicity, the efficacy of current treatments for FK remains limited. It is needed to develop new approaches to control the cornea damage from FK. In this study, a nanobody (Nb) specific to β-glucan in the fungal cell wall was prepared. The conjugate of the Nb with natamycin (NAT), a traditional antifungal drug, was synthesized. Firstly, we found the Nb specific to β-glucan inhibited fungal growth by disrupting cell wall and biofilm formation.. In addition, the content of β-glucan in the fungal cell wall decreased after Nb treatment. The Nb also reduced the adhesion ability of fungal conidia to human corneal epithelial cells (HCECs). Further, we examined the difference between NAT and Nb-NAT in antifungal growth. Nb-NAT showed better antifungal effects than NAT which was caused by the interaction between Nb and β-glucan. Moreover, Nb concentration below 0.5 mg/mL did not affect the viability of HCECs. Nb-NAT had less cytotoxicity and ocular surface irritation than NAT. Nb specific to β-glucan attenuated Aspergillus fumigatus (A. fumigatus) virulence and relieved inflammatory responses in FK. Nb-NAT treatment of the cornea improved therapeutic effects compared with NAT. It decreased clinical scores and expression level of inflammatory factors. To our knowledge, this study is the first to report a Nb specific to β-glucan and Nb-NAT for the treatment of FK. These unique functions of the Nb specific to β-glucan and Nb-NAT would render it as an alternative molecule to control fungal infections including FK. STATEMENT OF SIGNIFICANCE: Fungal keratitis is a corneal disease with a high rate of blindness. Due to the poor dissolution and high corneal toxicity exhibited by traditional eye drops, the efficacy of current therapeutic treatments for fungal keratitis (FK) remains limited. To enhance the therapeutic effect of natamycin in treating fungal keratitis, this study developed an innovative approach by preparing a β-glucan-specific nanobody and loading it with the antifungal drug natamycin. The β-glucan-specific nanobody has the ability to control both fungal pathogen invasion and inflammation, which can cause damage to the cornea in FK. The conjugation with the β-glucan-specific nanobody significantly increased the antifungal capacity of natamycin and reduced its toxicity. The further application of natamycin conjugated with the β-glucan-specific nanobody could be expanded to other diseases caused by fungal pathogen infections.

Recent advancements in fusion protein technologies in oncotherapy: A review

Cancer is a complicated, adaptable, and heterogeneous disease caused by a wide variety of genetic changes that might impair ability of cells to function normally. The majority of the tumors can only be shrunk using conventional oncology therapies like chemotherapy, radiation, and surgical resection, and the tumor often recurs. The inability of conventional cancer therapies to completely destroy the Cancer Stem Cells (CSCs) that otherwise lead to therapy resistance is thus addressed by therapeutic approaches that concentrate on targeting CSCs and their micro-environmental niche. In this review, we summarize approaches that are used for the development of fusion proteins and their therapeutic applications for treating cancer. The main purpose of making advancements towards the fusion technology instead of using conventional treatment methods is to achieve a prolonged half-life of the therapeutic drugs. The fusion of drugs to the immune response enhancing cytokines or the fusion of antibody and cytokines not only increases half-life but also increase the stability of the anti-tumor drug. Several molecules including different fragments of antibodies, cytokines, Human Serum Albumin, transferrin, XTEN polymers, Elastin-like polypeptides (ELPs) can be employed as a fusion partner and the resulting fusion proteins are reported to show enhanced anti-tumor response.

Bioengineering and computational analysis of programmed cell death ligand-1 monoclonal antibody

The trans-membrane proteins of the B7 family programmed cell death ligand-1 (PD-L1) and programmed death-1 (PD-1) play important roles in inhibiting immune responses and enhancing self-tolerance via T-cell modulation. Several therapeutic antibodies are used to promote T-cell proliferation by preventing interactions between PD-1/PD-L1. Recombinant technology appears to be quite useful in the production of such potent antibodies. In this study, we constructed recombinant molecules by cloning variable regions of the PD-L1 molecule into pMH3 vectors and transferring them into mammalian cell lines for expression. G418 supplementation was used to screen the recombinant clones, which were then maintained on serum-free medium. The full-length antibody was isolated and purified from the medium supernatant at a concentration of 0.5-0.8 mg/ml. Antibody binding affinity was investigated using ELISA and immunofluorescence methods. The protein-protein interactions (PPI) were determined using a docking approach. The SWISS model was utilized for homology modeling, while ZDOCK, Chimera, and PyMOL were used to validate 3D models. The Ramachandran plots were constructed using the SWISS model, which revealed that high-quality structures had a value of more than 90%. Current technologies allow for the accurate determination of antigen-antibody interactions.