Explore the vast range of titles available.

Background Production of human monoclonal antibodies that shows broadly neutralising activity is needed for the prevention of HIV-1. Here we devised a novel approach and produced 11 different human scFvs against the V3 region of HIV-1 envelope. Method: The peripheral blood mononuclear cells (PBMCs) were isolated from an HIV-1 clade C infected drug naïve Indian patient whose plasma exhibited neutralising antibodies against a panel of viruses. PBMCs were EBV transformed in 96 well plate and then expanded into 24 well stage followed by 6 well and finally to flask stage. The transformed cells (wells) were screened against HIV-1 consensus C V3 peptide at each stage and only the positive cells (wells) were carried onto the next stage. Total RNA from these enriched positive antibody secreting cells at the flask stage was isolated and cDNA was synthesised. Results: By EBV transformation and preselection of V3 specific clones we successfully constructed a small phage library. One round of bio panning was done against HIV-1 consensus C and B V3 peptides. Randomly, 40 clones were selected and checked for their binding. Out of 40 clones, 13 showed positivity in phage ELISA. DNA fingerprinting analysis using BstN1 followed by sequencing showed that 11 out of 13 clones were distinct. Expression of positive clones was tested by SDS-PAGE and Western blot. All the 11 anti -V3 scFvs showed cross-reactivity against both the V3 peptides and did not show any reactivity against other unrelated peptides. The scFvs showed varying degrees of neutralisation against tier 1 and tier 2 viruses and cross neutralising activity against clade A, B and C viruses. Conclusion This is the first study to generate anti-V3 scFvs against HIV-1 Clade C. Further assessment of the neutralisation efficiency of these scFvs would reveal their potential for passive immunotherapy.

Bispecific antibodies (bsAb) that target two independent epitopes or antigens have been extensively explored in translational and clinical studies since they were first developed in the 1960s. Many bsAbs are being tested in clinical trials for treating a variety of diseases, mostly cancer. Here, we provide an overview of various types of bsAbs in clinical studies and discuss their targets, safety profiles, and efficacy. We also highlight the current challenges, potential solutions, and future directions of bsAb development for cancer treatment. Graphical Abstract In this review, N. Li, Y. Nie & colleagues provide an overview of the current clinical development and future directions of bi‐specific antibodies for cancer treatment.

Cell-penetrating peptides (CPPs) are invaluable tools for delivering various substances into cells by crossing biological membranes. However, the effects of cell-penetrating peptide fusion proteins on the biological activity of antibodies remain to be fully understood. Here, we engineered a recombinant protein, LP-scFv, which combines the single-chain variable region of anti-human epidermal growth factor receptor-2 with a novel and non-oxic cell-penetrating peptide as a leader peptide. The introduction of this leader peptide led to a more than twofold increase in the internalization efficiency of the single-chain antibody, as confirmed using microscopic analysis and flow cytometry. The effects of the single-chain antibodies and LP-scFv on cell viability were evaluated using the MTT assay. Both the single-chain antibodies and LP-scFv reduced the viability of BT474 and NCI-N87 cells in a dose-dependent manner while exhibiting minimal toxicity towards MCF-7 and MCF-10A cells. Further investigation into LP-scFv’s mechanism revealed that the induced leader peptide does not alter the MAPK-ERK1/2 and PI3K/AKT pathways of single-chain antibodies. An enhanced antitumor activity was also confirmed in an NCI-N87 tumor xenograft model in mice with a reduction of 45.2% in tumor growth inhibition (vs. 23.1% for scFv) with a 50 mg/kg dose after orthotopic injection administration, which was equivalent to that of trastuzumab (vs. 55.7% for trastuzumab). Overall, these results indicate that LP-scFv exhibits significant permeation activity in HER2-positive cells to enhance the intracellular dose effect on antitumor activity in vitro and in vivo. This research lays the foundation for designing novel antibody-based therapies for cancer.

Antibodies and antibody-derived molecules are continuously developed as both therapeutic agents and key reagents for advanced diagnostic investigations. Their application in these fields has indeed greatly expanded the demand of these molecules and the need for their production in high yield and purity. While full-length antibodies require mammalian expression systems due to the occurrence of functionally and structurally important glycosylations, most antibody fragments and antibody-like molecules are non-glycosylated and can be more conveniently prepared in E. coli-based expression platforms. We propose here an updated survey of the most effective and appropriate methods of preparation of antibody fragments that exploit E. coli as an expression background and review the pros and cons of the different platforms available today. Around 250 references accompany and complete the review together with some lists of the most important new antibody-like molecules that are on the market or are being developed as new biotherapeutics or diagnostic agents.

Many therapeutic proteins are small in size and are rapidly cleared from circulation. Consequently, half-life extension strategies have emerged to improve pharmacokinetic properties, including fusion or binding to long-lasting serum proteins, chemical modifications with hydrophilic polymers such as PEGylation, or, more recently, fusion to PEG mimetic polypeptides. In the present study, two different PEG mimetic approaches, the GlycoTAIL and the FlexiTAIL, were applied to increase the hydrodynamic radius of antibody fragments of different sizes and valencies, including scFv, diabody, and scFv-EHD2 fusion proteins. The GlycoTAIL and FlexiTAIL sequences of varying lengths are composed of aliphatic and hydrophilic residues, with the GlycoTAIL furthermore comprising N-glycosylation sites. All modified proteins could be produced in a mammalian expression system without reducing stability and antigen binding, and all modified proteins exhibited a prolonged half-life and increased drug disposition in mice. The strongest effects were observed for proteins comprising a FlexiTAIL of 248 residues. Thus, the GlycoTAIL and FlexiTAIL sequences represent a flexible and modular system to improve the pharmacokinetic properties of proteins.

The human leucine-rich repeat-containing protein 15 (LRRC15) is a membrane protein identified as a marker of CAF (cancer-associated fibroblast) cells whose overexpression is positively correlated with cancer grade and outcome. Nuclear molecular imaging (i.e., SPECT and PET) to track LRRC15 expression could be very useful in guiding further therapeutic strategies. In this study, we developed an ScFv mouse phage-display library to obtain small fragment antibodies against human LRRC15 for molecular imaging purposes. Mice were immunized with recombinant human LRRC15 (hLRRC15), and lymph node cells were harvested for ScFv (single-chain variable fragment) phage-display analysis. The built library was used for panning on cell lines with constitutive or induced expression after transfection. The choice of best candidates was performed by screening various other cell lines, using flow cytometry. The selected candidates were reformatted into Cys-ScFv or Cys-diabody by addition of cysteine, and cloned in mammalian expression vectors to obtain batches of small fragments that were further used in site-specific radiolabeling tests. The obtained library was 1.2 × 107 cfu/µg with an insertion rate >95%. The two panning rounds performed on cells permittedenrichment of 2 × 10−3. Screening with flow cytometry allowed us to identify 28 specific hLRRC15 candidates. Among these, two also recognized murine LRCC15 and were reformatted into Cys-ScFv and Cys-diabody. They were expressed transiently in a mammalian system to obtain 1.0 to 4.5 mg of Cys fragments ready for bioconjugation and radiolabeling. Thus, in this paper, we demonstrate the relevance of the phage-display ScFv library approach for the fast-track development of small antibodies for imaging and/or immunotherapy purposes.

Background Chimeric antigen receptor (CAR) -T cell therapy is an efficient therapeutic strategy for specific hematologic malignancies. However, positive outcomes of this novel therapy in treating solid tumors are curtailed by the immunosuppressive tumor microenvironment (TME), wherein signaling of the checkpoint programmed death-1 (PD-1)/PD-L1 directly inhibits T-cell responses. Although checkpoint-targeted immunotherapy succeeds in increasing the number of T cells produced to control tumor growth, the desired effect is mitigated by the action of myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs) in the TME. Previous studies have confirmed that targeting triggering-receptor-expressed on myeloid cells 2 (TREM2) on TAMs and MDSCs enhances the outcomes of anti-PD-1 immunotherapy. Methods We constructed carcinoembryonic antigen (CEA)-specific CAR-T cells for colorectal cancer (CRC)-specific antigens with an autocrine PD-1-TREM2 single-chain variable fragment (scFv) to target the PD-1/PD-L1 pathway, MDSCs and TAMs. Results We found that the PD-1-TREM2-targeting scFv inhibited the activation of the PD-1/PD-L1 pathway. In addition, these secreted scFvs blocked the binding of ligands to TREM2 receptors present on MDSCs and TAMs, reduced the proportion of MDSCs and TAMs, and enhanced T-cell effector function, thereby mitigating immune resistance in the TME. PD-1-TREM2 scFv-secreting CAR-T cells resulted in highly effective elimination of tumors compared to that achieved with PD-1 scFv-secreting CAR-T therapy in a subcutaneous CRC mouse model. Moreover, the PD-1-TREM2 scFv secreted by CAR-T cells remained localized within tumors and exhibited an extended half-life. Conclusions Together, these results indicate that PD-1-TREM2 scFv-secreting CAR-T cells have strong potential as an effective therapy for CRC.

Chimeric antigen receptor T cell (CAR-T) therapy demonstrated remarkable success in long-term remission of cancers and other autoimmune diseases. Currently, six products (Kymriah, Yescarta, Tecartus, Breyanzi, Abecma, and Carvykti) are approved by the US-FDA for treatment of a few hematological malignancies. All the six products are autologous CAR-T cell therapies, where delivery of CAR, which comprises of scFv (single-chain variable fragment) derived from monoclonal antibodies for tumor target antigen recognition is through a lentiviral vector. Although available CAR-T therapies yielded impressive response rates in a large number of patients in comparison to conventional treatment strategies, there are potential challenges in the field which limit their efficacy. One of the major challenges is the induction of humoral and/or cellular immune response in patients elicited due to scFv domain of CAR construct, which is of non-human origin in majority of the commercially available products. Generation of anti-CAR antibodies may lead to the clearance of the therapeutic CAR-T cells, increasing the likelihood of tumor relapse and lower the CAR-T cells efficacy upon reinfusion. These immune responses influence CAR-T cell expansion and persistence, that might affect the overall clinical response. In this review, we will discuss the impact of immunogenicity of the CAR transgene on treatment outcomes. Finally, this review will highlight the mitigation strategies to limit the immunogenic potential of CARs and improve the therapeutic outcome.

By the emergence of recombinant DNA technology, many antibody fragments have been developed devoid of undesired properties of natural immunoglobulins. Among them, camelid heavy-chain variable domains (VHHs) and single-chain variable fragments (scFvs) are the most favored ones. While scFv is used widely in various applications, camelid antibodies (VHHs) can serve as an alternative because of their superior chemical and physical properties such as higher solubility, stability, smaller size, and lower production cost. Here, these two counterparts are compared in structure and properties to identify which one is more suitable for each of their various therapeutic, diagnosis, and research applications.

How single-chain variable fragments (scFvs) affect the functions of chimeric antigen receptors (CARs) has not been well studied. Here, the components of CAR with an emphasis on scFv were described, and then several methods to measure scFv affinity were discussed. Next, scFv optimization studies for CD19, CD38, HER2, GD2 or EGFR were overviewed, showing that tuning the affinity of scFv could alleviate the on-target/off-tumor toxicity. The affinities of scFvs for different antigens were also summarized to designate a relatively optimal working range for CAR design. Last, a synthetic biology approach utilizing a low-affinity synthetic Notch (synNotch) receptor to achieve ultrasensitivity of antigen-density discrimination and murine models to assay the on-target/off-tumor toxicity of CARs were highlighted. Thus, this review provides preliminary guidelines of choosing the right scFvs for CARs.