Small sized EGFR1 and HER2 specific bifunctional antibody for targeted cancer therapy

Molecular and functional insight into anti-EGFR nanobody: Theranostic implications for malignancies

Targeted therapy and imaging are the most popular techniques for the intervention and diagnosis of cancer. A potential therapeutic target for the treatment of cancer is the epidermal growth factor receptor (EGFR), primarily for glioblastoma, lung, and breast cancer. Over-production of ligand, transcriptional up-regulation due to autocrine/paracrine signalling, or point mutations at the genomic locus may contribute to the malfunction of EGFR in malignancies. This exploit makes use of EGFR, an established biomarker for cancer diagnostics and treatment. Despite considerable development in the last several decades in making EGFR inhibitors, they are still not free from limitations like toxicity and a short serum half-life. Nanobodies and antibodies share similar binding properties, but nanobodies have the additional advantage that they can bind to antigenic epitopes deep inside the target that conventional antibodies are unable to access. For targeted therapy, anti-EGFR nanobodies can be conjugated to various molecules such as drugs, peptides, toxins and photosensitizers. These nanobodies can be designed as novel immunoconjugates using the universal modular antibody-based platform technology (UniCAR). Furthermore, Anti-EGFR nanobodies can be expressed in neural stem cells and visualised by effective fluorescent and radioisotope labelling.

The use of peptides, aptamers, and variable domains of heavy chain only antibodies in tissue engineering and regenerative medicine

Over the years, much research has been focused on the use of small molecules such as peptides or aptamers or more recently on the use of variable antigen-binding domain of heavy chain only antibodies in the field of tissue engineering and regenerative medicine. The use of these molecules originated as an alternative for the larger conventional antibodies, of which most drawbacks are derived from their size and complex structure. In the field of tissue engineering and regenerative medicine, biological functionalities are often conjugated to biomaterials in order to (re-)create an in vivo like situation, especially when bioinert biomaterials are used. Those biomaterials are functionalized with these functionalities for instance for the purpose of cell attachment or cell targeting for targeted drug delivery but also for local enrichment or blocking of ligands such as growth factors or cytokines on the biomaterial surface. In this review, we further refer to peptides, aptamers, and variable antigen-binding domain of heavy chain only antibodies as biological functionalities. Here, we compare these biological functionalities within the field of tissue engineering and regenerative medicine and give an overview of recent work in which these biological functionalities have been explored. We focus on the previously mentioned purposes of the biological functionalities. We will compare structural differences, possible modifications and (chemical) conjugation strategies. In addition, we will provide an overview of biologicals that are, or have been, involved in clinical trials. Finally, we will highlight the challenges of each of these biologicals. STATEMENT OF SIGNIFICANCE: In the field of tissue engineering there is broad application of functionalized biomaterials for cell attachment, targeted drug delivery and local enrichment or blocking of growth factors. This was previously mostly done via conventional antibodies, but their large size and complex structure impose various challenges with respect of retaining biological functionality. Peptides, aptamers and VHHs may provide an alternative solution for the use of conventional antibodies. This review discusses the use of these molecules for biological functionalization of biomaterials. For each of the molecules, their characteristics, conjugation possibilities and current use in research and clinical trials is described. Furthermore, this review sets out the benefits and challenges of using these types of molecules for different fields of application.

NANOBODY® Molecule, a Giga Medical Tool in Nanodimensions

Although antibodies remain the most widely used tool for biomedical research, antibody technology is not flawless. Innovative alternatives, such as Nanobody® molecules, were developed to address the shortcomings of conventional antibodies. Nanobody® molecules are antigen-binding variable-domain fragments derived from the heavy-chain-only antibodies of camelids (VHH) and combine the advantageous properties of small molecules and monoclonal antibodies. Nanobody® molecules present a small size (~15 kDa, 4 nm long and 2.5 nm wide), high solubility, stability, specificity, and affinity, ease of cloning, and thermal and chemical resistance. Recombinant production in microorganisms is cost-effective, and VHH are also building blocks for multidomain constructs. These unique features led to numerous applications in fundamental research, diagnostics, and therapy. Nanobody® molecules are employed as biomarker probes and, when fused to radioisotopes or fluorophores, represent ideal non-invasive in vivo imaging agents. They can be used as neutralizing agents, receptor-ligand antagonists, or in targeted vehicle-based drug therapy. As early as 2018, the first Nanobody®, Cablivi (caplacizumab), a single-domain antibody (sdAb) drug developed by French pharmaceutical giant Sanofi for the treatment of adult patients with acquired thrombocytopenic purpura (aTTP), was launched. Nanobody® compounds are ideal tools for further development in clinics for diagnostic and therapeutic purposes.

Aptamers and nanobodies as alternatives to antibodies for ligand-targeted drug delivery in cancer

Targeted drug delivery (TDD) is the selective delivery of a therapeutic agent specifically to the site of action to avoid adverse effects and systemic toxicity and to reduce the dose required. Ligand TDD or active TDD involves using a ligand-drug conjugate comprising a targeting ligand linked to an active drug moiety that can either be free or encapsulated within a nanocarrier (NC). Aptamers are single-stranded oligonucleotides that bind to specific biomacromolecules because of their 3D conformation. Nanobodies are the variable domains of unique heavy chain-only antibodies (HcAbs) produced by animals of the Camelidae family. Both these types of ligand are smaller than antibodies and have been used to efficiently target drugs to particular tissues or cells. In this review, we describe the applications of aptamers and nanobodies as ligands for TDD, their advantages and disadvantages compared with antibodies, and the various modalities for targeting cancers using these ligands. Teaser: Aptamers and nanobodies are macromolecular ligands that can actively chaperone drug molecules to particular cancerous cells or tissues in the body to target their pharmacological effects and improve their therapeutic index and safety.

Detection of Barrett's neoplasia with a near-infrared fluorescent heterodimeric peptide

BACKGROUND

Esophageal adenocarcinoma (EAC) is a molecularly heterogeneous disease with poor prognosis that is rising rapidly in incidence. We aimed to demonstrate specific binding by a peptide heterodimer to Barrett's neoplasia in human subjects.

METHODS

Peptide monomers specific for EGFR and ErbB2 were arranged in a heterodimer configuration and labeled with IRDye800. This near-infrared (NIR) contrast agent was topically administered to patients with Barrett's esophagus (BE) undergoing either endoscopic therapy or surveillance. Fluorescence images were collected using a flexible fiber accessory passed through the instrument channel of an upper gastrointestinal endoscope. Fluorescence images were collected from 31 BE patients. A deep learning model was used to segment the target (T) and background (B) regions.

RESULTS

The mean target-to-background (T/B) ratio was significantly greater for high grade dysplasia (HGD) and EAC versus BE, low grade dysplasia (LGD), and squamous epithelium. At a T/B ratio of 1.5, sensitivity and specificity of 94.1 % and 92.6 %, respectively, were achieved for the detection of Barrett's neoplasia with an area under the curve of 0.95. No adverse events attributed to the heterodimer were found. EGFR and ErbB2 expression were validated in the resected specimens.

CONCLUSIONS

This "first-in-human" clinical study demonstrates the feasibility of detection of early Barrett's neoplasia using a NIR-labeled peptide heterodimer.

Significant Growth Inhibition by a Bispecific Affibody Targeting Oncoprotein E7 in both HPV16 and 18 Positive Cervical Cancer in vitro and in vivo

The infection with HPV 16 and 18 high-risk types account for more than 80 % of cervical cancer incidence, but there is still no targeted agent against HPV for cervical cancer therapy. Our previous study constructed a bispecific affibody Z_16-18 targeting HPV16 and 18 early antigen 7 (E7, responsible for the infected cell malignant transformation). In the present study, we prepared Z_16-18 in prokaryotic expression system and confirmed its significant growth inhibition both on SiHa (HPV16 positive) and HeLa (HPV18 positive) cervical cancer cells by arresting cell cycle at G₀/G₁ phase. The IC₅₀ of Z_16-18 on SiHa and HeLa were close in value. Z_16-18 could specifically target E7 in both SiHa and HeLa, and exhibited prominent targeted enrichment on tumor tissues derived from SiHa or HeLa, resulting in the inhibition of tumourigenesis and tumour growth in vivo. Furthermore, Z_16-18 could inhibit the interaction between E7 and pRb to block the E7-pRb carcinogenic pathway, resulting in the decreased release of E2F and the cell growth inhibition characterized by the decrease of CDK6 and Cyclin D1. This study provides a new strategy for targeted therapy based on affibody, and Z_16-18 has great potential for utilisation and development as an agent targeting HPV16 and HPV18 related cervical cancer.

Research Progress and Applications of Multivalent, Multispecific and Modified Nanobodies for Disease Treatment

Recombinant antibodies such as nanobodies are progressively demonstrating to be a valid alternative to conventional monoclonal antibodies also for clinical applications. Furthermore, they do not solely represent a substitute for monoclonal antibodies but their unique features allow expanding the applications of biotherapeutics and changes the pattern of disease treatment. Nanobodies possess the double advantage of being small and simple to engineer. This combination has promoted extremely diversified approaches to design nanobody-based constructs suitable for particular applications. Both the format geometry possibilities and the functionalization strategies have been widely explored to provide macromolecules with better efficacy with respect to single nanobodies or their combination. Nanobody multimers and nanobody-derived reagents were developed to image and contrast several cancer diseases and have shown their effectiveness in animal models. Their capacity to block more independent signaling pathways simultaneously is considered a critical advantage to avoid tumor resistance, whereas the mass of these multimeric compounds still remains significantly smaller than that of an IgG, enabling deeper penetration in solid tumors. When applied to CAR-T cell therapy, nanobodies can effectively improve the specificity by targeting multiple epitopes and consequently reduce the side effects. This represents a great potential in treating malignant lymphomas, acute myeloid leukemia, acute lymphoblastic leukemia, multiple myeloma and solid tumors. Apart from cancer treatment, multispecific drugs and imaging reagents built with nanobody blocks have demonstrated their value also for detecting and tackling neurodegenerative, autoimmune, metabolic, and infectious diseases and as antidotes for toxins. In particular, multi-paratopic nanobody-based constructs have been developed recently as drugs for passive immunization against SARS-CoV-2 with the goal of impairing variant survival due to resistance to antibodies targeting single epitopes. Given the enormous research activity in the field, it can be expected that more and more multimeric nanobody molecules will undergo late clinical trials in the next future. Systematic Review Registration.

An anti-EGFR/anti- HER2 Bispecific Antibody with Enhanced Antitumor Activity Against Acquired Gefitinib-Resistant NSCLC Cells

BACKGROUND

Acquired resistance to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) is a recurrent phenomenon during clinical therapy of non‑small-cell lung cancer (NSCLC). Studies have shown that HER2 is a key factor contributing to drug resistance in a variety of cancers. Furthermore, we have observed that HER2 is overexpressed in PC-9 NSCLC cells with acquired gefitinib-resistance (PC-9/GR) as compared to that in PC-9 cells.

OBJECTIVE

We hypothesized that blocking both EGFR and HER2 may serve as a potential strategy for treatment of NSCLC with acquired gefitinib-resistance.

METHODS

To target both EGFR and HER2 simultaneously, we developed a bispecific antibody HECrossMAb, which was derived from a humanized Cetuximab and Trastuzumab. The binding affinity of HECrossMAb for EGFR and HER2 was measured using enzyme-linked immunosorbent assay. The MTT assay was used to determine the effect of HECrossMAb on the proliferation of PC‑9 and PC‑9/GR cells in vitro. Finally, the effect of HECrossMAb on PI3K/AKT signaling and associated transcription factors was measured using western blot analysis.

RESULTS

Our results showed that HECrossMAb exerts enhanced cytotoxicity in both PC-9 and PC-9/GR cells by inhibiting the activation of PI3K/AKT signaling and expression of relevant transcription factors such as AEG-1, c-Myc, and c-Fos.

CONCLUSION

Our results suggest that HECrossMAb may function as a potential therapeutic agent for the treatment of NSCLC overexpressing EGFR and HER2.

The influence of testosterone suppression on HER2 immunoexpression in prostatic neoplastic tissue

During initial risk assessments, the metastatic potential of prostate cancer (PCa) may not be fully considered. The tumor's multicentric origin, which is associated with genetic mutations, may explain existing treatment limitations. Investigating human epidermal growth factor receptor 2 (HER2) expression in patients with different stages of PCa may therefore increase understanding of the mechanisms associated with the development of castration resistance. The present study examined the association between HER2 expression and the histologic features of PCa subjected to radical prostatectomy (RP) and evaluated the role of testosterone suppression in HER2 expression. In group 1, specimens from individuals who underwent RP without prior neoadjuvant androgen deprivation therapy (ADT) were included (n=42). In group 2 (PCa with ADT), specimens from individuals who underwent RP and received neoadjuvant cyproterone acetate during distinct periods (200 mg daily for 1-24 months) were included (n=150; cohort derived from a previous study). Immunohistochemical expression of HER2 was associated with prognostic factors such as perineural invasion, extra-prostatic disease, T stage, serum prostate-specific antigen (PSA), angiolymphatic invasion and surgical margins. Univariate regression analysis indicated that perineural invasion, PSA, International Society of Urological Pathology, angiolymphatic invasion, margin, T stage and neoadjuvant ADT was associated with HER2 expression. Ordinal regression analysis indicated a significant effect of neoadjuvant ADT alone on HER2 expression (P<0.001). In addition, regression analysis indicated a significant effect of neoadjuvant ADT alone on HER2 expression (odd ratio=0.01; 95% CI, 0.00, 0.02; P<0.001). HER2 was expressed in PCa samples but was not associated with known prognostic factors. The use of short-acting ADT and the consequent blockage of testosterone effect may suppress the expression of HER2 in PCa cells.

Nanobodies as efficient drug-carriers: Progress and trends in chemotherapy

Nanobodies (Nb) have a promising future as a part of next generation chemodrug delivery systems. Nb, or VHH, are small (15 kDa) monomeric antibody fragments consisting of the antigen binding region of heavy chain antibodies. Heavy chain antibodies are naturally produced by camelids, however the structure of their VHH regions can be readily reproduced in industrial expression systems, such as bacteria or yeast. Due to their small size, high solubility, remarkable stability, manipulatable characteristics, excellent in vivo tissue penetration, conjugation advantages, and ease of production, Nb have many advantages when compared against their antibody precursors. In this review, we discuss the generation and selection of Nbs via phage display libraries for easy screening, and the conjugation techniques involved in creating target-specific nanocarriers. Furthermore, we provide a comprehensive overview of recent developments and perspectives in the field of Nb drug conjugates (NDCs) and Nb-based drug vehicles (NDv) with respect to antitumor therapeutics.

Principles and Current Clinical Landscape of Multispecific Antibodies against Cancer

Building upon the resounding therapeutic success of monoclonal antibodies, and supported by accelerating progress in engineering methods, the field of multispecific therapeutic antibodies is growing rapidly. Over 140 different molecules are currently in clinical testing, with excellent results in recent phase 1-3 clinical trials for several of them. Multivalent bispecific IgG-modified formats predominate today, with a clear tendency for more target antigens and further increased valency in newer constructs. The strategies to augment anticancer efficacy are currently equally divided between disruption of multiple surface antigens, and additional redirection of cytotoxic T or NK lymphocytes against the tumor. Both effects complement other modern modalities, such as tyrosine kinase inhibitors and adoptive cell therapies, with which multispecifics are increasingly applied in combination or merged, for example, in the form of antibody producing CAR-T cells and oncolytics. While mainly focused on B-cell malignancies early on, the contemporary multispecific antibody sector accommodates twice as many trials against solid compared to hematologic cancers. An exciting emerging prospect is the targeting of intracellular neoantigens using T-cell receptor (TCR) fusion proteins or TCR-mimic antibody fragments. Considering the fact that introduction of PD-(L)1 inhibitors only a few years ago has already facilitated 5-year survival rates of 30-50% for per se highly lethal neoplasms, such as metastatic melanoma and non-small-cell lung carcinoma, the upcoming enforcement of current treatments with "next-generation" immunotherapeutics, offers a justified hope for the cure of some advanced cancers in the near future.

Nanobody: A Small Antibody with Big Implications for Tumor Therapeutic Strategy

The development of monoclonal antibody treatments for successful tumor-targeted therapies took several decades. However, the efficacy of antibody-based therapy is still confined and desperately needs further improvement. Nanobodies are the recombinant variable domains of heavy-chain-only antibodies, with many unique properties such as small size (~15kDa), excellent solubility, superior stability, ease of manufacture, quick clearance from blood, and deep tissue penetration, which gain increasing acceptance as therapeutical tools and are considered also as building blocks for chimeric antigen receptors as well as for targeted drug delivery. Thus, one of the promising novel developments that may address the deficiency of monoclonal antibody-based therapies is the utilization of nanobodies. This article provides readers the significant factors that the structural and biochemical properties of nanobodies and the research progress on nanobodies in the fields of tumor treatment, as well as their application prospect.

Dromedary camels as a natural source of neutralizing nanobodies against SARS-CoV-2

The development of prophylactic and therapeutic agents for coronavirus disease 2019 (COVID-19) is a current global health priority. Here, we investigated the presence of cross-neutralizing antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in dromedary camels that were Middle East respiratory syndrome coronavirus (MERS-CoV) seropositive but MERS-CoV free. The tested 229 dromedaries had anti–MERS-CoV camel antibodies with variable cross-reactivity patterns against SARS-CoV-2 proteins, including the S trimer and M, N, and E proteins. Using SARS-CoV-2 competitive immunofluorescence immunoassays and pseudovirus neutralization assays, we found medium-to-high titers of cross-neutralizing antibodies against SARS-CoV-2 in these animals. Through linear B cell epitope mapping using phage immunoprecipitation sequencing and a SARS-CoV-2 peptide/proteome microarray, we identified a large repertoire of Betacoronavirus cross-reactive antibody specificities in these dromedaries and demonstrated that the SARS-CoV-2–specific VHH antibody repertoire is qualitatively diverse. This analysis revealed not only several SARS-CoV-2 epitopes that are highly immunogenic in humans, including a neutralizing epitope, but also epitopes exclusively targeted by camel antibodies. The identified SARS-CoV-2 cross-neutralizing camel antibodies are not proposed as a potential treatment for COVID-19. Rather, their presence in nonimmunized camels supports the development of SARS-CoV-2 hyperimmune camels, which could be a prominent source of therapeutic agents for the prevention and treatment of COVID-19.

Generation of a nanobody against HER2 tyrosine kinase using phage display library screening for HER2-positive breast cancer therapy development

Human epidermal growth factor receptor 2 (HER2) protein overexpression is found in ~30% of invasive breast carcinomas and in a high proportion of noninvasive ductal carcinomas in situ. Targeted cancer therapy is based on monoclonal antibodies and kinase inhibitors and reflects a new era of cancer therapy. However, delivery to tumor cells in vivo is hampered by the large size (150 kDa) of conventional antibodies. Furthermore, there are many disadvantages with the current anti-HER2 drug, including drug resistance and adverse effects. Nanobodies (15 kDa), single-domain antibody (sdAb) fragments, can overcome these limitations. This study produced the recombinant sdAb against the HER2-tyrosine kinase (HER2-TK) domain using phage display technology. Three specific anti-HER2-TK sdAbs were selected for further characterization. Hallmark VHH residue identification and amino acid sequence analysis revealed that clone numbers 4 and 22 were VH antibodies, whereas clone number 17 was a VH H antibody (nanobody). The half-maximal inhibitory concentration of VHH17 exhibited significantly greater HER2 kinase-inhibition activity than the other clones. Consistent with these results, several charges and polar residues of the HER2-TK activation loop that were predicted based on mimotope analysis also appeared in the docking result and interacted via the CDR1, CDR2 and CDR3 loops of VHH17. Furthermore, the cell-penetrable VHH17 (R9 VHH17) showed cell-penetrability and significantly decreased HER2-positive cancer cell viability. Thus, the VH H17 could be developed as an effective therapeutic agent to treat HER2-positive breast cancer.

A bird's eye view of the advanced approaches and strategies for overshadowing triple negative breast cancer

Triple negative breast cancer (TNBC) is one of the most aggressive form of breast cancer. It is characterized by the absence of estrogen, progesterone and human epidermal growth factor receptors. The main issue with TNBC is that it exhibits poor prognosis, high risk of relapse, short progression-free survival and low overall survival in patients. This is because the conventional therapy used for managing TNBC has issues pertaining to poor bioavailability, lower cellular uptake, increased off-target effects and development of resistance. To overcome such pitfalls, several other approaches are explored. In this context, the present manuscript showcases three of the most widely used approaches which are (i) nanotechnology-based approach; (ii) gene therapy approach and (iii) Phytochemical-based approach. The ultimate focus is to present and explain the insightful reports based on these approaches. Further, the review also expounds on the identified molecular targets and novel targeting ligands which are explored for managing TNBC effectively. Thus, in a nutshell, the review tries to highlight these existing treatment approaches which might inspire for future development of novel therapies with a potential of overshadowing TNBC.

Aptamers with Tunable Affinity Enable Single-Molecule Tracking and Localization of Membrane Receptors on Living Cancer Cells

Tumor cell-surface markers are usually overexpressed or mutated protein receptors for which spatiotemporal regulation differs between and within cancers. Single-molecule fluorescence imaging can profile individual markers in different cellular contexts with molecular precision. However, standard single-molecule imaging methods based on overexpressed genetically encoded tags or cumbersome probes can significantly alter the native state of receptors. We introduce a live-cell points accumulation for imaging in nanoscale topography (PAINT) method that exploits aptamers as minimally invasive affinity probes. Localization and tracking of individual receptors are based on stochastic and transient binding between aptamers and their targets. We demonstrated single-molecule imaging of a model tumor marker (EGFR) on a panel of living cancer cells. Affinity to EGFR was finely tuned by rational engineering of aptamer sequences to define receptor motion and/or native receptor density.

Synthesis of a novel 99mTc labeled GE11 peptide for EGFR SPECT imaging

PURPOSE

This study investigated a novel SPECT agent for the noninvasive imaging of EGFR-overexpressing tumors.

METHODS

The EGFR-targeting peptide GE11 was synthesized with the introduction of four amino acids (GGGC) to its C-terminal to act as a strong chelator and radiolabeled using ^99mTc. The radiochemical yield of the ^99mTc-peptide-GE11 were evaluated using RP-HPLC. Cellular assays of the probe were performed on two NSCLC cell lines: A549 (high expression) and H23 (low expression). Biodistribution and SPECT imaging were performed in BALB/c nude mice bearing A549 and H23 NSCLC xenografts.

RESULTS

The ^99mTc-peptide-GE11 was prepared at high efficiency with radiochemical yield of 98.40 ± 1.00 % and it showed favorable stability. The cellular uptake was significantly higher in A549 than in H23 at all time points (especially at 1 h, which was 10.34 ± 0.72 and 2.04 ± 0.18, respectively). A nearly 56% reduction in probe uptake was observed after pretreatment with excess unlabeled peptides. The performance of SPECT imaging and biodistribution demonstrated higher uptake of the ^99mTc-peptide-GE11 in A549 xenograft than in H23 xenografts.

CONCLUSION

The new SPECT tracer ^99mTc-peptide-GE11 showed EGFR specificity, favorable pharmacokinetics and great potential for EGFR-targeted imaging.

Combination therapy with B7H3-redirected bispecific antibody and Sorafenib elicits enhanced synergistic antitumor efficacy

Rationale: Current traditional treatment options are frequently ineffective to fight against ovarian cancer due to late diagnosis and high recurrence. Therefore, there is a vital need for the development of novel therapeutic agents. B7H3, an immune checkpoint protein, is highly expressed in various cancers, representing it a promising target for cancer immunotherapy. Although targeting B7H3 by bispecific T cell-engaging antibodies (BiTE) has achieved successes in hematological malignancies during recent years, attempts to use them for the treatment of solid cancers are less favorable, in part due to the heterogeneity of tumors. Sorafenib is an unselective inhibitor of multiple kinases currently being tested in clinical trials for several tumors, including ovarian cancer which showed limited activity and inevitable side effect for ovarian cancer treatment. However, it is able to enhance antitumor immune response, which indicates sorafenib may improve the efficiency of immunotherapy.

Methods: We evaluated the expression of B7H3 in ovarian cancer using online database and validated its expression of tumor tissues by immunohistochemistry staining. Then, B7H3 expression and the effects of sorafenib on ovarian cancer cell lines were determined by flow cytometry. In addition, 2D and 3D ovarian cancer models were established to test the combined therapeutic effect in vitro. Finally, the efficiency of B7H3×CD3 BiTE alone and its combination with sorafenib were evaluated both in vitro and in vivo.

Results: Our data showed that B7H3 was highly expressed in ovarian cancer compared with normal samples. Treatment with sorafenib inhibited ovarian cancer cell proliferation and induced a noticeable upregulation of B7H3 expression level. Further study suggested that B7H3×CD3 BiTE was effective in mediating T cell killing to cancer cells. Combined treatment of sorafenib and B7H3×CD3 BiTE had synergistic anti-tumor effects in ovarian cancer models.

Conclusions: Overall, our study indicates that combination therapy with sorafenib and B7H3×CD3 BiTE may be a new therapeutic option for the further study of preclinical treatment of OC.

In vivo studies of a peptidomimetic that targets EGFR dimerization in NSCLC

Studies related to lung cancer have shown a link between human epidermal growth factor receptor-2 (HER2) expression and poor prognosis in patients with non-small cell lung cancer (NSCLC). HER2 overexpression has been observed in 3-38% of NSCLC, while strong HER2 protein overexpression is found in 2.5% of NSCLC. However, HER2 dimerization is important in lung cancer, including EGFR mutated NSCLC. Since HER2 dimerization leads to cell proliferation, targeting the dimerization of HER2 will have a significant impact on cancer therapies. A peptidomimetic has been designed that can be used as a therapeutic agent for a subset of NSCLC patients overexpressing HER2 or possessing HER2 as well as EGFR mutation. A cyclic peptidomimetic (18) has been designed to inhibit protein-protein interactions of HER2 with its dimerization partners EGFR and HER3. Compound 18 exhibited antiproliferative activity in HER2-positive NSCLC cell lines at nanomolar concentrations. Western blot analysis showed that 18 inhibited phosphorylation of HER2 and Akt in vitro and in vivo. Stability studies of 18 at various temperature and pH (pH 1 and pH 7.6), and in the presence of liver microsomes indicated that 18 was stable against thermal and chemical degradation. Pharmacokinetic parameters were evaluated in nude mice by administrating single doses of 4 mg/kg and 6 mg/kg of 18 via IV. The anticancer activity of 18 was evaluated using an experimental metastasis lung cancer model in mice. Compound 18 suppressed the tumor growth in mice when compared to control. A proximity ligation assay further proved that 18 inhibits HER2:HER3 and EGFR: HER2 dimerization. Overall, these results suggest that 18 can be a potential treatment for HER2-dimerization related NSCLC.

Two engineered site-specific antibody-drug conjugates, HLmD4 and HLvM4, have potent therapeutic activity in two DLL4-positive tumour xenograft models

The humanized Delta-like 4 (DLL4) monoclonal antibody H3L2 with a quite high affinity for hrDLL4 inhibits the DLL4-mediated human umbilical vein endothelial cell (HUVEC) phenotype, inducing dysfunctional angiogenesis and tumour cell apoptosis, which effectively arrests breast cancer cell growth in vivo. To develop a more effective therapy, an engineered cysteine residue at alanine 121 (Kabat numbering) on each H3L2 heavy chain or at valine 207 (Kabat numbering) on each H3L2 light chain was established by site-directed mutagenesis. Three engineered antibodies, THL4, TH2 and TL2, were identified, and the specific-site antibody-drug conjugates (ADCs) THL4-mpeoDM1 (named HLmD4), TH2-mpeoDM1 (named HmD2), TL2-mpeoDM1 (named LmD2) and THL4-vcMMAE (named HLvM4), were produced, which exhibit much more potent antitumour activity than the naked antibody. The engineered ADCs can be directed against DLL4 and effectively internalized, followed by the release of small molecule cytotoxic agents, e.g., DM1 or MMAE, into the cytosol, which inhibit the synthesis of microtubules and induce G2/M phase growth arrest and cell death through the induction of apoptosis. ADC-conjugated DM1 was highly potent against DLL4-expressing cells in vitro. We systematically compared the in vitro potency and the in vivo preclinical efficacy and safety profiles of the heterogeneous conventional ADC, H3L2-mpeoDM1 (named JmD4) with that of the homogeneous engineered conjugate HLmD4. The engineered anti-DLL4 ADCs, particularly HLmD4, showed more potent antitumour activity than Docetaxel and superior safety compared with JmD4 in two xenograft tumour models. Our findings indicate that engineered ADCs have promising potential as effective preclinical therapies for cancers.

Generation of novel affibody molecules targeting the EBV LMP2A N-terminal domain with inhibiting effects on the proliferation of nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) induced by latent infection with Epstein-Barr virus (EBV) remains the most common head and neck cancer in Southeast Asia, especially in the southern part of China. It is well known that persistent expression of two EBV latent membrane proteins (LMP1/LMP2A) plays a key role in nasopharyngeal carcinogenesis. Therefore, the therapeutic approach of targeting the LMP1/LMP2A protein and subsequently blocking the LMP1/LMP2A-mediated signalling pathway has been considered for treating patients with NPC. Recently, affibody molecules, a new class of small (~6.5 kDa) affinity proteins, have been confirmed to be powerful generalisable tools for developing imaging or therapeutic agents by targeting specific molecules. In this study, three EBV LMP2A N-terminal domain-binding affibody molecules (Z_LMP2A-N85, Z_LMP2A-N110 and Z_LMP2A-N252) were identified by screening a phage-displayed peptide library, and their high affinity and specificity for the EBV LMP2A N-terminal domain were confirmed by surface plasmon resonance (SPR), indirect immunofluorescence, co-immunoprecipitation and near-infrared small animal fluorescence imaging in vitro and in vivo. Moreover, affibody molecules targeting the EBV LMP2A N-terminal domain significantly reduced the viability of the EBV-positive cell lines C666-1, CNE-2Z and B95-8. Further investigations showed that affibody Z_LMP2A-N110 could inhibit the phosphorylation of AKT, GSK-3β and β-catenin signalling proteins, leading to suppression of β-catenin nuclear translocation and subsequent inhibition of c-Myc oncogene expression, which may be responsible for the reduced viability of NPC-derived cell lines. In conclusion, our findings provide a strong evidence that three novel EBV LMP2A N-terminal domain-binding affibody molecules have great potential for utilisation and development as agents for both molecular imaging and targeted therapy of EBV-related NPC.

Nanobody-based CD38-specific heavy chain antibodies induce killing of multiple myeloma and other hematological malignancies

Rationale: CD38 is a target for the therapy of multiple myeloma (MM) with monoclonal antibodies such as daratumumab and isatuximab. Since MM patients exhibit a high rate of relapse, the development of new biologics targeting alternative CD38 epitopes is desirable. The discovery of single-domain antibodies (nanobodies) has opened the way for a new generation of antitumor therapeutics. We report the generation of nanobody-based humanized IgG1 heavy chain antibodies (hcAbs) with a high specificity and affinity that recognize three different and non-overlapping epitopes of CD38 and compare their cytotoxicity against CD38-expressing hematological cancer cells in vitro, ex vivo and in vivo. Methods: We generated three humanized hcAbs (WF211-hcAb, MU1067-hcAb, JK36-hcAb) that recognize three different non-overlapping epitopes (E1, E2, E3) of CD38 by fusion of llama-derived nanobodies to the hinge- and Fc-domains of human IgG1. WF211-hcAb shares the binding epitope E1 with daratumumab. We compared the capacity of these CD38-specific hcAbs and daratumumab to induce CDC and ADCC in CD38-expressing tumor cell lines in vitro and in patient MM cells ex vivo as well as effects on xenograft tumor growth and survival in vivo. Results: CD38-specific heavy chain antibodies (WF211-hcAb, MU1067-hcAb, JK36-hcAb) potently induced antibody-dependent cellular cytotoxicity (ADCC) in CD38-expressing tumor cell lines and in primary patient MM cells, but only little if any complement-dependent cytotoxicity (CDC). In vivo, CD38-specific heavy chain antibodies significantly reduced the growth of systemic lymphomas and prolonged survival of tumor bearing SCID mice. Conclusions: CD38-specific nanobody-based humanized IgG1 heavy chain antibodies mediate cytotoxicity against CD38-expressing hematological cancer cells in vitro, ex vivo and in vivo. These promising results of our study indicate that CD38-specific hcAbs warrant further clinical development as therapeutics for multiple myeloma and other hematological malignancies.

Structure and development of single domain antibodies as modules for therapeutics and diagnostics

Since their discovery just over 25 years ago, the single variable domain from heavy-chain-only antibodies plays a role in an increasing number of antibody-based applications. Structural and biophysical studies have revealed that the small, ∼15 kDa, single variable domain found in camelids displays versatility in target recognition. Such insight has served as the foundation to develop and engineer VHH domains with enhanced properties capable of targeting a range of therapeutically relevant protein antigens or low-molecular weight haptens. Furthermore, the modular nature of VHH domains allows them to be introduced into constructs that are simply not possible with conventional antibodies. Here, we review the structural and biophysical properties of VHH domains, highlight recent VHH-based therapeutics and diagnostics, and provide insight into VHH engineering that may pave the way to next-generation single domain antibody applications.

CD-340 functionalized doxorubicin-loaded nanoparticle induces apoptosis and reduces tumor volume along with drug-related cardiotoxicity in mice

Background and objective

Targeted drug delivery of nanoparticles decorated with site-specific recognition ligands is of considerable interest to minimize cytotoxicity of chemotherapeutics in the normal cells. The study was designed to develop CD-340 antibody-conjugated polylactic-co-glycolic acid (PLGA) nanoparticles loaded with a highly water-soluble potent anticancer drug, doxorubicin (DOX), to specifically deliver entrapped DOX to breast cancer cells.

Methods

The study showed how to incorporate water-soluble drug in a hydrophobic PLGA (85:15) based matrix which otherwise shows poor drug loading due to leaching effect. The optimized formulation was covalently conjugated to anti-human epidermal growth factor receptor-2 (HER2) antibody (CD-340). Surface conjugation of the ligand was assessed by flow cytometry, confocal microscopy, and gel electrophoresis. Selectivity and cytotoxicity of the experimental nanoparticles were tested on human breast cancer cells SKBR-3, MCF-7, and MDA-MB-231. Both CD-340-conjugated and unconjugated nanoparticles were undergone in vitro and in vivo characterization.

Result

Higher level of incorporation of DOX (8.5% W/W), which otherwise shows poor drug loading due to leaching effect of the highly water-soluble drug, was seen in this method. In HER2-overexpressing tumor xenograft model, radiolabeled antibody-conjugated nanoparticles showed preferentially more of the formulation accumulation in the tumor area when compared to the treatments with the unconjugated one or with the other control groups of mice. The ligand conjugated nanoparticles showed considerable potential in reduction of tumor growth and cardiac toxicity of DOX in mice, a prominent side-effect of the drug.

Conclusion

In conclusion, CD-340-conjugated PLGA nanoparticles containing DOX preferentially delivered encapsulated drug to the breast cancer cells and in breast tumor and reduced the breast tumor cells by apoptosis. Site-specific delivery of the formulation to neoplastic cells did not affect normal cells and showed a drastic reduction of DOX-related cardiotoxicity.

Anti-CD24 Antibody-Nitric Oxide Conjugate Selectively and Potently Suppresses Hepatic Carcinoma

Nitric oxide (NO) has a wide range of potential applications in tumor therapy. However, a targeted delivery system for NO donors has remained elusive, creating a bottleneck that limits its druggability. The antibody-drug conjugate (ADC) is a targeted drug delivery system composed of an antibody linked to an active cytotoxic drug. This design may compensate for the weak targeting ability and various biological functions of the NO donor. In this study, we designed the NO donor HL-2, which had a targeted, cleaved disulfide bond and an attachable maleimide terminal. We conjugated HL-2 with an antibody that targeted CD24 through a thioether bond to generate an ADC-like immunoconjugate, antibody-nitric oxide conjugate (ANC), which we named HN-01. HN-01 showed efficient internalization and significantly increased the release of NO in hepatic carcinoma cells in vitro. HN-01 induced apoptosis of tumor cells and suppressed tumor growth in hepatic carcinoma-bearing nude mice through antibody-dependent co-toxicity; HN-01 also increased NO levels in tumor cells. Collectively, this study expands the concept of ADC and provides an innovative NO donor and ANC to address current challenges in targeted delivery of NO. This new inspiration for an ANC design can also be used in future studies for other molecules with intracellular targets. SIGNIFICANCE: This study is the first to expand the concept of ADC with an antibody-nitric oxide conjugate that suppresses hepatic carcinoma in vitro and in vivo.

Discovery of Nonpeptide, Reversible HER1/HER2 Dual-Targeting Small-Molecule Inhibitors as Near-Infrared Fluorescent Probes for Efficient Tumor Detection, Diagnostic Imaging, and Drug Screening

The abnormal expression of epidermal growth factor receptors HER1(EGFR) and HER2 is strongly associated with cancer invasion, metastasis, and angiogenesis. Their molecular detection is mainly executed using genetically encoded or antibody-based diagnostic tracers, but no dual-targeting small-molecule bioprobe has been achieved. Here, we report the novel small-molecule fluorescent probes Cy3-AFTN and Cy5-AFTN as potent dual-targeting inhibitors for efficient detection of HER1/HER2 expression in cancer cells and in vivo tumor diagnostic imaging. Unlike the irreversible HER1/HER2 inhibitors, Cy3-AFTN and Cy5-AFTN were designed as reversible/noncovalent probes based on the clinical drug afatinib, by making the molecule structurally impossible for receptor-mediated Michael additions. The synthesized probes were validated with live cell fluorescence imaging, flow cytometry and confocal-mediated competitive binding inhibition, molecular docking study, and in vivo xenograft tumor detection. The probes are competitively replaceable by other HER1/HER2 inhibitors; thus, they are potentially useful in fluorometric high-throughput screening for drug discovery.

Monoclonal antibody-based therapeutics, targeting the epidermal growth factor receptor family: from herceptin to Pan HER

Objectives

Monoclonal antibody-based of cancer therapy has been considered as one of the most successful therapeutic strategies for both haematologic malignancies and solid tumours in the last two decades. Epidermal growth factor receptor (EGFR) family signalling pathways play a key role in the regulation of cell proliferation, survival and differentiation. Hence, anti-EGFR family mAbs is one of the most promising approaches in cancer therapy.

Key findings

Here, recent advances in anti-EGFR mAb including approved or successfully tested in preclinical and clinical studies have been reviewed. Although we focus on monoclonal antibodies against the EGF receptor, but the mechanisms underlying the effects of EGFR-specific mAb in cancer therapy, to some extend the resistance to existing anti-EGFR therapies and some therapeutic strategies to overcome resistance such as combination of mAbs on different pathways are briefly discussed as well.

Summary

The EGFR family receptors, is considered as an attractive target for mAb development to inhibit their consecutive activities in tumour growth and resistance. However, due to resistance mechanisms, the combination therapies may become a good candidate for targeting EGFR family receptors.

Single-Domain Antibodies and the Promise of Modular Targeting in Cancer Imaging and Treatment

Monoclonal antibodies and their fragments have significantly changed the outcome of cancer in the clinic, effectively inhibiting tumor cell proliferation, triggering antibody-dependent immune effector cell activation and complement mediated cell death. Along with a continued expansion in number, diversity, and complexity of validated tumor targets there is an increasing focus on engineering recombinant antibody fragments for lead development. Single-domain antibodies (sdAbs), in particular those engineered from the variable heavy-chain fragment (VHH gene) found in Camelidae heavy-chain antibodies (or IgG2 and IgG3), are the smallest fragments that retain the full antigen-binding capacity of the antibody with advantageous properties as drugs. For similar reasons, growing attention is being paid to the yet smaller variable heavy chain new antigen receptor (VNAR) fragments found in Squalidae. sdAbs have been selected, mostly from immune VHH libraries, to inhibit or modulate enzyme activity, bind soluble factors, internalize cell membrane receptors, or block cytoplasmic targets. This succinct review is a compilation of recent data documenting the application of engineered, recombinant sdAb in the clinic as epitope recognition “modules” to build monomeric, dimeric and multimeric ligands that target, tag and stall solid tumor growth in vivo. Size, affinity, specificity, and the development profile of sdAbs drugs are seemingly consistent with desirable clinical efficacy and safety requirements. But the hepatotoxicity of the tetrameric anti-DR5-VHH drug in patients with pre-existing anti-drug antibodies halted the phase I clinical trial and called for a thorough pre-screening of the immune and poly-specific reactivities of the sdAb leads.

Dual-Targeted Molecular Imaging of Cancer

Molecular imaging is critical to personalized and precision medicine. Although singly targeted imaging probes are making an impact both clinically and preclinically, molecular imaging strategies using bispecific probes have enabled improved visualization of cancer in recent years through synergistic targeting of two ligands. In this Focus on Molecular Imaging review, we outline how peptide-, antibody-, and nanoparticle-based platforms have affected this emerging strategy, providing examples and pointing out areas in which the greatest clinical impact may be realized.

The two novel DLL4-targeting antibody-drug conjugates MvM03 and MGD03 show potent anti-tumour activity in breast cancer xenograft models

The anti-human Delta-like 4 (DLL4) monoclonal antibody MMGZ01 has a high affinity to hrDLL4 and arrests the DLL4-mediated human umbilical vein endothelial cell (HUVEC) phenotype, promotes immature vessels, and effectively reduces breast cancer cell growth in vivo. To develop a much more effective therapy, we conjugated MMGZ01 with two small-molecule cytotoxic agents, i.e., monomethyl auristatin E (MMAE) and doxorubicin (DOX), with different linkers to generate antibody-drug conjugates (ADCs), i.e., MMGZ01-vc-MMAE (named MvM03) and MMGZ01-GMBS-DOX (named MGD03), that are more potent therapeutic agents than naked antibody therapeutic agents. The produced anti-DLL4 ADCs can be effectively directed against DLL4 and internalized. Then, the release of MMAE or DOX into the cytosol can induce G2/M or G0/G1 phase growth arrest and cell death through the induction of apoptosis. In vitro, MvM03 was highly potent and selective against DLL4 cell lines. The anti-DLL4 ADCs, particularly MvM03, showed more potent anti-tumour activity than Docetaxel, which is an inhibitor of the depolymerisation of microtubules, in two xenograft breast cancer tumour models. Our findings indicate that anti-DLL4 ADCs have promising potential as an effective therapy for breast cancer.

Quantum-Dot-Based Theranostic Micelles Conjugated with an Anti-EGFR Nanobody for Triple-Negative Breast Cancer Therapy

A quantum-dot (QD)-based micelle conjugated with an anti-epidermal growth factor receptor (EGFR) nanobody (Nb) and loaded with an anticancer drug, aminoflavone (AF), has been engineered for EGFR-overexpressing cancer theranostics. The near-infrared (NIR) fluorescence of the indium phosphate core/zinc sulfide shell QDs (InP/ZnS QDs) allowed for in vivo nanoparticle biodistribution studies. The anti-EGFR nanobody 7D12 conjugation improved the cellular uptake and cytotoxicity of the QD-based micelles in EGFR-overexpressing MDA-MB-468 triple-negative breast cancer (TNBC) cells. In comparison with the AF-encapsulated nontargeted (i.e., without Nb conjugation) micelles, the AF-encapsulated Nb-conjugated (i.e., targeted) micelles accumulated in tumors at higher concentrations, leading to more effective tumor regression in an orthotopic triple-negative breast cancer xenograft mouse model. Furthermore, there was no systemic toxicity observed with the treatments. Thus, this QD-based Nb-conjugated micelle may serve as an effective theranostic nanoplatform for EGFR-overexpressing cancers such as TNBCs.

Human Antibody Fusion Proteins/Antibody Drug Conjugates in Breast and Ovarian Cancer

Considerable research efforts have been dedicated to understanding ovarian and breast cancer mechanisms, but there has been little progress translating the research into effective clinical applications. Hence, personalized/precision medicine has emerged because of its potential to improve the accuracy of tumor targeting and minimize toxicity to normal tissue. Targeted therapy in both breast and ovarian cancer has focused on antibodies, antibody drug conjugates (ADCs), and very recently the introduction of human antibody fusion proteins. Small molecule inhibitors and monoclonal antibodies (mAbs) are used in conjunction with chemotherapeutic drugs as a form of treatment but problems arise from a board expression of the target antigen in healthy tissues. Also, insufficient tumor penetration due to tight binding affinity and macromolecular size of mAbs compromise the efficacy of these ADCs. A more targeted approach is thus needed, and ADCs were designed to meet this need. However, in ADCs the method of conjugation of drug to antibody is >1, altering the structure of the drug which leads to off-target effects. Random conjugation also causes the drug to affect the pharmokinetics and biodistribution of the antibody and may cause nonspecific binding and internalization. Recombinant therapeutic proteins achieve controlled conjugation reactions and combine cytotoxicity and targeting in one molecule. They can also be engineered to extend half-life, stability and mechanism of action, and offer novel delivery routes. SNAP-tag fusion proteins are an example of a theranostic recombinant protein as they provide a unique antibody format to conjugate a variety of benzyl guanine modified labels, e.g. fluorophores and photosensitizers in a 1:1 stoichiometry. On the one hand, SNAP tag fusions can be used to optically image tumors when conjugated to a fluorophore, and on the other hand the recombinant proteins can induce necrosis/apoptosis in the tumor when conjugated to a photosensitizer upon exposure to a changeable wavelength of light. The dual nature of SNAP-tag fusions as both a diagnostic and therapeutic tool reinforces its significant role in cancer treatment in an era of precision medicine.

A camelid nanobody against EGFR was easily obtained through refolding of inclusion body expressed in Escherichia coli

Using anti-EGFR (epidermal growth factor receptor) nanobody is a good choice for diagnoses and therapeutics for high EGFR expression diseases. In the present study, the percentage composition of anti-EGFR nanobody attained 25% of the total cell protein expressed in Escherichia coli BL21 (DE3). However, almost all nanobodies were expressed as inclusion bodies. To acquire active nanobodies, a series of dilution refolding procedures were optimized after inclusion bodies were dissolved into 6 M urea and purified with immobilized metal affinity chromatography. The results showed the refolding rate of the anti-EGFR nanobodies attained to 73%, and about 100 mg nanobodies were refolded from 1 L cells under the conditions that the initial nanobody concentration was 0.3 mg/mL, the dilution speed was 2.5 mL/Min, the dilution buffer was Tris-HCl at pH 8.0, the additives were 0.2 M Arg, 5 mM reduced glutathione (GSH), and 1 mM oxidized glutathione (GSSG). Then the activity of the refolded nanobodies was confirmed. The results showed that the refolded anti-EGFR nanobodies, in a dose-dependent manner, bounded to the tumor cell surface of A431 and MCF-7 and significantly inhibited the proliferation of A431 caused by the epidermal growth factor. Our study provides a facile method to rapidly, efficiently, and massively prepare anti-EGFR antibodies and promotes anti-EGFR-based recognition in cancer diagnoses and therapeutics.

Selective targeted delivery of doxorubicin via conjugating to anti-CD24 antibody results in enhanced antitumor potency for hepatocellular carcinoma both in vitro and in vivo

PURPOSE

Antibody-drug conjugates (ADCs) represent a promising therapeutic approach for clinical application. Cluster of differentiation 24 (CD24) is over-expressed in several human malignancies, especially in hepatocellular carcinoma (HCC). We aimed to develop a new class of CD24-targeted ADCs for HCC.

METHODS

DOX was conjugated with G7mAb by a heterobifunctional cross-linker GMBS (N-[gamma-maleimido butyryloxy] succinimide ester) and further analyzed using HPLC. The targeting specificity and endocytosis of the newly generated ADC, G7mAb-DOX, were characterized using flow cytometry assay, near-infrared fluorescence imaging and laser scanning confocal microscope. The antitumor effects were evaluated in nude mice bearing HCC xenografts.

RESULTS

G7mAb-DOX with average two drug molecules per antibody was selectively captured and endocytosed by CD24 (+) tumor cells in vitro. In vivo, the ADC was proved to target tumor tissues, suppress tumor growth and prolong the survival of HCC-bearing nude mice with improved efficacy and less systemic toxicity compared with either G7mAb or DOX single-agent treatment.

CONCLUSION

These studies provide proof of concept for development of DOX-based ADCs which provide a novel approach for HCC-targeted immune therapy in clinical application.

Engineering a high-affinity humanized anti-CD24 antibody to target hepatocellular carcinoma by a novel CDR grafting design

Cluster of differentiation 24 (CD24) is a specific surface marker involved in the tumorigenesis and progression of hepatocellular carcinoma (HCC). However, all reported anti-CD24 antibodies are murine ones with inevitable immunogenicity. To address this, a method using both molecular structure and docking-based complementarity determining region (CDR) grafting was employed for humanization. After xenogeneic CDR grafting into a human antibody, three types of canonical residues (in the VL/VH interface core, in the loop foundation, and interaction with loop residues) that support loop conformation and residues involved in the antigen-binding interface were back-mutated. Four engineered antibodies were produced, among which hG7-BM3 has virtually identical 3-D structure and affinity parameters with the parental chimeric antibody cG7. In vitro, hG7-BM3 demonstrated superior immunogenicity and serum stability to cG7. Antibody-dependent cellular cytotoxicity (ADCC), tumor cell internalization and in vivo targeting assays indicate that hG7-BM3 has the potential for development as an antibody-drug conjugate (ADC). We therefore generated the hG7-BM3-VcMMAE conjugate, which was shown to induce tumor cell apoptosis and effectively suppress nude mice bearing HCC xenografts. In conclusion, our study provides new inspiration for antibody humanization and an ADC candidate for laboratory study and clinical applications.

Novel Linear Peptides with High Affinity to αvβ3 Integrin for Precise Tumor Identification

Development of alternative linear peptides for targeting αvβ3 integrin has attracted much attention, as the traditional peptide ligand, cyclic RGD, is limited by inferior water-solubility and complex synthesis. Using pharmacophore-based virtual screening and high-throughput molecular docking, we identified two novel linear small peptides RWr and RWrNM with high affinity and specificity to αvβ3 integrin. The competitive binding with cyclic RGD (c(RGDyK)) and cellular uptake related to the integrin expression levels verified their affinity to αvβ3 integrin. The intermolecular interaction measurement and dynamics simulation demonstrated the high binding affinity and stability, especially for RWrNM. In vivo peptide-guided tumor imaging and targeted therapy further confirmed their specificity. Results indicated that the newly identified small linear peptide RWrNM, with high affinity and specificity to αvβ3 integrin, better water-solubility, and simplified synthetic process, could overcome limitations of the current cyclic RGD peptides, paving the way for diverse use in diagnosis and therapy.

Camelid and shark single domain antibodies: structural features and therapeutic potential

In addition to canonical antibodies composed of heavy and light chains, the adaptive immune systems of camelids and cartilaginous fish comprise heavy-chain only isotypes (HcAb) devoid of light chains, where antigen-binding is mediated exclusively by one variable domain. Due to their inherent favorable attributes, such as high affinity and specificity for their cognate antigen, extraordinary stability, small size and, most importantly, the possibility to complement classical antibodies in terms of 'drugable' target-space, HcAb-derived entities evolved as promising candidates for biomedical applications of which many have already proven to be successful in early stage clinical trials.

Affinity enhancement of nanobody binding to EGFR: in silico site-directed mutagenesis and molecular dynamics simulation approaches

Epidermal growth factor receptor (EGFR), a transmembrane glycoprotein, is overexpressed in many cancers such as head-neck, breast, prostate, and skin cancers for this reason it is a good target in cancer therapy and diagnosis. In nanobody-based cancer diagnosis and treatment, nanobodies with high affinity toward receptor (e.g. EGFR) results in effective treatment or diagnosis of cancer. In this regard, the main aim of this study is to develop a method based on molecular dynamic (MD) simulations for designing of 7D12 based nanobody with high affinity compared with wild-type nanobody. By surveying electrostatic and desolvation interactions between different residues of 7D12 and EGFR, the critical residues of 7D12 that play the main role in the binding of 7D12 to EGFR were elucidated and based on these residues, five logical variants were designed. Following the 50 ns MD simulations, pull and umbrella sampling simulation were performed for 7D12 and all its variants in complex with EGFR. Binding free energy of 7D12 (and all its variants) with EGFR was obtained by weighted histogram analysis method. According to binding free energy results, GLY101 to GLU mutation showed the highest binding affinity but this variant is unstable after 50 ns MD simulations. ALA100 to GLU mutation shows suitable binding enhancement with acceptable structural stability. Suitable position and orientation of GLU in residue 100 of 7D12 against related amino acids of EGFR formed some extra hydrogen and electrostatic interactions which resulted in binding enhancement.

HER2-positive breast cancer targeting and treatment by a peptide-conjugated mini nanodrug

HER2+ breast cancer is one of the most aggressive forms of breast cancer. The new polymalic acid-based mini nanodrug copolymers are synthesized and specifically characterized to inhibit growth of HER2+ breast cancer. These mini nanodrugs are highly effective and in the clinic may substitute for trastuzumab (the marketed therapeutic antibody) and antibody-targeted nanobioconjugates. Novel mini nanodrugs are designed to have slender shape and small size. HER2+ cells were recognized by the polymer-attached trastuzumab-mimetic 12-mer peptide. Synthesis of the nascent cell-transmembrane HER2/neu receptors by HER2+ cells was inhibited by antisense oligonucleotides that prevented cancer cell proliferation and significantly reduced tumor size by more than 15 times vs. untreated control or PBS-treated group. We emphasize that the shape and size of mini nanodrugs can enhance penetration of multiple bio-barriers to facilitate highly effective treatment. Replacement of trastuzumab by the mimetic peptide favors reduced production costs and technical efforts, and a negligible immune response.