Identification and characterization of Ch806 mimotopes

Phage Display-Based Nanotechnology Applications in Cancer Immunotherapy

Phage display is a nanotechnology with limitless potential, first developed in 1985 and still awaiting to reach its peak. Awarded in 2018 with the Nobel Prize for Chemistry, the method allows the isolation of high-affinity ligands for diverse substrates, ranging from recombinant proteins to cells, organs, even whole organisms. Personalized therapeutic approaches, particularly in oncology, depend on the identification of new, unique, and functional targets that phage display, through its various declinations, can certainly provide. A fast-evolving branch in cancer research, immunotherapy is now experiencing a second youth after being overlooked for years; indeed, many reports support the concept of immunotherapy as the only non-surgical cure for cancer, at least in some settings. In this review, we describe literature reports on the application of peptide phage display to cancer immunotherapy. In particular, we discuss three main outcomes of this procedure: (i) phage display-derived peptides that mimic cancer antigens (mimotopes) and (ii) antigen-carrying phage particles, both as prophylactic and/or therapeutic vaccines, and (iii) phage display-derived peptides as small-molecule effectors of immune cell functions. Preclinical studies demonstrate the efficacy and vast potential of these nanosized tools, and their clinical application is on the way.

Overview of Current Immunotherapies Targeting Mutated KRAS Cancers

The occurrence of somatic substitution mutations of the KRAS proto-oncogene is highly prevalent in certain cancer types, which often leads to constant activation of proliferative pathways and subsequent neoplastic transformation. It is often seen as a gateway mutation in carcinogenesis and has been commonly deemed as a predictive biomarker for poor prognosis and relapse when conventional chemotherapeutics are employed. Additionally, its mutational status also renders EGFR targeted therapies ineffective owing to its downstream location. Efforts to discover new approaches targeting this menacing culprit have been ongoing for years without much success, and with incidences of KRAS positive cancer patients being on the rise, researchers are now turning towards immunotherapies as the way forward. In this scoping review, recent immunotherapeutic developments and advances in both preclinical and clinical studies targeting K-ras directly or indirectly via its downstream signal transduction machinery will be discussed. Additionally, some of the challenges and limitations of various K-ras targeting immunotherapeutic approaches such as vaccines, adoptive T cell therapies, and checkpoint inhibitors against KRAS positive cancers will be deliberated.

Epidermal growth factor receptor mimotope alleviates renal fibrosis in murine unilateral ureteral obstruction model

Macrophages have been recognized as a vital factor that can promote renal fibrosis. Previously we reported that the EGFR mimotope could alleviate the macrophage infiltration in the Sjögren's syndrome-like animal model. In current study, we sought to observe whether the active immunization induced by the EGFR mimotope could ameliorate renal fibrosis in the murine Unilateral Ureteral Obstruction (UUO) model. A series of experiments showed the EGFR mimotope immunization could ameliorate renal fibrosis, reduce the expressions of fibronectin, α-SMA and collagen I and alleviate the infiltrations of F4/80+ macrophages in UUO model. Meanwhile, the EGFR mimotope immunization could inhibit the EGFR downstream signaling. Additionally, the frequency of and F4/80+CD9+/FAS+ macrophages significantly increased in spleen after the EGFR mimotope immunization. These evidence suggested that the EGFR mimotope could alleviate renal fibrosis by both inhibiting EGFR signaling and promoting macrophages apoptosis.

Identification and suppression of epidermal growth factor receptor variant III signaling in fibroblast-like synoviocytes from aggressive rheumatoid arthritis by the mimotope

Epidermal growth factor receptor (EGFR) signaling has been reported to play a vital role in the pathogenesis of rheumatoid arthritis (RA). In current study, we sought to observe whether the active immunization induced by the mimotope could recognize EGFR, inhibit their signaling and disrupt the pathogenic behavior of fibroblast-like synoviocytes (FLS) from RA patients. We prepared a linked EGFR mimotope and performed series of experiments to detect whether the mimotope could induce the desired immune responses. To our surprises, we detected the expression of EGFR variant III (EGFRvIII), but not EGFR in the synovial tissues and FLS from patients with aggressive RA by the linked EGFR mimotope-induced antibodies (LEMIA). Meanwhile, LEMIA could inhibit the signaling caused by the autophosphorylation of EGFRvIII in the FLS. The proliferation, migration, invasion and anti-apoptosis capabilities of the EGFRvIII-expressed FLS were disrupted by LEMIA. These results suggest that EGFRvIII signaling may participate in the malignant behaviors of FLS from aggressive RA. Meanwhile, the linked EGFR mimotope could be used to detect the expression of EGFRvIII and developed to be a potential therapy agent against the aggressive FLS.

Tumor-targeting peptides from combinatorial libraries

Cancer is one of the major and leading causes of death worldwide. Two of the greatest challenges in fighting cancer are early detection and effective treatments with no or minimum side effects. Widespread use of targeted therapies and molecular imaging in clinics requires high affinity, tumor-specific agents as effective targeting vehicles to deliver therapeutics and imaging probes to the primary or metastatic tumor sites. Combinatorial libraries such as phage-display and one-bead one-compound (OBOC) peptide libraries are powerful approaches in discovering tumor-targeting peptides. This review gives an overview of different combinatorial library technologies that have been used for the discovery of tumor-targeting peptides. Examples of tumor-targeting peptides identified from each combinatorial library method will be discussed. Published tumor-targeting peptide ligands and their applications will also be summarized by the combinatorial library methods and their corresponding binding receptors.

Mimotope mimicking epidermal growth factor receptor alleviates mononuclear cell infiltration in exocrine glands induced by muscarinic acetylcholine 3 receptor

The muscarinic type 3 receptor (M3R) plays a pivotal role in the pathogenesis of Sjögren's syndrome (SS). Characterization of the crosstalk between M3R and EGFR has been investigated in some human malignancies. In the current study, we sought to investigate whether EGFR mimic immunization could alleviate the abnormal immune responses in an experimental SS-like model triggered by M3R peptides. After immunization with the combination of mimotope and M3R peptide, the active immunization targeting EGFR induced by the mimotope could reduce the marked infiltration of mononuclear cells, the high titer of antibodies against M3R and the accumulation of crucial pro-inflammatory cytokines in mice immunized with M3R peptide. Mechanistic analysis showed that mimotope immunization could alleviate the autoimmune response through inhibiting mitochondrion-mediated anti-apoptosis and up-regulating the FAS apoptosis pathway. These results may help to clarify the role of M3R in the pathogenesis of SS and suggested that transactivation of the EGFR signaling pathway may help M3R activate the autoimmune response in the pathogenesis of SS.

Head and neck cancer: from anatomy to biology

The 20th century saw great advances in anatomy-based (surgery and radiotherapy) and chemotherapy approaches for treating head and neck squamous cell carcinoma (HNSCC) and improving quality of life (QoL). However, despite these advances, the survival rate in HNSCC remains at ∼50%. Front-line treatments often cause severe toxicity and debilitating long-term impacts on QoL. In recent decades, dramatic advances have been made in our knowledge of fundamental tumor biology and signaling pathways that contribute to oncogenesis and cancer progression. These insights are presenting unprecedented opportunities to develop more effective and less toxic treatments that are specific to particular molecular targets. This review discusses some of the major, potentially targetable, molecular pathways associated with head and neck carcinogenesis. We present the general mechanism underlying the functional components for each signaling pathway, discuss how these components are aberrantly regulated in HNSCC and describe their potential as therapeutic targets. We have restricted our discussion to "drug-able targets" such as oncogenes including those associated with HPV, tumor hypoxia and microRNAs and present these changes in the context of HNSCC patient care. The specific targeting of these pathways to achieve cancer control/remission and reduce toxicity is now challenging conventional treatment paradigms in HNSCC. This new "biologic era" is transforming our ability to target causal pathways and improve survival outcomes in HNSCC.

The monoclonal antibody CH12 enhances the sorafenib-mediated growth inhibition of hepatocellular carcinoma xenografts expressing epidermal growth factor receptor variant III

The multikinase inhibitor sorafenib is the first oral agent to show activity against human hepatocellular carcinoma (HCC). Although the clinical application of sorafenib has shown good tolerability in the studied populations, it also causes multiple human dose-limiting toxicities. Thus, there is a strong need to reduce the overall dose of sorafenib. We have reported that the epidermal growth factor receptor variant III (EGFRvIII) expression can decrease the sensitivity of HCC cells to chemotherapeutic drugs. Therefore, we sought to explore whether EGFRvIII can affect the sensitivity of HCC cells to sorafenib. In this study, we observed that EGFRvIII expression significantly decreased the sensitivity of HCC cells to sorafenib. To enhance the antitumor effect and reduce the overall dose of sorafenib, we evaluated the combined effects of CH12, a monoclonal antibody against EGFRvIII, and sorafenib on the growth of HCC cells expressing EGFRvIII in vitro and in vivo. The results showed that, when CH12 was combined with sorafenib, the tumor growth suppression effect was significantly increased, and the concentration of sorafenib required for growth inhibition was substantially reduced. Mechanistically, the combination could more noticeably downregulate the phosphorylation of constitutively active extracellular signal-regulated kinase (ERK), Akt (Thr308), and signal transducer and activator of transcription 3 (STAT3) than sorafenib alone. Collectively, these findings demonstrate that CH12 interacts additively with sorafenib to strongly inhibit the tumor growth of HCC xenografts expressing EGFRvIII by enhancing the sorafenib-mediated inhibition of the MEK/ERK, phosphoinositide 3-kinase/AKT, and STAT3 pathways.

Recombinant IgE antibody engineering to target EGFR

Monoclonal antibodies have become a mainstay for the targeted treatment of cancer today. Some of the most successful targets of monoclonal antibodies are constituted by the epidermal growth factor receptor family spearheaded by the epidermal growth factor receptor (EGFR). Prompted by studies indicating that IgE compared to IgG may harness alternate effector functions to eradicate malignant cells, we addressed the establishment, engineering, and the potential tumoricidal effects of recombinant anti-EGFR IgE. Therefore, two different therapeutic EGFR-specific antibodies, 225 and 425, were chosen for re-cloning into different chimeric IgE and IgG formats and produced in human cells. Simultaneous antibody binding to the sEGFR demonstrated accessibility of both epitopes for recombinant IgE. Proliferation and cytotoxicity assays demonstrated signal blocking and effector mediating capability of IgE isotypes. Pronounced degranulation in the presence of sEGFR upon activation exclusively with two IgE antibodies verified the epitope proximity and provides evidence that tumor-targeting by anti-EGFR IgE is safe with regard to soluble target structures. Degranulation mediated by tumor cells expressing EGFR could be demonstrated for singular and combined IgE antibodies; however, use of two IgE specificities was not superior to use of one IgE alone. The data suggest that the surface distribution of EGFR is optimally suited to mount a robust effector cell trigger and corroborate the potential and specificity of the IgE/IgE receptor network to react to xenobiotic or pathogenic patterns for targeting malignancies.

Screening and identification of the mimic epitope of the adhesion protein of Mycoplasma genitalium

Mycoplasma genitalium adhesion protein (MgPa) is the major adhesion protein of M. genitalium, and its C-terminal domain (amino acid 1075–1444) is the most immunogenic region. However, the exact epitopes of the adhesion protein of M. genitalium are still unclear. We used the purified polyclonal antibody against the recombinant adhesion protein to screen the mimic epitopes of MgPa using a random 12-peptide phage display library. Immunoscreening via the phage display peptide library revealed that 3 motifs (P-S-A-A/V-X-R-F/W-E/S-L-S-P, A-K-I/L-T/Q-X-T-L-X-L, and K-S-L-S-R-X-D-X-I) may represent 3 different mimotopes of MgPa. Results of bioinformatics analysis by MIMOX demonstrated that the key consensus amino acid residues in the aligned mimotopes may be S, A, and F for cluster 1; A, K, I, T, and L for cluster 2; and K, S, L, R, D, and I for cluster 3. Three representative phages could recognize sera from M. genitalium-positive patients to varying degrees, whereas they could not recognize the sera from Mycoplasma pneumoniae -positive patients or the sera from healthy people. These findings will help to clarify the mimic epitopes of MgPa to facilitate diagnosis of the antigen and to understand the antigenic structure of MgPa.

New promising molecular targets in head and neck squamous cell carcinoma

PURPOSE OF REVIEW

Despite advances in multimodality therapy, the overall 5-year survival rate is 40-50% in patients with head and neck squamous cell carcinoma (HNSCC) and current multimodality approaches impart significant toxicities. This review highlights promising targets with the potential to improve clinical outcomes in HNSCC.

RECENT FINDINGS

In addition to mutagenic exposure to tobacco and alcohol as risk factors, recent studies have shown that human papillomavirus is one of the main causes of HNSCC and as such is being investigated as a therapeutic target. Furthermore, recent data generated from whole exome sequencing of HNSCC, new insights into the biology of DNA damage repair, and increased understanding of tumor hypoxia responses are pointing to new therapeutic possibilities for treating HNSCC.

SUMMARY

HNSCC is a heterogeneous disease. Improved treatment will require a rapid translation of basic science research, and the simultaneous development of novel therapeutics and corresponding biomarkers to guide their application.

Cancer vaccines inducing antibody production: more pros than cons

To date, passive immunotherapy with monoclonal antibodies is a well-established option in clinical oncology. By contrast, anticancer vaccines are less advanced, with the exception of successfully applied prophylactic vaccines against oncogenic virus infections. The creation of therapeutic vaccines is still a great challenge mostly due to the self-nature of tumor antigens. Therapeutic vaccines may be based on patient-specific material including pulsed effector cells, or tumor-associated antigens and derivatives thereof, such as peptides, mimotopes and nucleic acids. The latter represents a more universal approach, which would set an ideal economic framework resulting in broad patient access. In this article we focus on cancer vaccines for antibody production, in particular mimotope vaccines. The collected evidence suggests that they will open up new treatment options in minimal residual disease and early stage disease.

Generation and characterization of peptide mimotopes specific for anti ErbB-2 monoclonal antibodies

The erbb-2 gene receptor is often over-expressed in human cancer and its overexpression is accompanied by worse prognosis. Targeting erbb-2 gene with antibodies is an effective approach to curtail the progression of erbb-2 gene-expressing cancer types. Two monoclonal antibodies, L-26 and N-12, previously generated in our laboratory, have shown effective tumor inhibition in mice, especially when used in combination. Here, we describe novel peptide mimics of erbb-2 gene protein epitopes, also called mimotopes, that were selected from a constraint random 12-mer peptide phage library, specific for the antibodies L-26 and N-12. Initial sequencing analyses revealed little sequence conservation among the peptide mimotopes, and no sequence homology with the erbb-2 gene protein. However, computational analyses of the two groups of peptides, specific for L-26 and N-12, suggested different epitopes on the erbb-2 gene extracellular domain. In vitro assays showed that the phage displayed peptide mimotopes were specific to their respective antibodies. Selected cyclic peptide mimotopes, but not their corresponding linear equivalents, were able to inhibit binding of the antibodies L-26 and N-12 to the surface of erbb-2 gene-expressing cancer cells in a concentration-dependent manner. In line with this observation, phage-displayed cyclic peptides successfully competed in vitro with recombinant erbb-2 gene protein for binding to their respective antibodies L-26 or N-12. Consistent with the antibody inhibition experiments, we detected specific anti-erbb-2 gene antibodies following vaccination with KLH-coupled cyclic peptides but not with multiple antigenic linear peptides. Potentially, the selected peptides could serve as a starting point for the development of a vaccine against erbb-2 gene over-expressing cancer.

Growth suppression of human hepatocellular carcinoma xenografts by a monoclonal antibody CH12 directed to epidermal growth factor receptor variant III

Human hepatocellular carcinoma (HCC) is considered difficult to cure because it is resistant to radio- and chemotherapy and has a high recurrence rate after curative liver resection. Epidermal growth factor receptor variant III (EGFRvIII) has been reported to express in HCC tissues and cell lines. This article describes the efficacy of an anti-EGFRvIII monoclonal antibody (mAb CH12) in the treatment of HCC xenografts with EGFRvIII expression and the underlying mechanism of EGFRvIII as an oncogene in HCC. The results demonstrated that CH12 bound preferentially to EGFRvIII with a dissociation constant (K(d)) of 1.346 nm/liter. In addition, CH12 induces strong antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity in Huh7-EGFRvIII (with exogenous expression of EGFRvIII) and SMMC-7721 (with endogenous expression of EGFRvIII) cells. Notably, CH12 significantly inhibited the growth of Huh7-EGFRvIII and SMMC-7721 xenografts in vivo with a growth inhibition ratio much higher than C225, a U. S. Food and Drug Administration-approved anti-EGFR antibody. Treatment of the two HCC xenografts with CH12 significantly suppressed tumor proliferation and angiogenesis. Mechanistically, in vivo treatment with CH12 reduced the phosphorylation of constitutively active EGFRvIII, Akt, and ERK. Down-regulation of the apoptotic protectors Bcl-x(L), Bcl-2, and the cell cycle regulator cyclin D1, as well as up-regulation of the cell-cycle inhibitor p27, were also observed after in vivo CH12 treatment. Collectively, these results indicate that the monoclonal antibody CH12 is a promising therapeutic agent for HCC with EGFRvIII expression.