Prognostic and Clinicopathological Significance of Epidermal Growth Factor Receptor (EGFR) Expression in Oral Squamous Cell Carcinoma: Systematic Review and Meta-Analysis

The aim of this systematic review and meta-analysis was to evaluate the current evidence in relation to the clinicopathological and prognostic significance of epidermal growth factor receptor (EGFR) overexpression in patients with oral squamous cell carcinoma (OSCC). We searched MEDLINE/PubMed, Embase, Web of Science, and Scopus for studies published before November 2022. We evaluated the quality of primary-level studies using the QUIPS tool, conducted meta-analyses, examined inter-study heterogeneity via subgroup analyses and meta-regressions, and performed small-study effects analyses. Fifty primary-level studies (4631 patients) met the inclusion criteria. EGFR overexpression was significantly associated with poor overall survival (hazard ratio [HR] = 1.38, 95% confidence intervals [CI] = 1.06-1.79, p = 0.02), N+ status (odds ratio [OR] = 1.37, 95%CI = 1.01-1.86, p = 0.04), and moderately-poorly differentiated OSCC (OR = 1.43, 95% CI = 1.05-1.94, p = 0.02). In addition, better results were obtained by the application of a cutoff point ≥10% tumor cells with EGFR overexpression (p < 0.001). In conclusion, our systematic review and meta-analysis supports that the immunohistochemical assessment of EGFR overexpression may be useful as a prognostic biomarker for OSCC.

Potentiating Therapeutic Effects of Epidermal Growth Factor Receptor Inhibition in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a subset of breast cancer with aggressive characteristics and few therapeutic options. The lack of an appropriate therapeutic target is a challenging issue in treating TNBC. Although a high level expression of epidermal growth factor receptor (EGFR) has been associated with a poor prognosis among patients with TNBC, targeted anti-EGFR therapies have demonstrated limited efficacy for TNBC treatment in both clinical and preclinical settings. However, with the advantage of a number of clinically approved EGFR inhibitors (EGFRis), combination strategies have been explored as a promising approach to overcome the intrinsic resistance of TNBC to EGFRis. In this review, we analyzed the literature on the combination of EGFRis with other molecularly targeted therapeutics or conventional chemotherapeutics to understand the current knowledge and to provide potential therapeutic options for TNBC treatment.

Targeting CD44v6 for fluorescence-guided surgery in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is an often highly invasive tumor, infiltrating functionally important tissue areas. Achieving complete tumor resection and preserving functionally relevant tissue structures depends on precise identification of tumor-free resection margins during surgery. Fluorescence-guided surgery (FGS), by intraoperative detection of tumor cells using a fluorescent tracer, may guide surgical excision and identify tumor-positive resection margins. Using a literature survey on potential surface molecules followed by immunohistochemical validation, we identified CD44 variant 6 (CD44v6) as a constitutively expressed antigen in the invasion zone of HNSCC lesions. The monoclonal anti-CD44v6 antibody BIWA was labeled with both a near-infrared fluorescent dye (IRDye800CW) and a radioactive label (Indium-111) and dual-modality imaging was applied in a locally invasive tumor mouse model. BIWA accurately detected human HNSCC xenografts in mice with a tumor uptake of 54 ± 11% ID/g and invasion regions with an accuracy of 94%. When dissected under clinical-like conditions, tumor remnants approximately 0.7 mm in diameter consisting of a few thousand cells were identified by fluorescence imaging, resulting in reliable dissection of invasive microregions. These data indicate that CD44v6 is a suitable target for reliable near-infrared detection and FGS of invasive HNSCC lesions in vivo.

Trispecific antibodies for CD16A-directed NK cell engagement and dual-targeting of tumor cells

Bispecific antibodies that redirect the lytic activity of cytotoxic immune effector cells, such as T- and NK cells, onto tumor cells have emerged as a highly attractive and clinically validated treatment modality for hematological malignancies. Advancement of this therapeutic concept into solid tumor indications, however, is hampered by the scarcity of targetable antigens that are surface-expressed on tumor cells but demonstrate only limited expression on healthy tissues. To overcome this limitation, the concept of dual-targeting, i.e. the simultaneous targeting of two tumor-expressed surface antigens with limited co-expression on non-malignant cells, with multispecific antibodies has been proposed to increase tumor selectivity of antibody-induced effector cell cytotoxicity. Here, a novel CD16A (FcγRIIIa)-directed trispecific, tetravalent antibody format, termed aTriFlex, is described, that is capable of redirecting NK cell cytotoxicity to two surface-expressed antigens. Using a BCMA/CD200-based in vitro model system, the potential use of aTriFlex antibodies for dual-targeting and selective induction of NK cell-mediated target cell lysis was investigated. Bivalent bispecific target cell binding was found to result in significant avidity gains and up to 17-fold increased in vitro potency. These data suggest trispecific aTriFlex antibodies may support dual-targeting strategies to redirect NK cell cytotoxicity with increased selectivity to enable targeting of solid tumor antigens.

Noninvasive Interrogation of DLL3 Expression in Metastatic Small Cell Lung Cancer

The Notch ligand DLL3 has emerged as a novel therapeutic target expressed in small cell lung cancer (SCLC) and high-grade neuroendocrine carcinomas. Rovalpituzumab teserine (Rova-T; SC16LD6.5) is a first-in-class DLL3-targeted antibody-drug conjugate with encouraging initial safety and efficacy profiles in SCLC in the clinic. Here we demonstrate that tumor expression of DLL3, although orders of magnitude lower in surface protein expression than typical oncology targets of immunoPET, can serve as an imaging biomarker for SCLC. We developed ⁸⁹Zr-labeled SC16 antibody as a companion diagnostic agent to facilitate selection of patients for treatment with Rova-T based on a noninvasive interrogation of the in vivo status of DLL3 expression using PET imaging. Despite low cell-surface abundance of DLL3, immunoPET imaging with ⁸⁹Zr-labeled SC16 antibody enabled delineation of subcutaneous and orthotopic SCLC tumor xenografts as well as distant organ metastases with high sensitivity. Uptake of the radiotracer in tumors was concordant with levels of DLL3 expression and, most notably, DLL3 immunoPET yielded rank-order correlation for response to SC16LD6.5 therapy in SCLC patient-derived xenograft models. Cancer Res; 77(14); 3931-41. ©2017 AACR.

Selecting Targets for Tumor Imaging: An Overview of Cancer-Associated Membrane Proteins

Tumor targeting is a booming business: The global therapeutic monoclonal antibody market accounted for more than $78 billion in 2012 and is expanding exponentially. Tumors can be targeted with an extensive arsenal of monoclonal antibodies, ligand proteins, peptides, RNAs, and small molecules. In addition to therapeutic targeting, some of these compounds can also be applied for tumor visualization before or during surgery, after conjugation with radionuclides and/or near-infrared fluorescent dyes. The majority of these tumor-targeting compounds are directed against cell membrane-bound proteins. Various categories of targetable membrane-bound proteins, such as anchoring proteins, receptors, enzymes, and transporter proteins, exist. The functions and biological characteristics of these proteins determine their location and distribution on the cell membrane, making them more, or less, accessible, and therefore, it is important to understand these features. In this review, we evaluate the characteristics of cancer-associated membrane proteins and discuss their overall usability for cancer targeting, especially focusing on imaging applications.

Production and characterization of a peptide-based monoclonal antibody against CD44 variant 6

The gene that codes for the CD44 family members consists of 20 exons, nine of which encode the standard form of the molecule. The other exons can be inserted in various combinations into the membrane proximal region of the extracellular domain of the protein, giving rise to variant isoforms (CD44v). CD44 variants, especially the CD44v6, have been reported to regulate tumor invasion, progression, and metastasis of carcinomas. Producing a high affinity monoclonal antibody against human CD44v6 provides a powerful tool to monitor and trace CD44v6 function in different biological fluids. In this study, a synthetic peptide from CD44v6 was conjugated to keyhole limpet hemocyanin (KLH) and injected into BALB/c mice. Splenocytes from the immunized mice were fused with murine SP2/0 myeloma cells followed by selection of antibody producing hybridoma cells. After screening of hybridoma colonies by ELISA, high affinity antibodies were selected and purified by affinity chromatography. Western blot, immunocytochemistry, and flow cytometry experiments were used to characterize the antibodies. Six stable hybridoma cell lines, designated as 1H1, 1H2, 2A12, 2G11, 3H3, and 3H7, were obtained. Flow cytometry and immunocytochemistry results showed that the new monoclonal antibodies recognized CD44v6 on the cell surface. This novel panel of anti-CD44v6 antibodies has the potential for investigating the role of CD44v6 in cancer pathogenesis.

Radiolabeled Cetuximab Conjugates for EGFR Targeted Cancer Diagnostics and Therapy

The epidermal growth factor receptor (EGFR) has evolved over years into a main molecular target for the treatment of different cancer entities. In this regard, the anti-EGFR antibody cetuximab has been approved alone or in combination with: (a) chemotherapy for treatment of colorectal and head and neck squamous cell carcinoma and (b) with external radiotherapy for treatment of head and neck squamous cell carcinoma. The conjugation of radionuclides to cetuximab in combination with the specific targeting properties of this antibody might increase its therapeutic efficiency. This review article gives an overview of the preclinical studies that have been performed with radiolabeled cetuximab for imaging and/or treatment of different tumor models. A particularly promising approach seems to be the treatment with therapeutic radionuclide-labeled cetuximab in combination with external radiotherapy. Present data support an important impact of the tumor micromilieu on treatment response that needs to be further validated in patients. Another important challenge is the reduction of nonspecific uptake of the radioactive substance in metabolic organs like liver and radiosensitive organs like bone marrow and kidneys. Overall, the integration of diagnosis, treatment and monitoring as a theranostic approach appears to be a promising strategy for improvement of individualized cancer treatment.

Effect of cetuximab treatment in squamous cell carcinomas

The purpose of this study was to assess the effects of the monoclonal antibody cetuximab in a panel of cultured squamous cell carcinoma cell lines. This antibody, targeting the epidermal growth factor receptor (EGFR), is emerging as a promising agent for treatment of several cancers. As this antibody comes into clinical use, the identification of predictive markers of therapeutic benefit remains a pressing issue. Cells were first characterized according to EGFR expression, cell doubling time, and BRAF and K-ras mutations. The effects of cetuximab on cell-cycle distribution, proliferation, as well as cell growth rate were then evaluated. Cetuximab decreased cell proliferation in three out of four cell lines in a time-dependent manner, and all cell lines were found to exhibit wild type K-ras and BRAF genes. A possible correlation between EGFR expression and cetuximab effect on growth inhibition rate was observed, whereas reduction of cell doubling time seemed to be more dependent on initial growth rate. In addition, other factors may further influence the long-term treatment response of cetuximab. Moreover, the time-dependent manner of cetuximab response demonstrates the importance of long-term measurements for this substance.

Regulatory T cells and their prognostic value for patients with squamous cell carcinoma of the head and neck

Regulatory T cells (Treg) are important regulators of anti-cancer immune responses, and an increase in Treg frequency was observed in the blood of cancer patients. Blood samples from 112 patients with head and neck squamous cell carcinoma antigen (HNSCC) were obtained at the time of tumour diagnosis, and lymphocyte subpopulations (CD3⁺; CD3⁻CD16⁺CD56⁺; CD4⁺; CD8⁺; CD19⁺; CD4⁺CD45RA⁺) with emphasis on Treg counts (CD3⁺CD4⁺CD25⁺), complete blood count and tumour markers (squamous cell carcinoma [SCC]; CEA; α-1-antitrypsin [AAT]; Cyfra 21–1; C-reactive protein [CRP]) were analysed. The data were grouped according to TNM classification, and their significance for the course of the disease at an interval of 1 year after the end of the therapy was determined. The percentage of CD8⁺ cells increased and the CD/D8 ratio decreased with tumour grade. The ratio of B lymphocytes decreased in patients with locoregional metastases (11.25%versus 9.22%). Treg (15.2%) and CD4⁺ cells (45.3%) increased, while NK cells (11.8%) decreased in HNSCC patients compared to controls (9.0%, 38.1% and 15.8%, respectively). The data obtained at time of diagnosis were used to assess the significance of tumour markers (SCC, Cyfra 21–1 and AAT) for evaluation of prognosis. The erythrocyte counts (4.64 × 10¹²/l versus 4.45 × 10¹²/l) and haemoglobin levels (14.58 g/dl versus 14.05 g/dl) decreased, while Treg counts (8.91%versus 15.70%) increased in patients with early recurrence. Our results show that examination of these parameters could be helpful for prognostication in HNSCC patients and aid improvement of treatment strategy.