Gene status of head and neck squamous cell carcinoma cell lines and cetuximab-mediated biological activities

Novel Insights of Anti-EGFR Therapy in HNSCC: Combined with Immunotherapy or Not?

PURPOSE OF REVIEW

The efficacy of anti-EGFR therapy is still unfavorable in recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) patients. Disorder of antitumor immunity and aberrantly expressed checkpoint biomarkers had been validated to involve anti-EGFR therapy tolerance and efficacy. Here we review the immunomodulation of anti-EGFR therapy in the tumor immune microenvironment (TIME) of HNSCC and assist clinicians in finding the potential strategies to rescue anti-EGFR tolerance therapy in the era of immunotherapy for HNSCC.

RECENT FINDINGS

Anti-EGFR therapy, especially cetuximab, was validated to induce the innate and adaptive immune responses of HNSCC patients. It is mainly through inducing natural killer (NK) cells mediating antibody-dependent cell-mediated cytotoxicity (ADCC), recruiting multiple tumor-infiltrating immune cells, and finally remodeling the TIME. Moreover, mountains of preclinical models and clinical trials revealed that combining anti-EGFR agents with immunotherapy could enhance the antitumor effectiveness in HNSCC. Anti-EGFR therapy may usher in another dawn in the treatment of patients with HNSCC through combination with immunotherapy. We offer an overview of the ongoing efforts to make out the immunomodulation of the EGFR pathway in both innate and adaptive immune responses; update the constant preclinical models and clinical trials for the combination of anti-EGFR and immunotherapy in HNSCC; and finally evaluate the efficacy and advantages of the combination therapeutic strategies in clinical use.

The Role of Akt in Acquired Cetuximab Resistant Head and Neck Squamous Cell Carcinoma: An In Vitro Study on a Novel Combination Strategy

The epidermal growth factor receptor (EGFR) is a therapeutic target in head and neck squamous cell carcinoma (HNSCC). Resistance to EGFR-targeted therapies, such as cetuximab, poses a challenging problem. This study aims to characterize acquired cetuximab resistance mechanisms in HNSCC cell lines by protein phosphorylation profiling. Through this, promising combination treatments can be identified to possibly overcome acquired cetuximab resistance in HNSCC. Protein phosphorylation profiling showed increased phosphorylation of Akt1/2/3 after cetuximab treatment in acquired cetuximab resistant cells compared to cetuximab sensitive cells, which was confirmed by western blotting. Based on this protein phosphorylation profile, a novel combination treatment with cetuximab and the Akt1/2/3 inhibitor MK2206 was designed. Synergy between cetuximab and MK2206 was observed in two cetuximab sensitive HNSCC cell lines and one acquired cetuximab resistant variant in simultaneous treatment schedules. In conclusion, this study demonstrates that increased Akt1/2/3 phosphorylation seems to be characteristic for acquired cetuximab resistance in HNSCC cell lines. Our results also show an additive to synergistic interaction between cetuximab and MK2206 in simultaneous treatment schedules. These data support the hypothesis that the combination of cetuximab with PI3K/Akt pathway inhibition might be a promising novel therapeutic strategy to overcome acquired cetuximab resistance in HNSCC patients.

The Right Partner in Crime: Unlocking the Potential of the Anti-EGFR Antibody Cetuximab via Combination With Natural Killer Cell Chartering Immunotherapeutic Strategies

Cetuximab has an established role in the treatment of patients with recurrent/metastatic colorectal cancer and head and neck squamous cell cancer (HNSCC). However, the long-term effectiveness of cetuximab has been limited by the development of acquired resistance, leading to tumor relapse. By contrast, immunotherapies can elicit long-term tumor regression, but the overall response rates are much more limited. In addition to epidermal growth factor (EGFR) inhibition, cetuximab can activate natural killer (NK) cells to induce antibody-dependent cellular cytotoxicity (ADCC). In view of the above, there is an unmet need for the majority of patients that are treated with both monotherapy cetuximab and immunotherapy. Accumulated evidence from (pre-)clinical studies suggests that targeted therapies can have synergistic antitumor effects through combination with immunotherapy. However, further optimizations, aimed towards illuminating the multifaceted interplay, are required to avoid toxicity and to achieve better therapeutic effectiveness. The current review summarizes existing (pre-)clinical evidence to provide a rationale supporting the use of combined cetuximab and immunotherapy approaches in patients with different types of cancer.

Rationale for combination of therapeutic antibodies targeting tumor cells and immune checkpoint receptors: Harnessing innate and adaptive immunity through IgG1 isotype immune effector stimulation

Immunoglobulin (Ig) G1 antibodies stimulate antibody-dependent cell-mediated cytotoxicity (ADCC). Cetuximab, an IgG1 isotype monoclonal antibody, is a standard-of-care treatment for locally advanced and recurrent and/or metastatic squamous cell carcinoma of the head and neck (SCCHN) and metastatic colorectal cancer (CRC). Here we review evidence regarding the clinical relevance of cetuximab-mediated ADCC and other immune functions and provide a biological rationale concerning why this property positions cetuximab as an ideal partner for immune checkpoint inhibitors (ICIs) and other emerging immunotherapies. We performed a nonsystematic review of available preclinical and clinical data involving cetuximab-mediated immune activity and combination approaches of cetuximab with other immunotherapies, including ICIs, in SCCHN and CRC. Indeed, cetuximab mediates ADCC activity in the intratumoral space and primes adaptive and innate cellular immunity. However, counterregulatory mechanisms may lead to immunosuppressive feedback loops. Accordingly, there is a strong rationale for combining ICIs with cetuximab for the treatment of advanced tumors, as targeting CTLA-4, PD-1, and PD-L1 can ostensibly overcome these immunosuppressive counter-mechanisms in the tumor microenvironment. Moreover, combining ICIs (or other immunotherapies) with cetuximab is a promising strategy for boosting immune response and enhancing response rates and durability of response. Cetuximab immune activity–including, but not limited to, ADCC–provides a strong rationale for its combination with ICIs or other immunotherapies to synergistically and fully mobilize the adaptive and innate immunity against tumor cells. Ongoing prospective studies will evaluate the clinical effect of these combination regimens and their immune effect in CRC and SCCHN and in other indications.

Inhibition of epithelial-mesenchymal transition by cetuximab via the EGFR-GEP100-Arf6-AMAP1 pathway in head and neck cancer

BACKGROUND

Despite improved survival by the addition of a monoclonal antibody against epidermal growth factor receptor (EGFR), cetuximab, to chemotherapy or radiotherapy for squamous cell carcinoma of the head and neck (SCCHN), cetuximab by itself is not a potent antiproliferative agent against SCCHN. We aimed to elucidate working mechanism of cetuximab in SCCHN.

METHODS

The effect of cetuximab on the proliferation, migration, invasion, epithelial-mesenchymal transition, and signaling events downstream of the EGFR were investigated in 4 SCCHN cell lines. The in vivo efficacy of cetuximab was evaluated in a xenotransplant model.

RESULTS

Cetuximab inhibited migration, invasion, epithelial-mesenchymal transition, and lymph node metastasis by suppressing EGFR-GEP100-Arf6-AMAP1 pathway, but it did not inhibit cancer cell proliferation.

CONCLUSION

The improved survival by the addition of cetuximab is likely to be attributable to the antiepithelial-mesenchymal transition action of cetuximab via inhibiting EGFR-GEP100-Arf6-AMAP1 pathway. © 2016 Wiley Periodicals, Inc. Head Neck 39: 476-485, 2017.

The relevance of ADCC for EGFR targeting: A review of the literature and a clinically-applicable method of assessment in patients

BACKGROUND

Advances in the understanding of tumor biology have led to the development of targeted therapies as monoclonal antibodies (MoAbs) in clinical oncology. Among their suggested mechanisms of action monoclonal antibodies (IgG1) selectively directed against tumor membrane receptors mediate of antibody-dependent cellular cytotoxicity (ADCC) by triggering Fc-γRIII on natural killer (NK) cells.

METHODS

This study reviews the clinical context of ADCC measurement with a particular focus on EGFR targeting and describes an ex vivo ADCC method applied to MoAbs (cetuximab and panitumumab), against epidermal growth factor receptor (EGFR). The test performance was evaluated on different target cells lines (CAL166, A431, HNO91, CAL27), with different effector cells (peripheral blood mononuclear cells or natural killers -NK-) and in various experimental conditions, in order to establish a truly clinically applicable method.

RESULTS

Using the experience available in the published literature, we optimized all variables involved in the experimental design: target cells type, numbers and ratio target cells and NK cells (effector cells) per well, time of exposure and repeatability.

CONCLUSION

ADCC measurement may be of clinical relevance in the context of treatment with MoAbs. This study describes a non-radioactive method which has proven satisfactory in terms of sensitivity, reproducibility, feasibility and cost effectiveness for the measurement of ADCC activity mediated by NK with an orientation towards the EGFR target.

YAP1 is a potential biomarker for cetuximab resistance in head and neck cancer

OBJECTIVES

Targeted therapy against the epidermal growth factor receptor (EGFR) only variably represents a therapeutic advance in head and neck squamous cell carcinoma (HNSCC). This study addresses the need of biomarkers of treatment response to the EGFR-targeting antibody cetuximab (Erbitux®).

MATERIALS AND METHODS

The intrinsic cetuximab sensitivity of HNSCC cell lines was assessed by a crystal violet assay. Gene copy number analysis of five resistant and five sensitive cell lines was performed using the Affymetrix SNP 6.0 platform. Quantitative real-time PCR was used for verification of selected copy number alterations and assessment of mRNA expression. The functional importance of the findings on the gene and mRNA level was investigated employing siRNA technology. The data was statistically evaluated using Mann-Whitney U-test and Spearman's correlation test.

RESULTS

Analysis of the intrinsic cetuximab sensitivity of 32 HNSCC cell lines characterized five and nine lines as cetuximab sensitive or resistant, respectively. Gene copy number analysis of five resistant versus five sensitive cell lines identified 39 amplified protein-coding genes, including YAP1, in the genomic regions 11q22.1 or 5p13-15. Assessment using qPCR verified that YAP1 amplification associated with cetuximab resistance. Amplification of YAP1 correlated to higher mRNA levels, and RNA knockdown resulted in increased cetuximab sensitivity. Assessment of several independent clinical data sets in the public domain confirmed YAP1 amplifications in multiple tumor types including HNSCC, along with highly differential expression in a subset of HNSCC patients.

CONCLUSION

Taken together, we provide evidence that YAP1 could represent a novel biomarker gene of cetuximab resistance in HNSCC cell lines.

Anti-epidermal growth factor receptor therapy in head and neck squamous cell carcinoma: focus on potential molecular mechanisms of drug resistance

Targeted therapy against the epidermal growth factor receptor (EGFR) is one of the most promising molecular therapeutics for head and neck squamous cell carcinoma (HNSCC). EGFR is overexpressed in a wide range of malignancies, including HNSCC, and initiates important signal transduction pathways in HNSCC carcinogenesis. However, primary and acquired resistance are serious problems and are responsible for low single-agent response rate and tumor recurrence. Therefore, an improved understanding of the molecular mechanisms of resistance to EGFR inhibitors may provide valuable indications to identify biomarkers that can be used clinically to predict response to EGFR blockade and to establish new treatment options to overcome resistance. To date, no predictive biomarker for HNSCC is available in the clinic. Therapeutic resistance to anti-EGFR therapy may arise from mechanisms that can compensate for reduced EGFR signaling and/or mechanisms that can modulate EGFR-dependent signaling. In this review, we will summarize some of these molecular mechanisms and describe strategies to overcome that resistance.

Genetic deregulation of the PIK3CA oncogene in oral cancer

The phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway is one of the most commonly deregulated pathways in human cancers. PI3K comprises a catalytic (p110α) and regulatory subunit (p85), and p110α is encoded by the PIK3CA gene. Here, we summarize the known genetic alterations, including amplifications and mutations, of the PIK3CA oncogene in oral cancer. We discuss in detail PIK3CA mutations and their mutual exclusivity with pathway genes in addition to the incidence of PIK3CA mutations in relation to ethnicity. We describe the constitutive activation of PI3K signaling, oncogenicity, and the genetic deregulation of the PIK3CA gene and its association with oral cancer disease stage. We emphasize the importance of therapeutically targeting the genetically deregulated PIK3CA oncogene and its signaling. We also discuss the implications of targeting Akt and/or mTOR, which are the downstream effectors of PI3K that may possibly pave the way for molecular therapeutic targets for PIK3CA-driven oral carcinogenesis. Furthermore, this critical review provides a complete picture of the PIK3CA oncogene and its deregulation in oral cancer, which may facilitate early diagnosis and improve prognosis through personalized molecular targeted therapy in oral cancer.

Copy number amplification of the PIK3CA gene is associated with poor prognosis in non-lymph node metastatic head and neck squamous cell carcinoma

Background

Deregulation of the EGFR signaling pathway is one of the most frequently observed genetic abnormalities that drives cancer development. Although mutations in the downstream components of the EGFR signaling pathway, including KRAS, BRAF and PIK3CA, have been reported in numerous cancers, extensive mutation and copy number analysis of these genes in clinical samples has not been performed for head and neck squamous cell carcinoma (HNSCC).

Methods

We examined the mutations and copy number alterations of KRAS, BRAF and PIK3CA in 115 clinical specimens of HNSCC obtained from surgically treated patients.

We used DNA sequencing to detect mutations and the copy number changes were evaluated by qPCR and array comparative genomic hybridization (CGH) analysis.

Results

We examined the mutations and copy number alterations of KRAS, BRAF and PIK3CA in 115 clinical specimens of HNSCC obtained from surgically treated patients. We identified 3 mutations (2.6%) in K-RAS and 3 mutations (2.6%) in PIK3CA. Copy number amplification was found in 37 cases (32.2%) for PIK3CA, 10 cases (8.7%) for K-RAS and 2 cases (1.7%) for BRAF. Kaplan-Meier survival analysis revealed that copy-number amplification of PIK3CA was markedly associated with cancer relapse in patients without lymph node metastasis. (Log-rank test, p = 0.026)

Conclusions

Copy number amplification of the PIK3CA gene is associated with poor prognosis in HNSCC patients without lymph node metastasis. The PIK3CA copy number status will serve as a marker of poor prognosis in patients with HNSCC.

HER family receptor and ligand status in thymic carcinoma

Overexpression and gene amplification of the HER family of receptors and their ligands are important prognostic factors in many solid tumors and treatment targeting these molecules has recently become available. The role of this group of receptors has only rarely been described in thymic epithelial neoplasms and never before in a series of cases consisting exclusively of thymic carcinoma. Twenty-four primary squamous cell carcinomas of the thymus were examined for immunohistochemical expression of epidermal growth factor receptor (EGFR), phosphorylated EGFR (pEGFR), HER2, phosphorylated HER2 (pHER2), HER3, phosphorylated HER3 (pHER3) and their ligands epidermal growth factor (EGF), transforming growth factor-α (TGF-α), amphiregulin and epiregulin. Fluorescence in situ hybridization (FISH) analysis for amplification of the EGFR and HER2 genes was performed including assessment of the copy numbers of EGFR and HER2 gene per cell and the ratio of EGFR and HER2 to centromere 7 and 17, respectively. Significant immunohistochemical expression was observed for EGFR (33.3%), pEGFR (33.3%), HER2 (58.3%), HER3 (45.8%), TGF-α (54.1%), amphiregulin (25.0%) and epiregulin (91.7%). A single case showed HER2 gene amplification by FISH. Increased EGFR and HER2 gene copy numbers were observed in 2 (8.4%) and 18 cases (75%), respectively. Eight cases (33.3%) showed an increased HER2:CEP17 ratio. The results of this study indicate that EGFR and HER2 amplification is a rare event in thymic carcinoma, however, protein expression for HER receptors as well as their ligands is a common finding indicating that targeted therapy directed against these molecules may be considered in the treatment of these tumors.