MEF2B is a member of the BCL6 gene transcriptional complex and induces its expression in diffuse large B-cell lymphoma of the germinal center B-cell-like type.

Myocyte enhancer-binding factor 2B (MEF2B) has been implicated as a transcriptional regulator for BCL6. However, details about the interaction between MEF2B and BCL6 during expression, as well as the relationship of MEF2B to the expression of other germinal center (GC) markers, have not yet been fully explained. Using germinal center B-cell-like diffuse large B-cell lymphoma (GC-DLBCL) and activated B-cell diffuse large B-cell lymphoma (ABC-DLBCL) cell lines, we analyzed the expression of MEF2B and its associations with BCL6, CD10, and ERK. Furthermore, small interfering RNA (siRNA) was used to study the possible effects of MEF2B knockdown on these proteins and cell growth. Analysis of the BCL6 transcriptional complex was performed using electrophoretic mobility shift assay. The correlation between MEF2B expression and the genetic type of DLBCL was assessed using immunohistochemistry on 111 patient samples, and via in silico analysis of publicly available microarray (Gene Expression Omnibus (GEO)) datasets. Our results indicate that the expression of MEF2B protein is important for the growth of GC-DLBCL cells, as evidenced by MEF2B knockdown inhibition of cell growth and the subsequent suppression of BCL6, CD10, and ERK phosphorylation. Analysis of BCL6 transcription factors in nuclear extracts of MEF2-expressing DLBCL cells showed involvement of MEF2B with AP-2α and BCL6 proteins in the formation of the BCL6 gene transcriptional complex. Indeed, differential expression of MEF2B in the GC-DLBCL is statistically significant compared to the ABC-DLBCL in the GEO datasets, as well as in tissue microarray, as indicated via immunohistochemistry (Visco-Young algorithm). Our findings indicate that MEF2B is an essential component of the BCL6 gene transcriptional complex for the regulation of DLBCL growth via the promotion of BCL6 expression. Beyond its regulatory role in DLBCL growth, MEF2B expression correlated positively with BCL6 and CD10 expression, and was preferentially expressed in the GBC-DLBCL group.

Developing a Predictive Model for Clinical Outcomes of Advanced Non-Small Cell Lung Cancer Patients Treated With Nivolumab.

INTRODUCTION: Despite significant improvement of clinical outcomes of advanced non-small-cell lung cancer (NSCLC) patients treated with immunotherapy, our knowledge of optimal biomarkers is still limited. PATIENTS AND METHODS: We retrospectively evaluated 159 advanced NSCLC patients in our institution treated with nivolumab after disease progression during platinum-based chemotherapy. We correlated several variables with progression-free survival (PFS) to develop the immunotherapy, Sex, Eastern Cooperative Oncology Group performance status, Neutrophil-to-lymphocyte ratio (NLR), and Delta NLR (iSEND) model. We categorized patients into iSEND good, intermediate, and poor risk groups and evaluated their clinical outcomes. Performance of iSEND at 3, 6, 9, and 12 months was evaluated according to receiver operating characteristic (ROC) curves and internally validated using bootstrapping. The association of iSEND risk groups with clinical benefit was evaluated using logistic regression. RESULTS: Median follow-up was 11.5 months (95% confidence interval [CI], 9.4-13.1). There were 50 deaths and 43 with disease progression without death. PFS rates at 3, 6, 9, and 12 months were 78.4%, 63.7%, 55.3%, and 52.2% in iSEND good; 79.4%, 44.3%, 25.9%, and 19.2% in iSEND intermediate; and 65%, 25.9%, 22.8%, and 17.8% in iSEND poor. Time-dependent area under ROC curves of iSEND for PFS at 3, 6, 9, and 12 months were 0.718, 0.74, 0.746, and 0.774. The iSEND poor group was significantly associated with progressive disease at 12 ± 2 weeks (odds ratio, 9.59; 95% CI, 3.8-26.9; P < .0001). CONCLUSION: The iSEND model is an algorithmic model that can characterize clinical outcomes of advanced NSCLC patients receiving nivolumab into good, intermediate, or poor risk groups and might be useful as a predictive model if validated independently.

Rare occurrence of EGFRvIII deletion in head and neck squamous cell carcinoma.

BACKGROUND: The epidermal growth factor receptor (EGFR) is a transmembrane tyrosine kinase receptor and is overexpressed in up to 90% of head and neck squamous cell carcinoma (HNSCC) cases. The EGFR truncation mutation, EGFR variant III (EGFRvIII), harbors an in-frame deletion of exons 2-7 (801 bp) that leads to the constitutive activation of downstream signaling. EGFRvIII has been reported in ∼40% of glioblastomas (GBM), but its presence in HNSCC remains controversial. METHODS: EGFRvIII deletion in 638 HNSCC samples was analyzed using: (i) quantitative Real-Time polymerase chain reaction (qRT-PCR) on 108 HNSCC samples with direct detection of the EGFRvIII breakpoint, (ii) RNA-Seq analysis on 7 HNSCC tumor tissues and 425 The Cancer Genome Atlas (TCGA) HNSCC samples, and (iii) immunohistochemistry (IHC) for EGFRvIII using an established antibody (L8A4) on a tissue microarray of 105 HNSCC samples. RESULTS: qRT-PCR did not show the presence of EGFRvIII in any of the samples analyzed. Furthermore, we could not detect any EGFRvIII transcripts in the RNA-Seq data of the seven HNSCC samples. However, 2 samples out of 425 TCGA HNSCC samples had EGFRvIII specific reads. EGFRvIII IHC results were assessed as negative for all samples. CONCLUSION: Our results firmly establish that EGFRvIII is very rare in HNSCC as only 2 out of 638 (0.31%) samples we analyzed overall, or 2 out of 540 (0.37%) using mRNA based approaches, were positive for EGFRvIII. EGFRvIII is extremely rare in HNSCC and the clinical significance remains unclear. We propose not to include EGFRvIII testing in regular diagnostic tests for HNSCC.

Integrative analysis of head and neck cancer identifies two biologically distinct HPV and three non-HPV subtypes.

PURPOSE: Current classification of head and neck squamous cell carcinomas (HNSCC) based on anatomic site and stage fails to capture biologic heterogeneity or adequately inform treatment. EXPERIMENTAL DESIGN: Here, we use gene expression-based consensus clustering, copy number profiling, and human papillomavirus (HPV) status on a clinically homogenous cohort of 134 locoregionally advanced HNSCCs with 44% HPV(+) tumors together with additional cohorts, which in total comprise 938 tumors, to identify HNSCC subtypes and discover several subtype-specific, translationally relevant characteristics. RESULTS: We identified five subtypes of HNSCC, including two biologically distinct HPV subtypes. One HPV(+) and one HPV(-) subtype show a prominent immune and mesenchymal phenotype. Prominent tumor infiltration with CD8(+) lymphocytes characterizes this inflamed/mesenchymal subtype, independent of HPV status. Compared with other subtypes, the two HPV subtypes show low expression and no copy number events for EGFR/HER ligands. In contrast, the basal subtype is uniquely characterized by a prominent EGFR/HER signaling phenotype, negative HPV-status, as well as strong hypoxic differentiation not seen in other subtypes. CONCLUSION: Our five-subtype classification provides a comprehensive overview of HPV(+) as well as HPV(-) HNSCC biology with significant translational implications for biomarker development and personalized care for patients with HNSCC.

mTOR as a molecular target in HPV-associated oral and cervical squamous carcinomas.

PURPOSE: The incidence of head and neck squamous cell carcinomas (HNSCC) associated with human papillomavirus (HPV) infection has increased over the past decades in the United States. We aimed at examining the global impact of HPV-associated HNSCC and whether the established key role of mTOR activation in HNSCC is also observed in HPV(+) HNSCC lesions, thereby providing novel treatment options for HPV-associated HNSCC patients. EXPERIMENTAL DESIGN: An international HNSCC tissue microarray (TMA) was used to analyze the expression of p16(INK4A), a surrogate for HPV infection, and Akt-mTOR pathway activation. Results were confirmed in a large collection of HPV(-) and HPV(+) HNSCC cases and in a cervical cancer (CCSCC) TMA. Observations were validated in HNSCC and CCSCC-derived cell lines, which were xenografted into immunodeficient mice for tumorigenesis assays. RESULTS: Approximately 20% of all HNSCC lesions could be classified as HPV(+), irrespective of their country of origin. mTOR pathway activation was observed in most HPV(+) HNSCC and CCSCC lesions and cell lines. The preclinical efficacy of mTOR inhibition by rapamycin and RAD001 was explored in HPV(+) HNSCC and CCSCC tumor xenografts. Both mTOR inhibitors effectively decreased mTOR activity in vivo and caused a remarkable decrease in tumor burden. These results emphasize the emerging global impact of HPV-related HNSCCs and indicate that the activation of the mTOR pathway is a widespread event in both HPV(-) and HPV-associated HNSCC and CCSCC lesions. CONCLUSIONS: The emerging results may provide a rationale for the clinical evaluation of mTOR inhibitors as a molecular targeted approach for the treatment of HPV-associated malignancies.

RON (MST1R) is a novel prognostic marker and therapeutic target for gastroesophageal adenocarcinoma.

RON (MST1R) is one of two members of the MET receptor tyrosine kinase family, along with parent receptor MET. RON has a putative role in several cancers, but its expression and function is poorly characterized in gastroesophageal adenocarcinoma. A recognized functional role of MET tyrosine kinase in gastroesophageal cancer has led to early phase clinical trials using MET inhibitors, with unimpressive results. Therefore, the role of RON in gastroesophageal cancer, as well as its role in cooperative signaling with MET and as a mechanism of resistance to MET inhibition, was studied in gastroesophageal tissues and cell lines. By IHC, RON was highly over-expressed in 74% of gastroesophageal samples (n=94), and over-expression was prognostic of poor survival (p=0.008); RON and MET co-expression occurred in 43% of samples and was prognostic of worst survival (p=0.03). High MST1R gene copy number by quantitative polymerase chain reaction, and confirmed by fluorescence in situ hybridization and/or array comparative genomic hybridization, was seen in 35.5% (16/45) of cases. High MST1R gene copy number correlated with poor survival (p=0.01), and was associated with high MET and ERBB2 gene copy number. A novel somatic MST1R juxtamembrane mutation R1018G was found in 11% of samples. RON signaling was functional in cell lines, activating downstream effector STAT3, and resulted in increased viability over controls. RON and MET co-stimulation assays led to enhanced malignant phenotypes over stimulation of either receptor alone. Growth inhibition as evidenced by viability and apoptosis assays was optimal using novel blocking monoclonal antibodies to both RON and MET, versus either alone. SU11274, a classic MET small molecule tyrosine kinase inhibitor, blocked signaling of both receptors, and proved synergistic when combined with STAT3 inhibition (combination index < 1). These preclinical studies define RON as an important novel prognostic marker and therapeutic target for gastroesophageal cancer warranting further investigation.

The MET receptor tyrosine kinase is a potential novel therapeutic target for head and neck squamous cell carcinoma.

Recurrent/metastatic head and neck cancer remains a devastating disease with insufficient treatment options. We investigated the MET receptor tyrosine kinase as a novel target for the treatment of head and neck squamous cell carcinoma (HNSCC). MET/phosphorylated MET and HGF expression was analyzed in 121 tissues (HNSCC/normal) by immunohistochemistry, and in 20 HNSCC cell lines by immunoblotting. The effects of MET inhibition using small interfering RNA/two small-molecule inhibitors (SU11274/PF-2341066) on signaling, migration, viability, and angiogenesis were determined. The complete MET gene was sequenced in 66 head and neck cancer tissue samples and eight cell lines. MET gene copy number was determined in 14 cell lines and 23 tumor tissues. Drug combinations of SU11274 with cisplatin or erlotinib were tested in SCC35/HN5 cell lines. Eighty-four percent of the HNSCC samples showed MET overexpression, whereas 18 of 20 HNSCC cell lines (90%) expressed MET. HGF overexpression was present in 45% of HNSCC. MET inhibition with SU11274/PF-2341066 abrogated MET signaling, cell viability, motility/migration in vitro, and tumor angiogenesis in vivo. Mutational analysis of 66 tumor tissues and 8 cell lines identified novel mutations in the semaphorin (T230M/E168D/N375S), juxtamembrane (T1010I/R988C), and tyrosine kinase (T1275I/V1333I) domains (incidence: 13.5%). Increased MET gene copy number was present with >10 copies in 3 of 23 (13%) tumor tissues. A greater-than-additive inhibition of cell growth was observed when combining a MET inhibitor with cisplatin or erlotinib and synergy may be mediated via erbB3/AKT signaling. MET is functionally important in HNSCC with prominent overexpression, increased gene copy number, and mutations. MET inhibition abrogated MET functions, including proliferation, migration/motility, and angiogenesis. MET is a promising, novel target for HNSCC and combination approaches with cisplatin or EGFR inhibitors should be explored.