The possible relevance of the expression of MHC antigens and of EGF receptor in aggressive oral tumours

EGFR is not amplified in ameloblastoma

OBJECTIVE

The aim of this study was to investigate alterations in the EGFR gene and its protein expression for a better understanding of the biologic behavior of ameloblastoma.

STUDY DESIGN

Twenty-five samples of ameloblastoma were selected, and dual-color fluorescence in situ hybridization assay was performed. The results of the assay and immunohistochemistry reaction for EGFR and Ki67 were associated with clinicopathologic features and recurrence.

RESULTS

All analyzed cases presented disomy without any gene polysomy or amplification. With regard to EGFR immunoexpression, 3 cases (12%) were considered negative, and 22 (88%) were positive, of which 13 (52%) were weak and 9 (36%) were strong. All samples presented low positivity for Ki67. There was no association between EGFR expression and clinicopathologic features or recurrence (P > .05). In some cases, EGFR immunoexpression was observed without gene amplification.

CONCLUSIONS

Ameloblastoma development, progression, or recurrence does not appear to be related to EGFR amplification or polysomy.

STAT1-Induced HLA Class I Upregulation Enhances Immunogenicity and Clinical Response to Anti-EGFR mAb Cetuximab Therapy in HNC Patients

The goal of this study was to characterize the molecular mechanisms underlying cetuximab-mediated upregulation of HLA class I antigen-processing machinery components in head and neck cancer (HNC) cells and to determine the clinical significance of these changes in cetuximab-treated HNC patients. Flow cytometry, signaling studies, and chromatin immunoprecipitation (ChIP) assays were performed using HNC cells treated with cetuximab alone or with Fcγ receptor (FcγR)-bearing lymphocytes to establish the mechanism of EGFR-dependent regulation of HLA APM expression. A prospective phase II clinical trial of neoadjuvant cetuximab was used to correlate HLA class I expression with clinical response in HNC patients. EGFR blockade triggered STAT1 activation and HLA upregulation, in a src homology-containing protein (SHP)-2-dependent fashion, more prominently in HLA-B/C than in HLA-A alleles. EGFR signaling blockade also enhanced IFNγ receptor 1 (IFNAR) expression, augmenting induction of HLA class I and TAP1/2 expression by IFNγ, which was abrogated in STAT1(-/-) cells. Cetuximab enhanced HNC cell recognition by EGFR853-861-specific CTLs, and notably enhanced surface presentation of a non-EGFR peptide (MAGE-3271-279). HLA class I upregulation was significantly associated with clinical response in cetuximab-treated HNC patients. EGFR induces HLA downregulation through SHP-2/STAT1 suppression. Reversal of HLA class I downregulation was more prominent in clinical responders to cetuximab therapy, supporting an important role for adaptive immunity in cetuximab antitumor activity. Abrogating EGFR-induced immune escape mechanisms and restoring STAT1 signaling to reverse HLA downregulation using cetuximab should be combined with strategies to enhance adaptive cellular immunity.

Epidermal growth factor receptor expression in ameloblastoma

Ameloblastoma is a locally aggressive tumor with possible lethal potential. Currently extensive surgery is the most acceptable treatment modality.

AIM

To investigate the presence of EGFR in ameloblastoma in order to consider using newly developed anti-EGFR therapeutic agents in cases of unresectable tumors. The study consisted of 58 formalin-fixed, paraffin-embedded specimens of ameloblastoma that were immunohistochemically stained with a monoclonal anti-EGFR antibody (clone 31G7). Positive and negative controls determined specificity of the antibody. A staining score based on the staining intensity and the proportion of stained cells was established, ranging between 0 and 2. All specimens were EGFR positive; 8 (14%) exhibited the maximum score of 2 and 19 (33%) scored between 1 and 2. Since ameloblastomas are EGFR-positive tumors, anti-EGFR agents could be considered to reduce the size of large tumors and to treat unresectable tumors that are in close proximity to vital structures.