Identification of Targetable ERBB2 Aberrations in Head and Neck Squamous Cell Carcinoma

ERBB2 (formerly HER2) is an important drug target in breast cancer, where anti-ERBB2 therapy has been shown to lead to improvements in disease recurrence and overall survival. ERBB2 status in head and neck squamous cell carcinoma (HNSCC) has not been well studied. Identification of ERBB2-positive tumors and characterization of response to ERBB2 therapy could lead to targeted treatment options in HNSCC.

To identify ERBB2 aberrations in HNSCCs and investigate the potential for ERBB2-targeted therapy in HNSCCs.

A retrospective case series of patients with laryngeal (42 tumor specimens) and oral cavity (94 tumor specimens) SCC enrolled in the University of Michigan Head and Neck Specialized Program of Research Excellence was conducted. Publicly available sequencing data (The Cancer Genome Atlas), as well as data from other studies, were reviewed to identify additional mutations and overexpression in ERBB2 in HNSCC. Established HNSCC cell lines were used for follow-up in vitro analysis. The study was conducted from October 1, 2014, to August 30, 2015.

With the use of targeted, amplicon-based sequencing with the Oncomine Cancer Panel, the copy number and mutation status of commonly altered genes in HNSCCs were assessed. Immunohistochemical staining was performed on tissue microarrays of HNSCCs to assess the expression of ERBB2. Western blotting for HNSCC cell line ERBB2 expression and cell survival assays after treatment with ERBB2 inhibitors were performed.

The prevalence of ERBB2 genetic aberrations and ERBB2 overexpression in laryngeal and oral cavity SCCs, prevalence of ERBB2 aberrations in HNSCC in The Cancer Genome Atlas, ERBB2 protein expression in HNSCC cell lines, and response of HNSCC cell lines to targeted ERBB2 inhibitors.

Of the 42 laryngeal SCC samples screened by targeted sequencing, 4 (10%) were positive for ERBB2 amplification. Two of these samples showed ERBB2 overexpression on immunohistochemistry. Two of the 94 oral cavity SCC samples (2%) were positive for ERBB2 on immunohistochemistry. Analysis of 288 patients from publicly available HNSCC sequencing data revealed 9 amplifications (3%) in ERBB2. Protein expression was variable across HNSCC cell lines, and a subset of these cell lines showed responsiveness to anti-ERBB2 therapy.

ERBB2 aberrations were identified in a subset of HNSCCs. These tumors may be responsive to targeted therapy against ERBB2. Screening for ERBB2 aberrations and applying targeted therapy in ERBB2-positive patients may be useful in personalized therapy trials, particularly in patients who are refractory to current treatment paradigms.