Afatinib against Esophageal or Head-and-Neck Squamous Cell Carcinoma: Significance of Activating Oncogenic HER4 Mutations in HNSCC

Abstract

The prognosis for patients with advanced esophageal or head-and-neck squamous cell carcinoma (ESCC or HNSCC) remains poor, and the identification of additional oncogenes and their inhibitors is needed. In this study, we evaluated the sensitivities of several ESCC and HNSCC cell lines to HER inhibitors (cetuximab, erlotinib, and afatinib) in vitro and found two cell lines that were hypersensitive to afatinib. Sequence analyses for the afatinib-targeted HER family genes in the two cell lines revealed that one cell line had a previously reported activating EGFR L861Q mutation, whereas the other had an HER4 G1109C mutation of unknown function. No amplification of HER family genes was found in either of the two cell lines. The phosphorylation level of HER4 was elevated in the HER4 G1109C mutation-overexpressed HEK293 cell line, and the mutation had a transforming potential and exhibited tumorigenicity in an NIH3T3 cell line, indicating that this HER4 mutation was an activating oncogenic mutation. Afatinib dramatically reduced the phosphorylation level of EGFR or HER4 and induced apoptosis in the two cell lines. In vivo, tumor growth was also dramatically decreased by afatinib. In a database, the frequencies of HER family gene mutations in ESCC or HNSCC ranged from 0% to 5%. In particular, HER4 mutations have been found relatively frequently in HNSCC. Considering the addiction of cancer cells to activating oncogenic EGFR or HER4 mutations for proliferation, HNSCC or ESCC with such oncogenic mutations might be suitable for targeted therapy with afatinib.

Targeting the HER family with Pan-HER effectively overcomes resistance to cetuximab

“…Recently, mutations in the genes encoding other RTKs, such as FGFR1 or PDGFRA were found in CRC PDX models with intrinsic resistance to cetuximab (47). Nakamura et al also found HER4 mutation in cetuximabresistant ESCC or HNSCC cells (48). These RTK crosstalk mechanisms associated with resistance have also been reported in other tumors such as NSCLC, breast cancer or melanoma (49).…”

Targeting the HER Family with Pan-HER Effectively Overcomes Resistance to Cetuximab

“…Recently, mutations in the genes encoding other RTKs, such as FGFR1 or PDGFRA were found in CRC PDX models with intrinsic resistance to cetuximab (47). Nakamura et al also found HER4 mutation in cetuximab-resistant ESCC or HNSCC cells (48). These RTK crosstalk mechanisms associated with resistance have also been reported in other tumors such as NSCLC, breast cancer or melanoma (49).…”

Interactions between anti-EGFR therapies and cytotoxic chemotherapy in oesophageal squamous cell carcinoma: Why clinical trials have failed and how they could succeed

“…Targeting EGFR with EGFR tyrosine kinase inhibitors (TKi), such as ge tinib, erlotinib or afatinib, inhibits the proliferation of oesophageal cancer cell lines in vitro (15)(16)(17), but, clinical trials of EGFR inhibitors in oesophageal cancer, including ESCC, have shown mixed results. Monotherapy trials in unselected patients with EGFR inhibitors indicate that there is an EGFR-driven minority ESCC subgroup who gain survival, symptomatic control and health-related quality of life bene ts from EGFR inhibitors (18)(19)(20)(21).…”