Direct and immune mediated antibody targeting of ERBB receptors in a colorectal cancer cell-line panel

Shazad Q Ashraf,Neil J Mortensen,Angela M Nicholls,Walter F Bodmer,Jennifer L Wilding,Triantafyllia G Ntouroupi

doi:10.1073/pnas.1218750110

Abstract

A significant proportion of colorectal cancer (CRC) patients are resistant to anti-ERBB1 [avian erythroblastic leukemia viral (v-erb-b) oncogene homolog, receptor for EGF] monoclonal antibodies (Mabs). We evaluated both immune and nonimmune effects of cetuximab (anti-ERBB1 Mab), trastuzumab (anti-ERBB2 Mab), pertuzumab (anti-ERBB2 Mab), and lapatinib (dual ERBB1 and ERBB2 tyrosine kinase inhibitor) in a large well-characterized panel of 64 CRC cell lines to find response predictive tumor characteristics. There was a significant correlation between the direct effects of cetuximab and lapatinib. Both agents were associated (P = 0.0004) with "triple' wild-type status in KRAS, BRAF, and PIK3CA exon 20. Most cell lines were resistant to the direct effects of anti-ERBB2 Mabs, suggesting that the effects of lapatinib might mainly be through ERBB1. Microarray mRNA expression profiles of sensitive and resistant cell lines showed that although ERBB1 receptor or ligand levels did not associate with cetuximab sensitivity, high levels of ERBB2 (P = 0.036) and amphiregulin (P = 0.026) predicted sensitivity to lapatinib. However, higher ERBB1 expression predicted susceptibility to cetuximab-induced antibody-dependent cellular cytotoxicity and occurred independently of KRAS/BRAF/PIK3CA mutations (P = 0.69). Lapatinib may be an effective alternative therapy to cetuximab in triple wild-type tumors. Microarray analysis provides suggestive biomarkers for resistance. ERBB1 levels, independent of mutation status, predict immune killing. Therefore, anti-ERBB1 antibodies may be considered in CRC tumors with higher ERBB1 expression and favorable FcγR polymorphisms.

Highlights

A significant proportion of colorectal cancer (CRC) patients are resistant to anti-ERBB1 [avian erythroblastic leukemia viral (v-erbb) oncogene homolog, receptor for EGF] monoclonal antibodies (Mabs)
Sixty-four CRC cell lines were screened for direct growth sensitivity to cetuximab
In keeping with clinical findings, our data demonstrate a strong association between KRAS status and nonimmune response to cetuximab and lapatinib in a CRC cell-line panel [3, 9]

Summary

Introduction

A significant proportion of colorectal cancer (CRC) patients are resistant to anti-ERBB1 [avian erythroblastic leukemia viral (v-erbb) oncogene homolog, receptor for EGF] monoclonal antibodies (Mabs) We evaluated both immune and nonimmune effects of cetuximab (anti-ERBB1 Mab), trastuzumab (anti-ERBB2 Mab), pertuzumab (anti-ERBB2 Mab), and lapatinib (dual ERBB1 and ERBB2 tyrosine kinase inhibitor) in a large well-characterized panel of 64 CRC cell lines to find response predictive tumor characteristics. Emerging evidence associates mutations or loss-of-function in genes other than KRAS, for example BRAF, PIK3CA (exon 20), and PTEN with resistance to cetuximab [3, 7,8,9] Such associations are more likely to be associated with direct rather than immune based effects of antibodies, suggesting that tyrosine kinase inhibitors (TKIs) such as lapatinib, a dual ERBB1 and ERBB2 (v-erb-b2 erythroblastic leukemia viral oncogene homolog 2) receptor inhibitor, might be effective as an alternative therapy [10]. The objective of our study was to use a large well-characterized panel of more than 60 CRC cell lines to define further the tumor characteristics that predict both the direct and immune mediated responses to cetuximab, and to compare the results with the use of other anti-ERBB antibodies and with the TKI, lapatinib

Objectives

Methods

Results

Conclusion