Growth response of human colorectal tumour cell lines to treatment with afatinib (BIBW2992), an irreversible erbB family blocker, and its association with expression of HER family members

Abstract

Abstract. Despite the approval of the anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (mAbs), cetuximab and panitumumab, for the treatment of colorectal cancer patients, there is currently no reliable predictive marker for response to therapy. In addition, the duration of response is often limited. Therefore, this study aimed to investigate the effect of afatinib, an irreversible erbB family blocker, as a single agent or in combination with cytotoxic drugs (5-fluorouracil, irinotecan and oxaliplatin) or mAb ICR62 on the proliferation of a panel of human colorectal tumour cell lines and the association between the expression levels of the EGFR family members and response to treatment. Of the cells examined, EGFR-overexpressing DiFi cells were the most sensitive to treatment with both afatinib (IC 50 =45 nM) and ICR62 (IC 50 =4.33 nM). Afatinib also inhibited the growth of other tumour cell lines with IC 50 values which ranged from 0.33 µM (CCL-221) to 1.62 µM (HCT-116). A significant association was found between the co-expression of EGFR, human epidermal growth factor receptor (HER)-2 and HER-3 and response to treatment with afatinib (R=0.915, P=0.021). Treatment with afatinib and cytotoxic drugs was accompanied by an increase in the proportion of these cells in the sub-G0/G1 and in the S and G2/M phase of the cell cycle, respectively. We conclude that afatinib as monotherapy or in combination with other drugs shows activity in colorectal tumour cells and that determination of the co-expression of HER family members should be conducted in clinical trials using drugs targeting erbB signaling. This approach could lead to the identification of a specific subpopulation of cancer patients more likely to benefit from erbB-directed therapy.

Anti-tumour activity of afatinib, an irreversible ErbB family blocker, in human pancreatic tumour cells

“…In addition, the combination of erlotinib and gemcitabine produced antagonistic effects in MiaPaCa-2 (Table 2). Antagonism has also been reported when afatinib was combined with another cytotoxic drug (5-FU) in some colorectal cancer cells (Khelwatty et al , 2011). The different outcome of the same drug combination in different cell lines indicates the complex nature of drug/drug interactions and illustrates the elaborate biology behind these agents, which simultaneously force cells to perform G1- and S-phase arrests.…”

A comprehensive review of the preclinical efficacy profile of the ErbB family blocker afatinib in cancer

“…In two of these lines, expressing wild-type KRAS, gefitinib and lapatinib were requiring somewhat higher concentrations; in two other lines expressing mutated KRAS, afatinib retained its potency, whereas gefitinib and lapatinib became ineffective. Afatinib also inhibited growth of nine colorectal cancer cell lines, but its potency varied considerably across lines and was tightly correlated with the expression levels of EGFR, HER2 and ErbB3 (Khelwatty et al 2011). Growth inhibition by afatinib was also observed in a panel of pancreatic cancer cell lines (Ioannou et al 2011, 2013).…”

“…However, in an EGFR-mutated cell line resistant to EGFR inhibition in vitro most likely due to a exon 9 deletion in PTEN (H1650), the combination of afatinib and cetuximab was not effective (Chang and Wang 2012). An EGFR antibody, ICR62, exhibited supra-additive growth inhibition with afatinib in a colorectal cancer cell line (DiFi) (Khelwatty et al 2011). The combination of afatinib and cetuximab has also been evaluated clinically in patients failing on erlotinib or gefitinib therapy and early results from the phase I trial showing a 40 % response rate are promising (Janjigian et al 2012).…”

“…In that study, afatinib was also synergistic with permetrexed and with a thymidylate synthase inhibitor in an in vivo xenograft model; in contrast, gefitinib did not exhibit such synergism. In an in vitro study with colorectal cancer cell lines, the combination of afatinib with 5-fluouracil was antagonistic in three lines, but additive or even synergistic in two others (Khelwatty et al 2011). The combination of afatinib with the VEGF antibody bevacizumab was found to be superior to either drug alone in mice harbouring NSCLC xenografts with an EGFR exon 19 deletion/T790M or with a L858R/T790M mutation (Ninomiya et al 2013).…”

A Chemocentric Approach to the Identification of Cancer Targets

“…In addition, further evidences exist in the literature of drugs targeting primarily some of those targets and having an effect on the proliferation of human colorectal tumour cell lines, including HCT116 [40], [43]. Among them, raloxifene is a high affinity binder of both ESR1 and ESR2 and has been reported to inhibit HCT116 cell growth in a dose-dependent manner [40] and afatinib is a potent EGFR inhibitor that was recently shown to inhibit the growth of HCT116 cell lines with an IC 50 value of 1.62 µM [43]. These examples provide ample bibliographical support to the relevance in colon cancer for some of those proteins that would have been otherwise completely overlooked.…”