BACKGROUND: By transactivacion, phosphorylated insulin growth factor receptor I (IGF-1R) can activate epidermal growth factor receptor (EGFR). MMP-7, produced by colorectal cancer cells, also can activate IGF-1R by degrading IGFBP-3 and releasing IGF-I.
METHODS: A cohort of patients (pts) with advanced colorectal cancer (CRC), under second- or third-line treatment with cetuximab or panitumumab, was tested using immunohistochemistry for expression of the activated form of IGF-1R (p-IGF-1R) and MMP-7. KRAS and BRAF mutation status was determined by sequencing and allelic discrimination analysis, respectively. Analyses were performed in primary CRC tumor samples or metastases, and the association of immunohistochemistry findings, mutational results, and treatment outcomes was investigated in both univariate and multivariate analyses.
RESULTS: Expression of activated IGF-1R and MMP-7 was observed in 51 and 49% of pts, respectively. Co-expression of MMP-7 and pIGF-1R (double positivity, DP) was observed in 28 pts (25%). There was no association between KRAS or BRAF mutational status and DP (p=0.52). Pts with DP responded more poorly to first-line chemotherapy (p=0.005) and to anti-EGFR treatment (p=0.01) than non-DP pts. In wild type (WT) KRAS pts, those with DP have poorer PFS (2.7 months vs. 3.5m, p=0.036; HR 1.98, 95% CI 1.05-3.75) and OS (6.4 months vs. 8.6 m, p=0.010; HR 2.33, 95%CI 1.23-4.43) in the adjusted multivariate analysis.
CONCLUSIONS: Our study suggests that concomitant expression of MMP-7 and activation of p-IGF-1R (DP) correlates with poor prognosis in WT KRAS pts treated with anti-EGFR.
