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Skin toxicity is a frequent adverse event of epidermal growth factor receptor (EGFR) targeting agents. Occurrence of cetuximab-induced skin toxicity (Cet-ST) correlates with better treatment response and longer survival times. Molecular markers predicting Cet-ST are still missing. This investigation analyzed the value of Cet-ST for treatment efficacy in a randomized trial comparing cetuximab plus capecitabine/irinotecan to cetuximab plus capecitabine/oxaliplatin as first-line treatment of metastatic colorectal cancer. Patient characteristics and molecular parameters (KRAS mutation, EGFR-FISH, EGFR-IHC and EGFR intron-1 polymorphism) of the tumour were correlated with response and Cet-ST. Cet-ST grade 0-1 was observed in 31%, grade 2-3 in 69% of patients. Outcome favoured patients with grade 2-3 Cet-ST with regard to overall response rate (62 vs. 41%), PFS (7.8 vs. 5.2 months) and overall survival (OS) (30.3 vs. 18.0 months). First-cycle rash was observed in 66% of patients and corresponded with longer survival (30.7 vs. 20.2 months, p = 0.007). Patients without Cet-ST had a poor outcome (PFS, 1.9 months; OS, 11 months). The correlation of Cet-ST with survival was specifically evident in patients with KRAS codon-12-mutated tumours assumed to be cetuximab resistant. In multivariate analysis of patient characteristics, male gender and younger age were significantly correlated with Cet-ST. Among molecular parameters, no significant correlation with Cet-ST was found. Cet-ST is an early predictor of treatment efficacy in cetuximab-treated patients. This effect of Cet-ST is independent of the KRAS mutation status, suggesting that Cet-ST rather relates to constitutional factors of the patient than alterations of the EGFR pathway in the tumour., (Copyright © 2012 UICC.)

Background: The epidermal growth factor receptor (EGFR) is an important target in the treatment of metastatic colorectal carcinoma (mCRC). The combination of anti-EGFR antibodies with chemotherapy has led to a higher response rate of certain kinds of tumor as well as a significant prolongation of the progression-free interval. The KRAS protein is an important mediator in the signal transduction cascade regulated by the EGFR. A KRAS mutation is present in 30% to 49% of all colorectal carcinomas. Mutations in the KRAS gene can be demonstrated by the methods of molecular pathology and are a very important factor in the selection of molecular biological treatment options targeted against EGFR., Methods: Selective literature review., Results: Patients bearing mutations of the KRAS gene do not benefit from treatment with the EGFR antibodies cetuximab and panitumumab., Conclusions: Activating mutations of the KRAS gene are biomarkers for resistance to cetuximab or panitumumab. Thus, anti-EGFR therapies are approved for the treatment of metastatic colorectal carcinoma only on condition that the mutation state of the KRAS gene is determined first, because the combination of chemotherapy with anti-EGFR is expected to increase the response rate only in patients with the wild-type KRAS gene.

Modern chemotherapy combinations for metastatic colorectal cancer (mCRC) comprise infusional 5-fluorouracil (5-FU), leucovorin, and irinotecan or oxaliplatin. The fluoropyrimidine derivative capecitabine is at least as effective as 5-FU plus leucovorin bolus regimens. It displays a favorable toxicity profile and offers the advantages of oral administration. The epidermal growth factor receptor antibody cetuximab induces synergistic antitumor activity when combined with chemotherapy. In pretreated patients, cetuximab can restore the sensitivity to irinotecan and, therefore, has been registered in this setting. Several phase I/II trials have investigated the combination of cetuximab with irinotecan-based or oxaliplatin-based chemotherapy for the first-line treatment of mCRC. These combinations have been proven to be safe and have provided promising efficacy data. A recent phase III trial confirmed improved progression-free survival, response rates, and a particularly significant increase of secondary resection rates for the combination of FOLFIRI (infusional 5-FU/leucovorin/irinotecan) plus cetuximab compared with FOLFIRI alone. In this review, we discuss the background of combining XELIRI (capecitabine/irinotecan) or XELOX (capecit-abine/oxaliplatin) with cetuximab for the first-line treatment of mCRC and present available data of these combined cytotoxic and targeted treatment approaches.

Cetuximab is a chimeric monoclonal antibody that binds to the epidermal growth factor receptor and thereby inhibits cell proliferation, metastasis and angiogenesis. Preclinical studies indicate that cetuximab induces synergistic antitumor activity when combined with chemotherapy or radiation. This observation is supported by clinical trials demonstrating that cetuximab improves tumor response when used in conjunction with modern chemotherapy in patients with metastatic colorectal cancer. Improved treatment efficacy may help to increase the rate of hepatic metastasis resection after downsizing of initially unresectable lesions. In pretreated patients, cetuximab may restore the sensitivity to irinotecan and, therefore, has been registered in this setting. Ongoing studies are investigating the integration of anti-epidermal growth factor receptor and anti-vascular endothelial growth factor strategies into new treatment regimens. Promising results have already been obtained in a trial combining irinotecan, bevacizumab and cetuximab.