Epidermal growth factor receptor expression discrepancies in metastatic colorectal cancer patients treated with cetuximab plus irinotecan-based chemotherapy refractory to irinotecan and oxaliplatin

Preclinical and clinical studies on afatinib in monotherapy and in combination regimens: Potential impact in colorectal cancer

Targeting the epidermal growth factor receptor (EGFR) with monoclonal antibodies (mAbs) or tyrosine kinase inhibitors (TKI) has been an interesting therapeutic strategy because aberrant activation of this receptor plays an important role in the tumorgenesis of many cancer types, including colorectal cancer (CRC). After the initial promising results of EGFR-targeted therapies, therapeutic resistance is a major clinical problem. In order to overcome resistance to these EGFR-targeted therapies, new treatment options are necessary. In contrast to first generation EGFR inhibitors, afatinib (BIBW2992) is a second-generation irreversible ErbB family blocker that inhibits EGFR as well as HER2 and HER4. Consequently, treatment with afatinib may result in a distinct and more pronounced therapeutic benefit. Preclinical studies have reported promising results for afatinib in monotherapy as well as in combination with other drugs in CRC model systems. Furthermore, clinical studies examining afatinib as single agent and in combination therapy demonstrated manageable safety profile. Nevertheless, only limited antitumor activity has been observed in CRC patients. Although several combination treatments with afatinib have already been investigated, no optimal combination has been identified for CRC patients yet. As molecular tumor characteristics have gained increased importance in the choice of treatment, additional studies with biomarker-driven patient recruitment are required to further explore afatinib efficacy in CRC.

Genetic and immune factors underlying the efficacy of cetuximab and panitumumab in the treatment of patients with metastatic colorectal cancer

Efficacy of monoclonal anti-EGFR antibodies (cetuximab, panitumumab) used in combination with chemotherapy or alone has been demonstrated in clinical trials of patients with mCRC. Both drugs block signaling EGFR pathway in malignant cells (blocking ligand binding and EGFR dimerization). Obtaining treatment responses with anti-EGFR agents is possible only in a selected subgroup of patients with mCRC. Successful treatment with cetuximab and panitumab is possible almost exclusively in patients without RAS mutations. Research on predictive value of EGFR gene copy number, PI3KCA gene mutations, P53 and PTEN, and EGFR their ligands concentrations is ongoing. Cetuximab, as IgG1 class antibody, can cause antibody dependent cellular cytotoxicity against neoplasm cells, while panitumumab, as IgG2 class antibody, does not induce such effect. Therefore a potential predictor cetuximab therapy may be the presence of different polymorphic forms of the genes for receptor immunoglobulin Fc fragments: FcγRIIa and FcγRIII subclasses.

KRAS mutation status and clinical outcome of preoperative chemoradiation with cetuximab in locally advanced rectal cancer: a pooled analysis of 2 phase II trials

PURPOSE

Cetuximab-containing chemotherapy is known to be effective for KRAS wild-type metastatic colorectal cancer; however, it is not clear whether cetuximab-based preoperative chemoradiation confers an additional benefit compared with chemoradiation without cetuximab in patients with locally advanced rectal cancer.

METHODS AND MATERIALS

We analyzed EGFR, KRAS, BRAF, and PIK3CA mutation status with direct sequencing and epidermal growth factor receptor (EGFR) and Phosphatase and tensin homolog (PTEN) expression status with immunohistochemistry in tumor samples of 82 patients with locally advanced rectal cancer who were enrolled in the IRIX trial (preoperative chemoradiation with irinotecan and capecitabine; n=44) or the ERBIRIX trial (preoperative chemoradiation with irinotecan and capecitabine plus cetuximab; n=38). Both trials were similarly designed except for the administration of cetuximab; radiation therapy was administered at a dose of 50.4 Gy/28 fractions and irinotecan and capecitabine were given at doses of 40 mg/m2 weekly and 1650 mg/m2/day, respectively, for 5 days per week. In the ERBIRIX trial, cetuximab was additionally given with a loading dose of 400 mg/m2 on 1 week before radiation, and 250 mg/m2 weekly thereafter.

RESULTS

Baseline characteristics before chemoradiation were similar between the 2 trial cohorts. A KRAS mutation in codon 12, 13, and 61 was noted in 15 (34%) patients in the IRIX cohort and 5 (13%) in the ERBIRIX cohort (P=.028). Among 62 KRAS wild-type cancer patients, major pathologic response rate, disease-free survival and pathologic stage did not differ significantly between the 2 cohorts. No mutations were detected in BRAF exon 11 and 15, PIK3CA exon 9 and 20, or EGFR exon 18-24 in any of the 82 patients, and PTEN and EGFR expression were not predictive of clinical outcome.

CONCLUSIONS

In patients with KRAS wild-type locally advanced rectal cancer, the addition of cetuximab to the chemoradiation with irinotecan plus capecitabine regimen was not associated with improved clinical outcome compared with chemoradiation without cetuximab.

Biweekly cetuximab plus irinotecan as second-line chemotherapy for patients with irinotecan-refractory and KRAS wild-type metastatic colorectal cancer according to epidermal growth factor receptor expression status

BACKGROUND

Cetuximab plus irinotecan has been shown to be effective in metastatic colorectal cancer (mCRC) patients with wild-type (WT) KRAS and positive EGFR expressions (EGFR+). Retrospective analysis revealed that the efficacy of cetuximab was similar in mCRC patients negative (EGFR-) and positive for EGFR. However, the efficacy of cetuximab has not been assessed prospectively in EGFR- mCRC patients.

METHODS

This was a prospective, multicenter phase II study assessed the efficacy and safety of biweekly cetuximab (500 mg/m(2)) and irinotecan (150-180 mg/m(2)) in patients with histologically proven adenocarcinoma with WT-KRAS and measurable lesion(s), either EGFR + or EGFR-, determined immunohistochemically, who failed first-line irinotecan-containing chemotherapy. The primary endpoint was response rate (RR), and the secondary endpoints included safety, progression-free survival (PFS) and overall survival (OS).

RESULTS

Forty patients were enrolled; 20 EGFR + and 20 EGFR-; their baseline characteristics were balanced. The overall RR was 45% (18/40, 95% CI 29.6-60.4), 55% (11/20) in EGFR + and 35% (7/20) in EGFR- patients. Median PFS was 7.1 months (95% CI 4.8-9.4), 8.3 months in EGFR + and 4.9 months in EGFR- patients. Median OS was 18.5 months (95% CI 15.2-21.8), 17.2 months in EGFR + and 18.5 months in EGFR- patients. Grade 3 or 4 toxicities included neutropenia in 5 patients (12.5%) and febrile neutropenia/skin rash/asthenia in 2 (5%).

CONCLUSIONS

Biweekly cetuximab plus irinotecan as second-line treatment showed significant anti-tumor activity in patients with irinotecan-refractory mCRC and WT-KRAS regardless of EGFR expression status.