Epidermal growth factor receptor expression discrepancies in metastatic colorectal cancer patients treated with cetuximab plus irinotecan-based chemotherapy refractory to irinotecan and oxaliplatin.
OBJECTIVE
This study was designed to evaluate the efficacy and safety of cetuximab plus irinotecan-based therapy in metastatic colorectal cancer refractory to irinotecan and oxaliplatin. In addition, discrepancies in the expression of epidermal growth factor receptor were examined by immunohistochemistry using two different antibodies.


METHODS
The records of patients with metastatic colorectal cancer who were heavily pretreated with irinotecan and oxaliplatin and subsequently received cetuximab plus irinotecan-based therapy were reviewed. Differences in the expression of epidermal growth factor receptor detected by the PharmDx antibody and the clone H11 antibody in these patients were compared.


RESULTS
Between February 2005 and August 2007, 52 patients were treated; median age was 53.5 years. The confirmed overall response rate was 30.8 percent, and the disease control rate was 67.3 percent. Median time to progression was 3.1 months, and median overall survival was 8.1 months. Of the 27 patients evaluable for epidermal growth factor receptor status, epidermal growth factor receptor expression was positive in 12 patients (44.4 percent) using the clone H11 antibody test and in 26 patients (96.3 percent) with the PharmDx kit.


CONCLUSIONS
Cetuximab plus irinotecan-based therapy showed promising antitumor activity even in patients with metastatic colorectal cancer refractory to irinotecan and oxaliplatin. In addition, discrepancies in the expression of the epidermal growth factor receptor detected by the clone H11 antibody and the PharmDx kit were observed.
Han
Hye-Suk
HS
Center for Clinical Trials, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
Chang
Hee Jin
HJ
Hong
Yong Sang
YS
Kim
Sun Young
SY
Lee
Keun Seok
KS
Jung
Kyung Hae
KH
D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000627:therapeutic use; D002166:Camptothecin / Q000031:analogs & derivatives / Q000627:therapeutic use; D000068818:Cetuximab; D016009:Chi-Square Distribution; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology*; D018450:Disease Progression; D066246:ErbB Receptors / Q000276:immunology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D000077146:Irinotecan; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009944:Organoplatinum Compounds / Q000627:therapeutic use; D000077150:Oxaliplatin; D016016:Proportional Hazards Models; D015996:Survival Rate
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D009944:Organoplatinum Compounds; D000077150:Oxaliplatin; D000077146:Irinotecan; D066246:ErbB Receptors; D000068818:Cetuximab; D002166:Camptothecin