FCGR2A and FCGR3A polymorphisms associated with clinical outcome of epidermal growth factor receptor expressing metastatic colorectal cancer patients treated with single-agent cetuximab.
OBJECTIVE
Cetuximab, a chimeric immunoglobulin G 1 (IgG1) anti-epidermal growth factor receptor (EGFR) monoclonal antibody (mAb), has shown efficacy in 10% of patients with metastatic colorectal cancer (CRC). Recent studies demonstrate antibody-dependent cell-mediated cytotoxicity (ADCC) is one of the modes of action for rituximab and trastuzumab. Fragment c (Fc) portion of IgG1 mAb has shown to induce ADCC. Fragment c gamma receptors (FcgammaR) play an important role in initiating ADCC. Studies have shown that two IgG FcgammaR polymorphisms (FCGR2A-H131R and FCGR3A-V158F) independently predict response to rituximab in patients with follicular lymphoma. We tested the hypothesis of whether these two polymorphisms are associated with clinical outcome in metastatic CRC patients treated with single-agent cetuximab.


METHODS
Thirty-nine metastatic CRC patients were enrolled onto the ImClone0144 trial. Using an allele-specific polymerase chain reaction (PCR) -based method, gene polymorphisms of FCGA2A-H131R and FCGA3A-V158F were assessed from genomic DNA extracted from peripheral blood samples.


RESULTS
FCGR2A-H131R and FCGR3A-V158F polymorphisms were independently associated with progression-free survival (PFS; P = .037 and .055, respectively; log-rank test). Combined analysis of these two polymorphisms showed that patients with the favorable genotypes (FCGR2A, any histidine allele, and FCGR3A, any phenylalanine allele) showed a median PFS of 3.7 months (95% CI, 2.4 to 4.4 months), whereas patients with any two unfavorable genotypes (FCGR2A arginine/arginine or valine/valine) had a PFS of 1.1 months (95% CI, 1.0 to 1.4 months; P = .004; log-rank test).


CONCLUSIONS
Our preliminary data suggest that these two polymorphisms may be useful molecular markers to predict clinical outcome in metastatic CRC patients treated with cetuximab and that they may indicate a role of ADCC of cetuximab.
Zhang
Wu
W
Division of Medical Oncology, Department of Pathology, University of Southern California, Norris Comprehensive Cancer Center, Keck School of Medicine, Los Angeles, CA 90033, USA.
Gordon
Michael
M
Schultheis
Anne M
AM
Yang
Dong Yun
DY
Nagashima
Fumio
F
Azuma
Mizutomo
M
Chang
Heung-Moon
HM
Borucka
Eva
E
Lurje
Georg
G
Sherrod
Andy E
AE
Iqbal
Syma
S
Groshen
Susan
S
Lenz
Heinz-Josef
HJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000009:adverse effects / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D000920:Antibody-Dependent Cell Cytotoxicity; D000970:Antineoplastic Agents / Q000009:adverse effects / Q000627:therapeutic use*; D000068818:Cetuximab; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000401:mortality / Q000473:pathology; D018572:Disease-Free Survival; D066246:ErbB Receptors / Q000378:metabolism; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D017452:Receptors, IgG / Q000235:genetics*; D015996:Survival Rate
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; C445323:FCGR2A protein, human; C496124:FCGR3A protein, human; D017452:Receptors, IgG; D066246:ErbB Receptors; D000068818:Cetuximab