Effect of erlotinib on epidermal growth factor receptor and downstream signaling in oral cavity squamous cell carcinoma.
BACKGROUND
The purpose of this study was to determine if there are differences in biomarker modulation and epidermal growth factor receptor (EGFR) degradation between the tumor and the normal mucosa after treatment with an EGFR inhibitor, erlotinib, in head and neck cancer.


METHODS
Patients with primary oral cavity squamous cell cancers received a course of erlotinib, 150 mg every day for 7 days before surgical resection. Tumor and normal mucosa biopsies were obtained both pre-erlotinib and post-erlotinib. Changes in known markers of EGFR activity (phospho, AKT, STAT3) were measured by immunoblotting, whereas changes in tissue distribution were analyzed by immunohistochemical analysis.


RESULTS
Twelve patients were enrolled; 7 had evaluable paired tumors and normal mucosa biopsies pretreatment and posttreatment. Expression of EGFR was higher in tumors compared to the normal mucosa (p = .005). Erlotinib administration was associated with marked inhibition of phosphorylated epidermal growth factor receptor (pEGFR) and reduction in total EGFR protein (p = .004, p = .007) in tumors, whereas there was heterogeneity in EGFR inhibition in the normal mucosa (p = .10 [pEGFR], and p = .07 [EGFR]). Reduced levels of pSrc and pSTAT3 and enhanced p27 levels were noted in tumors after erlotinib. Cell culture studies confirmed that EGFR is degraded in tumor cells after prolonged treatment with erlotinib.


CONCLUSIONS
Our results show that EGFR inhibition by erlotinib led to a marked reduction in EGFR protein levels in patients. Differential effects of erlotinib on tumors compared to the normal mucosa suggest there may be individual patient heterogeneity. These preliminary data suggest EGFR degradation should be further analyzed as a potential biomarker in selecting patients likely to benefit from EGFR inhibitors.
Department of Radiation Oncology, University of Michigan Medical Center, Ann Arbor, Michigan 48109, USA. ctsien@umich.edu
Christina I
CI
Tsien
Mukesh K
MK
Nyati
Aarif
A
Ahsan
Susmita G
SG
Ramanand
Douglas B
DB
Chepeha
Francis P
FP
Worden
Joseph I
JI
Helman
Nisha
N
D'Silva
Carol R
CR
Bradford
Gregory T
GT
Wolf
Theodore S
TS
Lawrence
Avraham
A
Eisbruch
D000293:Adolescent; D000328:Adult; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy* / Q000378:metabolism; D018929:Cell Culture Techniques; D002648:Child; D002675:Child, Preschool; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000069347:Erlotinib Hydrochloride; D005260:Female; D006258:Head and Neck Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009061:Mouth Mucosa / Q000187:drug effects / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011799:Quinazolines / Q000494:pharmacology*; D050796:STAT3 Transcription Factor / Q000378:metabolism; D000077195:Squamous Cell Carcinoma of Head and Neck; D055815:Young Adult
D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D000069347:Erlotinib Hydrochloride; D066246:ErbB Receptors; D051057:Proto-Oncogene Proteins c-akt