Treatment of pancreatic cancer xenografts with Erbitux (IMC-C225) anti-EGFR antibody, gemcitabine, and radiation.
OBJECTIVE
To investigate treatment of human pancreatic cancer cell lines and xenografts with combinations of Erbitux (IMC-C225) anti-epidermal growth factor receptor (EGFR) antibody, gemcitabine, and radiation.


METHODS
BxPC-3 and MiaPaCa-2 human pancreatic carcinoma cells were treated in vitro for 24 h with IMC-C225 (5 microg/mL), then exposed to epidermal growth factor (EGF) (10 mM) for 5 min. Immunoblots were screened for EGFR expression and the ability of IMC-C225 to block EGF-induced tyrosine phosphorylation of EGFR. Cells were treated with IMC-C225 (5 microg/mL) on Day 0, the IC(50) dose of gemcitabine on Day 1 for 24 h, followed by 3 Gy 60Co irradiation on Day 2, or the combination of each agent. For cell proliferation, cells were counted on Day 4, and for apoptosis, cells were stained with annexin V-FITC and propidium iodide, then analyzed by FACS. Cells were treated with the same single or multiple treatments and analyzed in a clonogenic cell survival assay. The effect of IMC-C225, gemcitabine, and radiation on the growth of BxPC-3 and MiaPaCa-2 tumor xenografts was determined. Athymic nude mice bearing established s.c. tumor xenografts of 6-8 mm diameter received 6 weeks of treatment with IMC-C225 (1 mg every 3 days x 6) alone or in combination with gemcitabine (120 mg/kg i.v. every 6 days x 6), and 6 weekly fractions of 3 Gy radiation on the days after gemcitabine administration. Tumor growth was measured with Vernier calipers.


RESULTS
BxPC-3 and MiaPaCa-2 cell lines expressed low levels of EGFR. IMC-C225 inhibited EGF-induced tyrosine phosphorylation of the EGF receptor on both cell lines. Treatment of cells with a combination of IMC-C225 + gemcitabine + radiation produced the highest induction of apoptosis and inhibition of proliferation in vitro. Combination treatment with IMC-C225, gemcitabine, and radiation produced 100% complete regression of MiaPaCa-2 tumors for more than 250 days, and the greatest growth inhibition of BxPC-3 tumors compared to any single or dual treatments.


CONCLUSIONS
The IMC-C225 therapy in combination with gemcitabine chemotherapy and radiation therapy demonstrated statistically significantly greater efficacy over the single and double combination therapies. This form of multimodality treatment shows potential clinical application in the treatment of pancreatic cancer in humans.
Buchsbaum
Donald J
DJ
Department of Radiation Oncology, University of Alabama at Birmingham, Wallace Tumor Institute, Room 674, 1824 6th Avenue South, Birmingham, AL 35294, USA. djb@uab.edu
Bonner
James A
JA
Grizzle
William E
WE
Stackhouse
Murray A
MA
Carpenter
Mark
M
Hicklin
Daniel J
DJ
Bohlen
Peter
P
Raisch
Kevin P
KP
D000818:Animals; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D017209:Apoptosis; D002453:Cell Cycle / Q000187:drug effects / Q000528:radiation effects; D002455:Cell Division; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D000068818:Cetuximab; D003131:Combined Modality Therapy; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000627:therapeutic use*; D066246:ErbB Receptors / Q000032:analysis / Q000037:antagonists & inhibitors* / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D008807:Mice, Inbred BALB C; D009368:Neoplasm Transplantation; D010190:Pancreatic Neoplasms / Q000628:therapy*; D010766:Phosphorylation; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured; D000093542:Gemcitabine
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D003841:Deoxycytidine; D066246:ErbB Receptors; D000068818:Cetuximab; D000093542:Gemcitabine