Abstract

PURPOSE: To develop effective combination therapy against pancreatic ductal adenocarcinoma (PDAC) with a combination of chemotherapy, CHK1 inhibition, and EGFR-targeted radioimmunotherapy. EXPERIMENTAL DESIGN: Maximum tolerated doses were determined for the combination of gemcitabine, the CHK1 inhibitor PF-477736, and Lutetium-177 ((177)Lu)-labeled anti-EGFR antibody. This triple combination therapy was investigated using PDAC models from well-established cell lines, recently established patient-derived cell lines, and fresh patient-derived xenografts. Tumors were investigated for the accumulation of (177)Lu-anti-EGFR antibody, survival of tumor-initiating cells, induction of DNA damage, cell death, and tumor tissue degeneration. RESULTS: The combination of gemcitabine and CHK1 inhibitor PF-477736 with (177)Lu-anti-EGFR antibody was tolerated in mice. This triplet was effective in established tumors and prevented the recurrence of PDAC in four cell line-derived and one patient-derived xenograft model. This exquisite response was associated with the loss of tumor-initiating cells as measured by flow cytometric analysis and secondary implantation of tumors from treated mice into treatment-naive mice. Extensive DNA damage, apoptosis, and tumor degeneration were detected in the patient-derived xenograft. Mechanistically, we observed CDC25A stabilization as a result of CHK1 inhibition with consequent inhibition of gemcitabine-induced S-phase arrest as well as a decrease in canonical (ERK1/2 phosphorylation) and noncanonical EGFR signaling (RAD51 degradation) as a result of EGFR inhibition. CONCLUSIONS: Our study developed an effective combination therapy against PDAC that has potential in the treatment of PDAC. Clin Cancer Res; 20(12); 3187-97. (c)2014 AACR.

Authors	Al-Ejeh, F.; Pajic, Marina; Shi, Wei; Kalimutho, M.; Miranda, Mariska; Nagrial, Adnan M.; Chou, Angela; Biankin, Andrew V.; Grimmond, Sean; Brown, M. P.; Khanna, Kum Kum
Journal	CLINICAL CANCER RESEARCH
Pages	3187-97
Volume	20
Date	15/06/2014
Grant ID
Funding Body
URL	http://www.ncbi.nlm.nih.gov/pubmed/?term=10.1158/1078-0432.CCR-14-0048