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Gemcitabine and CHK1 inhibition potentiate EGFR-directed radioimmunotherapy against pancreatic ductal adenocarcinoma

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.

Type Journal
ISBN 1078-0432 (Print) 1078-0432 (Linking)
Authors Al-Ejeh, F.; Pajic, M.; Shi, W.; Kalimutho, M.; Miranda, M.; Nagrial, A. M.; Chou, A.; Biankin, A. V.; Grimmond, S. M.; Australian Pancreatic Cancer Genome, Initiative; Brown, M. P.; Khanna, K. K.;
Garvan Authors Dr Adnan Nagrial , Dr Angela Chou , Dr Marina Pajic
Publisher Name CLIN CANCER RES
Published Date 2014-06-01 00:00:00
Published Volume 20
Published Issue 12
Published Pages 3187-97
URL http://www.ncbi.nlm.nih.gov/pubmed/24838526
Status Published In-print
OpenAccess Link https://publications.gimr.garvan.org.au/download.php?12304_12885/14_AlEjeh_CCR_.pdf