Anti-KRAS monoclonal antibody, clone 5G7

Background OncogenicK-Rasmutations in colorectal cancer (CRC) combined withAPCmutations worsen CRC prognosis and lower drug effectiveness. Thus, inhibition of both Wnt/beta-catenin and Ras-MAPK signaling may be a rational strategy to improve the treatment of this cancer. Objective To identify a novel compound inhibiting both Wnt/beta-catenin and Ras-MAPK signaling in CRC. Methods and Patients We developed a two-part screening system consisting of analysis of TOP flash reporter cells and then potential toxicity effects on primary neural stem cells (NSCs). We then screened 2000 chemical compounds and tested efficacy of candidates against isogenic colon cancer cells harboring wild-type or mutantK-Ras.We employed immunohistochemistry and immunocytochemistry to determine marker signatures associated with development of disease phenotypes. Results We identified CPD0857, a compound that inactivates Wnt/beta-catenin signaling and promotes ubiquitin-dependent proteasomal degradation of beta-catenin and Ras proteins. CPD0857 effectively decreased proliferation and increased apoptosis of CRC cell lines, and overcame resistance of CRC harboringAPCandK-Rasmutations to treatment with an EGFR monoclonal antibody (mAb). Moreover, CPD0857 attenuated invasiveness of highly migratory CRC cells in vitro. Accordingly, xenograft mice treated with CPD0857 showed slower tumor growth and significant decreases in both beta-catenin and Ras protein expression. Conclusions CPD0857 may be a potential drug for treating aggressive CRC carrying mutations that aberrantly activate Wnt/beta-catenin and Ras-ERK pathways.

Human cancer cell lines are frequently used as model systems to study molecular mechanisms and genetic changes in cancer. However, the model is repeatedly criticized for its lack of proximity to original patient tumors. Therefore, understanding to what extent cell lines cultured under artificial conditions reflect the phenotypic and genomic profiles of their corresponding parental tumors is crucial when analyzing their biological properties. To directly compare molecular alterations between patient tumors and derived cell lines, we have established new cancer cell lines from four patients with gastrointestinal tumors. Tumor entities comprised esophageal cancer, colon cancer, rectal cancer and pancreatic cancer. Phenotype and genotype of both patient tumors and derived low-passage cell lines were characterized by immunohistochemistry (22 different antibodies), array-based comparative genomic hybridization and targeted next generation sequencing (48-gene panel). The immunophenotype was highly consistent between patient tumors and derived cell lines; the expression of most markers in cell lines was concordant with the respective parental tumor and characteristic for the respective tumor entities in general. The chromosomal aberration patterns of the parental tumors were largely maintained in the cell lines and the distribution of gains and losses was typical for the respective cancer entity, despite a few distinct differences. Cancer gene mutations (e.g., KRAS, TP53) and microsatellite status were also preserved in the respective cell line derivates. In conclusion, the four examined newly established cell lines exhibited a phenotype and genotype closely recapitulating their parental tumor. Hence, newly established cancer cell lines may be useful models for further pharmacogenomic studies.