Abstract 2402: The impact of genomic heterogeneity in colorectal carcinoma on therapy response - a study on monoclonal primary colon cultures

Proceedings: AACR 107th Annual Meeting 2016; April 16-20, 2016; New Orleans, LA Introduction: Individual response to chemotherapy in colorectal cancer patients is highly variable and the underlying mechanisms of treatment resistance of colorectal cancer cells are poorly understood. Recent studies revealed a considerable degree of genomic and genetic tumor heterogeneity. We hypothesize that the intra-tumoral heterogeneity has a direct impact on treatment response as sub-populations of cancer cells are resistant to currently used chemotherapeutics and facilitate tumor growth under treatment. Experimental procedures: Patient-derived primary colorectal cell lines were established employing three different methodological approaches: (i) mouse xenografts and reintroduction of the graft to culture, (ii) conditional reprogramming by Rho kinase inhibition in combination with irradiated feeder cells and (iii) organoid growth in Matrigel with Wnt-, R-spondin and Noggin conditioned medium. Established primary cultures were characterized genomically by array CGH and spectral karyotyping (SKY). Results: To date, we successfully established eight patient-derived primary colorectal cell lines. Culture conditions were optimized for long-term in vitro growth of colorectal primary tissue. Array CGH has identified patterns of chromosomal imbalances in these cell lines, i.e. gains of chromosomes 7, 13 and 20 as well as a loss of chromosome 18. Additionally, gene amplifications of MYC and EGFR were identified. As these aberrations are typically found in colorectal cancer, the established primary tissue derived cell lines closely reflect the nature of the tumor in vivo in terms of genomic instability. Array CGH findings were confirmed using SKY. Sub-cultivation of single cell derived monoclonal cell lines will facilitate addressing the tumor heterogeneity in terms of their genomic and genetic background using genome and transcriptome analyses. Single-cell derived lines will then be exposed to chemotherapeutic drugs currently used in clinical routine such as 5-FU and Oxaliplatin. The respective sensitivity will be correlated to the aberration profiles. Conclusion: Exploration of tumor heterogeneity in terms of their genomic and genetic background in the context of treatment response might facilitate understanding of therapy resistance. Moreover, reliable prediction of the patient's response to the employed chemotherapeutic drug is a necessary step towards individualized treatment in colorectal cancer. Citation Format: Rudiger Meyer, Nicole E. McNeil, Ewa Krawczyk, Daniel W. Rosenberg, Zhongqiu Zhang, Richard Schlegel, Jens K. Habermann, Thomas Ried. The impact of genomic heterogeneity in colorectal carcinoma on therapy response - a study on monoclonal primary colon cultures. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2402.