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THE HROC COLLECTION AND MATCHING PAIRS OF COLORECTAL CANCER MODELS (PDX AND CELL LINES) FROM PRIMARIES AND METASTASES
Michael Linnebacher*1, Claudia Maletzki1, Christina S. Mullins1, Michael Gock1, Maja Huehns2, Friedrich Prall2, Ernst Klar1
1General Surgery, University of Rostock, Rostock, Germany; 2Institute of Pathology, University of Rostock, Rostock, Germany
Background: The goal was to establish colorectal cancer (CRC) models from primary and metastatic tumors representing all molecular subclasses, anatomic sites, grading and staging types from consecutively operated patients. Samples were collected in the context of an integrated biobanking concept (PMID:26054386) with strict SOPs.
Material and Methods: Resection specimens were fresh from surgery; tissue cubes (ca. 3×3×3mm) were cut from the deep invasive parts with a sterile scalpel and transferred into sterile tubes containing freezing medium for transient cryopreservation [PMID:20615215]. Neighbouring pieces processed to cell suspensions were taken into culture. For PDX generation, pieces were implanted s.c. into immunodeficient mice. Outgrowing PDX were harvested with 800 to 1,400mm3. Original tumor, cell line and PDX tissues were characterized including fingerprint, mutation, MSI and methylation analyses [PMID:19578746]. Testing for stem cell properties, treatment response, metabolic and functional behaviour etc. of selected model pairs have started [PMID:26618628, 25926053, 27312529].
Results: Tumoral tissue, normal colonic epithelium, blood cells and sera were collected from 432 cases and stored at -170°C. In total, 53 CRC cell (from 281 cultures; 18.9% overall success) and 122 PDX lines (from 191; 63.9%) were generated and characterized at least basically. Immortalized B cell lines were generated as controls. Several proof-of-concept studies show that the HROC in vitro and in vivo models are an important contribution [PMID:24962950, 23300683, 27087592]. All CRC molecular subclasses, anatomic sites, grading and staging types are represented including one each Crohn’s, neuroendocrine and duodenum plus 11 Lynch cases. Sigma carcinomas engrafted worse (p=0.017; Chi2), metastases better then primaries (0.029), graft success was better with higher N (0.047) and M (0.009) status and grading (0.018). Sporadic standard types engrafted worse (0.025) and Lynch cases better (p=0.016).
Cell line generation was better with higher N (p<0.05) and G (p=0.015), success of PDX engraftment (p<0.001), presence of an APC mutation (p=0.044) and ascending localization (p=0.004); rectal localization was a negative predictor (p=0.032). Cultures were easier to generate from PDX then from primaries (p<0.001).
Of note, the PDX collection contains 10 sets of a primary tumor and one or two matching metastases from the same patient. Five such sets were established as cell cultures. The treatment response tests revealed surprisingly few differences in the response of primaries and matching metastases.
Conclusion: The HROC collection is one of the largest model collections from consecutive clinical CRC cases worldwide. Especially interesting are models of matching primaries and metastases and of rare clinical cases for research but especially preclinical therapy development.
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