Abstract 1450: Autopsy derived orthotopic xenograft (ADOX) mouse models for terminal pediatric brain tumors

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Brain tumors are the leading cause of cancer related death in children, and there is biological differences between treatment naive tumors and their therapy resistant relapses. As surgery is rarely an option for terminal brain tumors that have failed existing therapies, autopsy is frequently the only chance to obtain tumor tissues. Despite the urgent need of models of terminal brain tumors, it remains unknown if autopsied tumors can be used for in vitro and in vivo model development. To determine if (some) tumor cells can survival postmortem anoxia/starvation to proliferate in vitro and, more importantly, to form orthotopic xenograft tumors, we collected 29 autopsied brain tumors, including 15 diffuse intrinsic pontine gliomas (DIPG), 7 glioblastomas (GBM), 4 medulloblastomas (MB), 2 ependymoma and 1 atypical teratoid/rhabdoid tumor (ATRT), and made the following discoveries. i) A small fraction of tumor cells exhibited strong survival capacity and remained viable, ranging from 0.5%-40% (13.5% ± 10.9%), in tumors harvested 5-72 hrs (31.2 ± 25 hrs) after patients’ death. Cell viability, however, did not appear to be strictly correlated with the length of autopsy time (r = 0.17), suggesting that ample time should be given to the families to say goodbye to their loved ones. ii) While many autopsied tumor cells appear to have stayed alive for short terms in culture, only one pair of permanent lines (monolayer in FBS media and neurosphere in serum-free media) were established from a GBM tumor. iii) Direct implantation of tumor cells into matched locations in the brains of SCID mice led to the formation of xenograft tumors in 17 of 22 tumors (7 additional tumors are still pending). 8 of the 17 autopsy derived orthotopic (ADOX) models have been subtransplanted in mouse brains for > 3 times (5 DIPGs and 1 each of GBM, MB and ATRT). Detailed characterization confirmed their replication of histopathological features and genetic/genomic abnormalities of the patient tumors. iv) To identify the cellular origin of surviving patient tumor cells that propagated ADOX model formation, time course analysis of putative cancer stem cells (CD133, CD15, CD24/CD44, CD57, CD117) was performed. CD57+ tumor cells were found to be the most abundant subpopulations in the autopsied tumors, and their fractions increased in the ADOX tumors during serial subtransplantations. Additionally, CD57+ cells alone were able to form orthotopic xenografts, establishing their role as cancer stem cells. In conclusion, we have demonstrated that a fraction of tumor cells can survive the lengthy period of postmortem anoxia/starvation and regain tumorigenic capabilities in mouse brains; and identified CD57 as a new marker of the therapy-resistant cells with extraordinary survival and tumorigenic (TREST) capabilities. This novel panel of ADOX models should facilitate biological studies and preclinical drug screening of therapy-resistant pediatric brain tumors. Citation Format: Lin Qi, Baxter A. Patricia, Kogiso Mari, Du Yuchen, Lindsay Holly, Liu Zhigang, Xiumei Zhao, Yujing Zhang, Jack MF Su, Adekunle Adesina, Andrew W. Walter, Jeffery Murray, Rene McNall-Knapp, Javad Nazarian, Will Parsons, Murali Chintagumpala, Susan Blaney, Xiao-Nan Li. Autopsy derived orthotopic xenograft (ADOX) mouse models for terminal pediatric brain tumors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1450. doi:10.1158/1538-7445.AM2015-1450