PDTM-03. CHICKEN EMBRYO CHORIOALLANTOIC MEMBRANE (CAM) ASSAY AS A XENOGRAFT MODEL FOR TREATMENT OF DIFFUSE INTRINSIC PONTINE GLIOMAS

Abstract BACKGROUND Diffuse intrinsic pontine gliomas (DIPG), known today as diffuse midline gliomas with the H3K27M mutation, are inoperable and aggressive brain tumors found predominantly in children. Despite extensive research no treatment or cure has been elucidated. Studies in 2012 showed that the majority of DIPG tumors have the H3K27M mutation, but the development of novel therapeutics has been hindered by lack of good laboratory models. Although patient derived cell lines with the H3K27M mutation have increased, the development of good murine xenografts are lagging, requiring extensive time and money. Previous studies have shown that the chicken embryo Chorioallantoic Membrane (CAM) model is an affordable and time-efficient method of studying tumor biology and response to treatment. We sought to develop this in H3K27M tumors to bridge the gap between in vitro—in vivo studies. METHODS Three patient-derived H3K27M cell lines were cultured and implanted on the chick embryo CAM on day 9 post-fertilization. Tumors underwent multiple drug treatment with 0.5uM or 2.0uM Alisertib (days 11, 13, 15) or a single targeted radiation treatment at 2 Grey (day 13). Tumor volume was assessed via ultrasound on day 16. The tumor specimens were harvested and analyzed by immunohistochemistry. RESULTS Patient-derived DIPG cells implanted on the CAM maintain their molecular characteristics and form tumors on the surface of the CAM as evidenced by H&E and H3K27M status. Statistically significant differences in volume were found in three H3K27M DIPG lines in Alisertib treated tumors compared to the control (p< 0.001, p< 0.001, p= 0.005). Statistically significant differences in tumor volume were found when treating two DIPG lines with targeted radiation therapy compared to controls (p= 0.01, p= 0.02). CONCLUSIONS These results validated the CAM assay as a reliable xenograft model for studying DIPG tumor biology and determining efficacy of drug and radiation treatment.