TMIC-85. TGFB2 AND IFNGR2 MRNA EXPRESSION LEVELS IN THE TUMOR MICROENVIRONMENT (TME) PROGNOSITICALLY IMPACT OS IN PEDIATRIC DIPG PATIENTS

Abstract

Abstract DIPG patients expressed significantly higher levels of TGFB2 and IFNGR2 than control pons samples and the expression profile indicated higher levels of TGFB2 than TGFB1 and TGFB3 in DIPG patients suggesting TGFB2 mRNA level is preferentially increased in DIPG patients. TGFB2 is a prognostic indicator (HR for patients in the TGFB2high group of DIPG patients = 2.88 (1.12-7.39); P = 0.028) for poor overall survival (OS) independent of IFNGR2 levels, the age of the patient, and the significant interaction effect observed between IFNGR2 and TGFB2. Predictive modeling using the Cox regression parameters showed that the context of low expression of IFNGR2, TGFB2low resulted in more favorable OS times compared to TGFB2high whereby the median OS time of 11 months for the TGFB2low group of patients was greater than the upper 95% confidence limit for the TGFB2high group of patients (Median = 7 months; Upper 95% Confidence interval = 10 months). At higher levels of IFNGR2 expression, the TGFB2high group of patients exhibited a median OS time of 15 months that was within the (95% confidence interval for the TGFB2low group of patients (Median = 13 months; 95% CI = 10-17 months). Worse survival outcomes comparing DIPG patients with high versus low TGFB2 levels in the context of low levels of IFNGR2 levels suggest that abrogating the TGFB2 mRNA expression in the immunologically cold tumor microenvironment indicated by low levels of IFNGR2 expression can potentially treat pediatric DIPG patients. Furthermore, DIPG patients with low levels of JAK1 or STAT1 mRNA expression in combination with TGFB2high also exhibited poor OS outcomes suggesting that the inclusion of (Interferon-gamma) IFNγ to stimulate and activate JAK1 and STAT1 in anti-tumor immune cells present the brainstem tumor microenvironment can enhance the effect of TGFB2 blockade.