TMIC-38. CD39 EXPRESSION IN GLIOBLASTOMA TUMOR MICROENVIRONMENT DOES NOT AFFECT SURVIVAL OR T-CELL EXHAUSTION

Abstract Glioblastoma (GBM) is the most common malignant brain tumor with a median survival of 15 months. GBM very difficult to treat due numerous factors, including paucity immune infiltration itself. Efforts overcome this have led use checkpoint inhibitors such as PD-1 inhibitor, which revolutionized treatment many other solid tumors, and yet not been successful in GBM. This has studies investigating various similar markers. One marker CD39, highly upregulated functions first enzyme metabolic pathway ATP breakdown adenosine. Additionally, CD39 thought contribute T-cell exhaustion. Like PD-1, inhibition had preliminary success tumors. However, when tested on GBM, blocking did improve mice, even conjunction inhibition. Our team sought determine if expression cell surface functioned an exhaustion by injecting two different lines into global null mice. There was no benefit seen either line compared wild type Next, known markers TIM3, LAG3 infiltrating lymphocytes were analyzed. Expression TIM3 2B4 found be increased CD39KO mice comparison (p < 0.01). LAG3, TIGIT, CTLA4 decreased peripheral blood These results demonstrate complex nature signaling microenvironment that our continues investigate.