Background: Ruxolitinib is a novel, potent, and selective inhibitor of JAK1 (Janus kinase 1) and JAK2 with modest to marked selectivity against TYK2 (tyrosine kinase 2) and JAK3, respectively. Ruxolitinib interferes with the signaling of a number of cytokines and growth factors that are important for hematopoiesis and immune function. JAK signaling involves recruitment of signal transducers and activators of transcription (STATs) to cytokine receptors, activation, and subsequent localization of STATs to the nucleus leading to modulation of gene expression. Dysregulation of the JAK/STAT pathway has been associated with several types of cancer and increased proliferation and survival of malignant cells. Methods: Newly diagnosed patients with unmethylated MGMT Glioblastoma or grade III glioma were recruited to Arm 1. Every patient received ruxolitinib and 60 Gy radiation for 6 weeks over 6 weeks (2Gy x 30). The dose of Ruxolitinib was administered given the 3+3 design. Level 1 or starting dose was 10 mg twice daily, level 2 was 15 mg twice daily, level 3 was 20 mg twice daily and level -1 was 5 mg twice daily. Arm 2 was started once safe dose was established for Arm 1 for each dose level. Patients with methylated MGMT glioblastoma or grade III glioma were eligible for Arm 2. Every patient received ruxolitinib + radiation x 60 Gy + daily temozolomide at 75 mg/m2 for 6 weeks over 6 weeks. Overall survival (OS) and progression-free survival (PFS) were estimate by Kaplan-Meier method and compared using log rank test. Results: 45 patients had survival data, 25 patients were Arm I and 20 arm II. The median OS and PFS were 18.2 (95% CI: 3.6-NA) months for Arm 1 and were not reached for Arm 2. OS and PFS Rate at 1 year was 61% (95% CI: 43-85%) and 51% (35-76%) for Arm 1, and 95% (85-100%) for Arm 2 (p = 0.01 and p = 0.002), respectively. Conclusions: Patients that received ruxolitinib + radiation x 60 Gy + daily temozolomide at 75 mg/m2 for 6 weeks over 6 weeks (Arm 2) had significantly better PFS and OS than those that received ruxolitinib + radiation x 60 Gy alone. Clinical trial information: NCT03514069