FOCUSED ULTRASOUND FOR TREATMENT OF CHILDREN DIAGNOSED WITH DIFFUSE MIDLINE GLIOMAS

BACKGROUND Diffuse midline glioma (DMG) is a highly aggressive and fatal brain tumor that predominantly impacts children and young adults. The infiltrative pattern and rapid growth characteristics of DMG causes a significant challenge in finding an effective treatment. Additionally, the blood-brain barrier (BBB) poses a significant challenge by restricting the passage of therapeutic drugs to tumor bed. Currently the established standard of care is radiotherapy (RT), which is transitory. Thus there is a need for improved treatment options. OBJECTIVE Focused ultrasound (FUS) is an advancing non-invasive technology that has been used to open BBB and enhance drug delivery. We hypothesize that a combination therapy of FUS with pharmacological agents will be an effective and non-invasive treatment option for children diagnosed with DMG. METHOD Syngeneic DMG murine models were used to study the combination therapy of FUS with ONC201, FUS with anti-PD1 and FUS with RT. FUS mediated BBB opening was monitored with contrast-enhanced T1-weighted MRI. FUS-mediated drug delivery was validated with western blot, assessment of ROS, and optical label imaging. Kaplan Meier analysis was used to assess survival benefits. Single cell RNA-sequencing (scRNA-Seq) analysis is being done to assess the treatment effects of FUS and RT combination therapy. RESULTS/CONCLUSION We found that FUS and ONC201 combination therapy resulted in a decrease in NDUFA12 protein (a biomarker of ONC201 response) and an increase in ROS production compared to ONC201 monotherapy. For FUS and anti-PD1 combination therapy, an increased anti-PD1 delivery to the brainstem was detected. The overall survival of mice treated with FUS and anti-PD1 combination therapy increased when compared to anti-PD1 alone. Our preliminary scRNA-Seq analysis showed that combination therapy of FUS and RT induces innate immune response compared to the untreated group. Combination therapy with focused ultrasound shows a promising outcome by increasing the efficacy of therapeutic drugs and immunotherapy.