Malignant brain tumors are the first cause of death by cancer in children and adolescents. The dismal prognosis of malignant brain tumors is partially due to the existence of the blood brain barrier (BBB), a physiological barrier that limits the penetration of almost all molecules from the blood stream to the brain, including antineoplastic drugs.~It has been shown that the application of low intensity ultrasound on the brain in association with intravenous microbubbles leads to transient and safe opening of the BBB. Many preclinical studies have demonstrated that ultrasound-induced opening of the BBB increases the distribution of therapeutic molecules into the brain and allows tumor control and increases survival in animal models (mice, rabbits, pigs, primates).~An innovative implantable ultrasound system, the SonoCloud device, has been developed in order to repeatedly open the BBB in synchronization with chemotherapy protocols.~This intracranial and subcutaneous device is not visible and MRI compatible and allows repeatable and ambulatory treatments. Moreover, such a device allows the delivery of low intensity ultrasound in a controlled and reproductible manner.~A phase I/IIa trial has confirmed the feasibility and safety of this technique in adult patients treated for recurrent glioblastoma with carboplatin-based chemotherapy.~This study will assess the feasibility and safety of ultrasound-induced opening of the BBB with the SonoCloud device in pediatric patients treated with carboplatin chemotherapy for a recurrent supra-tentorial malignant brain tumor. The study will determine the maximum tolerated ultrasound acoustic pressure that can be used for BBB opening and the safety of the activation of 3, then 9 transducers with the SonoCloud-9® device. Patients will follow 6 months cycles of treatment. If the treatment is well tolerated, patients will be able to be treated for 6 more cycles.~The magnitude and intensity of the BBB opening, its clinical (overall survival) and radiological (progression-free survival) efficacy will be assessed as secondary endpoints. Safety of the ultrasound contrast agent SonoVue will also be evaluated in this indication in the pediatric population.~An ancillary study will assess circulating tumor DNA (ctDNA) concentrations in patients with recurrence of a supra-tentorial malignant brain tumor, at diagnosis and during repeated opening of the BBB. The study will assess the correlation between ctDNA concentrations and tumor evolution.
Purpose : the aim of this study is to assess the feasibility and safety of ultrasound-induced opening of the blood-brain barrier (BBB) with the SonoCloud-9 implantable ultrasound device in pediatric patients treated for a recurrent malignant supra-tentorial brain tumor treated with carboplatin.~Study hypothesis : the blood-brain barrier can be transiently and safely opened with pulsed low intensity ultrasound immediately prior to intravenously delivered chemotherapy. The opening of the BBB with the SonoCloud-9 system will increase the tumor exposure to carboplatin and increase progression-free and overall survival in pediatric patients treated for a recurrent malignant supra-tentorial brain tumor.