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.

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.

Inclusion Criteria:

• patient aged ≥ 5 years old and < 18 years old
• patient able to receive sonications and perform MRI studies without sedation
• diagnosis of supra-tentorial primary malignant brain tumor (e.g. malignant glioma, embryonal tumor including ATRT, ependymoma)
• recurrence or progression of brain tumor after at least a first line of standard treatment (multifocal tumors and metastatic disease allowed)
• indication of treatment with carboplatin, validated in multidisciplinary meeting
• Karnofsky performance scale index (patients ≥ 16 years old) or Lansky performance status (patients < 16 years old) > 50% (a patient with a performance status score altered by a motor deficit due to tumor infiltration will be allowed to be included)
• no threat of brain herniation or uncontrolled intracranial hypertension
• corticosteroids treatment ≤ 1mg/kg/day
• neutrophils > 1.5 x 109/L
• platelets > 100 x 109/L
• total bilirubin < 1.5x upper limit of normal, AST et ALT < 2.5x upper limit of normal
• serum creatinin < 1.5x upper limit of normal for the age or creatinine clairance >70mL/min/1.73m2 (EDTA method or 24h urine)
• coagulation parameters in the normal limits for age (fibrinogen, prothrombin time and activated clotting time)
• no grade 2 or more toxicity depending on the NCI-CTCAE v5.0 criteria
• no healed wound on the scalp
• covered by health insurance
• for patients of chilbearing age (15-17 years old) : a negative pregnancy test and an efficient method of birth control
• written consent signed by the patient (if possible) and his parents or legal representatives.

Exclusion Criteria:

• weight <15kg

• significant intra-tumoral bleeding (hematoma) or ipsilateral subdural effusion

• antineoplastic treatment other than carboplatin taken at the same time or stopped since less than:

  • 6 weeks for nitrosoureas
  • 1 month for temozolomide
  • 1 month for bevacizumab
  • 5 half-lives for tyrosin kinase inhibitors
  • 3 weeks for any other chemotherapy

for the first sonication session

• radiotherapy during the last 6 weeks

• any other cancer treated during the last 5 years

• any other uncontrolled disease or active infection

• any other co-morbidity that could compromise participation to the study (in the judgement of the clinical investigator)

• any anatomical particularity (skull thickness, thin skin) that could compromise a safe implantation of the device and/or compromise the quality of the treatment (in the judgement of the clinical investigator)

• implanted defibrillator/pacemaker, neurostimulator, cochlear implant, intracerebral ferromagnetic vascular clip

• any contraindication to general anesthesia

• any contraindication to MRI or known allergy to gadolinium or other MRI contrast agent/

• any contraindication to ultrasound contrast agent:

  • allergy to the active substance or any excipient
  • acute coronary syndrome or uncontrolled ischemic heart disease
  • chronic heart failure or history of acute heart failure or heart failure grade III or IV
  • treatment with dobutamine
  • severe pulmonary arterial hypertension
  • uncontrolled systemic hypertension
  • respiratory distress syndrome

• carboplartin hypersensitivity

• treatment with phenytoin or fosphenytoin

• earlier vaccination with attenuated alive vaccine

• diminished auditory acuity ≥ grade 3 on CTCAE classification

• history of thermoregulation disorder

• impossibility of a rigorous medical follow-up due to geographic, social or mental reasons

• pregnant and lactating women

• contemporaneous treatment by anticoagulant or platelet aggregation inhibiting drugs

• contemporaneous treatment possibly toxic for the central nervous system. The following treatments are excluded if taken less than 5 half-lives before the ultrasound session (unknown toxicity in case of BBB disruption) :

  • benzodiazepine (or any sedative or hypnotique drug)
  • antihistamine
  • proconvulsant drugs
  • butyrophenone, phenothiazine, or any "conventional" antipsychotic drug
  • barbiturate
  • MAO inhibitor
  • anticholinergic
  • anticoagulant

• any contemporaneous treatment that, in the judgement of the clinical investigator, could induce brain toxicity after BBB disruption