Sonodynamic Therapy With ExAblate System in Glioblastoma Patients

Despite progress made in many cancer treatments, High-Grade Gliomas (HGG) remain an extraordinary challenge. Their aggressive and infiltrative nature, the limited efficacy and inherent risk of surgical resection combined with radiotherapy, and the difficulty in delivering anticancer drugs to the brain, make the prognosis for patients with gliomas grim. Therefore, new and less-invasive alternatives to existing procedures are needed.

Sono-Dynamic Therapy (SDT) represents an emerging approach that offers the possibility of noninvasively eradicating solid tumors in a site-directed manner. It involves the delivery of a non-toxic chemical agent that selectively accumulates into target areas and the subsequent exposure of the targeted tissue to relatively low-intensity ultrasound. These procedures (sensitization and ultrasound exposure) are both per se harmless, but, when combined, result in activation of the chemical agent and subsequent cytotoxic events limited to the target tissue volume. SDT offers significant advantages because ultrasound energy can be tightly focused and delivered through the intact skull to deep areas of the brain, depending on the frequency. SDT is achieved by focusing low-intensity and lowfrequency ultrasound, which, as opposite to high-intensity ultrasonic beams, can be focused effectively within the whole intracranial space with the currently available device ExAblate 4000, Insightec, Haifa, Israel). This would enable to target also tumors in the peripheral area of the intracranial space. 5-ALA is a PpIX (Protoporphyrin IX) precursor that selectively accumulates in HGGs because of an enhanced uptake and metabolism from tumor cells. It is used for intra-operative guidance in surgery as tumoral tissues shows an exceeding fluorescence under certain light conditions due to PpIX accumulation, as compared to the normal surrounding parenchyma. It is therefore a good candidate for SDT. 5-ALA can exert sono-dynamic effects against HGGs, as it has been shown in several preclinical studies. Pre-clinical data on a safety experiment conducted at the University of Virginia showed that SDT with 5-ALA was not exerting a toxic effect to the normal brain [Raspagliesi L. et al. 2021].

The idea of the present study is to investigate the antitumor effects of SDT in patients affected by HGGs attained with low-frequency Focused Ultrasound. Focused Ultrasound under MRI-guidance can be safely delivered through an intact human skull to perform SDT in combination with 5-ALA with a low risk of transient adverse effects, and will be evaluated during follow-up visits, postprocedural serial MRI, and histology.

The main goal of this prospective, non-randomized, single-arm study is to evaluate the safety and feasibility of SDT in patients with newly diagnosed cerebral glioblastomas using the ExAblate Model 4000 Type-2 "Neuro-System". The ExAblate Model 4000 Type-2 "Neuro-System" is intended for use as a tool to induce targeted tumor's inhibition of growth and cell destruction in patients with cerebral lobar glioblastomas.

Patients harboring newly diagnosed lobar glioblastoma according to RANO criteria will provide informed consent, will be screened, and will undergo study SDT treatment using the ExAblate Model 4000 Type-2 "Neuro-System". After SDT treatment, patients will perform a strict neuro-radiological follow-up (minimum of 2 MRI) and undergo tumor resection about 15-21 days after SDT, according to the clinical and radiological status.

The main purpose of this study is to evaluate the safety and feasibility of SDT. In particular, safety will be evaluated by patient examination and MRI during the treatment, and by follow-up by daily clinical visits and MRI every 5 (± 2) days according to clinical and radiologic findings. Safety data will be assessed during each visit through a combination of MRI evaluations, clinical assessments, and neurological examinations, according to the clinical findings assessed until the decision to proceed with surgical resection. Feasibility will be evaluated performing 4 MRI (Day 1, 5, 10, 15) after SDT treatment evaluating tumor size, morphology and perilesional edema until tumor resection.

A secondary objective of the present study is to assess the efficacy of the treatment; in particular, to investigate the antitumor effects of SDT in patients affected by HGGs attained with low-frequency

Focused Ultrasound, the following data will be collected:

• Tumor volume changes after SDT according to sonicated tumors volumes (by imaging).
• Histology after tumor resection, comprising assessment of apoptosis and necrosis.

Despite all current treatment modalities, glioblastoma patient's prognosis remains dismal. By proving that procedure is safe and feasible this study will establish the SDT treatment modality as a possible alternative or a synergistic tool to current treatment modalities. It will also pave the way to the application of SDT in other forms of brain tumors, both intra- and extra-axial, and to the development of tumor specific sono-sensitizers.

Inclusion criteria

• Men or women, age between 18 and 75 years, inclusive.
• Suspected primary lobar Glioblastoma clearly measurable on the basis of Response Assessment in Neuro-Oncology (RANO) criteria
• Newly diagnosed brain glioblastomas located in a surgically accessible brain region for resection
• The targeted tumor resection volume measures between 1 cm and 6 cm in diameter.
• Karnofsky rating 70-100.
• ASA score 1-3.
• Able to attend all study visits.
• No previous brain surgery.
• No previous radiation treatment.
• No previous systemic treatment for the tumor.
• Able and willing to give Informed Consent.
• No contraindication to MRI.
• No contraindication to brain surgery.
• Contraceptive use by both male and female subjects consistent with local regulations regarding the methods of contraception for those participating in clinical studies.

• Male participants: Male participants must agree that, if their partner is at risk of becoming pregnant, they will use an effective method of contraception. The participants must agree to use the contraception during the whole period of the study and for 12 weeks after the study intervention injection.
• Female participants: A female participant is eligible to participate if she is not pregnant or breastfeeding, and one of the following conditions applies: (i) is a woman of nonchildbearing potential (WONCBP) as defined in Appendix C Contraception and Barrier Guidance OR (ii) is a WOCBP and using an acceptable contraceptive method as described in Appendix C: Contraceptive and Barrier Guidance during the study intervention period (at a minimum until after the last dose of study intervention).

Exclusion criteria

• Brain glioblastoma presenting with the following characteristics:

• Brain edema and/or mass effect that causes midline shift of more than 15 mm
• Evidence of recent intracranial hemorrhage within the targeted tumor volume
• Calcifications in the focused ultrasound sonication path (system tools may not tailor the treatment around these calcifications)
• The sonication pathway to the tumor involves either:

• more than 30% of the skull area traversed by scars, scalp disorders (e.g., eczema), or atrophy of the scalp
• Clips, shunts, or other metallic implanted objects in the skull or the brain
• Cardiac disease or unstable hemodynamic status including:

• Documented myocardial infarction within six months of enrolment
• Unstable angina on medication
• Congestive heart failure
• Left ventricular ejection fraction < 50%
• Right-to-left, bidirectional, or transient right-to-left cardiac shunts
• History of a hemodynamically unstable cardiac arrhythmia
• Cardiac pacemaker
• Severe hypertension
• Anti-coagulant therapy or medications known to increase risk of hemorrhage within washout period prior to treatment
• History of a bleeding disorder, coagulopathy or with a history of spontaneous tumor hemorrhage
• Abnormal level of platelets (<100000) or INR >1.3
• Cerebral or systemic vasculopathy
• Known allergy sensitivity or contraindications to gadolinium
• Contraindications to MRI such as non-MRI-compatible implanted devices
• Subjects not fitting comfortably into the MRI scanner
• Difficulty lying supine and still for up to 4 hours in the MRI unit or claustrophobia
• Positive pregnancy test (for pre-menopausal women) (see Appendix C)
• Severely impaired renal function with estimated glomerular filtration rate <30mL/min/1.73m2 and/or on dialysis
• Respiratory: chronic pulmonary disorders (e.g., severe emphysema, COPD, pulmonary vasculitis, or other causes of reduced pulmonary vascular cross-sectional area).
• Other contraindications to 5-ALA, including chronic or acute porfiria, and hypersensibility to 5-ALA or porfirins
• Any illness or medical condition that in the investigator's opinion precludes participation in this study
• Patients unable to sign an Informed Consent