Fetoscopic Endoluminal Tracheal Occlusion with Smart-TO balloon: efficacy of removal and safety

IntroductionOne of the drawbacks of fetoscopic endoluminal tracheal occlusion (FETO) for congenital diaphragmatic hernia is the need for a second invasive intervention to reestablish airway patency. The "Smart-TO" (Strasbourg University-BSMTI, France) is a new balloon for FETO, which spontaneously deflates when positioned near a strong magnetic field, e.g., generated by a magnetic resonance image (MRI) scanner. Translational experiments have demonstrated its efficacy and safety. We will now use the Smart-TO balloon for the first time in humans. Our main objective is the efficacy of prenatal deflation of the balloon by the magnetic field generated by an MRI scanner. Material and methodsThis is a phase-I study conducted in the fetal medicine units of Antoine-Beclere Hospital, France, and UZ Leuven, Belgium. Conceived in parallel, protocols were amended by the local Ethics Committees, resulting in some minor differences. This trial is a single-arm interventional feasibility study. Twenty (France) and 25 (Belgium) participants will have FETO with the Smart-TO balloon. Balloon deflation will be scheduled at 34 weeks or earlier if clinically required. The primary endpoint is the successful deflation of the Smart-TO balloon after exposure to the magnetic field of an MRI, assessed through ultrasound immediately after MRI-exposure. The secondary objective is to report on the safety of the balloon. The percentage of fetuses in whom the balloon is deflated after exposure will be calculated with its 95% confidence interval. Safety will be evaluated by reporting the nature, number, and percentage of serious unexpected or adverse reactions. ConclusionThis phase-I study may provide the first evidence of the potential to reverse the occlusion by Smart-TO and free the airways non-invasively, as well a safety data.