TheraSonic: the deeptech start-up leveraging ultrasound to cross the brain's barrier

From Alzheimer's and Parkinson's to brain tumours and rare diseases...  pathologies of the central nervous system represent one of the greatest medical challenges of our time. They all face the same limitation: 98% of known therapeutic molecules are unable to cross into the brain. "Even when a relevant target has been identified and an effective drug developed, it remains useless as long as the blood-brain barrier cannot be crossed," explains Benoît Larrat, co-founder and CEO of the start-up TheraSonic. To bridge this gap between the molecule and its target, TheraSonic is banking on a breakthrough technology.
 

From fundamental research to company creation

The story began in 2010 at NeuroSpin, on the Saclay plateau, where Benoît Larrat, then a post-doctoral fellow in the BAOBAB unit, was exploring the use of MRI-guided ultrasound for brain therapy. He gradually developed a structured research programme, and his early work led to instrumental developments and proof-of-concepts in animals, demonstrating that, under certain conditions, ultrasound can facilitate the passage of drugs across the blood-brain barrier.

Between 2017 and 2021, Benoît Larrat led a project funded by the French National Research Agency (ANR) that brought together several academic and industrial partners to design a prototype intended for human use. In 2018, he teamed up with Anthony Novell, then a CNRS research fellow at the BioMaps laboratory, and a specialist in medical acoustics, who had long been involved in the laboratory's research with NeuroSpin. In 2020, to embark on clinical trials, Benoît Larrat joined the CEA's Magellan programme. "At that stage, continuing the project required a change of scale, which only an entrepreneurial framework could provide." This maturation phase, which included a business course at HEC, focused on structuring the project, assessing the market, refining the prototype and preparing for technology transfer.

Together with Anthony Novell, he co-founded TheraSonic. Benoît Larrat then left research to become a full-time entrepreneur, while Anthony Novell continued his academic activities alongside his contribution to the deeptech's development. In December 2023, TheraSonic was officially launched. It is supported by the M2Care medtech fund, whose start-up studio model provides structuring operational guidance. The company also enjoys backing from the Gustave Roussy cancer centre, a future partner in clinical trials.
 

A robotic technology for intracranial targeting

The device is based on a mechanism that has been known for around twenty years, but remains challenging to master: the localised and temporary opening of the blood-brain barrier using focused ultrasound. Following the injection of gaseous microbubbles, already used in ultrasound as contrast agents, a low-intensity ultrasound beam causes these microbubbles to oscillate. This mechanical agitation generates stress on the walls of cerebral blood vessels, temporarily loosening the tight junctions, the protein structures that hold the endothelial cells tightly together along the inner lining of blood vessels. "The effect is both reversible and localised. It lasts only a few hours and is limited to the specific areas exposed to the ultrasound," explains Benoît Larrat.

However, to achieve this opening safely and effectively requires extremely precise targeting through the skull, a structure that varies greatly between individuals and across different regions of the brain. TheraSonic is therefore developing a system that combines digital twins and medical robotics. This enables real-time recalculation and adjustment of the beam's trajectory. This robotic module, developed at the CNRS by teams at the University of Strasbourg under the direction of Jonathan Vappou, automatically treats multiple focal points with a degree of precision unattainable by the human hand.

The first clinical indication targeted by the company involves brain metastases from breast, lung or skin cancers, which are some of the most common cancer tumours that spread to the brain. "We're also working on neurodegenerative diseases and paediatric applications in gene therapy, where there are not currently any effective treatment options."
 

A patented technology on its way to the clinic

TheraSonic is based on three families of patents originating from the CEA, filed between 2018 and 2023 under exclusive license. Backed by these innovations, the start-up now has an operational prototype and is finalising its application with the French National Agency for the Safety of Medicines and Health Products (ANSM), with a view to launching the first clinical trials at Gustave Roussy in 2026. The team plans to collect data from patients so that it can rapidly improve the device in preparation for a commercial version.

Winner of Bpifrance's i-Lab Grand Prize in 2024, TheraSonic has already raised €2.7 million and is preparing a new €5 million funding round for early 2026. It is also supported by the Paris-Saclay Cancer Cluster, which recognised its work during a paediatric cancer hackathon organised with the Imagine For Margo association, Fondation S and LifeArc. In addition, TheraSonic was voted the 2025 public favourite award at the annual day of innovative medical device start-ups hosted by the French medical technologies industry association (Syndicat National de l’Industrie des Technologies Médicales, SNITEM).
 

Local roots and international ambitions

Based between Paris and Lyon, TheraSonic is an integral part of France's health innovation ecosystem. The deeptech start-up is a member of the Villejuif Biocluster, the Paris-Saclay Cancer Cluster and French Tech Paris-Saclay. These networks provide privileged access to academic, hospital and industrial partners, facilitating contacts with pharmaceutical companies, in particular for integrating its technology into clinical trials or reviving therapeutic programmes that have previously been shelved due to a lack of efficacy. "Many molecules fail in phase 2 or 3 clinical trials because they don't sufficiently reach the brain. Our technology could give them a second chance."

Already in discussions with several leading specialist hospitals, TheraSonic is preparing for international expansion, initially prioritising Europe and North America. The company is continuing to build its team, with recruitment planned in software development, medical robotics and regulatory affairs. For Benoît Larrat, this transition to entrepreneurship is a logical next step. "It's perfectly possible to have a successful academic career and then move into entrepreneurship, provided you have the right support." Deeptech is therefore a natural progression that can unlock the full potential of research results by developing a product with a medical impact.