Leo Cancer Care and Mevion Medical Systems Partnership Drives Momentum for Upright Proton Therapy

Leo Cancer Care and Mevion Medical Systems have achieved multiple milestones since their 2022 collaboration, with recent developments bringing them closer to the first treatment using the ultra-compact proton therapy solution.

By combining the world’s smallest proton accelerator by Mevion with Leo Cancer Care’s Marie upright patient positioning system and in-room CT scanner, the companies developed the Mevion S250-FIT™. This innovative system fixes the accelerator on the ground while the patient gently rotates in front of the beam, allowing radiation to be delivered from multiple angles without the need for a large rotating gantry. Aiming to bring this much needed treatment option to those that need it most.

Proton therapy is increasingly recognized for its precision and potential to reduce side effects across multiple cancer types. However, widespread access has long been limited by the size, complexity, and cost of conventional gantry-based systems. The Mevion S250-FIT addresses these barriers, offering a solution that fits inside of a conventional LINAC vault and a more affordable path to proton therapy.

Since the partnership began in 2022, developments have moved quickly. The first system integration was completed in 2023, followed by the installation of the first unit at Stanford Medicine Cancer Center in January 2025. Both Mevion and Leo Cancer Care have since received FDA 510(k) clearance for their respective technologies.

Momentum is growing, with Stanford Medicine Cancer Center in Palo Alto having already installed the solution, and BayCare in Tampa, Atlantic Health System in New Jersey, and Nebraska Medicine among the first centers committed to installing the S250-FIT. Many of these organizations would have previously faced challenges adopting proton therapy due to space or cost constraints, underscoring the new opportunities this compact solution provides.

At ASTRO 2025 in San Francisco, Mevion announced new clinical partners, welcoming Loma Linda University Health to the growing community of those adopting the solution.

For the first time at ASTRO, Mevion and Leo Cancer Care showcased a full-scale demonstration system, giving attendees the chance to experience an upright setup first-hand. With so much progress realized in just a few short years, ASTRO 2025 marked a milestone moment, a true coming of age for this pioneering partnership in proton therapy.