How A High-Tech Chair Could Revolutionize Cancer Radiation Therapy

^{For decades, Stanford Health Care had been trying to install a state-of-the-art proton therapy machine to add to its array of high tech cancer treatments. But try as it might, it just couldn’t find a place to put one.}

^{Proton therapy machines, which deliver targeted radiation to cancerous tumors, are massive contraptions. They typically need a facility the size of a three-story football field to accommodate them and buildout costs are similarly gargantuan: between $50 million and $100 million. Even for a prestigious institution like Stanford, the hurdles to installation were daunting, particularly given Palo Alto’s pricey real estate and lack of space for such construction.}

^{“The closest that we came was several years ago when we worked out an arrangement with the Palo Alto VA hospital that is close to us,” Stanford professor of radiation oncology Dr. Billy Loo told Forbes. “The approvals went all the way up to the top of the VA administration in Washington, but as the project proceeded month by month, the cost estimates escalated….It became totally infeasible."}

^{Three years ago, Stanford found an alternative: Startup Leo Cancer Care had developed a variation on the standard proton therapy machine design. Instead of rotating the radiation beam around a patient laying flat in a bed, it designed a chair in which a seated patient rotated around the beam. That seemingly simple change had transformative consequences. It helped trim the space required to about 1,700 square feet from more than 29,000 square feet–a more than 90% reduction. That made it significantly less expensive and easier to fit where they wanted it, even with the extensive radiation shielding proton therapy machines require.}

^{Stanford teamed up Leo Cancer Care, which makes the chair and imaging technology, with Mevion Medical Systems, which had developed a small proton accelerator, and in 2024 they started building out the new facility. Dr. Loo hopes that its use will help Stanford’s doctors treat cancers more effectively with fewer risks. “The concept is very simple, but the implementation is quite sophisticated,” Loo said. “It has a huge impact.”}

^{It’s early days for Leo Cancer Care still and this is a hard and capital-intensive business. But the West Sussex, U.K.- and Middleton, Wis.-based company, which has raised a total of $150 million at a valuation of $280 million, including a recent $40 million round led by Catalio Capital Management, is gaining traction.}

“Particularly in the early days, people said, ‘This is just a rotating chair,’ and ‘Why has nobody thought of this before?’ But often the simplest ideas are the best.”

Leo Cancer Care cofounder and CEO Stephen Towe

^{Revenue reached $11 million last year, and is expected to more than double this year. Major hospitals and health systems began signing deals for Leo’s flagship product, called Marie (after Nobel laureate Marie Curie), that combines an upright patient positioning system and a CT scanner, even before it received FDA clearance for it in July. It works in partnership with beam delivery systems supplied by Mevion, Sumitomo, Hitachi and others. The company now counts Mayo Clinic, BayCare in Florida and proton therapy pioneer Loma Linda University Health among its customers. And it now has an $85 million backlog of orders, cofounder and CEO Stephen Towe told Forbes.}

^{“Everybody in the space is looking at Leo,” said PR Yu, whose solo VC firm Yu Galaxy was one of its earliest investors. “They are revolutionizing the industry already.” Towe hopes to reach $200 million in revenue within three or four years, and said that Leo is “actively pursuing an IPO,” perhaps as early as late-2026, depending on market conditions.}

^{The number of proton therapy machines in use today is tiny: Only 46 proton centers in the U.S. today and just over 100 worldwide, Towe said, while the global need for them is closer to 2,000. Proton therapy provides greater targeting in cancer treatment, allowing patients to receive effective therapy with less damage to normal tissue and lower radiation risk, but its cost has been prohibitive.}

^{Fixed-beam systems like Leo’s cost between $17 million and $22 million, versus $30 million or more for the traditional setup, Towe said. But the bigger cost savings comes from the buildout—Leo’s chair with a smaller accelerator can fit into a large room on a single floor; they don’t need three stories to accommodate them. He figures that the average cost savings all-in is around $35 million to $40 million—and in some cases closer to $70 million. That, combined with easier installation requirements, should make them more widely available. “There is a massive global need for these,” Towe said. “We are just not getting the proton therapy to patients. The reason is 100% cost. It’s always made clinical sense, but it’s not made financial sense.”}

^{Towe, 34, got interested in radiation oncology when his dad died of bowel cancer while he was an 18-year-old college student at Keele University in England. After getting his bachelor’s degree in mathematics and physics in 2012, he spent nearly five years working for the Swedish radiation therapy firm Elekta, including leading a team that was working on combining imaging with radiotherapy for cancer treatment. It was an exciting idea in theory. But practically it was unwieldy and slow. “What we had developed was bigger, more expensive, more complicated and could treat less patients per hour,” he said. “We had fallen into the trap of let’s develop something bigger and more interesting.”}

The old way of doing things required gantries that could weigh up to 600 tons for some types of treatment. “That’s about 80 elephants worth of equipment. It’s absolutely bonkers.”

Leo Cancer Care cofounder and CEO Stephen Towe

^{The experience left him wanting to find a different solution. For proton radiation therapy, the equipment is both enormous and complex. Cancer patients lie down, either supine or prone, and enormous gantries, weighing hundreds of tons, rotate around them. A proton therapy gantry can weigh 100 to 200 while one used in another form of cancer treatment, known as carbon ion, can weigh 600 tons. “That’s about 80 elephants worth of equipment,” Towe said. “It’s absolutely bonkers.”}

^{Researchers at University of Sydney in Australia were working on an alternative, and in 2017 Towe moved there from the U.K., despite never having set foot in the country before, to join the research effort. The company soon spun out of University of Sydney with the help of Rock Mackie, an emeritus professor of medical physics and human oncology at the University of Wisconsin-Madison and serial entrepreneur.}

^{“It wasn’t much at that point. It was basically a couple of patents,” said Mackie, 70, who is now Leo’s chairman. But he’d had success founding other companies previously, and, as he recalled, “I was pretty passionate about upright.” Decades ago, doctors treated patients upright, but because CT scanners required them to lie down, that went by the wayside when that imaging technology was adopted in the 1970s and 1980s, he recalled. But Mackie felt there would be both clinical and cost advantages to sitting up.}

^{By rotating a seated patient around the beam, the machine itself could be smaller, while also being more comfortable for the person being treated. Better yet, research now shows that patients who stay upright, whether seated or standing, are easier to treat because their organs move less, allowing the treatment to be even more targeted.}

^{In 2022, McLaren Health Care, which has 12 hospitals in Michigan plus a network of ambulatory surgery centers and imaging centers, was the first to sign on with Leo Cancer Care. The health system’s efforts over the past 15 years to set up a proton therapy center had been a nightmare, as the company it worked with went bankrupt and they had to sue a major supplier, Greg Lane, chief administrator at McLaren recalled. “It got to the point where the CEO and I were sitting there going, ‘We have two options, we either throw whatever money we have to finish this thing or tell the board we’re going to write down $55 million and not finish the project,” he said. “We both looked at each other and said, ‘Hell, no, we’re going to finish this.’”}

^{The center finally opened about five years ago, and, Lane said, has become quite successful—leading them to want to expand without going through the same grueling process again. The team, which already knew Mackie, vetted Leo’s technology, and ultimately signed a deal to invest and help develop the machine. “We don’t have the Stanford brand power, but we signed the first contract with Leo,” Lane said. Today, the construction is done, and Lane hopes to begin treating patients in December.}

^{“Particularly in the early days, people said, ‘This is just a rotating chair,’ and ‘Why has nobody thought of this before?’ But often the simplest ideas are the best,” Towe said. “It now enables us to go and completely push the boundaries of new things we can add to this platform because we have simplified it fundamentally. “}