Header Image: Bertrand Magy (left) and Max Houry (right), Co-founders of ATB Therapeutics.
When people in the future look back at 21st-century medicine, chemotherapies may strike them as archaic. These therapies use powerful chemicals to kill fast-growing cells in your body. They remain some of our best solutions for killing cancer cells but come at a steep cost to patients. People often experience harsh side effects — like nausea and hair loss — because these chemicals don’t discriminate well between the rapidly dividing cells of the tumor or the patient’s own body.
Magic Bullets
Antibody-drug conjugates (ADCs) are a modern alternative to traditional chemotherapies, with the idea initially proposed by Nobel laureate Paul Ehrlich over a century ago.
“ADCs are like magic bullets,” explains Bertrand Magy, CEO and Co-founder of ATB Therapeutics. “They use antibodies to find and bind to specific antigens on cancer cells. Once they’re locked in, ADCs deliver their cytotoxic payload — a drug which has been attached to the antibody via a chemical linker — aiming to kill the cancerous cells while sparing healthy tissue.”
“ADCs are like magic bullets… aiming to kill the cancerous cells while sparing healthy tissue.” – Bertrand Magy, ATB Therapeutics
ADCs are excellent in theory, and there are dozens of these therapies already approved or in development around the world. However, despite being one of the hottest areas in oncology, traditional ADCs have faced steep challenges in drug development.
“One of the primary issues is off-target toxicity,” says Max Houry, COO and Co-founder of ATB Therapeutics. “For example, the chemical linkers can break and release their payload too early. Another limitation is resistance. Cancer cells can learn to evade ADCs, including by expelling cytotoxins through drug-efflux pumps before they cause damage.”
Specialized Seeker Missiles
This is where ATB Therapeutics’ atbodies enter the field — weaponized antibodies, completely novel in both form and function.
Instead of the ‘antibody-linker-payload’ construction of classic ADCs, atbodies are a single, fused unit. “This means they’re not at risk of releasing their payload early, making them simultaneously safer and more effective as a therapy,” says Bertrand.
But the atbodies have another trick up their sleeve. Instead of carrying a classic chemical payload, ATB’s antibodies can be fused with a peptide, such as an enzyme, thanks to the startup’s special production method.
“The peptides provide a completely differentiated mode of action compared to classic cytotoxins,” says Max. “They kill cells by inhibiting protein production, which all cancer cells need to survive even if they’re not rapidly dividing. That means we can target cancer cells in ‘sleeper’ mode, as well as cells that are resistant to traditional chemotherapies or other ADC therapies.”
“We can target cancer cells in ‘sleeper’ mode, as well as cells that are resistant to traditional chemotherapies or other ADC therapies.” – Max Houry, ATB Therapeutics
Plants as Mini Factories
So what is this unique production method? “We call it the atbiofarm,” says Bertrand.
The atbiofarm technology uses plants as bioincubators — like miniature factories — to produce the atbodies. The company grows tobacco plants, but not the type you smoke: This is another species called Nicotiana benthamiana, which has long been employed as a model plant in research.
“The beauty of this system is its simplicity,” says Bertrand. The plants are grown in vertical farms, where each rack is dipped in a bacterial solution that transfers genetic material to the cells in the leaves.
“These cells then express the gene of interest — in our case, the fully fused atbodies. After a few weeks, we harvest the leaves and essentially make a smoothie. A quick clarification and purification process later, and our atbodies are ready to be used,” he says.
Return to the Roots
This plant-based production method was originally developed by the Belgian Professor Marc Van Montague back in the 1980s. ATB Therapeutics was founded in Marche-en-Famenne in 2018, but recently opened an R&D hub in the VIB Bio-Incubator in Ghent, where the technology originated.
“The bridge between Wallonia and Flanders is important to us,” says Max. “We’re building on a dual Belgian legacy for world-class biotech expertise in both antibodies and plants.”
“We’re building on a dual Belgian legacy for world-class biotech expertise in both antibodies and plants.” – Max Houry, ATB Therapeutics
But Seriously: Why Plants?
According to Bertrand, the atbiofarm technology solves several ADC manufacturing issues. “Classic ADC production requires a multi-step, complex process. You have to create the three different components, and then chemically conjugate the antibodies with the linkers and the payload,” he says. “There is plenty of room for things to go wrong.”
The company’s single-step plant-based method solves these problems, making it simpler, faster and cheaper to produce therapies. But the plants are also key to enabling the single unit atbody format.
“You can’t fuse antibodies with peptides in a standard system, because the enzymatic activity of the payload leads to self-intoxication,” Bertrand says. “And it simply doesn’t work in classical production systems, like mammalian or bacterial cell cultures.”
An Optimistic Mindset
The co-founders explain that the cutting-edge combination was the result of a top-down approach to innovation. “Bertrand and I met at university and decided to found a company by first looking for a gap in the market. We saw the promise and limitations of ADCs, and realized that this plant-based production was a potential way of solving a lot of issues,” says Max.
“In a way, it was our initial naïve mindset that led us to success” Bertrand adds. “We weren’t discouraged by the fact that nobody had done this before; it was a completely new approach, and we launched into it with optimism.
“Thankfully our belief was not misplaced, and we’ve since received a lot of support from investors and industry experts to turn our idea into reality.”
“In a way, it was our initial naïve mindset that led us to success. We weren’t discouraged by the fact that nobody had done this before.” – Bertrand Magy, ATB Therapeutics
A Platform Full of Potential
ATB Therapeutics has attracted a lot of attention since the company’s founding, raising a huge €54 million Series A in November 2024. The company has also attracted top talent, including the appointment of Torsten Dreier — co-founder of argenx — as Chief Development Officer and Mark Throsby — former CSO of Merus — as Executive Chair.
Usually, it’s tough for true pioneers to win early support for their innovation, but Max thinks the confidence comes down to this being a platform technology.
“It is extremely flexible,” he says. “We’ve already generated a whole portfolio of different antibodies and payloads, and thanks to the plants we can test new combinations very fast, screening for the best solutions.”
Read this article to learn about another Belgian platform technology by AstriVax Therapeutics!
ATB Therapeutics intends to use this platform for partnering with other biotech and pharmaceutical companies, as well as its own pipeline. The company currently has several assets in development, aiming to initiate clinical trials in 2028, with therapies targeting B lymphocytes in blood cancer and autoimmune disease.
“This is a powerful platform. We’re excited for both our company and partners to leverage it, to create solutions for as many patients as possible,” Bertrand concludes.
