For all the excitement around next-generation antibody therapies, a surprisingly mundane biological process is proving to be a critical bottleneck: How sugar molecules are arranged on the surface of therapeutic proteins.
Paris-based Kyron.bio is betting that solving this quiet but consequential problem could unlock a new class of safer, longer-lasting biologic drugs.
The biotech startup raised €5.5 million in seed funding in May this year to scale its glyco-engineering platform, a technology that allows unprecedented control over glycans, the complex sugar structures that decorate therapeutic antibodies. The round was led by HCVC, with participation from Verve Ventures, Entrepreneur First, Saras Capital, and several business angels. The raise also coincides with the launch of Kyron’s EIC Transition project, supported by the European Innovation Council.
Glycosylation is the cellular process of attaching sugars to proteins. While it might sound esoteric, its effects are far-reaching. Glycans influence how a drug behaves in the body, how long it lasts in circulation, and critically, whether the immune system flags it as a threat.
For many antibody drugs, that flag can mean failure.
The Immunogenicity Wall
Antibody-based therapies are promising because they can bind precisely to disease targets, mobilize the immune system against tumors, and are increasingly tailored to individual patient profiles.
Yet, despite billions poured into R&D, many of these therapies stumble at the very first hurdle: Phase I clinical trials, where safety and immune tolerance are assessed.
A common culprit is immunogenicity – the patient’s immune system identifying the therapeutic molecule as foreign and attacking it. That response not only reduces drug efficacy but can cause serious adverse reactions, like autoimmune diseases, especially in chronic conditions requiring long-term treatment.
According to Dr. Emilia McLaughlin, Kyron.bio’s CEO and co-founder, Biopharma companies are designing increasingly complex therapies. But that complexity often makes the molecules more ‘visible’ to the immune system- and current manufacturing processes offer little control over the parts of the molecule that are triggering that visibility.
Those “parts” are often the glycans — sugar structures added during cell-based drug production. Glycan profiles can vary wildly, even within the same production batch, making it nearly impossible to guarantee consistency, safety, or efficacy.
Engineering Control Over Chaos
Kyron.bio’s platform aims to address this inconsistency by engineering both the cells that produce antibody therapies and the glycan structures they attach. Their technology involves:
- Proprietary tools to structurally modify antibodies, preventing the types of glycan-related immune triggers that lead to rejection or resistance.
- Genetically modified CHO (Chinese Hamster Ovary) cell lines, designed to tightly regulate the glycosylation process.
The result, according to Kyron, is a glycan structure uniformity of over 97%, a level that significantly outperforms standard bioproduction techniques.
This isn’t just about aesthetics at the molecular level. Higher uniformity allows developers to reduce immunogenicity, improve half-life, and potentially design antibodies with new functional properties, such as extended circulation time or better tissue targeting.
In short, more predictable drugs that are less likely to be rejected and more likely to work.
From Underdog to Design Lever
Glycans have long been considered a sort of necessary but frustrating biological byproduct — too variable, too complex, and too difficult to control. In many biologic drug programs, they’re treated as background noise.
That’s exactly what Kyron.bio wants to change. The startup sees glycans "not as a nuisance, but as a design parameter. Until now, developers have worked around glycosylation. Kyron.bio wants them to work with it.
“To date, glycans have been massively under-exploited, limiting their potential in drug design," McLaughlin said. "By achieving comprehensive control over glycosylation in a fully scalable manner, we have unlocked the possibility to use precision glycosylation in drug design. This transforms glycans into a design tool for the first time, opening up new treatment avenues for patients.”
This reframing mirrors larger shifts happening in the field. With the rise of bispecific antibodies, antibody-drug conjugates, and other next-gen biologics, developers are under pressure to manage an increasing number of molecular variables, while still meeting regulatory standards for consistency and safety.
That’s where Kyron.bio sees opportunity. By offering a plug-and-play glyco-engineering solution that is compatible with existing pharma manufacturing infrastructure, the startup hopes to position itself as an enabling partner for both biotech innovators and established pharmaceutical players.
A Deeptech Bet on Glycobiology
For lead investor HCVC, the appeal is not just the platform. It’s the vision.
"Kyron.bio’s technology bridges a massive gap in therapeutics design. Their breakthrough in glycan control could shift the paradigm for antibody therapies, and we’re proud to support their vision,” said Alexis Houssou, HCVC Managing Partner.
It’s also a classic deeptech story: academic insight turned industrial tool. McLaughlin’s background includes a PhD at the Institut Pasteur, where she studied rare unicellular organisms and their unusual glycosylation pathways. That research laid the groundwork for Kyron.bio’s first patents.
Now based at Paris Biotech Santé, the startup sits within a growing ecosystem of French biotech companies looking to push the frontiers of therapeutic engineering - often with limited capital and long development timelines.
The company plans to use the new funding to expand its scientific team, scale its cell line production, and begin preclinical studies to validate the platform’s impact on real drug candidates.
What’s Next?
Kyron.bio isn’t developing its own pipeline of drugs, at least not yet. The near-term goal is to license the platform or co-develop candidates with partners, particularly in oncology and autoimmunity, where immunogenicity remains a major roadblock.
Still, the broader implications may extend beyond those fields. As biologics continue to dominate drug pipelines – and glyco-engineering gains traction as a viable design tool – Kyron.bio is positioning itself at a new interface in therapeutic development: one where precision sugars could prove just as crucial as genetic code.
Whether pharma is ready to embrace glycan control as a standard feature rather than an afterthought remains to be seen. But if the company’s platform lives up to its promise, it may help turn a previously overlooked corner of cellular biology into a critical lever for drug innovation.
