Biotech Aims For NET Gains By Targeting Neutrophil Extracellular Traps

Imagine a microscopic battlefield where your body’s first line of defense creates intricate, deadly traps. These are not science fiction, but a remarkable biological phenomenon called Neutrophil Extracellular Traps (NETs), a discovery that has turned immunology on its head.

The story begins in 2004, when scientists working at Arturo Zychlinsky’s lab at the Max Planck Institute in Berlin first observed something extraordinary happening inside neutrophils, the body’s most abundant white blood cells. These cellular defenders, once thought to simply engulf and destroy invaders, were doing something far more complex and fascinating. When faced with an infection, neutrophils would undergo a dramatic transformation, releasing a web-like structure that could capture and neutralize pathogens.

The Hidden Web

Picture a neutrophil as a microscopic warrior. Traditionally, these cells would directly attack invading bacteria. But NETs represent a more elaborate strategy – the cell essentially explodes, casting out a net made of its own genetic material and proteins. Furthermore, this net isn’t just a passive trap; it’s an active weapon loaded with antimicrobial proteins that can immobilize and destroy invading microorganisms.

But like many powerful biological mechanisms, NETs have a dark side. What evolved as a sophisticated defense strategy can become a weapon turned against the body itself. In conditions like lupus, rheumatoid arthritis and various inflammatory diseases, NETs go from being protective to destructive. They accumulate in tissues, drive inflammation and cause significant damage.

This complexity makes NETs a pharmaceutical Holy Grail target, and a challenge for drug developers. Targeting NETs is like trying to solve a multilayered puzzle while the puzzle itself is constantly changing shape.

The challenges are myriad. NETs can be triggered by multiple stimuli – inflammatory signals, bacterial infections, oxidative stress, even genetic predispositions. They form quickly, change rapidly, and interact with multiple biological systems. A drug that works in one context might completely fail in another.

Traditional pharmaceutical approaches of broad immune suppression won’t work, and completely blocking NET formation could leave the body defenseless against infections.

The NET Hunters

However, there are several biotech companies working to create a drug that can reduce harmful NET formation, preserve the body’s infection-fighting capabilities, and avoid causing broader immune system damage.

This is where companies like Neutrolis and Citryll enter the story. Neither are taking a sledgehammer approach but instead developing precision tools. Neutrolis uses an enzyme that can specifically break down NET structures, while Citryll has developed a monoclonal antibody (Mab) that can prevent NETs from forming in the first place.

Taking as third approach is the cancer-focused biotech Xenetic Biosciences, which integrates its DNase I platform with existing cancer treatments, such as CAR T cells, by degrading NETs to improve cancer therapy efficacy in solid tumors.

A group of Chinese researchers from Jilin University’s cancer center are exploring the use of nanoparticles to deliver drugs that modulate NETs, offering precise drug delivery and improved stability. Australian biotech Aculeus Therapeutics is developing small molecule inhibitors that block specific pathways involved in NET formation, thereby reducing the formation of NETs and their associated inflammatory effects.

These diverse approaches reflect the growing interest in targeting NETs to treat a variety of diseases, each with its own unique mechanism and therapeutic focus.

A Dual Approach

Under the leadership of CEO Eduardo Bravo, the Dutch biotech Citryll is advancing its dual approach to modulating the innate immune response through the development of its flagship asset, CIT-013, a precision instrument designed to interrupt inflammation at its source.

The antibody works through a dual mechanism. First, it prevents neutrophils from releasing their destructive payload. Then, it actively recruits macrophages to clear away the existing molecular debris. It’s like having both a firefighter to prevent a fire and a cleanup crew to remove the damage.

Citryll has strategically chosen two initial battlegrounds: rheumatoid arthritis and hidradenitis suppurativa. Patients with these diseases often face treatments that are almost as punishing as the disease itself, said Bravo. “We’re not just developing a drug,” he explained to In Vivo. “We’re creating hope for patients who have been told there are no good options.”

By targeting NETs without compromising other crucial neutrophil functions, first-in-class CIT-013 could become a treatment that fights disease without decimating the body’s natural defenses.

Beyond rheumatoid arthritis and hidradenitis suppurativa, Citryll sees CIT-013 as a potential blockbuster key to unlocking treatments for conditions that share a common thread – the destructive potential of unchecked inflammatory responses – such as lupus, atherosclerosis, and even Alzheimer’s disease, see therapeutic applicability below.

Recently published research has shown that the asset also inhibits the formation of eosinophil extracellular traps (EETs), web-like structures released by eosinophils, particularly against parasitic infections and in allergic reactions. EETs are mainly involved in combating parasitic infections and modulating allergic responses, while NETs are essential for trapping and killing a broader range of pathogens.

Strategic investors have also taken notice. Citryll closed an oversubscribed €85m Series B fundraise in December, co-led by Johnson & Johnson Innovation, Forbion and Novartis Venture Fund. The cash injection will “comfortably” take the company through to the CIT-013 through Phase II trials, with data expected by the end of 2026.

The recent financing round isn’t just about money – it’s a vote of confidence in a fundamentally new approach to understanding disease. The Cambridge, MA-based Neutrolis has also received this vote of confidence through a combination of venture capital and grants. The company has raised a total of $45m across several funding rounds, with notable investors including Morningside Group, Prefix Capital, and PBJ Capital.

This funding enables the company, led by CEO and CSO Toby Fox and COO Abdul Hakkim, to advance its pipeline of therapies including a lead molecule for lupus.

The Dark Side Of DNA

Neutrolis has developed a biomarker used in its clinical trials to measure the formation of NETs in the blood samples, which is absent or low in healthy subjects but elevated in conditions like COVID-19 and lupus. When applying its lead asset, these NET biomarkers drop back down to healthy subject levels which allows investigators them to confirm target engagement and the biological effect of the drug in patients.

Fox described the biomarker as an important part of Neutrolis’ workflow, which enables them to optimize the drug candidate selection in a rapid, iterative manner.

Fox and Hakkim’s scientific partnership stretches back nearly two decades, to a time when they were molecular biologists working in the laboratory of Arturo Zychlinsky. Fox had applied to work on his diploma thesis at Zychlinksy’s lab and still remembers the first phone call with his would-be mentor.

“I can still feel the telephone against my head,” he recalled to In Vivo. “I was sitting at my desk in a small town in Germany just studying for my finals, and Arturo told me he had just discovered that the neutrophil is able to release its DNA in an intact form into the extracellular space, and that the DNA then creates a molecular spider web that we termed neutrophil extracellular traps.

“This was such an iconic moment for me, because Arturo tells me that you have here an innate immune mechanism that relies not on the genetic code, but the physical properties of DNA, essentially assigning a secondary function to the most fundamental molecule in biology. That caught our attention, and I know Hakkim felt exactly the same way,” Fox explained.

Forward 20 years, and Hakkim persuaded his friend to quit his secure position in Germany to enter the struggling startup world and co-found Neutrolis to explore the “dark side of DNA,” the point at which it leaves the cell and it can exhibit pathogenic properties and functions compared to its role in coding genetic information.

To that end, Neutrolis has developed its exDNASE platform that generates human extracellular DNase enzymes, which Fox describes as “molecular scissors” that can chop down DNA and the NETs in the extracellular space. Its lead asset is an analogue of a DNase enzyme, specifically DNASE1L3, which is naturally produced by the immune system and is very precise and effective at degrading the DNA backbone of NETs with potential as a new therapeutic approach in conditions such as lupus, vasculitis and rheumatoid arthritis.

The company has now completed two clinical trials; one in healthy subjects and one in patients with hyperinflammation post-COVID infection. These trials demonstrated the safety, tolerability, and target engagement of Neutrolis’ therapy, and it is now focused on moving forward with clinical trials in lupus, both in patients with a genetic deficiency in DNASE1L3, as well as in patients with idiopathic lupus. Fox expects to report initial data from these lupus trials in the next 12-24 months.

Fox envisions a therapy that is not immunosuppressive, combinable with standard of care, and can be delivered in subcutaneous injections. “This is a great drug profile and KOLs also appreciate that we have a targeted approach that goes down to the root cause of the disease,” he said.

The ongoing research and development in this field hold significant potential for transforming the treatment of autoimmune and inflammatory diseases. By harnessing the power of NETs while mitigating their harmful effects, these advancements offer hope for more effective and less invasive therapies, ultimately improving patient outcomes and quality of life.