Why We’re Developing a Ricin Antidote

SERB Pharmaceuticals •

Last week German authorities foiled a plot to deploy cyanide and ricin in a potential terrorist attack, underscoring the longstanding threat that readily-available chemicals and toxins pose to civilian populations and political targets alike.

Ricin is a poison that can kill a person in as little as 36 hours, and yet the castor beans that contain it can be found in dozens of states, including in parks, fields and natural areas. Despite how potent and available this toxin is, there are no government-approved therapies for ricin exposure. That’s why SERB Pharmaceuticals, an expert in medical countermeasures, is working to develop a novel treatment for ricin poisoning.

By leveraging a modified form of ricin toxin and our expertise in polyclonal antibody development —gained through the acquisition of BTG Specialty Pharmaceuticals—we’ll be able to answer the growing call for an antidote to one of the world’s deadliest poisons. Here’s why finding a treatment is so crucial, especially during the current period of geopolitical upheaval, and how we plan to help governments, health agencies, and healthcare providers to respond.

Why We Need a Ricin Antidote Today

Bioterrorism attacks are increasing

If you’re familiar with history (or watch a lot of television), then you’re likely aware that ricin has been used for political assassinations—namely because it’s difficult to detect in victims’ bodies.

Perhaps one of the most famous examples of its use is the 1978 assassination of Bulgarian writer Georgi Markov, who was poisoned with a pellet launched from a specially outfitted umbrella while walking across Waterloo bridge in London. Since then, ricin has been developed and deployed with increasing frequency.

In the last decade, several ricin attacks in Europe and the United States made national headlines. In 2018, German police prevented a terrorist group with ties to the Islamic State (ISIL) from launching a ricin attack. Two years later, a package of letters addressed to President Donald Trump that contained ricin made its way to the White House.

Even before the incident in Germany, the war in Ukraine had raised the fear of major chemical or biological attack, spurring governments and health organizations to stockpile various antidotes to poisons used in chemical warfare.

Ricin can often be a death sentence

Ricin is one of the most toxic biological agents known; it’s classified as a Category B bioterrorism agent and a Schedule 1 chemical warfare agent. Humans only need ingest 10 micrograms to experience symptoms of toxicity, and that dosage threshold drops even lower if the ricin is inhaled or injected. What’s more, those symptoms often include severe vomiting, gastroenteritis and inflammation, and multiple organ failure. An estimated lethal oral dose in humans is approximately 1 milligram per kilogram—an amount small enough to fit in the palm of your hand.

Yet there are no prophylactic or post-exposure therapies for ricin toxin exposure that have FDA approval, and a very limited number of candidates under development.

Ricin is easy to procure and weaponize

Ricin is produced in the seeds of the castor plant (Ricinus communis), which can be ordered online, and is common enough that it  be found growing in highway medians. Since the toxin can easily be extracted from locally grown plants and weaponized at home, ricin has been adopted by would-be militants without a chemistry or pharmaceutical background. Its ability to be deployed as a powder, a mist, a pellet, or a liquid has resulted in many attempts to poison through the mail.

Our Approach

By relying on the same polyclonal platform used to develop and manufacture two of our commercially available products, SERB is uniquely positioned to develop a treatment for ricin poisoning.

We have developed a unique global manufacturing platform for the creation of broad-spectrum polyclonal antibodies. By separating the binding end of the fragment antibody, or Fab, from the rest of the antibody, known as the Fc (fragment crystallizable) region, we can potentially minimize unwanted effects on the immune system1. SERB is one of the few companies that can manufacture polyclonal antibodies at a commercial scale and with robust processes suitable for market authorisations in all territories.

We plan to leverage this technology to develop antibodies against a special antigen form of the ricin toxin. The process is scalable and can be fitted to our existing GMP manufacturing platform which is currently used to manufacture CroFab and DigiFab, FDA approved products produced for the last 20 years.

Looking Ahead

Having generated encouraging in vitro data for our ricin antibodies, in vivo studies are now underway to further assess the efficacy and safety of these antibodies. Our existing know-how in antibody development and commercial-stage manufacturing give us an opportunity to close a significant gap in the field of biodefense and medical countermeasures. By doing so, we aim to reaffirm our role as global leaders in the market for protection from chemical, biological, radiological and nuclear (CBRN) exposure.

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1 Bates A, Power CA. David vs. Goliath: The Structure, Function, and Clinical Prospects of Antibody Fragments. Antibodies. 2019; 8(2):28. https://doi.org/10.3390/antib8020028.

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