ExThera Medical: Drug resistance

Based in Martinez, California (US), ExThera Medical (ExThera) has developed a state-of-the-art device that filters harmful bacteria and viruses from patients’ blood in a dialysis-like circuit. This device, named Seraph, is proving to be a promising alternative for treating drug-resistant bloodstream diseases, which remain a significant health concern worldwide

A serious blood problem

Bacterial bloodstream infections are one of the top causes of death in North America and Europe, with an up to 677,000 cases estimated annually in North America and up to 1,200,000 cases in Europe. For some bloodstream diseases the mortality rate is as high as 50 percent.

In a report published earlier this year, the World Health Organisation (WHO) revealed that they had encountered high levels of antibiotic resistance to a number of serious bacterial infections across the world. The antibiotic resistance is present in both high- and low-income countries.

One factor driving antibiotic resistance is the overuse of antibiotics. A study at Bristol University found children with urinary tract infections more than 13 times as likely to have contracted drug-resistant strains if they had been given antibiotics in the previous six months.

Each of these credible, third-party reports tell a similar story: drug-resistant diseases pose a serious threat to global health. “There have been cases in China, Europe, and the United states where people have been infected by bacteria which has been resistant to all drugs,” said Dr. Keith McCrea, Chief Science Officer and Vice President of Research and Development at ExThera. “The doctors simply have little options to treat these infections effectively.”

Seraph® 100

ExThera wants to address the growing health problem of drug-resistant disease with a new and different treatment solution. The Seraph® Microbind® Affinity Blood Filter (Seraph 100), which is not currently approved for clinical use, uses a groundbreaking technology to capture and remove bacteria, viruses, toxins and pro-inflammatory cytokines from the blood.

“By quickly removing the circulating levels of pathogens and toxins in the blood, Seraph 100 should make a significant impact on drug-resistant infections along with hard-to-treat bacteremia and viremia,” says Dr. McCrea.

Since ExThera was founded in 2007 under a joint venture with a technology company at the Karolinska Institute (Stockholm), the company has focused entirely on developing the Seraph technology. They were first to report on a device-based method for removing bacteria from infected blood.

Seraph works as a filter for harmful pathogens and substances in the bloodstream. The patient’s blood flows through the device, passing over proprietary microspheres coated with molecular receptor sites. These receptor sites (on permanently-bound heparin) mimic the receptors found on human cells inside our blood vessels, which are what pathogens target when they invade the body. Confusing the biomimetic receptor sites with their human equivalents, the pathogens get captured and absorbed onto the Seraph surface, and thereby removed from the bloodstream.

The blood is continuously recycled back into the patient’s bloodstream with the blood cells still intact.

“The Seraph has been designed to be easily adapted into the clinical environment,” said Dr. McCrea. “Nephrologists were the first to use Seraph in our European clinical trial.”

There is a huge potential that Seraph will have a positive impact on many patients.
-Keith McCrea, Chief Science Officer and Vice President of Research and Development, ExThera Medical

At risk

Immunocompromised patients, such as children and the elderly, are a special target patient group for ExThera. Pediatric patients with hepatitis delta virus are faced with a 75 percent increase in mortality rate in comparison to an adult patient with the same disease. Seraph may be an alternative or complement to the toxic drugs doctors must use to treat these immunocompromised patients.

“For most pathogens, doctors still have effective antibiotics that they can use,” said Dr. McCrea. “There is usually more than one drug for treating a disease – however the toxicity issue is always a concern and release of fragments of dying bacteria may contribute to disease severity.”

“The WHO, US CDC, and European CDC all agree that we are in the post-antibiotic era, and alternative treatment options must be developed.”

There are other potential indications that may also be helped by the Seraph. Cancer mediators may also be effectively removed from circulation, to be confirmed in studies using Seraph.

“There is a huge potential that Seraph will have a positive impact on many patients,” said Dr. McCrea.

“Cancer is definitely an opportunity for us, as are chronic inflammatory diseases Bloodstream infections and sepsis are the near-term focus though.”


In their preclinical studies, ExThera scientists have found that the concentration of Carbapenem Resistant Enterobacteriaceae (CRE) bacteria in blood can be reduced by up to 99 percent in a single pass when circulating contaminated blood through the Seraph. With source control of the infection, a four-hour treatment having the blood continuously recirculating through the device could result in a >99.9 percent reduction in the concentration of bacteria in the patients’ bloodstream.

Bob Ward, CEO of ExThera, presented the results of a new prospective, non-randomized clinical trial of the safety and performance of the Seraph in early September.

“These findings from the Seraph 100 trial support our belief that the Seraph filter has the potential to change the landscape for treating bloodstream infections, impacting a significant unmet need for new treatment options,” said Ward.

In the study, patients on renal replacement therapy who developed bacteremia had the Seraph filter included in their dialysis treatment for only four hours, with regular measurement of the reduction of bacteria. This was followed by a 14-day monitoring of the patients.

All initial results indicate that the Seraph 100 was safe and effective, in addition to being compatible with commonly-used dialysis equipment and procedures. In patients with measurable bacteremia who were not responding to antibiotics, Seraph100 helped decrease the bacteria significantly. Vital signs, including heart rate and blood pressure, were all stable during the study.

“We are excited that we have completed our first clinical study in Europe and expect to publish our results soon,” said Dr. McCrea. “This will be the first time that a device has been used to treat bloodstream bacterial infections. After we obtain CE mark and FDA approval for Seraph 100, doctors will have another tool to treat infections beyond antibiotics alone.”

Intellectual Property

AWA has been ExThera’s IP partner for all European matters since the company was founded. Senior European Patent Attorney Torbjörn Presland is based at AWA’s Stockholm office and handles their European patents.

“The assignments from ExThera provide challenging work in view of the European exclusion from patentability of methods for medical treatment,” said Torbjörn.

Having their IP in check is an obvious choice for ExThera.

“Investors must see a strong patent portfolio before they are willing to invest in a small company like ExThera,” said Dr. McCrea. “Without patent protection, other companies could copy Seraph 100 without all of the significant development and regulatory costs associated with pioneering technology.”

As for the future of Seraph and ExThera, Dr. McCrea is optimistic.

“We will continue to create technology which can meet medical needs,” Dr. McCrea affirmed. “I believe Seraph 100 will make a real difference in combating drug resistance and difficult to treat infections. We hope to be on the market in Europe in Q2 2019, and are currently discussing our clinical trials with the FDA for US approval.”

ExThera Medical

For more information on ExThera Medical, please visit their website.

For their European IP matters, ExThera Medical is consulted by Torbjörn Presland at AWA’s Stockholm office.

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