Trial: BX004 reduces P. aeruginosa numbers with no signs of resistance

Therapy was well tolerated, with no side effects reported in Phase 1b/2a study

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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BX004, a virus-based cocktail designed to treat Pseudomonas aeruginosa infections in people with cystic fibrosis (CF), can reduce the number of bacteria in the lungs with no signs of resistance to treatment over time, a study has found.

Findings from the first part of a small Phase 1b/2a clinical study (NCT05010577) also showed BiomX’s therapy is well tolerated, with no patients discontinuing treatment or experiencing side effects related to the experimental treatment.

The trial is underway in several locations across the U.S., Europe, and Israel, and has begun enrolling participants for its Phase 2 portion. Data from that part is expected in November, the company announced in a press release.

Findings were recently shared at this year’s European Respiratory Society international congress, held September 9-13 in Milan, Italy. Urania Rappo, MD, senior director of clinical development at BiomX, presented the poster, titled “A novel treatment for chronic P. aeruginosa pulmonary infection in CF subjects – A phase 1b/2a randomized, double-blind, placebo-controlled, multicenter study to evaluate phage therapy.”

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Phage cocktail BX004 safe, seen to reduce P. aeruginosa in small trial

P. aeruginosa estimated to cause chronic infections in up to 50% of CF patients

In CF, thick mucus in the lungs can trap harmful bacteria and lead to recurrent infections that are serious and hard to treat. P. aeruginosa is a key bacteria that contributes to CF lung problems, and is estimated to cause chronic infections in about 30%-50% of people with the disease.

While antibiotics are often used to clear up infections, their overuse can cause some bacteria to develop resistance, or stop responding over time. When this happens, infections can become even harder to treat.

Bacteriophages, or phages for short, are virus that invade and replicate only inside bacterial cells, causing them to die while leaving human cells unharmed. Thus, phages may offer an alternative to antibiotics when it comes to hard-to-treat infections.

Each phage is specific to a particular species or strain of bacteria. BX004, in particular, is made of a phage cocktail that specifically binds to and destroys P. aeruginosa. 

The inhaled therapy has received fast track status from the U.S. Food and Drug Administration, which is expected to speed its development via more frequent communications with the regulatory agency.

BiomX launched the ongoing Phase 1/2 trial to investigate the safety and efficacy of BX004 in people with CF. In the first part, nine adults with a diagnosis of CF and chronic P. aeruginosa infections were randomly assigned to receive BX004 or a placebo.

Five men and two women, mean age of 29.6 years, received BX004 for seven days on top of their standard of care for CF. One man and one woman, ages 25 and 53, were given a placebo for the same period of time.

After 15 days, patients who had been treated with BX004 had a greater reduction in the number of P. aeruginosa bacteria in the lungs compared with those given a placebo.

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‘No emerging resistance to [BX004] during or after treatment’

The strains (types) of P. aeruginosa bacteria identified during screening were the exact same as those identified at the end of treatment, suggesting “no emerging resistance to [BX004] during or after treatment,” the researchers wrote.

The researchers also looked at BX004’s pharmacokinetics, or its movement into, through, and out of the body. Samples of sputum, or mucus brought up from the lungs, were collected before, during, and after treatment to check for the presence of phages.

Phages were detected in samples of sputum at all time points tested during and after treatment, but not before it had started nor in placebo-treated patients.

There were no reported side effects related to BX004, which was well tolerated, and no patients stopped taking the therapy or discontinued the trial.

Part two is now ongoing to test the safety and efficacy of BX004 in at least 24 adults with CF, who will receive the medication or a placebo for 10 days. Participants enrolled to date are similar to those who participated in part 1 — their mean age is 34.3, and about 55% are men. Nearly two-thirds (60%) are being treated with a CFTR modulator.

The trial is estimated to end in February 2024, and top-line results are expected later this year.