Microbiome drug gets Breakthrough Therapy status

An innovative treatment for debilitating and often deadly cases of recurrent C diff infection has been given a Breakthrough Therapy Designation by the FDA.

Developed by US biotech firm Rebiotix, RBX2660 works by restoring the balance of micro-organisms that reside in the gut, and could eventually help tens of thousands of patients affected by the condition.

Recurrent Clostridium difficile (C diff) infection is a hard-to-treat gastrointestinal (GI) infection that causes 29,000 deaths every year in the US alone.

Studies have shown that most cases of C diff infection occur after the normal micro-organisms that reside in the gut have been disrupted by antibiotic use. Restoring the balance of microbes is thought to be key to breaking the cycle of recurrence.

This is achieved by Microbiota Restoration Therapy – transplanting live, human-derived microbes into a sick person's intestinal tract. The drug builds on long-standing evidence that faecal transplants from patients with a healthy microbiome can restore balance to a patient's gut. The transplant is delivered via nasoduodenal tube, nasogastric tube or via an enema.

The company has simply refined this technique one stage further, by producing a stabilised, quality-controlled product, which is also delivered via an enema.

"The development of RBX2660 represents our commitment to harnessing the microbiome to develop therapies for debilitating and sometimes fatal disease for which there is currently no FDA-approved alternative," said Rebiotix chief executive Lee Jones.

RBX2660 has already been granted orphan drug status and fast-track status from the FDA.

Lee Jones added that the new breakthrough designation brings the company to the "cusp of delivering a revolutionary and validated treatment to patients" living with the condition.

C diff infection is characterised by severe diarrhoea, fever, and loss of appetite, and is a leading cause of hospital-acquired infection.

Currently, 20-30 per cent of patients with C diff go on to experience more than one episode of the disease, known as recurrent C diff infection. This is especially challenging to treat as there are currently no approved drugs to treat patients with two or more recurrences.

If approved and used widely, RBX2660 could also help in the wider battle against antimicrobial resistance, as C diff is frequently treated with antibiotics, despite them being involved in its development in the first place.

The Breakthrough Designation puts the privately-held company in pole position ahead of a field of competitors looking to develop new treatments based on the microbiome.

Numerous other companies are working in the microbiome field, but on different therapeutic targets. MicroBiome Therapeutics has a lead product focused on diabetes treatment, while UK-based 4D Pharma is targeting irritable bowel syndrome and paediatric Crohn's Disease.

These treatments are given orally, which patients will clearly favour over RBX2660's enema. But Rebiotix's focus on using a tried-and-trusted drug delivery approach for its novel treatment is likely to pay dividends for the company.