Today, a little bit of good news. Two late-stage treatments for recurring Clostridioides difficile (C.diff) infections have shown very promising results.[i] The even better news is that these treatments involve using natural gut bacteria to combat the pathogen.
The first (RBX2660) is somewhat more invasive, as it is delivered by enema. The manufacturer, a unit of Ferring called Rebiotix, has not yet given much information about what bacteria they are using. At an online Digestive Disease Week meeting, the Rebiotix representative stated that their product is similar to, but better than, ordinarily fecal microbiota transplantation. The representative stated that because FMT is obtained from human donors and thus, varies from specimen to specimen, they are striving to create a pharmaceutical-grade product with consistent results.
RBX2660’s main phase III clinical trial involved 320 patients who were randomized (in a 2:1 ratio) to either single doses of the product or a saline solution. Patients who had a recurrence of C.diff within 8 weeks were considered failures, and were reassigned to either open-label use of this product or else, were recommended to a different treatment. 270 of the patients, who had no short-term recurrence, were followed for 6 months in total. 70.4% were treated successfully versus 58.1% of those who were given the placebo. This means that there is a 98.6% chance that the product is superior to the placebo.
A second open-label trial of this product was also reported and in this study, those with inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) were also permitted to enroll. 125 patients (out of a hopeful 500 people over time) have thus far taken part and the efficacy appears similar to the double-blind study. 74% had no recurrence of C.diff in the following 6 months.
The second treatment, produced by Seres Therapeutics, is less invasive in that it is taken orally: it is a mixture of Firmicutes bacterial spores and is currently known as SER-109. The trials of this showed similar results to RBX2660. 182 patients started the trial: after 8 weeks, 40% of those who got the placebo had had a recurrent infection, compared to only 13% of those who received SER-109. Over 24 weeks of the trial, 47% of those who received the placebo relapsed; only 21% of those who received the real product did so.
When these products will become available to the public is not clear. Considering that upwards of 3 million people a year are infected in the USA alone (with 14,000 of those people dying)[ii], better treatments are pretty desperately needed.