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Updates on Investigational Microbiome-Directed Therapies for Recurrent C Difficile Infection From IDWeek 2021

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Teena Chopra, MD, MPH

Professor, Infectious Diseases
Wayne State University
Corporate Medical Director
Infection Prevention
Hospital Epidemiology
Detroit Medical Center
Detroit, Michigan

Teena Chopra, MD, MPH, has disclosed that she has received contracted research support from Cepheid and Ferring; has received consulting fees from Cepheid, Ferring, Merck, Pfizer, and Shionogi; and has received fees for non-CME services from AbbVie, Cepheid, Ferring, Pfizer, and Shionogi.

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Released: December 23, 2021

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According to the CDC, Clostridioides difficile (C difficile) is one of the most common causes of hospital-acquired infections. C difficile causes half a million infections per year, and recurrent C difficile infection (CDI) is particularly challenging because it is linked with a high mortality rate, corresponding with 15,000-30,000 deaths annually. Thus, it is a major and urgent threat.

Recurrent CDI also is challenging to treat. The currently available standard of care treatment options do not address the underlying problems of dysbiosis, an imbalance in the patient’s natural gut microflora. In fact, we currently treat this infection with broad-spectrum antibiotics, which can actually destroy the microbiome and lead to recurrence. To break the cycle of dysbiosis and restore the microbiome for our patients with recurrent CDI, we require therapies that are directed toward restoring the microbiome. That is why I was particularly excited to see studies of newer investigational microbiome-directed biotherapeutics at IDWeek 2021.

Investigational Microbiota-Based Live Biotherapeutic: RBX2660
RBX2660 is a novel, investigational microbiota-based live biotherapeutic designed to deliver a diverse spectrum of microbes to the gut to reduce recurrent CDI. The RBX2660 clinical program comprised 5 clinical trials (3 phase II and 2 phase III trials) that collectively enrolled 723 adults aged 18 years or older who had ≥1 recurrence after a primary episode of CDI and had completed ≥1 round of standard-of-care oral antibiotic therapy.

Across the studies, RBX2660 successfully met its primary endpoint of treatment success, defined as the absence of diarrhea due to recurrent CDI through 8 weeks post treatment. Indeed, 70.4% vs 58.1% of patients receiving RBX2660 vs placebo, respectively, achieved this endpoint, which exceeded the predefined criteria for statistical significance.

In addition, long-term treatment success was demonstrated, as most responders were free from CDI for 6 months and up to 24 months, with sustained clinical response success rates in the phase III program ranging from 82.0% to 92.1%.

Another presentation at IDWeek 2021 showed that RBX2660 was well tolerated, with most adverse events being gastrointestinal in nature, and <1% of discontinuations were due to treatment-emergent adverse events.

Overall, I am highly encouraged by these results, because this product is clearly manufactured in a consistent manner and able to show consistent results of reduced recurrent CDI within 8 weeks after treatment across 5 clinical studies.

Investigational Oral Microbiome Therapeutic: SER-109
Results were presented for another promising microbiome product for the treatment of CDI—SER-109—at IDWeek 2021.

SER-109 is novel, investigational oral microbiome therapeutic composed of purified bacterial spores developed to reduce CDI recurrence. The double-blind, randomized phase III ECOSPOR-III trial evaluated SER-109 vs placebo in 182 adults with ≥2 CDI recurrences.

Of interest, investigators found that, regardless of comorbidities, the risk of recurrence was reduced in patients with recurrent CDI receiving SER-109 (4 capsules daily for 3 days) vs patients receiving placebo. Indeed, 3.6%, 21.4%, and 10.3% of patients receiving SER-109 with 0, 1, and 2 comorbidities had recurrent CDI infection, but 31.0%, 51.6%, and 36.4% of patients receiving placebo experienced recurrent CDI infection.

Overall, a relative risk reduction of 68% was shown for recurrent CDI in patients receiving SER-109 vs placebo. Using CDiff32 (a disease-specific quality-of-life measure), investigators also showed that SER-109 was associated with better overall and mental health scores vs placebo. Finally, SER-109 was shown to have good safety, comparable with placebo.

RBX2660 and SER-109 are 2 promising therapies that, as a scientist and an ID physician, I’m really looking forward to using. It is high time to break the vicious cycle of dysbiosis in patients with recurrent CDI with a therapy that can actually help them regain the normal, healthy microbiome and prevent additional recurrences.

Your Thoughts?
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