Recurrence, Morbidity, Mortality in Patients With Clostridioides difficile Infection Treated With the Microbiota-Based Investigational Therapeutic RBX2660

Clostridium bacteria, computer illustration. Clostridia are spore-forming bacteria that include several human pathogenic species, C. difficile, C. tetani, C. botulinum, C. perfringens, and others. C. difficile is a normal inhabitant of the human intestine, but it can become a pathogen when antibiotics disrupt the normal intestinal flora and allow C. difficile to become established in the colon. A toxin produced by the bacteria can cause diarrhoea, abdominal pain, fever, inflammation of the colon, vomiting and dehydration. C. tetani is the causative agent of tetanus, C. botulinum causes food poisoning botulism, C. perfringens causes gas gangrene and also food poisoning. Clostridium novyi (oedematiens) causes gas gangrene and infectious necrotic hepatitis. The toxins produced by C. tetani (tetanospasmin) and C. botulinum are among the most dangerous known. Some of the clostridia species are involved in the development of bacterial vaginosis.
Researchers conducted study to determine whether a microbiota-based investigational live biotherapeutic (RBX2660) decreases the risk for recurrent Clostridioides difficile infection.

The following article is a part of conference coverage from the IDWeek 2021, being held virtually from September 29 to October 3, 2021. The team at Infectious Disease Advisor will be reporting on the latest news and research conducted by leading experts in the field. Check back for more from the IDWeek 2021.

A standardized, microbiota-based investigational live biotherapeutic, RBX2660, was found to consistently decrease the risk for recurrent Clostridioides difficile infections (rCDI), according to research presented at IDWeek, held virtually from September 29 to October 3, 2021.

In an analysis of 5 prospective clinical studies evaluating RBX2660, investigators included 3 Phase 2 trials (PUNCH CD [NCT01925417], PUNCH CD2 [NCT02299570], and PUNCH CD Open Label [NCT02589847]) and 2 Phase 3 trials (PUNCH CD3 [NCT03244644] and PUNCH CD3-OLS ad hoc analysis [NCT03931941]). A total of 629 Participants aged18 years and older who had completed standard-of-care (SOC) oral antibiotic therapy for treatment of rCDI were included in the analysis. Participants were assigned to receive either 1 or 2 doses of RBX2660 or placebo.

The primary outcome was treatment success (TS), defined as absence of rCDI at 8 weeks following treatment. Participants who responded to treatment were monitored for additional rCDI for at least 6 months after receiving the last dose of RBX2660. Participants who did not respond to treatment were administered SOC antibiotic therapy and/or additional RBX2660 and monitored for 8 weeks after the last dose of RBX2660.

RBX2660 was found to consistently decrease the risk for rCDI among participants included in the 5 trials, with TS rates ranging from 50.0% to 78.9%. Among patients who did not achieve TS with 1 dose of RBX2660, an additional dose of RBX2660 was found to further decrease the risk for rCDI during the subsequent 8 weeks of the trial period. Overall, TS rates ranged from 75.0% to 84.4%. Among participants in the CD, CD3, and CD3-OLS trials, 74.4% to 92.1% of those who received 1 dose of RBX2660 remained CDI free for 6 to 24 months.

“Initial lack of response to RBX2660 did not preclude clinical benefit of additional RBX2660 treatment,” in addition, “collectively, these data demonstrate consistency and reliability of the potential benefit of RBX2660 across an entire clinical program,” the researchers concluded.

Disclosure: Some author(s) declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of disclosures.


Bancke L, Su X. Efficacy of investigational microbiota-based live biotherapeutic RBX2660 in individuals with recurrent Clostridioides difficile infection: data from five prospective clinical studies. Presented at: IDWeek; September 29 to October 3, 2021. Poster 167.

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