Investigators Elucidate Outcomes and Costs in CDI

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In studies presented at the American College of Gastroenterology 2021 meeting, success was reported for RBX2660, a treatment for clostridioides difficile infection (CDI).

Investigators reported success with an investigational therapy for clostridioides difficile infection (CDI) as well as an improved understanding of health care outcomes for patients with CDI at the American College of Gastroenterology (ACG) 2021 meeting.

CDI causes severe diarrhea and colitis and is the most common health care–associated infection in the United States, affecting an estimated 462,100 individuals in 2017.

In a retrospective study of RBX2660, an investigational live microbiota-based biotherapeutic, investigators enrolled patients 18 years of age (mean 59.8) or older with recurrent CDI (rCDI).1 Most (96.8%) had been previously treated with an antibiotic (vancomycin, 81.9%).

Because trial eligibility is narrowly defined, investigators exercised “enforcement discretion” under FDA 2013 guidance for the treatment of patients nonresponsive to standard therapies.

They defined treatment success as the absence of CDI recurrence for 8 weeks or less following RBX2660 dosing.

Findings for RBX2660

Investigators said that 8 weeks after initial treatment with RBX2660, absence of CDI recurrence was noted in 82.8% of patients (53/64) in the primary safety set (PSS), which included patients not previously exposed to RBX2660.

Further, 88.7% of patients (47/53) who responded had a sustained clinical response at 6 months.

Investigators reported that for PSS patients, a single dose of RBX2660 was as efficacious as 2 doses of the same drug (83.3% vs 82.5%, respectively).

Findings for treatment emergent adverse events (TEAEs) were consistent with previous studies of RBX2660. Overall TEAEs were experienced by 62.5% of PSS patients (n = 40); and TEAEs related to RBX2660 were reported for 17.2% (n = 11).

There were 126 TEAEs reported for 32 patients (71.1%) with gastrointestinal and nonspecific inflammation; and for patients with immune-mediated autoimmune disorders, the respective numbers were 76 and 25 (59.5%).

TEAEs related to RBX2660 numbered 22 among 6 patients (13.3%) with gastrointestinal and nonspecific inflammation, and 9 among 4 patients (9.5%) with immune- mediated disorders, respectively.

“RBX2660 demonstrated safety and efficacy under real-world conditions for reduction of rCDI in adult patients,” investigators concluded. They said patients with comorbidities had comparable safety outcomes to the broader patient population.

Common comorbidities included gastroesophageal reflux disease (47.9%), irritable bowel syndrome (17.0%), gastritis (11.7%), and constipation, 8.5%.

“These results reinforce the safety and efficacy profile illustrated in 5 prior prospective studies of RBX2660, contributing to the totality of evidence of RBX2660 throughout the clinical development program,” they said.

Health Outcomes for IBD vs non-IBD


In the second study presented at ACG 2021, investigators compared health care outcomes in patients with primary CDI (pCDI) and rCDI, both with and without inflammatory bowel disease (IBD).2 They noted that IBD is a common chronic disorder that includes Crohn disease (CD) and ulcerative colitis (US).

As many as 35% of patients with pCDI will experience a recurrence, and roughly 65% of patients who have an initial recurrence will have a subsequent recurrence. There is a higher likelihood of death with rCDI, and health care resource utilization is also higher, authors of the study wrote. “Compared with pCDI, rCDI results in direct health care costs totaling over $2.8 billion annually in the United States.”

IBD leaves patients prone to CDI, and investigators said they sought to better understand the burden of CDI for patients 65 years of age or older. Their retrospective analysis employed Medicare fee-for-service claims data from 2009 to 2017 for patients with 1 or more CDI episode.

Authors of the study identified a pCDI episode as 1 or more inpatient stay with a CDI diagnosis or 1 or more outpatient claim with CDI diagnosis plus CDI treatment.

Investigators said 497,489 patients were identified with CDI, and 7.2% or 36,059 had IBD, consisting of CD (27.3%) or UC (72.7%).

Mortality was higher among patients with CDI but without IBD than for those with IBD (CD 42.9% vs 34.7%; UC 42.9% vs 40.0%).

Among patients with IBD, mortality was higher for those with pCDI (CD 37.6% and UC 44.6%) vs those with rCDI (CD 28.7%, UC 31.1%, P < .001).

For patients with pCDI and rCDI, the mean time to death was 67.1 days and 122.1 days, respectively; and for those with UC, 51.3 days and 115.6 days, also respectively.

The authors concluded that patients with CDI and IBD had lower mortality rates but higher health care resource use costs than patients without IBD. This was because of longer survival for the former group.

They hypothesized that patients with IBD are likely identified more rapidly given their higher risk, but require more resources to stabilize their condition.

They recommended that clinicians consider aggressive early treatment for patients to prevent pCDI and recurrences. “Aggressive treatment diminishes the risk of poor outcomes among the elderly Medicare population and lower costs for the growing Medicare population.”


1. Feuerstadt P, Harvey A, Bancke L. RBX2660, an investigational live microbiota-based biotherapeutic, improves outcomes of Clostidioides difficile infection in a real-world population: a retrospective study of use under enforcement discretion. Presented at ACG 2021, October 22-27. Poster 2217.

2. Feuerstadt P, Dahdal DN, Wong AC, et al. A real-world comparison of mortality, healthcare resource utilization, and cost among Medicare beneficiaries with clostridioides difficile infection (CDI) with and without inflammatory bowel disease (IBD). Presented at ACG 2021, October 22-27. Poster 2611.