Once antibiotic-resistant bacteria become established within the gut microbiota, they can cause infections in the host and be transmitted to other people and the environment. Currently, there are no effective modalities for decreasing or preventing colonization by antibiotic-resistant bacteria. Intestinal microbiota restoration can prevent Clostridioides difficile infection (CDI) recurrences. Another potential application of microbiota restoration is suppression of non-C. difficile multidrug-resistant bacteria and overall decrease in the abundance of antibiotic resistance genes (the resistome) within the gut microbiota. This study characterizes the effects of RBX2660, a microbiota-based investigational therapeutic, on the composition and abundance of the gut microbiota and resistome, as well as multidrug-resistant organism carriage, after delivery to patients suffering from recurrent CDI.
An open-label, multi-center clinical trial in 11 centers in the USA for the safety and efficacy of RBX2660 on recurrent CDI was conducted. Fecal specimens from 29 of these subjects with recurrent CDI who received either one (N = 16) or two doses of RBX2660 (N = 13) were analyzed secondarily. Stool samples were collected prior to and at intervals up to 6 months post-therapy and analyzed in three ways: (1) 16S rRNA gene sequencing for microbiota taxonomic composition, (2) whole metagenome shotgun sequencing for functional pathways and antibiotic resistome content, and (3) selective and differential bacterial culturing followed by isolate genome sequencing to longitudinally track multidrug-resistant organisms.
Successful prevention of CDI recurrence with RBX2660 correlated with taxonomic convergence of patient microbiota to the donor microbiota as measured by weighted UniFrac distance. RBX2660 dramatically reduced the abundance of antibiotic-resistant Enterobacteriaceae in the 2 months after administration. Fecal antibiotic resistance gene carriage decreased in direct relationship to the degree to which donor microbiota engrafted.
Microbiota-based therapeutics reduce resistance gene abundance and resistant organisms in the recipient gut microbiome. This approach could potentially reduce the risk of infections caused by resistant organisms within the patient and the transfer of resistance genes or pathogens to others.
ClinicalTrials.gov, NCT01925417; registered on August 19, 2013.
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This is a promising approach to managing CDI. Completion of a Phase 3 study, with positive results, is exciting and holds much promise for patients suffering with recurrent C. diff. infections.
We look forward to the final results and are truly grateful.
Rebiotix and Ferring announce world’s first with positive preliminary pivotal Phase 3 data for investigational microbiome-based therapy RBX2660
Rebiotix and Ferring are the first to announce positive preliminary results on primary
efficacy endpoint from ongoing pivotal Phase 3 clinical trial for RBX2660
RBX2660 is an investigational, non-antibiotic, microbiome-based therapy, developed to
reduce Clostridiodes difficile (C. diff) infection recurrences
The CDC defines C. diff as a major burden to patients and doctors and an urgent healthcare
threat causing an estimated half a million illnesses and thousands of deaths annually in the
US alone ( 1 , 2)
Source: Press Release
Roseville, Minnesota and Saint-Prex, Switzerland – 6 May, 2020, 07:00 EST –
Today, . These preliminary positive efficacy findings mark an important milestone, advancing RBX2660 in its clinical development program with a goal of bringing a US FDA approved therapy to patients. The clinical development program for RBX2660 is the most advanced in the world in evaluating the safety and efficacy of a standardized, non-antibiotic microbiome-based therapy.
RBX2660 is being developed to reduce C. diffinfection recurrences, an urgent unmet need for
patients and healthcare providers worldwide. Antibiotics, the current standard of care, have been shown to disrupt the microbiome and increase the risk of C. diff recurrence. 3
C. diff causes nearly 30,000 deaths each year in the US; in Europe, the incidence of C. diff is increasing, with recurrent bouts of infection representing 10-15% of all healthcare-related infections in hospitals annually. 4 , 5
As a live biotherapeutic, aiming to help restore the gut microbiome community, RBX2660 may bring an innovative therapeutic option to patients suffering from this potentially deadly infection. “C. diff infection is a significant public health threat that has limited treatment options. These positive preliminary findings represent a major step forward towards bringing an innovative, non-antibiotic option to patients that may help restore their gut microbiome, said Per Falk, Ferring’s President and Chief Science Officer. With health systems under increasing pressure due to viruses like COVID-19 and the rising threat of antimicrobial resistance, the need for new therapies is greater than ever. We believe the power of the microbiome has great potential and we look forward to bringing RBX2660 to patients soon.”
“Since founding Rebiotix in 2011, our mission has been to harness the power of the microbiome to treat complex diseases. Our first goal was to address C. diff, which poses a significant health threat to thousands worldwide every year,” said Lee Jones, CEO and founder of Rebiotix, a Ferring company.
The positive preliminary data on the primary efficacy endpoint are a major stepping stone
for the RBX2660 development program, bringing us closer to an approved microbiome therapy
available for healthcare providers to help patients. As a first-in-class, potentially paradigm-changing technology, we look forward to discussing our final data with the FDA in the latter part of this year.” The ongoing Phase 3 trial is a randomized, multicenter, double-blinded, placebo-controlled study. The trial also incorporates a safety assessment intended to follow patients for several months after receiving the investigational drug. The safety data will provide insight into the potential of using microbes as a therapeutic intervention. The full data package is anticipated in the second half of 2020.
This trial builds on nearly a decade of research and evaluation of the formulation, with robust clinicaland microbiome data collected over multiple controlled trials under the proprietary MRT drug platform.
About Clostridioides difficile infection (C. diff)
C. diff is a bacterium that causes diarrhea and colitis (an inflammation of the colon). 6 It is estimated to cause up to half a million illnesses in the US alone every year and is considered an urgent threat to public health by the CDC, and can lead to severe complications, including hospitalization, surgery, and death. 2 While antibiotics are the standard of care to address the infection, they are also the primary risk factor for disease recurrence. 3 Recurrence of C. diff occurs in approximately 15- 50% of patients. 7
About the microbiome
The human microbiome is a complex community of microorganisms which live on every surface of the body. The microbiome aids in the maintenance and development of the immune system,
metabolism, and other functions essential to human life. 8 The gastrointestinal tract houses the most dense and complex population of microbiota, which has an incredible influence over daily health – from aiding in food digestion to fighting disease. Clinical and scientific studies indicate antibiotics, viruses, stress and other factors can disturb the gut microbiota. This disruption, often referred to as “dysbiosis,” may have negative health impacts, and promote conditions for infections like C. dif infection to take hold. 9
Rebiotix and Ferring believe there is tremendous potential in microbiota-based therapies to address such illnesses, and are evaluating this therapeutic option through their
pioneering microbiota-based MRT drug platform, beginning with recurrent C. diff infection.
The investigational RBX2660 formulation is the first-in-class microbiota-based therapy to achieve positive preliminary Phase 3 study results. RBX2660 is being developed to help break the cycle of recurrent C. diff infection. The therapy has been granted Fast Track, Orphan, and Breakthrough Therapy designations from the US FDA. The RBX2660 ongoing pivotal Phase 3 trial, PUNCH CD3, is a randomized, multicenter, double-blinded, placebo-controlled study. For more information about the RBX2660 Phase 3 study, visit http://www.clinicaltrials.gov (NCT03244644).
About Ferring Pharmaceutical Ferring Pharmaceuticals is a research-driven, specialty biopharmaceutical group committed to helping people around the world build families and live better lives. Headquartered in Saint-Prex,Switzerland, Ferring is a leader in reproductive medicine and maternal health, and in specialty areas within gastroenterology and urology. Founded in 1950, privately-owned Ferring now employs approximately 6,500 people worldwide, has its own operating subsidiaries in nearly 60 countries and markets its products in 110 countries.Learn more at http://www.ferring.com, or connect with us on Twitter, Facebook, Instagram, LinkedIn and YouTube.
Rebiotix Inc, part of the Ferring Pharmaceuticals Group, is a late-stage clinical microbiome
company focused on harnessing the power of the human microbiome to revolutionize the treatment of challenging diseases. Rebiotix has a diverse pipeline of investigational drug products built on its pioneering microbiota-based MRT drug platform. The platform consists of investigational drug technologies designed to potentially rehabilitate the human microbiome by delivering a broad consortium of live microbes into a patient’s intestinal tract. For more information on Rebiotix and its pipeline of human microbiome-directed therapies for diverse disease states, visit http://www.rebiotix.com, or connect with us on Twitter, Facebook, LinkedIn and YouTube.
For more information, please contact
Rebiotix Inc., a Ferring Company
+1 651 705 8774 (direct)
1 Centers for Disease Control and Prevention. What Is C. Diff?17 Dec. 2018. Available at: https://www.cdc.gov/cdiff/what-is.html.
2 Centers for Disease Control and Prevention. Biggest Threats and Data, 14 Nov. 2019. Available at: https://www.cdc.gov/drugresistance/biggest-threats.html.
3 Theriot CM, Young VB. Microbial and metabolic interactions between the gastrointestinal tract and
Clostridium difficile infection. Gut Microbes. 2013;5(1):86-95. doi:10.4161/gmic.27131.
4 Lessa FC, Mu Y, Bamberg WM, et al., Burden of Clostridium difficile Infection in the United States. New
England Journal of Medicine. 2015;372(9):825-834. doi:10.1056/nejmoa1408913.
5 DRG Report 2016 Clostridium Difficile.
6 Centers for Disease Control and Prevention. Clostridiodes difficile Fact Sheet. Available at:
7 Stevens VW, Nelson RE, Schwab-Daugherty EM, et al., Comparative Effectiveness of Vancomycin and
Metronidazole for the Prevention of Recurrence and Death in Patients with Clostridium difficile Infection.
JAMA Intern Med. 2017;177(4):546–553. doi:10.1001/jamainternmed.2016.9045.
8 Mohajeri MH, Brummer RJM, Rastall RA, et al., The role of the microbiome for human health: from basic
science to clinical applications. Eur J Nutr. 2018;57(Suppl 1):1–14. doi:10.1007/s00394-018-1703-4.
9 Quigley EM. Gut bacteria in health and disease. Gastroenterol Hepatol (N Y). 2013;9(9):560–569.
Positive Topline Data from Open-Label Phase 2 Trial of RBX2660 in Recurrent Clostridium
difficile to be Presented for First Time
Rebiotix Inc., a clinical-stage microbiome company focused
on harnessing the power of the human microbiome to treat challenging diseases, today announced that three posters highlighting RBX2660 clinical and microbiome data will be featured at ID Week 2017 in San Diego, Oct. 4th to the 8th.
The posters describe clinical findings that highlight the key changes to
the human microbiome profiles of patients who received RBX2660, Rebotix’s Phase 3 drug candidate.
For the first time, researchers will discuss findings from the open-label Phase 2 trial of RBX2660 for the prevention of recurrent Clostridium difficile (C. diff.) infection. Data indicated that RBX2660 was well tolerated and achieved the primary efficacy endpoint of preventing C. diff. recurrence; patients treated with RBX2660 exhibited a treatment success rate of 78.8% compared with a historical control of 51.8% (p<0.0001, N=242). These results demonstrate a 55% reduction in recurrence for those patients treated with RBX2660 compared to the historical controls reflecting standard-of-care antibiotics today.
RBX2660 is currently being evaluated in a multinational Phase 3 clinical trial for the prevention of recurrent C. diff. Researchers will also be presenting two posters on the microbiome analyses of the Phase 2B randomized, placebo-controlled, double-blind clinical trial of RBX2660. The analyses, utilizing leading edge genomic sequencing technology to measure the patient’s microbiome, provide measurable evidence of RBX2660’s rehabilitative effect on human microbiome profiles of patients who were successfully treated with Rebiotix’s microbiota drug technology.
“The clinical potential of RBX2660 has been highlighted in multiple trials, including our recently
completed open-label Phase 2 study, and the data being presented at ID Week enables us to more fully understand RBX2660’s ability to rehabilitate a dysbiotic intestinal microbiome,” commented Lee Jones, president and CEO of Rebiotix. “These findings are important in that not only can we observe the clinical 2 effect of RB X2660, such as in the open-label Phase 2 study, but by analyzing the microbiota of RBX2660-treated patients, we can see how the microbiome changes in response to RBX2660 treatment and how those changes correlate to treatment success and to the microbiomes of healthy individuals.”
The first poster (#1863; to be presented Friday, Oct. 6th), titled RBX2660 is Safe, Superior to Antibiotic- Treated Controls for Preventing Recurrent Clostridium difficile, and May Rehabilitate Patient Microbiomes: Open Label Trial Results, reported data from an open-label Phase 2 study of RBX2660 that included 242 subjects. Data from the study indicated that RBX2660’s efficacy in preventing recurrent Clostridium difficile infection (rCDI) was higher (78.8%) than CDI-free rates in the Historical Control Group (51.8%, p<0.0001). The reduction in recurrence of C. diff between these two arms is approximately 55%. Moreover, the safety profile of RBX2660 was consistent with results from previous clinical trials, and microbiota analysis suggested that RBX2660 may rehabilitate patient microbiota as RBX2660-treated subjects’ microbiomes were significantly altered compared to baseline and more closely resembled the RBX2660 microbiome profile than at baseline (p<0.05 by Dirichlet multinomial Wald-type pairwise hypothesis test).
The second poster (#1267; to be presented Saturday, Oct, 7th), titled Successful Response to
Microbiota-Based Drug RBX2660 in Patients with Recurrent Clostridium Difficile Infection is Associated with More Pronounced Alterations in Microbiome Profile, involved an analysis of 58 patients whose stool samples were collected in the randomized Phase 2B clinical trial to determine the effect of RBX2660 on rCDI patient microbiomes. 16s RNA sequencing analyses of patients’ microbiomes indicated that RBX2660 treatment shifted the relative microbiome densities, with taxa-specific increase in Bacteroidia, Clostridia, and decrease in Gamma-proteobacteria abundance. Importantly, a larger shift from baseline microbiome was seen in responders to RBX2600 compared to non-responders, and RBX2660 treatment appears to increase microbiome diversity.
The third poster (#1870; to be presented Saturday, Oct. 7th), titled Microbiome Profile is Distinct in Patients with Successful Response to Microbiota-Based Drug RBX2660 Relative to Placebo Responders involved a sub-analysis of 57 patients who participated in the randomized Phase 2B clinical trial of RBX2660. 16s rRNA sequencing analysis was used to compare the microbiome changes from baseline of patients classified as responders to RBX2660 vs placebo. Investigators determined that RBX2660 treatment for rCDI is associated with greater changes in patient microbiomes than placebo treatment. Notably, at 7, 30 and 60 days, microbiomes from RBX2660-treated patients had high Kullback-Leibler divergence from baseline and significantly different means from baseline (p<0.001). Further, active responders trended toward higher Bacteroides and lower Gamma-proteobacteria and Bacilli after treatment, both of which are characteristic of a healthier microbiome. According to the 3 researchers, these changes are consistent with the hypothesis that RBX2660 can restore a healthier microbiome in rCDI patients.