1267. Successful Response to Microbiota-Based Drug RBX2660 in Patients with Recurrent Clostridium Difficile Infection is Associated with More Pronounced Alterations in Microbiome Profile
Session: Poster Abstract Session: C. difficile: From the Bench to Bedside
Friday, October 6, 2017
Room: Poster Hall CD
Background: Recurrent Clostridium difficile infections (rCDI) are associated with decreased diversity & altered intestinal microbiome compared to healthy patients. RBX2660, a standardized microbiota-based drug, is designed to restore microbiome diversity & composition in patients'. The effect of RBX2660 on rCDI patient microbiomes was evaluated by comparing pre- & post-treatment samples from PUNCH CD 2 - a randomized, double-blind, placebo-controlled study.

Methods: rCDIsubjects were randomized to receive blinded treatments of 2 doses of RBX2660 (Group A), 2 doses of placebo (Group B), or 1 dose each of RBX2660 & placebo (Group C), by enema 7 days apart. Subjects submitted stool samples at baseline, day 7, 30, & 60 after treatment. Stool samples from responders to RBX2660 treatment per protocol defined as the absence of CDI for 8 weeks after treatment were compared to non-responders.

Relative taxonomic abundances at the class level were determined using 16s rRNA sequencing analysis for 94 stool samples from 45 patients in Groups A & C. Relative abundance data were grouped longitudinally using Bray-Curtis dissimilarity index. Analyses were performed based on the Dirichlet-Multinomial distribution to compare group mean relative taxonomic abundances; Simpson & Shannon diversity indices were compared among groups longitudinally.

Results: Baseline patient microbiomes were similar across response groups. RBX2660 treatment shifted the relative microbiome densities with taxa-specific increase in Bacteroidia, Clostridia, and decrease in Gamma-proteobacteria abundance. A larger shift from baseline microbiome was seen in responders to RBX2600 compared to non-responders (Figure 1). Microbiome changes in responders were durable to 60 days. RBX2660 treatment increased Shannon and Simpson diversity at 7 days post-treatment in responders but not in non-responders (p<0.05).

Conclusion: RBX2660 treatment shifts patient intestinal microbiomes with greater alterations seen in those with a successful clinical outcome.

Funded by Rebiotix Inc., Roseville, MN.

Figure 1. Responders to RBX2660 have a greater change in taxa abundance from baseline relative to non-responders at 30 days. Dirichlet-Multinomial parameter pi presented as mean (95%CI).

Sahil Khanna, MBBS, MS1, Ken Blount, PhD2, Courtney Jones, BS2, Bill Shannon, PhD, MBA3 and Sharina Carter, PhD3, (1)Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, (2)Rebiotix Inc., Roseville, MN, (3)BioRankings LLC, St. Louis, MO


S. Khanna, Rebiotix, Inc.: Scientific Advisor , Consulting fee

K. Blount, Rebiotix, Inc.: Employee , Salary

C. Jones, Rebiotix, Inc.: Employee , Salary

B. Shannon, Rebiotix, Inc.: Research Contractor , Consulting fee

S. Carter, Rebiotix, Inc.: Research Contractor , Consulting fee

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