RBX2660 Clinical Trials

Rebiotix has conducted several trials of the lead microbiota-based product in the MRT™ drug platform, RBX2660, for the prevention of recurrent Clostridium difficile infection. RBX2660 is currently under study in a Phase 3 clinical trial in conjunction with the US Food and Drug Administration’s Investigational New Drug application.

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  • Phase 2 prospective multi-center, open-label study with 6-month follow-up
  • Primary objective: Assess the safety of RBX2660
  • Secondary objective: Efficacy defined as no CDI recurrence at 8 weeks


  • Forty patients were enrolled at 11 centers in the US; a total of 31 patients completed 6-month follow-up.
  • Overall efficacy was 87.1% (27/31).
  • Safety: Most commonly reported AEs were mild to moderate diarrhea, flatulence, abdominal pain/cramping and constipation and were self-limiting.
  • Twenty serious AEs were reported in 7 patients; none were related to RBX2660 or its administration.


  • RBX2660 demonstrated a satisfactory safety profile in a Phase 2 study targeted at recurrent CDI which included a rigorous, independent assessment of AEs.
  • Overall efficacy of 87.1% is in line with previously reported results.

Study: PUNCH CD 2


  • Phase 2B, prospective, multi-center randomized double-blind, placebo-controlled with 2-year follow-up
  • Primary efficacy objective: Assess the efficacy of RBX2660 vs. placebo defined as no CDI recurrence at 8 weeks
  • Primary safety objective: Assess the safety of RBX2660
  • A total of 120 patients enrolled at 21 sites in the U.S. and Canada
  • Patients were randomized into 3 treatment arms


Study: PUNCH Open Label


  • Prospective, multicenter, open-label, controlled Phase 2 study
  • Primary efficacy endpoint involved a comparison of patients treated with RBX2660 to a closely matched set of antibiotic only treated historical controls through 56 days
  • 31 active treatment sites and four control sites in the U.S. and Canada.
  • 132 RBX2660 and 110 historical control subjects were included in this topline analysis


Study: PUNCH CD 3 (Currently Enrolling)


The PUNCH CD 3 study is a Phase 3 clinical study to evaluate the safety and efficacy of Rebiotix RBX2660 for the prevention of recurrent Clostridium difficile infection (CDI).

This prospective, randomized, double-blinded, placebo-controlled clinical research study is expected to enroll up to 270 patients at 60 research sites in the U.S. and Canada. Patients that meet the study requirements and choose to enroll will be randomized to received either RBX2660, an investigational new drug, or a placebo. Two out of every three study patients will receive RBX2660, and one out of every three study patients will receive the placebo study treatment (2:1 randomization). Study patients whose CDI returns within 8 weeks after blinded study treatment may be scheduled to receive an RBX2660 treatment (no placebo). The study’s primary endpoint will compare the proportion of patients with treatment success following treatment with RBX2660 to prevent recurrent CDI within 8 weeks of blinded treament as compared to placebo.

Detailed Information & Site Locations

Visit: clinicaltrials.gov.

Study Participation

Email:  studyinfo@nullrebiotix.com