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Study design of the phase II PHOEBUS trial of MaaT013

Jan 25, 2024
Learning objective: After reading this article, learners will be able to cite a new clinical development in graft-versus-host disease.

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MaaT033 is a fecal microbiota product produced from pooled allogeneic human material. The GvHD Hub has previously reported on MaaT013 for gastrointestinal and steroid-refractory graft-versus-host disease. Previous studies have suggested that use of fecal microbiota therapy could improve outcomes, such as overall survival after an allogeneic hematopoietic stem cell transplant.1

At the 65th American Society of Hematology (ASH) Annual Meeting and Exposition, Florent Malard presented the planned study design and methods of the phase II PHOEBUS trial (NCT05762211) of MaaT013 in patients ≥50 years with hematologic malignancies undergoing allogeneic hematopoietic stem cell transplant.

Inclusion criteria1

Figure 1 outlines the key inclusion criteria of the PHOEBUS trial.

Figure 1. Key inclusion criteria

Study design1

  • The primary objective is overall survival at 12 months
  • Secondary objectives include quality of life, safety, and incidence of graft-versus-host disease
  • Patients will receive three MaaT013 or placebo capsules per day for 7 days before initiation of the conditioning regimen (between Day −21 and Day −7)
  • Patients will have monthly follow-ups until Month 6, and then every 3 months until Month 12

Key facts1

Figure 2. Key facts about the PHOEBUS trial* 

*Data from Malard.1 Created with

This trial is still ongoing and the first results are expected later in 2024.

  1. Malard F. A multicentre, randomized, double-blinded, phase 2b study evaluating the efficacy and safety of MaaT033, an oral, pooled microbiome ecosystem therapy in patients undergoing allogenic hematopoietic cell transplantation to improve overall survival: the Phoebus trial. Poster #4947. American Society of Hematology Annual Meeting and Exposition; Dec 11, 2023; San Diego, US.

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