Kaleido Biosciences, Inc. announced that completion of enrollment of 350 subjects in the controlled clinical study K031 evaluating Microbiome Metabolic Therapy (MMT™) candidate KB109 in the treatment of mild-to-moderate COVID-19. The multi-center, non-IND clinical study is designed to evaluate the effects of KB109 plus supportive self-care (SSC) compared to SSC alone for outpatients who are positive for SARs-Cov-2 and have symptoms. Study endpoints include safety and tolerability, biomarkers of the inflammatory response, and time to resolution of symptoms. The Kaleido KB109 development program involves two controlled, non-IND clinical studies including one study of 350 patients evaluating symptom resolution and one study of approximately 50 patients evaluating effects on microbiome composition and biomarkers of inflammatory response. Subjects are randomized to either receive SSC (the control group) or SSC plus KB109 for two weeks and then followed for a further three weeks. KB109 was selected for evaluation in COVID-19 studies based on its ability to increase microbiome production of short chain fatty acids, which act as modulators of the immune response.