MANTA and MANTA-RAy: Rationale and Design of Trials Evaluating Effects of Filgotinib on Semen Parameters in Patients with Inflammatory Diseases.

Filgotinib is a treatment for patients with ulcerative colitis and rheumatoid arthritis, and is being studied in other inflammatory diseases. Filgotinib works by blocking Janus kinase 1, an intracellular protein involved in inflammatory signalling processes. We designed the MANTA and MANTA-RAy trials with global health agencies to find out if filgotinib decreases the quality of semen in men with active inflammatory bowel disease (ulcerative colitis or Crohn's disease) (MANTA) or rheumatic disease (rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis or non-radiographic axial spondylitis) (MANTA-RAy). This paper describes the design of the two trials.Patients had normal sperm measurements and could not have had previous reproductive health issues. Nearly 250 patients were included in each trial. In both MANTA and MANTA-RAy, half of the patients were treated with 200 mg of filgotinib once a day for 13 weeks, and the other half with placebo. We determined if any patients had a decrease in number of sperm cells per millilitre (sperm concentration) by at least half after 13 weeks of treatment. We then monitored any patients who had such a decrease in sperm concentration for up to 52 weeks (while they received standard of care treatment) or until the decrease was reversed.The conclusions from the trials will be in a different paper and will be based on all the final data, including changes in sex hormones. This is the first large-scale clinical trial programme to measure the effect of a treatment on sperm in men with inflammatory bowel disease or rheumatic diseases.