Mass Balance Study of MT-1303

Inclusion Criteria: * Caucasian male aged 30 to 65 at Screening. * Body weight of ≥60 kg, and a BMI ranging from 18.0 to 32.0 kg/m2 at Screening and Day -1. * Normal or not clinically significant ECG as defined by a HR between 50 and 100 bpm inclusive at Screening, Day -1 and pre-dose. * Vital signs within the following ranges at Screening and Day -1,Body temperature: 35.0 to 37.5 °C,SBP: 90 to 140 mmHg,DBP: 50 to 90 mmHg. * Regular daily bowel movements. Exclusion Criteria: * Radiation exposure, including that from the present study, excluding background radiation but including diagnostic x-rays and other medical exposures, exceeding 5 mSv in the last 12 months or 10 mSv in the last 5 years. No occupationally exposed worker, as defined in the Ionising Radiation Regulations 1999, shall participate in the study. * Previous medical history of tuberculosis, or in the opinion of the Investigator, a recurrent medical history of cold sores, pharyngitis, urinary tract infection, diarrhoea/dysentery, chest infections or fungal infections. * Any surgical or medical condition which might significantly alter the absorption, distribution, metabolism or excretion of drugs or which may jeopardise the subject in case or participation in the study. The investigator should be guided by evidence of any of the following: * history of inflammatory bowel syndrome,gastritis, ulcers, gastrointestinal or rectal bleeding; * history of major gastrointestinal tract surgery such as gastrectomy, gastroenterostomy, or bowel resection