The efficacy and safety of rituximab on ME/CFS symptoms after administration to patients with myalgic encephalomyelitis/chronic fatigue syndrome will be compared in an exploratory, placebo-controlled, double-blind fashion. In the subsequent secondary evaluation period, subjects who received rituximab in the primary evaluation period will receive placebo, and the timing and duration of rituximab's effect will be explored throughout the entire evaluation period. Subjects who received placebo during the primary evaluation period will receive rituximab during the secondary evaluation period to explore changes in endpoints before and after switching from placebo to rituximab in the same subjects.
Patients diagnosed with ME/CFS who meet the Canadian criteria by a physician.
Patients with a severity score of 4 or higher on the Performance Status (PS) based ME/CFS severity classification by the Ministry of Health, Labour and Welfare Research Group
Patients who are between 18 and 65 years of age at the time of obtaining written consent
Patients who can be hospitalized (hospitalized from the day before administration and discharged the day after administration) at the time of the first dose of each of the primary and secondary evaluation periods
Patients with a history of severe hypersensitivity or anaphylactic reactions to components of rituximab or products derived from mouse protein
Patients whose cardiopulmonary function is judged by the treating physician to be not maintained
Patients complaining of fatigue that does not meet the diagnostic criteria for ME/CFS
Patients found to have other medical conditions that may cause symptoms