Myalgia Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

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.