Regarding the past, what is the trial you have always been dreaming of in CIDP?

Chronic inflammatory demyelinating polyradiculoneuropathy is an orphan disease of poorly understood cause. While first line treatments with corticosteroids, intravenous immunoglobulin and plasma exchange have at least short-term efficacy, no trial has shown that immunosuppressants work. In our dream, we will take advantage of the recently improved EU regulations to launch a Europe wide trial which will investigate the cause of the disease. It will compare three parallel groups, the anti-B cell agent rituximab, the anti-T cell agent abatacept and usual care. The trial will not be blinded and the design will be very simple. The primary outcome measure will be improvement from baseline of the overall neuropathy limitations scale (ONLS) score by 1 or more grades at 12 weeks without increase in concomitant corticosteroids or IVIg or use of plasma exchange. There will be an option to substitute improvement in the Rasch-built overall disability scale depending on future experience with that scale as the primary outcome measure. The trial will require 3 groups of 60 participants to detect an increase from 20% in the usual care group to 30% with one of the other agents with a power of 90% and P-value of 5%. It will be larger than any trial of an immunosuppressant agent so far performed in CIDP. However, recruitment will be easier because inclusion criteria will be broad and allow randomisation of any patient in whom their neurologist wishes to introduce an immunosuppressant. Avoidance of blinding and use of simple monitoring with facetime will simplify running the trial and reduce expense. The trial will follow participants and measure outcomes at 12 months. Other outcomes will consist only of grip strength, time to walk 10 m and Euroqol, the last allowing us to estimate the cost per QALY of rituximab or abatacept. Even including central analysis of key biomarkers, the trial will only cost 3 million euros, a fraction of the cost of the usual phase III pharmaceutical company trial.