Tessa Brand, Suzanne C. Franken, Marie Vermeiren, Agnes van Sonderen, M. Bruijn, Yvette S. Crijnen, Juliëtte Brenner, Jeroen Kerstens, Robin W. van Steenhoven, Peter A.E. Sillevis Smitt, Sharon Veenbergen, Dave L. Roelen, Maarten J. Titulaer, Juna M. de Vries
BACKGROUND AND OBJECTIVES: Anti-contactin-associated protein-like 2 (CASPR2) disease-previously considered a subtype of anti-voltage-gated potassium channel (VGKC-complex) encephalitis-is a relatively new disease entity, and information on long-term outcomes and relapses is limited. We investigated long-term clinical outcomes and factors associated with higher relapse rates. In addition, we compared different treatment strategies. METHODS: In this nationwide observational cohort study, patients with anti-CASPR2 disease were included. Clinical data were collected at diagnosis and during follow-up, both retrospectively and prospectively. RESULTS: < 0.0005 in post-second-line treatment group; ARR 0.09 vs 0.81). DISCUSSION: The relapse rate in anti-CASPR2 disease is much higher than previously reported. In patients prone to relapse, (repeated) courses of rituximab appear to be most effective in preventing future relapses beyond acute therapy and tapering with oral steroids. Anti-VGKC-complex concentrations in serum can aid in monitoring of relapses and disease course in most of the patients. It is recommended to repeat tumor screening when patients relapse. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that, in anti-CASPR2 disease, prolonged immunotherapy is associated with reduced relapse rates.