A Low Percentage of CD4+ Cells Can Predict Disease Reactivation after Natalizumab Discontinuation (P2.063)

Objective: to evaluate whether lymphocytes sub-population could be related to MS disease reactivation at natalizumab suspension. Background: Natalizumab is a very effective second-line treatment for active MS but its suspension can cause MS disease reactivation and rebound. At the moment the only risk factor for disease reactivation is the number of relapses before natalizumab introduction. Previously it has been suggested that low blood lymphocytes count during natalizumab treatment could be a risk factor for MS reactivation Methods: Data were retrospectively collected from one Italian MS centre. Peripheral lymphocyte subsets were analyzed by FACS in 91 MS patients before natalizumab discontinuation. Patients were treated with natalizumab for at least 6 months and monitored for at least 12 months after natalizumab discontinuation. Results: At the end of natalizumab treatment, a high percentage of CD4+ (OR 0.61) and a high CD4+/CD8+ ratio (OR 0.56) confer a low risk of disease reactivation. On the contrary, a high percentage of CD8+ cells is a risk factor for disease reactivation (OR 1.22). No correlation has been found for CD19+ and CD16+56+ cells. ROC analysis show only a significant threshold for CD4+ cells (40.5[percnt]) with an OR of 2.65 (p-value 0.034). Conclusions: Lymphocytes sub-population analysis could add important information on the risk of disease reactivation after natalizumab; in particular a low percentage of CD4 cells can predict disease reactivation. The analysis of CD4+ cells could improve our treatment approach to patients suspending natalizumab. Disclosure: Dr. Bertolotto received personal compensation from Biogen Idec, Biogen-Dompe, Merck-Serono, Farmades, Novartis, and Aventis as a speaker/consultant. Dr. Lo Re has received personal compensation for activities with Biogen as an employee. Dr. Malucchi has received personal compensation for activities with Biogen Idec, Merck Serono, Teva, and Novartis. Dr. di Sapio has received personal compensation for activities with Biogen-Dompe, Novartis, and Teva Neuroscience as a speaker and consultant and for activities with Merck-Serono, Biogen-Dompe, and Farmades as a reimbursement. Dr. Matta has received personal compensation for activities with Biogen Idec and Novartis. Dr. Malentacchi has received personal compensation for activities with Biogen as a speaker. Dr. Sperli has received personal compensation for activities with Biogen Idec and Novartis as a speaker. Dr. Oggero has received personal compensation for activities with Biogen Idec. Dr. Berchialla has nothing to disclose. Dr. Pautasso has nothing to disclose. Dr. Marco Capobianco has received personal compensation for activities with Biogen.