Reversal of Relapse Pattern during Pregnancy in Women Treated with Natalizumab up to Pregnancy (P2.096)

Objective: To determine MS disease activity during pregnancy in women who 1) stopped natalizumab u003e3 months prior to the last menstrual period (LMP) (n=16) or 2) stopped natalizumab during the last 3 months before the LMP (n=24) or 3) stopped natalizumab after the LMP but before the second trimester (n=91). Background: Pregnancy itself strongly reduces MS disease activity during third trimester, which might be higher in women who stopped natalizumab between 8 weeks and the LMP compared to women who received the last natalizumab after the Methods: Pregnancies were collected prospectively in the German MS and pregnancy registry nationwide, between 2007 and March 2015. Only pregnancies with delivery in the third trimester were included in this analysis. A standardized questionnaire was administered during pregnancy and postpartum. Detailed information on course of MS, pregnancy and outcome of pregnancy was obtained. Results: We analyzed 131 pregnancies, most of them (n=91) received the last natalizumab after their LMP. 50 (38[percnt]) women had 63 relapses during pregnancy (10/7,3[percnt] during first trimester; 29/22,4[percnt] during second trimester and 24/18,3[percnt] during third trimester). More women in group 1) (10/16; 62,5[percnt]) had at least one relapse during pregnancy compared to women in group 2) (11/24; 45,8[percnt]) and compared to group 3) (29/91; 31,9[percnt]) (p=0,05). Significantly more women of group 1) (4/16,25[percnt]) had a relapses during the first trimester compared to group 2) (n= 2;8,3[percnt]) and group 3) (n=3;3,3[percnt]) (p=0.002). Still 16-25[percnt] of all women experienced relapses during the third trimester (ns). Conclusions: The timing of relapse during pregnancy is tight to the discontinuation of natalizumab. Withdrawal of natalizumab u003e3 months prior to pregnancy increases the relapse risk during the first trimester. The typical relapse pattern during pregnancy is reversed in women treated with natalizumab up to pregnancy with a high proportion of women has relapses during the second and third trimester. Disclosure: Dr. Spicher has nothing to disclose. Dr. Thiel has nothing to disclose. Dr. Klaasen-Mielke has nothing to disclose. Dr. Brandau has nothing to disclose. Dr. Gold has received research support from Bayer HealthCare, Biogen Idec, Merck Serono, Novartis, and Teva Neuroscience. Dr. Hellwig has received personal compensation for activities with Bayer Schering, BiogenIdec, Merck Serono, Teva Aventis and Novartis as a speaker. Dr. Hellwig has received research support from the German Research Foundation.