Treatment with natalizumab during pregnancy in multiple sclerosis: The experience of implementing a clinical practice protocol (NAP-30).

BACKGROUND: Pregnancy planning in women with highly active multiple sclerosis (HAMS) who need a high-efficacy disease-modifying therapy (heDMT) currently requires a careful risk-benefit evaluation. This includes minimizing fetal drug toxicity and preventing MS reactivation. We describe our experience with natalizumab in women with HAMS and unplanned pregnancy by implementing a clinical practice protocol (NAP-30) designed to maintain the effectiveness of natalizumab during pregnancy, reduce fetal exposure and prevent complications. METHODS: This was an observational retrospective study including women with HAMS on active treatment with natalizumab who became unexpectedly pregnant in the period 2018-2021 and continued this treatment during pregnancy according to the NAP-30 protocol. MS clinical and radiological variables were analyzed before and during pregnancy and in the postpartum period, along with maternal and fetal toxicity during pregnancy and safety findings in newborns. We also describe the NAP-30 protocol, which includes the use of a bridging dose to adjust and maintain natalizumab infusions every 6 weeks during pregnancy up to week 30 and scheduled delivery at week 40. RESULTS: Six women (one in her first gestation) with a median age of 31.5 years at the onset of pregnancy (min-max: 24-37 years) were included. All were negative for anti-John Cunningham virus (JCV) antibodies and were on treatment with intravenous natalizumab 300 mg every 4 weeks. At the time of conception, three patients had received 12, 17 and 53 infusions of natalizumab, respectively, while for the remaining three patients natalizumab was their first DMT (two patients had received 6 infusions and one patient had received 3 infusions of natalizumab). All six patients received 6 doses of natalizumab during pregnancy according to the NAP-30 protocol. After delivery, all six patients restarted natalizumab every 4 weeks (median: 3 days; range: 2-4 days). No patients had relapses during pregnancy or at 6 months postpartum, nor did they develop any general health or laboratory abnormalities. The MRI scan performed at 4-6 months postpartum showed no new T2 lesions or gadolinium-enhancing lesions. No miscarriages or threatened miscarriages were reported. One of the patients underwent elective preterm delivery at week 35 after mild-to-moderate anemia was detected by fetal Doppler scan. The newborn had low birth weight (2080 g) and mild anemia, which resolved within two months with oral iron supplementation. The other infants were born with normal birth weight and showed no blood count abnormalities. After a median follow-up of 10 months, all six babies showed normal development with no complications detected. CONCLUSIONS: Based on our experience, the implementation of the NAP-30 protocol in women with HAMS and unplanned pregnancy undergoing treatment with natalizumab allows the continuation of natalizumab during pregnancy, with a very favorable clinical and radiological effectiveness and maternal-fetal safety profile during pregnancy and postpartum. Both in pregnancy with HAMS and in general, and particularly for successful implementation of the NAP-30 protocol, obstetric support and monitoring is essential for adequate pregnancy management.

Prevention of rebound effect after natalizumab withdrawal in multiple sclerosis. Study of two high-dose methylprednisolone schedules.

BACKGROUND: Natalizumab (NTZ) is a disease-modifying treatment (DMT) in multiple sclerosis (MS) whose discontinuation can produce a "rebound effect", consisting of severe clinical deterioration and/or evidence of disease reactivation on magnetic resonance imaging (MRI). OBJECTIVE: To analyze the efficacy of two treatment schedules with intravenous methylprednisolone (IVMP) administered during the washout period of natalizumab (i.e., before starting another DMT) in preventing the rebound phenomenon. METHODS: Five-year retrospective study of NTZ withdrawals after at least 24 uninterrupted doses. Two IVMP schedules were tested. In schedule 1 (3-month washout), 1, 2, and 3 g of IVMP were administered on the first, second, and third month respectively. In schedule 2 (2-month washout), 1 and 2 g of IVMP were administered on the first and second month respectively. A new DMT was started 10 days after the end of each schedule. Rebound was defined as at least one clinical relapse plus rebound activity on MRI (>5 gadolinium-enhanced lesions and a number of new/T2-enhanced and/or gadolinium-enhanced lesions greater than before initiation of NTZ) during washout or at 6 months after new DMT initiation (6M-DMT). Clinical and MRI evaluations were performed at 3, 6, 12, and 24 months after initiation of the new DMT. RESULTS: Fifty patients (68% women) were included, with a mean (SD) age of 37.76 (10.88) years and pre-NTZ annualized relapse rate (ARR) of 1.78 (1.04). During NTZ therapy, mean Expanded Disability Status Scale (EDSS) score was 3.7 (1.73) and ARR was 0.23 (0.39). The ARR (mean of both schedules) was 0.1 (0.71) during washout and 0.32 (0.84) at 6M-DMT. Rebound was observed in 10% of cases (n = 5), with no significant clinical or radiological differences (p>0.05) between the two IVMP schedules. Rebound was observed in younger patients and was associated with new MRI lesions and higher ARR at 3M-DMT and 6M-DMT respectively, with no difference in EDSS after 2 years of follow-up. Neither the ARR before NTZ initiation nor the choice of new DMT after NTZ discontinuation was associated with development of rebound effect. CONCLUSIONS: Both IVMP schedules were well tolerated during NTZ washout and rebound was observed in only 10% of cases. In our experience, administration of IVMP during NTZ washout could reduce the possibility of a rebound effect.

Clinical and radiological control of highly active relapsing-remitting multiple sclerosis with first-line natalizumab.

A 33-year-old man with gait instability, weakness of the left lower extremity, decreased visual acuity in the left eye, and urgency and urine incontinence was diagnosed of relapsing-remitting multiple sclerosis. He was treated with natalizumab (300 mg intravenously every 4 weeks) as first-line therapy, which reached at 6 months a favorable clinical evolution and dramatic radiological improvement (T2-weighted lesion load decreased by 50% and no gadolinium-enhancing T1 lesions) sustained over the course of 8 years. This clinical case shows the efficacy of natalizumab in a real-world setting and, particularly, the sustained effect of this drug in the long term as demonstrated by persistent radiological improvement. Natalizumab can be considered as the treatment of choice in relapsing-remitting multiple sclerosis forms presenting with two relapses and gadolinium-enhancing (Gd+) lesions.