Background/Purpose: Belimumab (BEL) is an anti-BLyS monoclonal antibody approved for SLE treatment. As few data about BEL use with regard to pregnancy are available, the aim of this study is to describe pregnancies exposed to BEL either preconceptionally or during pregnancy.

Methods: Data of prospectively-followed pregnancies (2014-2021) in SLE patients treated with BEL in 6 Italian centers where retrospectively collected, focusing on disease activity and outcome. Continuous data were reported as median (interquartile range).

Results: Twenty-one pregnancies in 21 SLE patients were collected (median age at conception: 34 [31-38] years; 13 in primigravidae (62%); 16 planned (76%); 18 spontaneous (86%)).

BEL (14 intravenous, 7 subcutaneous) was stopped in 3 cases preconceptionally, in 9 at positive pregnancy test and in 9 during pregnancy (4 during the 1^st trimester, 3 during the 2^nd trimester and 2 during the 3^rd trimester) (Table 1). The use of BEL during pregnancy had been agreed with the patient during preconception counselling.

Other treatments during pregnancy were: prednisone (90%); antimalarials (81%); azathioprine (48%); calcineurin-inhibitors (29%); low-dose acetylsalicylic acid (86%); low molecular weight heparin (57%).

At preconception visit, the median SLEDAI was 4 [2-4].

Three pregnancies had a flare (1 during the 2^nd and the 3^rd trimester; 2 during the 3^rd trimester), all in patients who withdrew BEL at positive pregnancy test.

Live-births were 86%.

Two miscarriages (at 7^th and 11^th week) and 1 intrauterine fetal death (at 37^th week; 21-trisomy with atrio-ventricular defect) occurred. One perinatal death occurred (in a patient with thrombotic+obstetric APS and lupus nephritis who underwent heterologous assisted reproductive technology -embryodonation- and developed eclampsia with cerebral haemorrage at 25^thweek; an urgent cesarean section was performed and the newborn died after 3 days).

Two pre-eclampsia were registered: 1 at 38^th week in a patient with history of lupus nephritis, double aPL positivity and active disease and 1 at 33^th week in a patient with cardiovascular risk factors (hypertension, obesity, cigarette smoke) and a history of pre-eclampsia in a previous pregnancy.

Four newborns were hospitalized in Intensive Care Unit (1 milk protein intolerance; 1 desaturation; 2 prematurity). One urine infection with sepsis occurred at 2 months in a baby with calico-pyelic and ureteral dilatation at birth (pre-term birth).

Eleven newborns received vaccinations according to national schedule (7 missing data).

Conclusion: In this case series, the use of BEL during pregnancy was discussed with some patients with a severe disease phenotype and at high risk of having a flare during pregnancy, in order to favor disease remission. While more data are needed, the timing of discontinuation should be individualized according to the single patient’s characteristics and preferences, with a risk-benefit evaluation.

« Back to ACR Convergence 2022

ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-use-of-belimumab-before-and-during-pregnancy-in-patients-with-systemic-lupus-erythematosus-an-italian-multicenter-case-series/