Safety of New Biologics (Vedolizumab and Ustekinumab) and Small Molecules (Tofacitinib) During Pregnancy: A Review

Two new biological drugs (vedolizumab and ustekinumab) and one small molecule (tofacitinib) have been recently approved for the treatment of inflammatory bowel disease. Therefore, we must be familiar with the safety of these new drugs during pregnancy and breastfeeding. In the present article, we critically review available data on the safety of new biologics (vedolizumab and ustekinumab) and small molecules (tofacitinib) during pregnancy and breastfeeding, with special focus on women with inflammatory bowel disease. Bibliographical searches (MEDLINE) up to April 2020 were performed. The timing and mechanisms of placental transfer of vedolizumab and ustekinumab are expected to be similar to anti-TNF agents. Animal studies show no evidence of adverse effects on pre- or post-natal development after administration of vedolizumab and ustekinumab. Just a few studies including patients treated with vedolizumab or ustekinumab during pregnancy have been published, reporting uneventful pregnancies in most cases. The clinical programme of both drugs and post-marketing studies showed no new safety concerns. Due to the expected safety of vedolizumab and ustekinumab during pregnancy, it may be recommended to plan the final pregnancy dose approximately 8 or 12 weeks, respectively, before the estimated date of delivery. Live vaccines should be avoided for up to a year in children exposed in utero to vedolizumab or ustekinumab unless drug elimination has been documented. Miniscule amounts of vedolizumab and ustekinumab are transferred to breast milk, so breastfeeding is probably safe. There is no evidence of adverse effect of vedolizumab or ustekinumab paternal exposure. Regarding tofacitinib, it is reasonable to assume that this molecule crosses the placenta from the beginning of pregnancy. In animal studies, tofacitinib was feticidal and teratogenic in rats and rabbits, although at exposures many times greater than the standard human dose. Reported outcomes of pregnancy cases identified from tofacitinib randomised controlled trials, post-approval and non-interventional studies, and spontaneous adverse-event reporting appear similar to those observed in the general population. Nevertheless, at present, the use of tofacitinib during pregnancy should be avoided. Although no human studies have reported outcomes of breastfeeding with small molecules such as tofacitinib, this drug is present in lactating rat milk so, at present, breastfeeding should be avoided. Pregnancy among patients with paternal exposure to tofacitinib appears to be safe. In summary, we can conclude that new biologic agents (vedolizumab and ustekinumab) and small molecules (tofacitinib) should be used during pregnancy only if the benefits to the mother outweigh the risks to the mother and unborn child.