Unexpected pregnancy in a patient with NMOSD after treatment with inebilizumab: a case report

Background Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune disease characterized by inflammatory demyelinating lesions affecting the optic nerve and spinal cord. As a rare condition, its clinical management—particularly in special populations such as pregnant patients—remains challenging. Inebilizumab, a B-cell-depleting biological agent used in NMOSD treatment, has demonstrated efficacy in disease control. However, no prior clinical reports have described its use in pregnant patients or the associated long-term maternal, fetal, and disease outcomes, leaving a critical gap in evidence. This case report, therefore, aims to address this knowledge deficit by presenting the first detailed account of an unexpected pregnancy in a patient receiving inebilizumab maintenance therapy, alongside the subsequent management strategies and outcomes. Case Presentation We report a female patient with anti-AQP4 ( A quaporin-4 ) antibody-positive NMOSD who experienced an unplanned pregnancy during three cycles of inebilizumab maintenance therapy. A multidisciplinary team (neurologists, obstetricians, and immunologists) collaborated to develop an individualized treatment plan. Following confirmation of pregnancy, her therapy was adjusted to low-dose methylprednisolone combined with azathioprine. During pregnancy, monitoring revealed persistently low B-cell counts, with low anti-AQP4 antibody titers in the second trimester. The patient achieved a safe delivery and promptly resumed inebilizumab post-partum. Notably, no NMOSD recurrence was observed during the pre-conception, pregnancy, or post-partum periods. Conclusions This first reported case provides novel evidence that inebilizumab-induced B-cell depletion exerts a sustained effect, contributing to stable NMOSD control throughout pregnancy and the post-partum period. It also offers pioneering clinical insights into managing biological agents in special populations such as pregnant patients, highlighting that safe treatment adjustments and favorable outcomes can be achieved through multidisciplinary collaboration. These findings fill a critical evidence gap and may inform clinical decision-making for this high-risk group.