Initiation of Nusinersen for SMA Soon After Birth May Allow for Normal Outcomes

For infants who have spinal muscular atrophy (SMA) diagnosed shortly after birth, rapid initiation of treatment can help elicit favorable outcomes, according to researchers’ findings published in Neuromuscular Disorders.

Publishing their findings on, to their knowledge, the earliest treated infants to date, the researchers detailed the outcomes of 2 patients treated with nusinersen in the first week of life after receiving a prenatal SMA diagnosis.

“In the developed world, newborn screening programs are becoming implemented as routine. We accept this as an important health provision which is supported by the results of this report with the children’s excellent evolution,” wrote the researchers. “The treatment options for affected babies should be discussed with the family in depth, and naturally this has to be done at a very early stage, preferably not beyond the newborn period.”

The case series included a male infant who was treated with nusinersen hours after birth and a female infant treated 3 days post birth. According to the researchers, both patients have improved since treatment initiation. The female patients is now 6 years old, with normal motor and mental function, and the male patient regained deep tendon reflexes (DTRs) within 40 days after receiving 4 doses of the treatment.

Diagnosed with SMA type 1 at a gestational age of 3 months, the male infant had homozygous deletion of SMN1 gene and 2 copies of the SMN2 gene. At birth, the patient was alert and spontaneous limb movements were present, with semiflexor arms, hips abducted and legs in a partially flexed position, and normal tone. There was a notable absence of DTRs.

“The absence of DTRs is an early sign of SMA type 1 in the neonatal period, even before the manifestation of hypotonia and muscle weakness,” detailed the investigators. “After rapid approval from the health authorities locally, treatment with nusinersen was initiated at 7 hours postnatally and continued according to the drug administration protocol.”

At 3 months, the patient achieved head control, and he could sit unsupported at 7.5 months. By 10 months, his CHOP-INTEND score was 54. According to the researchers, he is continuing to achieve motor milestones at a normal pace, and at 13 months was able to walk independently. He has never been hospitalized for respiratory infection and has not had difficulties with feeding.

The female infant, who received a prenatal SMA diagnosis at 11 weeks gestation, had a deletion of exons 7 and 8 of the SMN1 gene and had 3 copies of SMN2. Three days post birth, she received nusinersen and has never missed a dosage. By 700 days, the patient achieved the maximum score of 64 on the CHOP-INTEND test and physical examination has showed no scoliosis, contractures, or deformities.

The patient is enrolled in the NURTURE trial, designed for patients with asymptomatic SMA. To date, the patient is still following trial protocol.

Reference

Ünver O, Celik T, Memisog ̆lu A, et al. The outcome of two SMA cases treated with nusinersen at seven hours and at three days of life: the earliest ever. Neuromuscul Disord. Published online June 8, 2022. doi:10.1016/j.nmd.2022.06.002