WHY SPINRAZA? / HOW SPINRAZA WORKS

Works within the CNS, where motor neurons reside, to increase full-length SMN protein1,2

SPINRAZA® (nusinersen) is the first and only antisense oligonucleotide (ASO) for the treatment of SMA1,3-6

Designed to target a specific sequence on SMN2 pre-mRNA, SPINRAZA modifies splicing to increase exon 7 inclusion and production of full-length SMN protein1,7*

Mechanism of Action Delivered to the CNS Video Resource Download

*Based on findings from in vitro assays, transgenic animal models of SMA, and limited human postmortem data.1,8

By specifically targeting SMN2 to increase functional SMN protein, SPINRAZA works by targeting an underlying cause of CNS motor neuron loss in SMA1,2

  • SMA is a disease affecting motor neurons in the CNS, leading to progressive weakness2,9
  • Individuals with SMA have deletions or mutations in both copies of the SMN1 gene and rely only on the SMN2 gene to produce functional SMN protein2,9
  • However, the SMN2 gene by itself can only produce about 10% of the full-length, functional protein that is normally produced by SMN1 gene2,9
  • SPINRAZA is an ASO designed to target a specific sequence on the SMN2 gene pre-mRNA1
  • SPINRAZA binds to a sequence in the intron downstream of exon 7 in the SMN2 transcript to modify splicing1
  • Increasing exon 7 inclusion in SMN2 mRNA transcripts results in increased production of full-length SMN protein1

CNS, central nervous system; mRNA, messenger ribonucleic acid; SMA, spinal muscular atrophy; SMN, survival motor neuron; SMN1, survival motor neuron 1; SMN2, survival motor neuron 2.

As an ASO, SPINRAZA is delivered directly to the CNS1,7

Intrathecal delivery of nusinersen into the CSF
allows it to bypass the blood-brain barrier
Targets CNS tissues1
  • Distribution from the CSF to where motor neurons live1,10
  • Nusinersen is delivered to motor neurons to increase production of full-length functional SMN protein1,10
Prolonged half-life1
  • Continuous treatment approach1
  • Long half-life in the CSF between prescribed doses1
    • Half-life of up to 5.9 months (estimated to be 135-177 days)
Dosing independent of age or weight1
  • Drug exposure was relatively consistent in patients (age 8 days-15 years) based on pharmacokinetic data evaluated to support 12 mg dosing11

SPINRAZA is injected in the lumbar area of the spine—typically between L3 and L4, below the spinal cord12,13

SPINRAZA is injected in the lumbar area of the spine—typically between L3 and L4, below the spinal cord12,13

ASO, antisense oligonucleotide; CNS, central nervous system; CSF, cerebrospinal fluid; SMN, survival motor neuron.

Review the Warnings and Precautions,
including thrombocytopenia, coagulation
abnormalities, and renal toxicity1

SEE SPINRAZA SAFETY

Watch how SPINRAZA works to enhance the production of full-length SMN protein1

SPINRAZA is approved for all ages—adults, teens, children, infants1

SEE SPINRAZA SAFETY
Start your patient on spinraza

INDICATION

SPINRAZA® (nusinersen) is indicated for the treatment of spinal muscular atrophy (SMA) in pediatric and adult patients.

IMPORTANT SAFETY INFORMATION

Coagulation abnormalities and thrombocytopenia, including acute severe thrombocytopenia, have been observed after administration of some antisense oligonucleotides. Patients may be at increased risk of bleeding complications.

In the sham-controlled studies for patients with infantile-onset (Study 1) and later-onset (Study 2) SMA who received Low Dose Regimen (12 mg loading doses/12 mg maintenance doses), 24 of 146 SPINRAZA-treated patients (16%) with high, normal, or unknown platelet count at baseline developed a platelet level below the lower limit of normal, compared to 10 of 72 sham-controlled patients (14%). Two SPINRAZA-treated patients developed platelet counts <50,000 cells per microliter, with the lowest level of 10,000 cells per microliter recorded on study day 28. In patients who received High Dose Regimen (50 mg loading doses/28 mg maintenance doses), decreases in platelet counts were also observed.

Renal toxicity, including potentially fatal glomerulonephritis, has been observed after administration of some antisense oligonucleotides. SPINRAZA is present in and excreted by the kidney. In Study 1 and Study 2, 71 of 123 SPINRAZA-treated patients (58%) had elevated urine protein, compared to 22 of 65 sham-controlled patients (34%).

Laboratory testing and monitoring to assess safety should be conducted. Perform a platelet count, coagulation laboratory testing, and quantitative spot urine protein testing at baseline and prior to each dose of SPINRAZA and as clinically needed.

Severe hyponatremia was reported in an infant treated with SPINRAZA requiring salt supplementation for 14 months.

Cases of rash were reported in patients treated with SPINRAZA.

SPINRAZA may cause a reduction in growth as measured by height when administered to infants, as suggested by observations from the controlled study. It is unknown whether any effect of SPINRAZA on growth would be reversible with cessation of treatment.

The most common adverse reactions in the Low Dose Regimen (≥20% of SPINRAZA-treated patients and ≥5% more frequently than in control patients) that occurred in the infantile-onset controlled study were lower respiratory infection and constipation. Serious adverse reactions of atelectasis were more frequent in SPINRAZA-treated patients (18%) than in control patients (10%). Because patients in this controlled study were infants, adverse reactions that are verbally reported could not be assessed. The most common adverse reactions that occurred in the later-onset controlled study were pyrexia, headache, vomiting, and back pain. Post-lumbar puncture syndrome has also been observed after the administration of SPINRAZA.

The most common adverse reactions in the High Dose Regimen (≥10% of SPINRAZA-treated patients and ≥5% more frequently than control patients from Study 1) that occurred in patients with infantile-onset SMA were pneumonia, COVID-19, pneumonia aspiration, and malnutrition. COVID-19 was not discovered at the time of Study 1.

Please see full Prescribing Information.

As a courtesy, our full Prescribing Information is also available en Español. For prescribing decisions, please refer to official approved labeling.

References

1. SPINRAZA. Prescribing Information. Biogen; 2026. 2. Lunn MR, Wang CH. Spinal muscular atrophy. Lancet. 2008;371(9630):2120-2133. doi:10.1016/S0140-6736(08)60921-6 3. U.S. FDA approves Biogen’s SPINRAZA™ (nusinersen), the first treatment for spinal muscular atrophy [press release]. Cambridge, MA: Biogen. December 23, 2016. Accessed July 6, 2026. https://investors.biogen.com/news-releases/news-release-details/us-fda-approves-biogens-spinrazatm-nusinersen-first-treatment 4. Evrysdi. Prescribing Information. Genentech; 2026. 5. Zolgensma. Prescribing Information. Novartis; 2025. 6. Itvisma. Prescribing Information. Novartis; 2025. 7. Chiriboga CA, Swoboda KJ, Darras BT, et al. Results from a phase 1 study of nusinersen (ISIS-SMNRx) in children with spinal muscular atrophy. Neurology. 2016;86(10):890-897. doi:10.1212/WNL.0000000000002445 8. Finkel RS, Chiriboga CA, Vajsar J, et al. Treatment of infantile-onset spinal muscular atrophy with nusinersen: a phase 2, open-label, dose-escalation study. Lancet. 2016;388(10063):3017-3026. doi:10.1016/S0140-6736(16)31408-8 9. Darras BT, Royden Jones H Jr, Ryan MM, De Vivo DC, eds. Neuromuscular Disorders of Infancy, Childhood, and Adolescence: A Clinician’s Approach. 2nd ed. London, UK: Elsevier; 2015. 10. Podraza LC, Tadi P. Neuroanatomy, Motor Neuron. [Updated 2023 Jul 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan. Available from: https://ncbi.nlm.nih.gov/books/NBK554616/ 11. US Food and Drug Administration, Center for Drug Evaluation and Research. Medical Review: Spinraza (Application No. 209531Orig1s000). US FDA, 2017. https://www.accessdata.fda.gov/drugsatfda_docs/nda/2016/209531orig1s000medr.pdf. Accessed June 2, 2026. 12. Haché M, Swoboda KJ, Sethna N, et al. Intrathecal injections in children with spinal muscular atrophy: nusinersen clinical trial experience. J Child Neurol. 2016;31(7):899-906. doi:10.1177/0883073815627882 13. Ganapathy MK, Reddy V, Tadi P. Neuroanatomy, Spinal Cord Morphology. [Updated 2024 Sep 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK545206/

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