The U.S. Food and Drug Administration (FDA) approved Biogen's SPINRAZA™ (nusinersen) under Priority Review for the treatment of spinal muscular atrophy (SMA) in pediatric and adult patients. SPINRAZA (nusinersen)
is the first and only treatment approved in the U.S. for SMA.
In ENDEAR, a pivotal controlled clinical study, infantile-onset SMA patients treated with nusinersen achieved and sustained clinically meaningful improvement in motor function compared to untreated study participants. In addition, a greater percentage of patients on nusinersen survived compared to untreated patients. In open-label studies, some patients achieved milestones such as ability to sit unassisted, stand or walk when they would otherwise be unexpected to do so and maintained milestones at ages when they would be expected to be lost.
The overall findings of these studies support the effectiveness of SPINRAZA (nusinersen) across the range of SMA patients, and appear to support the early initiation of treatment.
The FDA approval of SPINRAZA was based on positive results from multiple clinical studies in more than 170 patients. The data package included the interim analysis of ENDEAR, a Phase 3 controlled study evaluating SPINRAZA (nusinersen) in infantile-onset, as well as open-label data in pre-symptomatic and symptomatic patients with, or likely to develop, Types 1, 2 and 3 SMA.
The SPINRAZA Phase 3 Registrational Study, ENDEAR was a randomized, double-blind, sham-controlled study in patients with infantile-onset (most likely to develop Type 1) SMA. At a planned interim analysis of ENDEAR, a greater percentage of infants treated with SPINRAZA achieved a motor milestone response compared to those who did not receive treatment (40% versus 0%; p<0.0001) as measured by the Hammersmith Infant Neurological Examination (HINE).
Additionally, a smaller percentage of patients on SPINRAZA died (23%) compared to untreated patients (43%). Data from the other efficacy endpoints analyzed were consistently in favor of infants who received treatment. Detailed interim results from ENDEAR will be presented at the British Paediatric Neurology Association (BPNA) Annual Conference in January 2017.
Biogen has also launched SMA360°™, a patient information portal that addresses nonmedical barriers to access to nusinersen for those prescribed the drug.
SPINRAZA (nusinersen) is an antisense oligonucleotide (ASO) that is designed to treat SMA caused by mutations in the chromosome 5q that leads to SMN protein deficiency. SPINRAZA (nusinersen) alters the splicing of SMN2 pre-mRNA in order to increase production of full-length SMN protein. ASOs are short synthetic strings of nucleotides designed to selectively bind to target RNA and regulate gene expression. Through use of this technology, SPINRAZA (nusinersen) has the potential to increase the amount of full-length SMN protein in patients with SMA.
SPINRAZA (nusinersen) is administered via intrathecal injection, which delivers therapies directly to the cerebrospinal fluid (CSF) around the spinal cord, where motor neurons degenerate in patients with SMA due to insufficient levels of SMN protein.
The most common adverse reactions reported for SPINRAZA (nusinersen) were upper respiratory infection, lower respiratory infection and constipation. Serious adverse reactions of atelectasis were more frequent in SPINRAZA (nusinersen)-treated patients. Coagulation abnormalities and thrombocytopenia, including acute severe thrombocytopenia, have been observed after administration of some antisense oligonucleotides.
Renal toxicity, including potentially fatal glomerulonephritis, has been observed after administration of some antisense oligonucleotides.