AveXis was down 6% today as Biogen and partner Ionis got an early present in the form of the first-ever approval for a drug that helps children with spinal muscular atrophy (SMA).
Spinraza (nusinersen), which had FDA priority review and fast-track tags, was approved (much earlier than analysts predicted) on Friday for the treatment of SMA in both pediatric and adult patients. It has however come with safety warnings, including risk of thrombocytopenia and renal toxicity.
Analysts at Leerink said they thought the drug wouldn’t see an approval until halfway through next year. They believe it could make around $2 billion by 2020, much more than it initially forecast, which it says could boost Biogen’s top line by 3% a year by the end of the decade.
On the safety side, Leerink said: "[These] likely stem from safety events seen in other antisense oligonucleotide programs such as Kynamro and potentially volanesorsen and IONIS-TTRrx. We caught up with Ionis who notes that no patient on nusinersen had a confirmed case of thrombocytopenia (defined as showing a second low platelet reading after an initial low platelet count). Ionis also notes that there were no renal events in Spinraza studies."
SMA can affect up to 10,000 children around the world and is one of the leading causes of early death and disability in young children. The disease has four types, with the first being the most severe. Biogen has tested its med on types 1-3.
Biogen said in a statement that it will start shipping the drug this week. The drug was originally licensed from Ionis, which will also receive a $60 million milestone payment and is in line for more marketed biobucks in the future.
“There has been a long-standing need for a treatment for spinal muscular atrophy, the most common genetic cause of death in infants, and a disease that can affect people at any stage of life,” said Dr. Billy Dunn, director of the Division of Neurology Products at the FDA.
In the recent phase 3 Endear study, Biogen’s med showed statistically and clinically significant improvement in the primary endpoint, which included greater movement in kicking, walking, crawling and sitting, than worsened.
As well as its Endear test, geared for infantile-onset SMA (who are most likely to develop Type 1), it also posted what it called “encouraging preliminary results from Nurture,” a phase 2 open-label study in presymptomatic infants, as well as a recent analysis of the ongoing midstage open-label study in patients with later-onset SMA (consistent with Types 2 or 3).
Biogen’s therapy works as an antisense oligonucleotide that is designed to alter the splicing of SMN2, a gene that is nearly identical to SMN1, in order to increase production of fully functional SMN protein. Spinraza is also on target to gain EMA approval in 2017.
This is good news for SMA patients and for Biogen/Ionis, but not so great news for AveXis, which will now see its SMA drug AVXS-101 be second to market, should it gain approval.
Its drug is designed to address the monogenetic root cause of SMA and prevent further muscle degeneration by addressing the defect in and/or loss of the primary SMN gene.
Back in the fall, it posted data from a small phase 1 study of AVXS-101 that showed that as of 15 Sept., two-thirds of patients in cohort 2 (which is what the company is looking to dose its patients on) “had achieved the ability to sit unassisted, including one patient whose achievement of this milestone was confirmed after September 15.”
AveXis is focusing on Type 1, the most severe form of the disease; around 90% of children born with this type never see their second birthday and in their short lives will never sit, crawl or walk.
The biotech got its IPO off this year based on the strength of its early SMA data but saw its shares down 5.6% after hours on Friday when Biogen announced its FDA approval.