Novartis has new data to back up the efficacy of Zolgensma, its gene therapy for spinal muscular atrophy, as it prepares for a possible FDA approval later this month.
Updated results from ongoing trials of Zolgensma (onasemnogene abeparvovec) – developed by Novartis’ AveXis unit – were presented at the American Academy of Neurology (AAN) meeting and showed that the one-off therapy provided rapid improvement in motor function in infants with the muscle-wasting disease.
If approved, Zolgensma would enter a field dominated by Biogen’s SMA therapy Spinraza (nusinersen), the only approved therapy at the moment, which brought in $518m in sales in the first three months of 2019. Spinraza has to be given by intrathecal injection into the cerebrospinal fluid every four months.
The gene therapy filed for treatment of type 1 SMA only at the moment, the most common form of the disease, with the FDA’s decision due to be followed by a verdict in Europe later this year.
Among the new results was interim data from the phase 1 STRONG trial in SMA type 2 which showed rapid motor function gains in infants who were able to sit but could not stand or walk at the time of study entry.
Two patients in a younger age group (aged 6 to 24 months at entry) gained the ability to stand independently, one of whom went on to walk alone, and one patient in an older group (aged 24 to 60 months) gained the ability to walk with assistance.
New data was also presented from the phase 3 STR1VE study in type 1 SMA patients who were less than six months old at entry, which also showed improvements in motor function from baseline. Out of 22 subjects, one patient could crawl, one patient could pull to a stand and 11 patients could sit without support for at least 30 seconds by the data cut-off.
Zolgensma also helped pre-symptomatic patients with motor milestone achievements in the phase 3 SPR1NT study in 18 infants with SMA types 1, 2 and 3 who were aged six weeks or less at the time of enrolment and showed age-appropriate motor development in the months after dosing.
According to AveXis’ chief medical officer Olga Santiago, the motor milestones achieved were in line with normal development seen in healthy infants and “reinforce the potential Zolgensma has as a foundational treatment for patients with SMA.”
SMA is caused by a faulty SMN1 gene coding for SMN protein, which leads to lower than normal levels and subsequent loss of motor nerve cells, muscle weakness and atrophy. Zolgensma is designed to deliver a normal copy of the SMN1 gene to motor neurons, bolstering the production of the protein.
Type 1 patients often don’t survive beyond a few years of life, while type 2 patients can live into adulthood and types 3 and 4 can have normal longevity.
The data back up the efficacy of Zolgensma, but the jury is still out over the role the therapy – if approved – will play alongside Spinraza and emerging therapies like PTC Therapeutics/Roche’s risdiplam, particularly as regulator are currently investigating an infection-related death in one patient in the STR1VE study.
Another issue is the price, with Novartis suggesting in the last that one-off cost of $4m could be justifiable given the massive cost of caring for SMA patients, although analysts reckon it won’t push the price that high.
Spinraza is priced at $750,000 for the first year, and $350,000 afterwards, but has to be given long-term. Chronic dosing will also be needed for risdiplam, an oral therapy which has data due for presentation at the AAN later today.
Jefferies said recently it sees the three therapies splitting the market into roughly equal thirds, with Zolgensma claiming newly-diagnosed patients who stand to gain the most from early intervention, driving sales of the therapy to $2.6bn at peak.
Spinraza and risdiplam will share the more established SMA market, and Spinraza could be protected from a big impact from the gene therapy becoming available as doctors may be reluctant to switch a patient who is already doing well on the drug.