After Spinraza's FDA approval nearly a decade ago, Biogen's spinal muscular atrophy (SMA) drug captured rapid momentum and delivered blockbuster-level sales in just its second year on the market. While it's been a reliable revenue contributor ever since, rival meds from Roche and Novartis have taken away some of Spinraza's steam over the years.
Now, Biogen is ready with its answer, as the FDA has approved the company's high-dose version of its SMA blockbuster. The new version features an "accelerated loading phase" of two 50-mg doses given 14 days apart, followed by 28-mg maintenance dose injections given every four months. Conversely, the low-dose version of Spinraza features a 4-dose loading phase that takes roughly two months to complete.
On a conference call last month, Biogen CEO Chris Viehbacher touted the "much higher levels of efficacy" seen in the study of the high-dose version, "which suggests that there is an increased benefit to getting to a therapeutic level faster." Speaking of the high-dose launch in other countries, he said Biogen has noted encouraging "adoption" by treatment-naive patients, as well as "switchbacks" from patients on rival offerings.
Supporting the approval are data from the phase 2/3 Devote study, which showed that treatment-naive, symptomatic infants with SMA who received the drug experienced statistically significant improvements in motor function compared to an untreated control group from a prior study. Specifically, treated patients in Devote experienced a 15.1-point improvement on the Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders scale, compared with an 11.1-point decline in untreated patients in Endear, a prior study of the low-dose version.
In an open-label portion of the study, patients who had previously received low-dose Spinraza transitioned to the high-dose version and experienced improvements in motor function after switching.
The approval of High Dose Spinraza represents Biogen's answer to Roche's Evrysdi, which scored its initial FDA nod in 2020 as a liquid medicine to be given orally or through a feeding tube. A year ago, the Roche drug won FDA approval in tablet form, adding to its desirable competitive profile. In a recent investor presentation (PDF), Roche noted that Evrysdi is "leading" in SMA, with more than 21,000 patients treated.
Additionally, while Novartis' Zolgensma is a gene therapy—meaning it carries its own set of competitive considerations—the groundbreaking drug has still been able to churn out blockbuster-level sales over the years.
Last year, Biogen's Spinraza sales came in at $1.55 billion compared with 1.76 billion Swiss francs ($2.11 billion) for Roche's Evrysdi and $1.23 billion for Novartis' Zolgensma.
Speaking on last month's conference call, Biogen CEO Viehbacher said a key consideration for physicians treating SMA patients is "efficacy versus convenience."
"If you ask them about efficacy, most of them believe it’s really Spinraza, but at some point, the convenience of the oral starts to attract patients," he said. With the high-dose version of Spinraza, "we’re going to be dramatically increasing the level of efficacy, and I think the choice between oral and efficacy will be harder for some physicians and parents."
Biogen plans to launch the new version of Spinraza in the U.S. in the coming weeks. It's already progressing with the rollout in certain countries overseas.