Pull to refresh
Logo
Daily Brief
Following Why Ranks Sign Up
Biogen's salanersen wins FDA breakthrough status for spinal muscular atrophy

Biogen's salanersen wins FDA breakthrough status for spinal muscular atrophy

New Capabilities

A once-yearly nerve drug aims to help children who keep declining after gene therapy

June 30th, 2026: Phase 3 STELLAR-2 expected to begin enrolling

Overview

Some children with spinal muscular atrophy get a one-time gene therapy, then slowly weaken again. There has been no clear next step for them. On June 4, 2026, the FDA gave Biogen's salanersen a designation meant to speed up that next step.

Spinal muscular atrophy is an inherited disease that kills the nerve cells controlling muscles. Salanersen is a once-a-year injection that tells the body to make more of a missing protein. Early data suggest it can slow nerve loss and, in some kids, restore movement they had lost.

Why it matters

For families whose child kept getting weaker after a costly gene therapy, this is the first treatment built specifically for that gap.

Questions about this story

No questions yet — be the first to ask.

Play on this story Voices Debate Predict Higher or Lower

Key Indicators

1 per year
Dosing frequency
Salanersen is injected once a year, versus every four months for Biogen's older drug Spinraza.
75%
Drop in nerve-damage marker
Mean reduction in neurofilament light chain at six months in patients with high baseline levels.
12 of 24
Children hitting new milestones
Half of the 24 Phase 1b participants reached at least one new WHO motor milestone.
1 in 10,000
Birth rate of SMA
Spinal muscular atrophy affects roughly one in every 10,000 live births.

Voices

Curated perspectives — historical figures and your fellow readers.

Ever wondered what historical figures would say about today's headlines?

Sign up to generate historical perspectives on this story.

Log in Sign Up

Play

Exploring all sides of a story is often best achieved with Play.

Log in to play. Track your picks, climb the leaderboards. Log in Sign Up
Predict 3 ways this could play out. Contrarian picks score more — points lock when the scenario resolves. Log in to play
Higher or Lower Two numbers from this story. Guess which is bigger. 5 rounds to set a streak. Log in to play
Connections Sixteen names from the news. Find the four hidden groups of four. Log in to play

People Involved

Stephanie Fradette
Stephanie Fradette
Leading salanersen's clinical program

Organizations Involved

Biogen
Biogen
Biotechnology Company
Developer and commercial owner of salanersen

Biogen makes Spinraza, the first approved SMA drug, and now wants salanersen to replace it.
Ionis Pharmaceuticals
Ionis Pharmaceuticals
Biotechnology Company
Discovered salanersen; licensed it to Biogen

Ionis invented the antisense chemistry behind both Spinraza and salanersen.
U.S. Food and Drug Administration
U.S. Food and Drug Administration
Federal Agency
Granted Breakthrough Therapy Designation

The U.S. regulator that decides which drugs reach patients and how fast.

Timeline

December 2016 June 2026

5 events Latest: June 30th, 2026
Tap a bar to jump to that date

  1. Phase 3 STELLAR-2 expected to begin enrolling

    Latest Clinical Trial

    Biogen expects to start enrolling infants treated with gene therapy into the sham-controlled STELLAR-2 trial.

  2. FDA grants Breakthrough Therapy Designation

    Regulatory

    The FDA grants salanersen breakthrough status, speeding its development and review for SMA.

  3. New Phase 1b motor data presented

    Clinical Data

    Biogen reports that children declining after gene therapy gained motor milestones like sitting and walking on salanersen.

  4. Biogen licenses salanersen from Ionis

    Deal

    Biogen takes global development and commercialization rights to the Ionis-discovered antisense drug salanersen.

  5. First SMA drug approved

    Regulatory

    The FDA approves Spinraza, Biogen's nusinersen, the first treatment ever for spinal muscular atrophy.

Historical Context

3 moments from history that rhyme with this story — and how they unfolded.

December 2016

Spinraza approval (2016)

The FDA approved Biogen's nusinersen, sold as Spinraza, as the first drug for spinal muscular atrophy. It works by the same splice-switching mechanism as salanersen but needs a spinal injection every four months.

Then

Children who once had no options began gaining motor function and surviving longer.

Now

Spinraza became a multibillion-dollar product and proved antisense drugs could treat inherited neurological disease.

Why this matters now

Salanersen is Biogen's attempt to replace its own Spinraza with a stronger, once-yearly version before competitors erode the franchise.

May 2019

Zolgensma approval (2019)

The FDA approved Novartis's onasemnogene abeparvovec, sold as Zolgensma, a one-time gene therapy for SMA priced above $2 million. It delivers a working copy of the missing gene in a single infusion.

Then

Families embraced a one-and-done option, and many treated infants thrived.

Now

Some children still declined over time, exposing a gap gene therapy alone did not close.

Why this matters now

Salanersen's early data target exactly those children: kids who got Zolgensma but kept weakening and had no clear next treatment.

August 2020

Evrysdi approval (2020)

The FDA approved Roche and Genentech's risdiplam, sold as Evrysdi, the first oral SMA drug. Taken as a daily liquid at home, it raised SMN protein without spinal injections.

Then

An at-home option broadened access and pressured injectable rivals.

Now

SMA shifted from untreatable to a market with several competing mechanisms and delivery methods.

Why this matters now

Salanersen enters a crowded field where convenience matters; once-yearly dosing is its main pitch against daily pills and frequent injections.

Sources

(6)
+1
GlobeNewswire BioSpace BioPharm International Clinical Trials Arena Ionis Pharmaceuticals GlobeNewswire