- New phase 1b data show that in SMA children who had previously received gene therapy but still had suboptimal clinical status and potential for improvement, Salanersen demonstrated favorable safety and efficacy during a one-year follow-up period.
- Salanersen is a novel antisense oligonucleotide (ASO) drug that may achieve high efficacy in SMA treatment with once-yearly dosing.
- Biogen also announced the design of the phase 3 clinical trial program for Salanersen, which has been initiated in multiple regions globally.
On March 11, 2026, Biogen presented additional results from the phase 1b study of Salanersen at the 2026 Muscular Dystrophy Association (MDA) Clinical & Scientific Conference. The study evaluated the efficacy and safety of Salanersen in pediatric patients who had previously received gene therapy (onasemnogene abeparvovec-xioi) but still had suboptimal clinical status.
The study showed that Salanersen was generally well tolerated. After treatment initiation, participants experienced slowed neurodegenerative progression and functional improvements, with some achieving new World Health Organization (WHO) motor milestones. These new results include at least one year of follow-up data from all subjects and represent an update from the interim data presented at the 2025 Cure SMA Conference. The company also presented the study design for the phase 3 clinical trial of Salanersen.
"Treatment for spinal muscular atrophy has made tremendous progress in recent years, but there remains room for further improvement in the current treatment landscape," said Dr. Thomas Crawford, co-director of the MDA Clinic at Johns Hopkins Medicine. "The progress with Salanersen is generating increasing interest from the scientific and clinical communities. These additional phase 1 data further strengthen our confidence in Salanersen's clinical profile and make us look forward to the phase 3 results."
Salanersen Phase 1b Study Results
In this analysis, 24 subjects (aged 0.5–12 years) were enrolled; all had received at least two doses of Salanersen (40 mg or 80 mg). The 80 mg dose will be further evaluated in the phase 3 study.
Among participants treated with 40 mg and 80 mg Salanersen who had elevated baseline neurofilament light chain (NfL) concentrations, a significant reduction in NfL levels (75%) was observed at six months. These reductions were maintained during follow-up. All 24 participants showed improvement from baseline in at least one endpoint. Notably, 12 of the 24 participants achieved at least one new WHO motor milestone, and all participants maintained their baseline-recorded motor milestones. In the ongoing phase 1 study, Salanersen was generally well tolerated at both the 40 mg and 80 mg doses, with most adverse events (AEs) being mild to moderate. The most common AEs in the 40 mg group were upper respiratory tract infection and vomiting, while in the 80 mg group, the most common AEs were pyrexia and upper respiratory tract infection.
Salanersen Phase 3 Clinical Program
Biogen also announced the phase 3 clinical development plan for Salanersen, which will evaluate the efficacy and safety of once-yearly 80 mg Salanersen in a broader SMA population.
The program includes three global studies:
- STELLAR-1: An open-label study evaluating Salanersen in treatment-naive, presymptomatic SMA infants up to 6 weeks of age.
- STELLAR-2: A randomized, double-blind, sham-controlled study evaluating Salanersen initiated approximately 6 months after gene therapy (onasemnogene abeparvovec-xioi) in presymptomatic SMA infants who received gene therapy at or before 6 weeks of age.
- SOLAR: An open-label study evaluating Salanersen in treatment-naive or risdiplam-treated adolescents and adults with SMA aged 15–60 years.
The two STELLAR studies are complementary and aim to compare multiple early treatment strategies (Salanersen alone, gene therapy alone, and Salanersen as an add-on to gene therapy) in asymptomatic newborns, informing future SMA treatment approaches. The clinical development program has begun: STELLAR-1 screening has started, SOLAR is planned to start in Q2 2026, and STELLAR-2 is planned to start in Q3 2026.
"Following encouraging phase 1b results, we are moving as quickly as possible to initiate the phase 3 STELLAR-1, STELLAR-2, and SOLAR studies for Salanersen," said Dr. Stephanie Fradette, Pharm.D., head of neuromuscular development at Biogen. "We designed these studies together with the SMA community to confidently answer the most relevant questions in the field and establish Salanersen's role in the future treatment landscape."
About Salanersen
Salanersen (BIIB115) is a novel, intrathecally administered antisense oligonucleotide (ASO) being developed for spinal muscular atrophy (SMA). Salanersen is designed to correct the splicing of SMN2 pre-messenger RNA to increase SMN protein production. It has a novel backbone chemistry with high potency, potentially enabling high efficacy with once-yearly dosing.
Excerpted and translated from Biogen's website. Original article: https://investors.biogen.com/news-releases/news-release-details/biogen-presents-additional-salanersen-data-showing-new-motor
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Biogen to Advance New SMA Candidate Salanersen into Registrational Studies
What this means for international patients
For international patients considering SMA treatment options, Salanersen represents a potential advancement in the therapeutic landscape. The phase 1b data suggest that even patients who have previously received gene therapy may benefit from add-on treatment with Salanersen. The phase 3 program will evaluate Salanersen across a wide age range, from presymptomatic infants to adults. Currently, Salanersen is not yet approved by regulatory authorities; it is an investigational drug. Patients interested in accessing Salanersen may consider participation in clinical trials, which are enrolling globally. Costs for SMA treatments vary widely; for example, gene therapy (onasemnogene abeparvovec) has a list price of approximately $2.1 million in the U.S. While Salanersen's pricing is not yet established, ASO therapies often range from $100,000 to $500,000 annually. Clinical trial participation may provide access at no cost. Timelines: STELLAR-1 screening is ongoing; SOLAR is expected to start in Q2 2026; STELLAR-2 in Q3 2026. Chinese hospitals involved in SMA care include Peking University First Hospital and Children's Hospital of Fudan University, but Salanersen trials are global and may include sites in China.
FAQ
What is Salanersen?
Salanersen is an investigational antisense oligonucleotide (ASO) designed to increase SMN protein production by correcting SMN2 splicing. It is administered intrathecally (into the spinal fluid) once yearly.
Who is eligible for the phase 3 trials?
Eligibility varies by study. STELLAR-1 enrolls presymptomatic infants up to 6 weeks old. STELLAR-2 enrolls infants who received gene therapy by 6 weeks of age. SOLAR enrolls adolescents and adults aged 15–60 who are treatment-naive or previously treated with risdiplam.
How does Salanersen differ from existing SMA treatments?
Existing treatments include nusinersen (given every 4 months), risdiplam (oral daily), and onasemnogene abeparvovec (one-time gene therapy). Salanersen aims for once-yearly dosing with high potency.
What were the main side effects in the phase 1b study?
Most adverse events were mild to moderate. Common side effects included upper respiratory tract infection, vomiting, and pyrexia.
Is Salanersen approved anywhere?
No, Salanersen is still investigational. It has not been approved by the FDA, EMA, or NMPA.
How can I learn more about clinical trial participation?
Visit ClinicalTrials.gov and search for "Salanersen" or contact Biogen directly. You may also consult your physician.
Next steps
If you or a loved one is considering SMA treatment options, including emerging therapies like Salanersen, we invite you to explore our comprehensive treatment guides and connect with specialists. For more information on SMA treatments and clinical trials, visit our treatments page.