7 Emerging Spinal Muscular Atrophy Therapies Offering Hope for Patients

The approval of three transformative spinal muscular atrophy therapies—SPINRAZA (Ionis/Biogen), EVRYSDI (Roche), and the groundbreaking gene therapy ZOLGENSMA (Novartis) has reshaped the spinal muscular atrophy treatment market. These breakthrough SMA medicines have significantly expanded SMA treatment options, offering meaningful clinical benefit across disease types, including spinal muscular atrophy type 1 treatments, spinal muscular atrophy type 2 treatments, and spinal muscular atrophy type 3 treatments. 

Today, treating spinal muscular atrophy requires more than a single intervention. Modern spinal muscular atrophy treatment strategies emphasize a comprehensive, multidisciplinary approach that combines disease-modifying SMA medicine with supportive care to reduce complications and improve long-term outcomes. This integrative spinal muscular atrophy solution relies on neurologists, pulmonologists, physical therapists, nutritionists, and rehabilitation specialists working together—particularly in pediatric spinal muscular atrophy treatment settings. As a result, outcomes have improved significantly compared with historical standards of care. As innovation accelerates, the SMA drug pipeline and broader SMA pipeline continue to expand with next-generation agents targeting muscle strength, neuromuscular transmission, and functional outcomes. Several new treatments for spinal muscular atrophy are progressing through advanced SMA clinical trials and spinal muscular atrophy clinical trials, signaling the next wave of SMA therapies.

Leading candidates in the development of the spinal muscular atrophy pipeline include Scholar Rock’s Apitegromab, Novartis’ intrathecal version of ZOLGENSMA (OAV101 IT), Biohaven’s Taldefgrobep Alfa, Biogen’s high-dose SPINRAZA and BIIB115, Chugai/Roche’s GYM329/RG6237, NMD Pharma’s NMD670, and several others.

Here’s an in-depth look at seven promising emerging therapies that could transform the future of spinal muscular atrophy treatment.

Scholar Rock’s Apitegromab

Apitegromab (SRK-015), developed by Scholar Rock, is an investigational therapy for spinal muscular atrophy that works by selectively inhibiting the activation of latent (inactive) myostatin, rather than targeting the already-active form or its receptor. Unlike SMN-enhancing spinal muscular atrophy medications, apitegromab aims to improve muscle strength directly, making it a potential adjunct SMA drug treatment.

The drug has received multiple regulatory designations: Orphan Drug, Fast Track, and Rare Pediatric Disease designations from the US FDA, as well as Orphan Medicinal Product status from the European Commission. Additionally, the European Medicines Agency (EMA) has granted it a Priority Medicines (PRIME) designation for the treatment of SMA.

In 2025, Scholar Rock’s Biologics License Application (BLA) for apitegromab was granted FDA Priority Review, with a PDUFA decision anticipated in September 2025. However, in September 2025, the FDA issued a Complete Response Letter (CRL) citing observations at a third-party manufacturing facility. Importantly, no concerns were raised regarding the drug’s safety or efficacy, and the company intends to resolve the manufacturing issues and resubmit the application.

Additionally, the company has submitted a Marketing Authorisation Application (MAA) to the European Medicines Agency (EMA) for the use of apitegromab in treating SMA. The EMA has validated the submission, confirming it is complete and ready for formal review.

These regulatory filings are supported by positive efficacy and safety results from the pivotal Phase III SAPPHIRE trial (NCT05156320), with topline data released in October 2024, along with data from the earlier Phase II TOPAZ trial and the long-term ONYX extension study. Findings from the SAPPHIRE trial, including both primary and secondary endpoints, were recently presented at the 2025 Muscular Dystrophy Association (MDA) Clinical & Scientific Conference.

SAPPHIRE met its primary endpoint, showing a statistically significant and clinically meaningful improvement in motor function in SMA patients treated with apitegromab alongside ongoing SMN-targeted therapies (nusinersen or risdiplam), compared to those receiving placebo with the same standard treatments. Motor function was assessed using the Hammersmith Functional Motor Scale Expanded (HFMSE), the recognized gold standard.

Following the CRL, Scholar Rock is addressing the manufacturing observations and updating its regulatory timeline, with US and EU launches contingent on successful resubmission and approval. If approved, apitegromab could become a key new possible treatment for spinal muscular atrophy, particularly for patients seeking functional gains beyond SMN restoration.

Novartis’ ZOLGENSMA

ZOLGENSMA remains one of the most impactful SMA medicines, currently indicated for the treatment of pediatric patients less than 2 years of age with spinal muscular atrophy (SMA) with bi-allelic mutations in the survival motor neuron 1 (SMN1) genes.

In November 2025, the FDA approved a new fixed-dose, intrathecally administered formulation of onasemnogene abeparvovec-brve to be marketed as Itvisma. Unlike the original intravenous ZOLGENSMA, Itvisma is indicated for children aged two years and older, as well as adolescents and adults with a confirmed SMN1 mutation—significantly expanding the eligible patient population. The intrathecal version uses fixed dosing rather than weight-based dosing, potentially offering a safer option for older and heavier patients through a smaller one-time spinal injection.

The approval was supported by results from the pivotal Phase III STEER trial, with additional data from the Phase IIIb STRENGTH study. Clinical findings demonstrated statistically significant improvements in motor function and stabilization of disease progression over 52 weeks. Additionally, Itvisma demonstrated a safety profile with adverse events that were consistent across both studies. The most common adverse events in the STEER study were upper respiratory tract infection and pyrexia, and the most common adverse events in the STRENGTH study were common cold, pyrexia, and vomiting.  

Itvisma has been launched at a wholesale acquisition cost (WAC) of USD 2.59 million, compared to ZOLGENSMA’s original 2019 price of USD 2.13 million for the one-time intravenous infusion.

Biohaven’s Taldefgrobep Alfa

Taldefgrobep is an experimental, muscle-targeted recombinant protein designed to increase muscle mass and strength in individuals with spinal muscular atrophy, particularly when used alongside approved SMA drugs. As part of the evolving SMA drug pipeline, it works by targeting myostatin, a protein that naturally restricts skeletal muscle growth, through two pathways: directly reducing myostatin levels and inhibiting downstream signaling. Blocking myostatin is considered a promising therapeutic approach for both children and adults with neuromuscular diseases, as elevated myostatin can hinder the muscle growth needed for developmental and functional progress.

In November 2024, Biohaven shared updates on taldefgrobep alfa’s development in SMA. In the RESILIENT SMA trial, the drug showed clinically meaningful improvements in motor function across all timepoints using the Motor Function Measurement-32 (MFM-32) scale. However, it did not achieve statistical significance in the primary endpoint at Week 48 compared to the placebo plus standard of care (SOC).

Encouraging efficacy signals were seen in several clinically and biologically defined subgroups, including variations in age, ability to walk, background therapy, and baseline myostatin levels. Among the largest demographic group (87% Caucasian, n=180), statistically significant improvements were seen on the MFM-32 scale at all timepoints, including Week 48 (p < 0.05). Additionally, a subgroup of patients with detectable baseline myostatin (n=123) demonstrated stronger efficacy results (p = 0.02).

Biohaven initiated discussions with the FDA to outline a potential registrational pathway. Data from the study were presented at the Cure SMA meeting in June 2025. The optional long-term extension phase of the trial remained ongoing, pending further data evaluation and regulatory interactions.

Biogen’s SPINRAZA and BIIB115

SPINRAZA has received approval in over 71 countries for the treatment of spinal muscular atrophy in infants, children, and adults. As a cornerstone therapy for SMA, it has been administered to more than 14,000 individuals globally. The approved 12 mg dosing schedule includes four loading doses over about 60 days, followed by maintenance doses every four months.

SPINRAZA is an antisense oligonucleotide (ASO) designed to address the root cause of motor neuron degeneration in SMA by consistently boosting the production of full-length survival motor neuron (SMN) protein. The drug is delivered directly into the central nervous system, where motor neurons are located, to target the disease at its origin.

The treatment has demonstrated long-term efficacy across various ages and SMA subtypes, with a well-established safety record supported by up to 10 years of patient data and extensive real-world use. The SPINRAZA development program includes over 10 clinical trials involving more than 460 participants, including two pivotal randomized studies (ENDEAR and CHERISH). The most frequently reported side effects in trials included respiratory infections, fever, constipation, headaches, vomiting, and back pain. Routine lab tests are used to monitor for potential risks such as kidney toxicity and coagulation issues, including severe thrombocytopenia observed with some ASOs.

Biogen holds the global rights to develop, produce, and commercialize SPINRAZA through a license from Ionis Pharmaceuticals, Inc. In January 2025, Biogen announced that the FDA had accepted its supplemental New Drug Application (sNDA), and the EMA had validated a submission for a higher-dose regimen of nusinersen. This proposed regimen features a faster initial dosing phase, two 50 mg doses 14 days apart, and higher maintenance doses of 28 mg every four months, compared to the current standard.

Despite SPINRAZA’s success, Biogen is pursuing further innovation. In January 2022, the company exercised its option to license salanersen (BIIB115), another ASO developed by Ionis that may allow for longer intervals between doses.

Biogen has announced plans to advance its investigational SMA therapy, salanersen, into registrational development after reporting positive interim Phase I findings. Complete Phase Ib data are expected in the first quarter of 2026. The initiation of a Phase III registrational trial in 2026 underscores the company’s ongoing commitment to strengthening the SMA drug pipeline. Together, these developments reaffirm SPINRAZA’s position as a foundational medicine for SMA while supporting the evolution of next-generation SMA therapies.

Chugai/Roche’s Emugrobart (GYM329/RG6237)

Emugrobart, developed by Chugai, is a next-generation antibody that leverages the company’s proprietary antibody engineering technologies, such as the recycling antibody and sweeping antibody platforms. Latent myostatin, primarily secreted by muscle cells in an inactive form, becomes active through enzymes like BMP-1 that degrade proteins. Once activated, myostatin suppresses muscle growth and hypertrophy. By blocking myostatin’s activity, GYM329 is designed to counteract muscle atrophy and improve muscle strength.

A global Phase II/III clinical trial is underway to evaluate the safety and efficacy of Emugrobart, an investigational anti-myostatin antibody, in combination with EVRYSDI (risdiplam) for the treatment of spinal muscular atrophy (SMA). The therapy is designed to enhance muscle growth and strength, with preclinical data suggesting superior muscle development compared with risdiplam alone.

Phase II data are expected to read out in 2026, with potential regulatory submissions projected for 2028 and beyond, contingent on positive clinical outcomes. If successful, emugrobart could become a complementary SMA drug within combination regimens, further diversifying spinal muscular atrophy treatments and strengthening the competitive spinal muscular atrophy drug market.

NMD Pharma’s NMD670

NMD670 is the lead development candidate from NMD Pharma. It is a first-in-class small molecule that targets and inhibits the skeletal muscle-specific chloride ion channel 1 (CIC-1). NMD Pharma has shown that inhibiting CIC-1 enhances the muscle’s sensitivity to weak nerve signals, thereby improving neuromuscular communication and restoring muscle function. This innovative approach has demonstrated clinical proof-of-concept in myasthenia gravis and preclinical potential in spinal muscular atrophy, Charcot-Marie-Tooth disease, and sarcopenia.

NMD670 is currently being evaluated in a Phase II clinical trial for SMA. NMD Pharma is accelerating ignaseclant’s clinical development in CMT alongside multiple near-term clinical catalysts across its neuromuscular pipeline, with Phase II studies in SMA and generalised myasthenia gravis (gMG) expected to deliver additional data in 2026.

The introduction of innovative spinal muscular atrophy drugs continues to transform the rare disease landscape. As newborn screening expands and earlier intervention becomes standard, demand for comprehensive spinal muscle atrophy treatment is expected to rise. Competition within the spinal muscular atrophy treatment market may influence pricing dynamics, reimbursement models, and global access strategies. Additionally, progress in SMA research is contributing to advances in adjacent neuromuscular segments, including the evolving bulbospinal muscular atrophy drug market.

While definitive cures for spinal muscular atrophy remain under investigation, the rapid expansion of the SMA pipeline, ongoing spinal muscular atrophy clinical trials, and emergence of combination strategies suggest continued evolution toward more durable, function-focused standards of care.

For stakeholders tracking regulatory updates, clinical data readouts, and commercial shifts across spinal muscular atrophy products, continued monitoring of the SMA drug pipeline remains essential.

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