Neuromuscular · Clinical trials
Spinal Muscular Atrophy (SMA) Clinical Trials
Approved therapies, the pivotal-trial endpoints they were judged on, the magnitude of benefit — and the drugs that failed their endpoints, and why.
Indication overview
About spinal muscular atrophy (sma) — and why its trials are hard
Spinal muscular atrophy (SMA) is an autosomal-recessive motor neuron disease caused by biallelic loss or mutation of the SMN1 gene, leading to deficient survival motor neuron (SMN) protein, degeneration of anterior-horn motor neurons, and progressive muscle weakness. Severity correlates inversely with SMN2 copy number, ranging from severe infantile-onset type 1 (historically fatal by age 2) to milder later-onset forms. SMA has been transformed from an untreatable, often lethal disorder into one of the great therapeutic success stories through three SMN-restoring therapies. Nusinersen, an intrathecal antisense oligonucleotide that modifies SMN2 splicing, was approved in 2016 on the ENDEAR trial. Onasemnogene abeparvovec (Zolgensma), a one-time AAV9 gene-replacement therapy delivering SMN1, was approved in 2019 (STR1VE/START). Risdiplam, an oral small-molecule SMN2 splicing modifier, was approved in 2020 (FIREFISH, SUNFISH). Endpoints are motor-milestone and motor-function scales—CHOP-INTEND in infants and the Hammersmith functional scales (HFMSE/HINE) in older patients—plus event-free (ventilation-free) survival. Newborn screening and early, pre-symptomatic treatment yield the best outcomes.
Approved therapies & pivotal evidence
What's been approved — and by how much it moved the endpoint
| Drug (brand) | Approved | Setting | Pivotal trial | Primary endpoint | Magnitude of benefit |
|---|---|---|---|---|---|
| Nusinersen (Spinraza) | 2016 | All SMA types; intrathecal antisense oligonucleotide (SMN2 splicing modifier) | ENDEAR (infantile-onset); CHERISH (later-onset) | Motor-milestone response (HINE); event-free survival; HFMSE change | ENDEAR: 51% of treated infants were motor-milestone responders vs 0% controls; significant reduction in death or permanent ventilation |
| Onasemnogene abeparvovec (Zolgensma) | 2019 | SMA in children <2 years; one-time IV AAV9 SMN1 gene-replacement therapy | STR1VE (and START phase 1) | Survival free of permanent ventilation; motor milestones (CHOP-INTEND, sitting independently) | In STR1VE, majority achieved event-free survival and independent sitting—milestones never reached in the natural history of type 1 |
| Risdiplam (Evrysdi) | 2020 | SMA (infants and later-onset); oral daily SMN2 splicing modifier | FIREFISH (type 1 infants); SUNFISH (type 2/3) | Ability to sit without support (BSID); MFM32 change | FIREFISH: ~29% of infants sat without support at 12 months (vs 0 expected); SUNFISH met MFM32 endpoint vs placebo |
Where trials have failed
Drugs that missed their endpoint — and what contributed
The most instructive lessons in spinal muscular atrophy (sma) development come from programmes that failed the endpoint that mattered.
| Drug / trial | Endpoint outcome | What contributed |
|---|---|---|
| Olesoxime (neuroprotective, non-SMN) — Phase 2 pivotal plus open-label extension | Initial phase 2 signal not confirmed; long-term extension failed to show sustained benefit and development was discontinued | Non-SMN mechanism proved inadequate versus emerging SMN-restoring therapies |
| Reldesemtiv / earlier CK-2127107 (fast skeletal muscle troponin activator) — Phase 2 in SMA | Did not meet primary endpoint in SMA; SMA program not advanced | Muscle-directed mechanism did not restore SMN or produce sufficient functional gains |
Choosing the right endpoint
Primary endpoints that matter in spinal muscular atrophy (sma) trials
- CHOP-INTEND — Motor-function scale validated for infantile-onset SMA; key measure in type 1 trials
- HINE motor-milestone response — Hammersmith Infant Neurological Examination milestones; primary endpoint domain in ENDEAR
- HFMSE / MFM32 / RULM — Functional scales for later-onset (type 2/3) patients; used in CHERISH and SUNFISH
- Event-free (ventilation-free) survival — Critical hard endpoint in type 1, historically fatal by age 2
- Achievement of developmental milestones (sitting, standing) — Clinically meaningful gains never seen in natural history of severe SMA
How iNGENū runs spinal muscular atrophy (sma) trials
Physician-led design, built for FDA submission
Endpoint & biomarker strategy
Board-certified specialists design endpoints and patient selection aligned to current FDA guidance for this indication.
FDA-ready data
Built to ICH-GCP and 21 CFR 312.120, with direct FDA submission — data accepted by the FDA, EMA and MHRA.
Faster, lower-cost delivery
~4-week ethics via the TGA CTN scheme, up to 43.5% R&D rebate, and 80–90% below US CRO cost.
Request a fixed-milestone proposal and a tailored endpoint & feasibility summary for this indication.
Frequently asked questions
Spinal Muscular Atrophy (SMA) clinical trials — FAQs
What treatments are available for SMA?
Why does early treatment matter so much?
How is treatment benefit measured?
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