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Spinal Muscular Atrophy Treatments Compared

Name: Spinal Muscular Atrophy Treatments Compared
Creator: Jason Hunter
Published: 2026-10-01

5 FDA-approved drugs, side by side from the current prescribing labels. Newest label Sep 2026. Checked October 1, 2026.

SMN2 splicing modifiersSpinraza · Evrysdi

One-time SMN1 gene therapyZolgensma · Itvisma

Add-on muscle therapyIsembyld

Five drugs are FDA-approved for spinal muscular atrophy. Four raise the missing SMN protein: Spinraza, injected into the spinal fluid 3 times a year after loading doses; Evrysdi, a daily liquid or tablet taken at home; and 2 forms of the one-time gene therapy onasemnogene, Zolgensma by IV infusion for children under 2 and Itvisma by spinal injection for people 2 and older. The fifth, Isembyld, approved September 11, 2026, is an infusion every 4 weeks that targets muscle and is only used on top of Spinraza or Evrysdi. The trials measured different motor scales in different ages, so their results are not a ranking.

Side by side

5 approved spinal muscular atrophy treatments at a glance

How each drug is given, how often, who it is approved for and when it was first approved, from the current FDA label.

Spinal Muscular Atrophy treatments compared: route, schedule, approved use and approval date
Drug	How it is given	How often	Approved for	First approved
Isembyld apitegromab-mstn Scholar Rock	IV infusion over 1 to 2 hours, every 4 weeks, on top of Spinraza or EvrysdiAbout 90 minutes per dose	10 mg/kg IV once every 4 weeks, infused over about 60 to 120 minutes	Adults and children 2 and older with SMA who are already taking an SMN2-targeted treatment (Spinraza or Evrysdi); it is an add-on, not a standalone treatment	September 11, 2026
Spinraza nusinersen Biogen	Injection into the spinal fluid (lumbar puncture) by a specialist, 3 times a year after loading dosesAbout 3 minutes per dose	Low dose: 4 loading doses of 12 mg (days 0, 14, 28, 58), then 12 mg every 4 months. High dose (added 03/2026): 2 loading doses of 50 mg 14 days apart, then 28 mg every 4 months	SMA in children and adults (all ages and types)	December 23, 2016
Zolgensma onasemnogene abeparvovec-xioi Novartis Gene Therapies	One-time IV infusion over 60 minutes at a hospital, with 2 months or more of steroidsAbout 60 minutes per dose	Single dose of 1.1 x 10^14 vg/kg IV over 60 minutes; oral prednisolone 1 mg/kg/day starting the day before, for 30 days, then tapered over 28 days or longer	Children under 2 years with SMA and bi-allelic SMN1 mutations	May 24, 2019
Itvisma onasemnogene abeparvovec-brve Novartis Gene Therapies	One-time injection into the spinal fluid (lumbar puncture) at a hospital, with 2 months or more of steroidsAbout 2 minutes per dose	Single fixed dose of 1.2 x 10^14 vg by intrathecal bolus over 1 to 2 minutes; oral prednisolone 1 mg/kg/day starting the day before, for 30 days, then tapered over 28 days or longer	Children 2 and older, teens and adults with SMA and a confirmed SMN1 mutation	November 24, 2025
Evrysdi risdiplam Genentech (Roche)	Daily liquid by mouth; a 5 mg tablet is available for people 2 and older weighing 20 kg or more	Once daily with or without food: 0.15 mg/kg under 2 months, 0.2 mg/kg from 2 months to under 2 years, 0.25 mg/kg from age 2 if under 20 kg, 5 mg (solution or tablet) if 20 kg or more	SMA in children and adults (all ages, including newborns)	August 7, 2020

The calendar

A year on each spinal muscular atrophy treatment

Every dose in a year, drawn to the label schedule, so the difference between a daily pill and a twice-yearly infusion is the picture.

Isembyld

Infusion

13 doses a year

Spinraza

Injection, at a clinic

3 doses a year

Zolgensma

One-time gene therapy, at a clinic

Given once

Itvisma

One-time gene therapy, at a clinic

Given once

Evrysdi

By mouth, at home

365 doses a year

Counts follow the label schedule for a full year on the maintenance dose. Drugs given in cycles or adjusted to blood tests have no fixed count, so their schedule is written out instead.

The evidence

What the pivotal spinal muscular atrophy trials showed

The primary result from the trial each FDA approval rests on, as reported on the label.

Before you compare

How to read the spinal muscular atrophy trial results

1
The motor results use different scales and ages
Infant trials report the share reaching milestones such as sitting; later-onset trials report point changes on the HFMSE or MFM32 scales. Zolgensma's trial was single-arm against natural history; the others had sham or placebo groups.
2
Zolgensma and Itvisma are the same gene therapy in 2 products
Someone who has had Zolgensma should not receive Itvisma. Both carry a boxed warning for liver injury and require 2 months or more of steroids.
3
Isembyld is not an alternative to the others
Its trial added it to Spinraza or Evrysdi and compared against those drugs alone. Spinraza's label added a higher-dose regimen in March 2026, tested against a historical sham group rather than the standard dose.

Spinal Muscular Atrophy pivotal trial results by drug
Drug	Pivotal trial	Primary result
Isembyld apitegromab-mstn Scholar Rock	SAPPHIRE (Study 1), 188 people aged 2 to 21; main efficacy group 103 children aged 2 to 12 Trial record or paper	HFMSE motor score rose 1.0 point on Isembyld vs fell 1.2 on placebo at 1 year (2.2-point difference, n=53 vs 50); 34% vs 14% gained 3 or more points
Spinraza nusinersen Biogen	Study 1 (ENDEAR), 121 infants; Study 2 (CHERISH), 126 children aged 2 to 12; Study 4 (DEVOTE) for the high dose, 75 infants Trial record or paper	ENDEAR: 51% of infants reached a HINE-2 motor milestone response vs 0% on sham (n=73 vs 37); CHERISH: HFMSE rose 3.9 points vs fell 1.0 on sham at 15 months (n=84 vs 42)
Zolgensma onasemnogene abeparvovec-xioi Novartis Gene Therapies	Study 1 (STR1VE), 21 infants; supported by Study 2 (START), 15 infants Trial record or paper	10 of 21 infants (48%) sat without support for 30 seconds or more, and 13 of 19 reached 14 months without permanent ventilation; natural history predicts no sitting and about 25% survival
Itvisma onasemnogene abeparvovec-brve Novartis Gene Therapies	STEER (Study 1), 126 people aged 2 to 17 treated (75 Itvisma, 51 sham) Trial record or paper	HFMSE motor score rose 2.39 points on Itvisma vs 0.51 on sham at 1 year (1.88-point difference, p=0.0074)
Evrysdi risdiplam Genentech (Roche)	SUNFISH Part 2 (Study 2), 180 non-ambulatory people aged 2 to 25; FIREFISH (Study 1), 62 infants Trial record or paper	SUNFISH: MFM32 motor score rose 1.36 points vs fell 0.19 on placebo at 12 months (1.55-point difference, n=120 vs 60); FIREFISH: 29% of infants (12 of 41) sat without support for 5 seconds at 12 months

Safety

Spinal Muscular Atrophy treatment side effects and warnings

Zolgensma and Itvisma carry a boxed warning, the FDA's strongest. The rest list their main precautions.

Spinal Muscular Atrophy treatments: most common side effects and key warnings from the FDA labels
Drug	Most common side effects	Key warning
Isembyld apitegromab-mstn Scholar Rock	upper respiratory tract infections 66%, vomiting 30% and cough 28%	No boxed warning. Fractures (9% vs 2% on placebo), including serious femur fractures; caution with low bone density or prior fractures.
Spinraza nusinersen Biogen	lower respiratory infection 55%, constipation 35% and teething 18%	No boxed warning. Low platelets and clotting problems (bleeding risk) and kidney toxicity; blood and urine tests required before every dose.
Zolgensma onasemnogene abeparvovec-xioi Novartis Gene Therapies	elevated liver enzymes 27% and vomiting 7%	Boxed warning Boxed warning: serious liver injury and acute liver failure, including deaths. Liver tests before and for at least 3 months after; steroids required.
Itvisma onasemnogene abeparvovec-brve Novartis Gene Therapies	upper respiratory tract infection 41%, upper gastrointestinal symptoms 27% and fever 25%	Boxed warning Boxed warning: serious liver injury. Also low platelets, peripheral sensory neuropathy (dorsal root ganglion toxicity), thrombotic microangiopathy and raised troponin.
Evrysdi risdiplam Genentech (Roche)	fever 22%, diarrhea 17% and rash 17%	No boxed warning and no Warnings and Precautions section. Label says it may harm an unborn baby based on animal data; animal data also show possible effects on male fertility.

Cost

Help paying for spinal muscular atrophy treatment

Drugmaker copay and free-drug programs, plus charity funds for the condition, checked every week.

Questions

Spinal Muscular Atrophy treatment questions people ask

Which SMA treatment can be taken at home?

Evrysdi (risdiplam), a once-daily liquid by mouth, or a 5 mg tablet for people 2 and older weighing at least 20 kg. Spinraza requires a lumbar puncture by a specialist, Zolgensma and Itvisma are one-time hospital procedures, and Isembyld is an IV infusion every 4 weeks that may be given at home in some cases.

What is the difference between Zolgensma and Itvisma?

Both deliver a working copy of the SMN1 gene once. Zolgensma, approved in 2019, is a weight-based IV infusion for children under 2. Itvisma, approved November 24, 2025, is a fixed dose injected into the spinal fluid for people 2 and older; in its trial the HFMSE motor score rose 2.39 points against 0.51 on sham at 1 year. Both carry a boxed warning for serious liver injury and need steroids for at least 2 months.

What does Isembyld do for SMA?

Isembyld (apitegromab), approved September 11, 2026, targets muscle rather than nerve. It is given by IV infusion every 4 weeks on top of Spinraza or Evrysdi, not instead of them. In its SAPPHIRE trial, the HFMSE motor score rose 1.0 point on Isembyld against a 1.2-point fall on placebo at 1 year in people aged 2 to 12. Its label warns about bone fractures, seen in 9% against 2%.

Is Spinraza or Evrysdi better?

No trial has compared them. In later-onset SMA, Spinraza's CHERISH trial reported a 4.9-point HFMSE difference against sham, 3.9 points gained against 1.0 lost, and Evrysdi's SUNFISH trial a 1.55-point MFM32 difference against placebo, on different scales in different populations. The practical difference is a lumbar puncture 3 times a year for Spinraza against a daily dose by mouth for Evrysdi.

Go deeper

More on Spinal Muscular Atrophy at Trial Friend

Sources

Where every number on this page comes from

Approved-drug facts are from the current FDA prescribing information on DailyMed, with the label's effective date. Investigational-drug facts are from ClinicalTrials.gov and the sources named in each row.

Isembyld (apitegromab-mstn) prescribing information, Scholar Rock, label dated Sep 2026. DailyMed. Pivotal trial: ClinicalTrials.gov
Spinraza (nusinersen) prescribing information, Biogen, label dated Mar 2026. DailyMed. Pivotal trial: ClinicalTrials.gov
Zolgensma (onasemnogene abeparvovec-xioi) prescribing information, Novartis Gene Therapies, label dated Jun 2026. DailyMed. Pivotal trial: ClinicalTrials.gov
Itvisma (onasemnogene abeparvovec-brve) prescribing information, Novartis Gene Therapies, label dated Jun 2026. DailyMed. Pivotal trial: ClinicalTrials.gov
Evrysdi (risdiplam) prescribing information, Genentech (Roche), label dated Feb 2026. DailyMed. Pivotal trial: ClinicalTrials.gov

This page compares what the FDA labels and pivotal trials report. It is not medical advice, and no trial on this page compared these drugs with each other. Written and checked by Jason Hunter; the method is on the editorial standards page.