ISEMBYLD has a well-established safety and tolerability profile
ISEMBYLD has a well-established safety and tolerability profile1,2
Adverse reactions reported in ≥20% of patients and more frequent than placebo1
| ADVERSE REACTION* | ISEMBYLD 10 mg/kg (n=53) | PLACEBO (n=50) |
| Upper respiratory tract infectionsa | 66% | 54% |
| Vomiting | 30% | 16% |
| Cough | 28% | 22% |
| Other viral infectionsb | 26% | 16% |
| Headache | 23% | 16% |
| Gastroenteritisc | 23% | 8% |
| Pharyngitisd | 21% | 14% |
| Hypersensitivitye | 21% | 16% |
99%
of children and adults completed the phase 3 study1,†
0
study withdrawals due to adverse events2
ISEMBYLD may increase the risk of fractures, including serious fractures. Use with caution in patients with a history of low bone density or multiple fractures. In patients who experience fractures, weigh the risks and benefits of continuing ISEMBYLD.
*All AEs were coded using the MedDRA version 26.1.
†Patient study population aged 2-21 years.
aIncludes nasopharyngitis, rhinovirus infection, sinusitis, viral upper respiratory tract infection, upper respiratory tract infection, nasal congestion, rhinorrhea, rhinitis. bIncludes metapneumovirus infection, parvovirus B19 infection, COVID-19, respiratory syncytial virus infection, respiratory syncytial virus bronchiolitis, influenza, parainfluenzae, adenovirus, respiratory tract infection viral, and viral infection. cIncludes other similar terms. dIncludes pharyngitis, pharyngitis streptococcal, oropharyngeal pain. eIncludes dermatitis acneiform, dermatitis atopic, eczema, flushing, rash, rash maculo-papular, urticaria.
The ongoing open-label extension study and Expanded Access Program are increasing clinical experience
ONYX EXTENSION STUDY
98%
of patients in the phase 3 study continued into the extension study2
Study Population: Children and adults living with SMA who have completed TOPAZ or SAPPHIRE3
Purpose: Open-label phase 3 extension, capturing additional safety (primary outcome) and efficacy3
EXPANDED ACCESS PROGRAM3,*,†
AGES
2-72
Patients aged 2 to 72 years received treatment with ISEMBYLD in the Expanded Access Program
*As of April 2026; value includes patients and healthy volunteers.
†The pivotal study of ISEMBYLD included patients aged 2-21 years.
‡Clinical studies of ISEMBYLD did not include patients aged 65 years and older to determine whether they respond differently from younger patients.
916
patient-years of experience in the ISEMBYLD clinical trial program (including TOPAZ, SAPPHIRE, and ONYX)3,*
patient-years of experience in the ISEMBYLD clinical trial program (including TOPAZ, SAPPHIRE, and ONYX)3,*
DOSING
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RELATED FAQ
What is the ISEMBYLD safety profile?
The safety and tolerability profile of ISEMBYLD is well established. There were zero study withdrawals due to adverse events in the phase 3 SAPPHIRE study. The most common adverse reactions (incidence ≥20% of patients treated with ISEMBYLD and more frequent than placebo) were upper respiratory tract infections, vomiting, cough, other viral infections, headache, gastroenteritis, pharyngitis, and hypersensitivity.1,2
ISEMBYLD may increase the risk of fractures, including serious fractures. Use with caution in patients with a history of low bone density or multiple fractures. In patients who experience fractures, weigh the risks and benefits of continuing ISEMBYLD.
References:
1. ISEMBYLD. Prescribing information. Scholar Rock, Inc; 2026. 2. Crawford TO, Servais L, Mercuri E, et al. Safety and efficacy of apitegromab in nonambulatory type 2 or type 3 spinal muscular atrophy (SAPPHIRE): a phase 3, double-blind, randomised, placebo-controlled trial. Lancet Neurol. 2025;24(9):727-739. 3. Data on file. Scholar Rock, Inc. Cambridge, MA.