Attaching cell-penetrating peptides to antisense drugs may solve the major delivery challenge facing spinal muscular atrophy treatments like nusinersen.
~90% defectiveAbout 90% of the protein produced by the SMN2 backup gene is non-functional, which is why SMA patients need therapy to correct the gene's output
What the researchers found
Nusinersen (Spinraza), the first FDA-approved antisense therapy for spinal muscular atrophy, faces significant delivery challenges because it must be injected directly into the spinal canal. Peptide-conjugated phosphorodiamidate morpholino oligomers (PPMOs) — antisense drugs linked to cell-penetrating peptides like Pip and DG9 — offer a potential solution by improving both intracellular uptake and systemic distribution.
The review traces how SMA is caused by mutations in the SMN1 gene, leaving patients dependent on the backup SMN2 gene that produces mostly non-functional protein (~90% defective). Antisense therapy corrects SMN2 splicing to produce functional SMN protein, but getting the drug into motor neurons throughout the body remains the central challenge that peptide conjugation aims to solve.
Why it matters
Spinal muscular atrophy is the most common genetic cause of death in infants. While nusinersen was a breakthrough, its requirement for repeated intrathecal injections (directly into the spinal fluid) limits accessibility and comfort. Cell-penetrating peptides attached to antisense drugs could enable systemic delivery — potentially turning a spinal injection into a simpler intravenous treatment.
The numbers in context
~90% of SMN2 protein is non-functional · FDA approved nusinersen 2016 · EMA approved 2017
How the study worked
Narrative review covering the history, development milestones, current therapeutic approaches, and emerging peptide-conjugated delivery strategies for antisense therapy in spinal muscular atrophy.
Who was studied
Patients with spinal muscular atrophy, particularly infants and children with SMN1 gene mutations
What this study cannot tell us
As a narrative review, this paper summarizes existing research without performing quantitative analysis. PPMOs for SMA are still largely preclinical, so the delivery advantages described are based on early-stage data rather than completed clinical trials.
How to read the evidence
This is a narrative review summarizing the current state of antisense therapy for SMA and the emerging potential of peptide-conjugated delivery. While it provides a comprehensive overview, PPMO approaches for SMA are still largely preclinical.
When this study was published
Published in 2023 in the European Journal of Cell Biology. The review captures the current state of SMA treatment and emerging PPMO technologies, making it relatively recent and relevant.
The bigger picture
Cell-penetrating peptides are emerging as a key technology for delivering large therapeutic molecules that can't easily cross cell membranes on their own. SMA represents one of the most compelling use cases: the antisense drug works, but getting it where it needs to go remains the bottleneck. PPMOs could transform not just SMA treatment but the entire antisense therapy field by solving the delivery problem that limits many gene-targeting drugs.
Questions still open
- How do PPMOs compare to gene therapy approaches like onasemnogene (Zolgensma) for long-term SMA outcomes?
- Which cell-penetrating peptide sequences show the best balance of delivery efficiency and safety in preclinical models?
- Could PPMO technology be applied to antisense therapies for other neuromuscular diseases like Duchenne muscular dystrophy?
Common questions
What is nusinersen and why does it need to be injected into the spine?
How could peptides improve SMA treatment?
Read the original research
Challenges and future perspective of antisense therapy for spinal muscular atrophy: A review.
European journal of cell biology, 102(2), 151326
Citation
Nakevska, Zorica; Yokota, Toshifumi. (2023). Challenges and future perspective of antisense therapy for spinal muscular atrophy: A review.. European journal of cell biology, 102(2), 151326. https://doi.org/10.1016/j.ejcb.2023.151326