Treatment-naïve infants with SMA receiving Biogen’s higher-dose nusinersen regimen achieved a 26.19-point advantage on CHOP-INTEND versus a prespecified matched sham cohort from ENDEAR (+15.1 vs -11.1; p<0.0001). In switchers aged 4–65 who moved from 12 mg to the higher dose after a median 3.9 years, mean gains at Day 302 were +1.8 on HFMSE and +1.2 on RULM. Neurofilament declined more rapidly than with 12 mg, and safety was broadly consistent with the known profile; in the 50-participant infantile-onset cohort, common AEs included pneumonia, respiratory failure, pyrexia, COVID-19, and URTI, with serious events most often pneumonia (including aspiration) and respiratory failure. The core development is publication in Nature Medicine of Phase 2/3 DEVOTE results evaluating a higher-dose regimen of intrathecal nusinersen: two 50 mg loading doses 14 days apart followed by 28 mg maintenance every four months, versus the established 12 mg schedule. DEVOTE enrolled 139 participants across SMA types. Part B data in symptomatic infants favored higher-dose over matched sham across primary and secondary measures and trended better than 12 mg on key biomarker and efficacy readouts. Part C showed functional improvement after transitioning from 12 mg. The high-dose regimen is already approved in the EU and Japan and is under FDA review with a PDUFA action date of April 3. Strategically, this is a lifecycle extension and defense of the SPINRAZA franchise against oral risdiplam and one-time gene therapy. Biogen is leaning on a tighter loading schedule and higher maintenance exposure to argue for faster neuroprotection and incremental functional benefit, while keeping the maintenance interval at four months. The program also reflects pragmatic trial design in a rare pediatric disease: leveraging a historical control from ENDEAR rather than running a head-to-head against the 12 mg regimen reduced timelines and operational complexity, at the cost of interpretability. The emphasis on neurofilament as a pharmacodynamic anchor fits a broader regulatory shift toward biomarker-supported evidence when conventional randomized comparators are impractical. For sites, the operational calculus changes at the margins. Two loading procedures instead of four could ease early procedural burden and scheduling pressure in neuraxial suites, particularly for sedated infants. However, intrathecal delivery logistics, anesthesia availability, and respiratory risk management remain unchanged, and the per-injection volume (5 mL) and dose increase will require pharmacy, handling, and supply chain updates. Sponsors and CROs should anticipate a wave of transition patients if the U.S. label is updated, with corresponding needs for standardized switch protocols, lab monitoring, and documentation workflows. Payers will scrutinize the magnitude of clinical benefit in older and previously treated populations, where effect sizes were modest, and may push for outcomes-based arrangements or step edits against oral therapy. The next catalyst is the FDA decision and the granularity of any U.S. label—particularly transition language, biomarker claims, and postmarketing commitments. Absent randomized data versus 12 mg, regulators could require additional confirmatory evidence or real-world analyses to substantiate superiority claims, especially beyond infantile-onset disease. Adoption will hinge on whether the higher dose meaningfully shifts functional trajectories in later-onset cohorts and whether sites can capitalize on the simplified loading to improve throughput. Watch for registry updates on neurofilament dynamics as a practical monitoring tool, manufacturing scale-up of the 50 mg and 28 mg presentations, and payer coverage policies that will determine how quickly switch demand translates into procedure volume at centers.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
