Biogen's Higher-Dose Spinraza: A Catalyst for SMA Dominance and BIIB's Next Growth Phase

The field of spinal muscular atrophy (SMA) treatment is on the cusp of a paradigm shift, and Biogen (NASDAQ: BIIB) stands at the forefront with its higher-dose nusinersen regimen. Recent clinical data from the DEVOTE trial and NURTURE study reveal transformative potential for SPINRAZA, the company's cornerstone therapy. These advancements not only enhance the drug's efficacy but also position Biogen to solidify its leadership in a market projected to grow rapidly. For investors, the near-term regulatory review of this regimen could unlock significant value, while the long-term implications for revenue and valuation multiples are equally compelling.

Clinical Data: A Quantum Leap in Efficacy

The higher-dose regimen—comprising two 50 mg loading doses followed by 28 mg maintenance—delivers statistically significant improvements over the standard 12 mg SPINRAZA. In the DEVOTE trial's Part B, treatment-naïve patients with infantile-onset SMA showed a 26.19-point improvement in CHOP-INTEND scores versus a sham control (p <0.0001). This metric, which assesses motor function, underscores the regimen's ability to halt or reverse disease progression. Even more striking was the 94% reduction in neurofilament light chain (NfL)—a biomarker of neurodegeneration—versus just 30% in the control group. These results suggest the higher dose not only improves motor outcomes but also slows neuronal damage, a critical differentiator in SMA therapies.

Part C of the trial, which evaluated patients transitioning from the standard dose, revealed further gains. Non-ambulatory participants improved by +2.5 points on the HFMSE scale, while ambulatory patients saw a +1.1-point increase. These findings are particularly impactful given that participants had already been on SPINRAZA for nearly four years. As Dr. Richard Finkel noted, this suggests “additional gains in function might be possible even in those with established disease.” For Biogen, this data opens the door to expanding SPINRAZA's label to include dose optimization for long-term patients—a population numbering over 14,000 globally.

The NURTURE study's eight-year follow-up reinforces the importance of early intervention. 92% of presymptomatic infants achieved independent walking, with none requiring permanent ventilation. This outcome, paired with the higher-dose data, positions SPINRAZA as the gold standard for both early and late-stage SMA management.

Regulatory Timeline: A Near-Term Catalyst

The FDA and EMA accepted Biogen's applications for the higher-dose regimen in January 2025, with reviews expected to conclude by mid-2026. However, the FDA's priority review designation for SPINRAZA historically accelerates timelines, and the robust clinical data could prompt an earlier approval. A positive decision would immediately expand SPINRAZA's addressable market:

• Untreated patients: Approximately 50% of SMA patients globally remain untreated due to delayed diagnoses or lack of access. The higher-dose's faster loading phase (two doses over 14 days vs. four doses over 60 days for the standard regimen) could simplify administration, improving uptake.
• Re-treatment opportunities: The regimen's potential to enhance outcomes in existing patients creates a recurring revenue stream, as many have been on SPINRAZA for years without dose adjustments.

Market Leadership: Outpacing Competitors

Biogen faces competition from Roche's risdiplam (Evrysar) and Pfizer'sonasemnogene abeparvovec (Zolgensma). However, the higher-dose SPINRAZA's dual advantages—superior motor function improvements and a proven safety profile—could widen Biogen's lead. Risdiplam, an oral therapy, lacks the NfL reduction data seen in DEVOTE, while Zolgensma's gene therapy approach is limited to younger patients. SPINRAZA's flexibility across all SMA types and ages, combined with the new regimen's efficacy, strengthens its value proposition.

Analysts estimate the SMA market could reach $3.5 billion by 2030. Biogen's current SPINRAZA sales of $1.2 billion annually (as of 2024) suggest significant upside if the higher-dose gains approval. A successful launch could lift revenue to $1.8–2.0 billion by 2027, with margins expanding due to reduced dosing frequency.

Investment Thesis: Why BIIB Is Poised to Rise

The higher-dose approval is a binary event with outsized potential. Even a delayed approval would not negate its long-term value, as Biogen's existing patient base and pipeline (e.g., gene therapies) provide stability. Key catalysts include:

1. Regulatory decisions (H2 2025–H1 2026): Positive outcomes could trigger a 15–20% stock surge.
2. Real-world evidence: Biogen's ability to demonstrate sustained benefits in post-approval studies could drive pricing power and reimbursement.
3. Global market expansion: Applications in Japan and Europe, if approved, would accelerate international adoption.

Current valuations reflect skepticism around Biogen's growth trajectory post-patent cliffs. However, SPINRAZA's new regimen could reposition BIIB as a growth stock. Analysts' median price target of $196 (a 25% premium to current levels) assumes approval, but upside exists if revenue estimates exceed expectations.

Risks and Considerations

• Regulatory hurdles: While the data is robust, agencies may request additional data on long-term safety or pediatric efficacy.
• Competitor actions: Roche and Pfizer may accelerate label expansions or pricing strategies.
• Operational execution: Biogen must ensure smooth supply chain management and physician education for the new dosing regimen.

Conclusion: A Buy on the Cusp of Transformation

Biogen's higher-dose nusinersen regimen is not just an incremental improvement—it represents a leap toward curative potential in SMA. With regulatory decisions imminent and a widening competitive advantage, BIIB is primed for a valuation reset. Investors seeking exposure to a rare disease leader with a clear catalyst should consider accumulating shares ahead of the FDA's decision. The next 12–18 months could cement SPINRAZA's legacy and Biogen's dominance in one of biotech's most promising markets.