Biogen (BIIB) Q1 2026 earnings review
Growth Portfolio Accelerates, but One-Time Items Mask Legacy Weakness
Biogen's Q1 2026 paints a picture of a company aggressively buying its way into a new era while artificially propping up the old one. Total revenue grew 2% YoY to $2.48B, and Non-GAAP EPS rose 18% to $3.57. However, the headline revenue beat was entirely salvaged by $59 million in favorable inventory and discount adjustments for the legacy MS drug TYSABRI. Without this channel fill, total product revenue would have contracted. The true bright spots remain the launch products: LEQEMBI in-market sales surged 74% YoY, and SKYCLARYS grew 22%. Management is leaning heavily into M&A to complete the pivot, announcing the acquisition of Apellis Pharmaceuticals and buying China rights for felzartamab. This aggressive business development comes at a steep near-term cost, driving a $1.00 cut to FY26 EPS guidance (now $14.25-$15.25).
🐂 Bull Case
The 'New Biogen' is gaining critical mass. LEQEMBI global in-market sales reached $168M (+74% YoY), SKYCLARYS hit $151M (+22% YoY), and ZURZUVAE doubled YoY to $55M. These assets are finally proving capable of anchoring the top line.
The proposed acquisition of Apellis Pharmaceuticals adds commercialized assets in retinal diseases and nephrology. Combined with the TJ Biopharma deal for felzartamab in China, Biogen is rapidly diversifying away from high-risk neuroscience. Apellis is expected to be accretive by 2027.
🐻 Bear Case
The legacy MS franchise posted $958M in revenue (flat YoY), but this was heavily skewed by $40M in US discount/inventory benefits and $19M in ex-US inventory timing for TYSABRI. Without these one-offs, the MS core is eroding rapidly.
The strategic pivot is expensive. FY26 Non-GAAP EPS guidance was slashed by $1.00 (from a $15.75 midpoint to $14.75) due to acquired IPR&D charges from aggressive dealmaking. This guidance does not even include the upcoming financial impacts of the Apellis transaction.
⚖️ Verdict: ⚪
Neutral. The long-term thesis is improving with the Apellis acquisition and strong launch metrics for LEQEMBI and SKYCLARYS. However, the near-term financials are messy, characterized by low-quality legacy revenue beats and persistent EPS dilution from business development.
Key Themes
Strategic Pivot via Apellis Acquisition
Biogen announced its intent to acquire Apellis Pharmaceuticals, a massive step in diversifying into immune-mediated retinal diseases and nephrology. This bolsters the foundation laid by felzartamab (kidney disease). Management expects the deal to materially increase the Non-GAAP EPS CAGR through the end of the decade, making it the cornerstone of the company's mid-term growth strategy.
LEQEMBI and SKYCLARYS Hitting Stride
The core launch products are accelerating. LEQEMBI global in-market sales reached $168M, up 74% YoY, showing strong real-world persistence (~78% of patients remain on therapy at 18 months). SKYCLARYS continues a steady climb, hitting $151M (+22% YoY) driven by global demand.
MS Franchise Propped Up by One-Offs
At first glance, the Multiple Sclerosis segment stabilized, posting $958M (flat YoY). However, TYSABRI's $441.5M print included $59M in favorable channel dynamics ($40M U.S. discount/inventory adjustments and $19M ex-U.S. inventory timing). Deducting this, the MS portfolio continues its structural, double-digit deceleration.
SPINRAZA Revenue Reversing
SPINRAZA global revenue fell 12% YoY to $374M. While management attributed the ex-U.S. weakness to the timing of shipments, the asset is clearly struggling against convenient oral competitors and gene therapies. The recent FDA approval of the High Dose Regimen is critical, but it remains to be seen if it can halt the decline.
ZURZUVAE Sequential Contraction
Despite posting a headline-grabbing 100% YoY growth number ($55M vs $28M), ZURZUVAE revenue actually contracted sequentially from $65.7M in 25Q4. Management blamed 'inventory dynamics,' but investors will need to monitor if the OB-GYN prescriber expansion has hit a near-term ceiling.
Pipeline Delivering Clinical Validation
The late-stage pipeline is showing signs of life. Litifilimab posted a second positive Phase 2 dataset in Cutaneous Lupus Erythematosus (CLE), showing meaningful disease reduction at 16 weeks. Salanersen also reported unprecedented Phase 1b data in SMA children who had suboptimal responses to prior gene therapy.
Other KPIs
Accelerating significantly from $222M in the prior year period. Operating cash flow was strong at $646M, aided by the acceleration of contract manufacturing activity. This provides crucial liquidity to fund the ongoing string of business development acquisitions.
Up 13% YoY. The increase was deliberately driven by heightened investments in late-stage pipeline programs, specifically litifilimab and felzartamab, aligning with management's strategy to pivot toward immunology and nephrology.
While lower than the massive $201M recorded in 25Q1, IPR&D charges remain a constant drag on profitability. Management expects another $0.80 per share hit in Q2 alone from the TJ Biopharma felzartamab deal and other milestones.
Guidance
Stable. Management reiterated their expectation that total revenue will decline versus 2025, driven by the structural erosion of the legacy MS franchise out-pacing the rapid growth of the new launch portfolio.
Decelerating. Guidance was cut by $1.00 from the prior range of $15.25-$16.25. The entirety of this cut is attributed to acquired IPR&D charges (including $0.55 from the TJ Biopharma deal). This notably excludes any potential impacts from the pending Apellis transaction, meaning further adjustments are highly likely in Q2.
Key Questions
MS Underlying Run-Rate
TYSABRI benefited from $59M in favorable discount and inventory adjustments this quarter. Excluding these one-time items, what is the true underlying erosion rate of the MS franchise, and when do you expect it to bottom?
ZURZUVAE Inventory Dynamics
ZURZUVAE sales fell sequentially from Q4 to Q1 due to 'inventory dynamics.' Can you quantify the specific dollar impact of the inventory drawdown, and does Q2 represent a clean reflection of end-user demand?
Apellis Integration and Margin Impact
With the Apellis acquisition expected to be accretive by 2027, how much margin dilution should investors expect in the back half of 2026 as you integrate their commercial infrastructure with your nephrology pipeline?
SPINRAZA Competitive Defense
SPINRAZA revenue declined 12% YoY. How much of this is strictly shipment timing versus actual market share loss, and how quickly can the newly approved High Dose Regimen shift the momentum?