Biogen Shares Drop 6.4% After CELIA Trial Data Misses Key Endpoint
Written by Emily J. Thompson, Senior Investment Analyst
Updated: May 15 2026
0mins
Source: PRnewswire
- Trial Setback: Biogen's shares fell 6.4% on May 14, 2026, after the CELIA trial data failed to meet its primary dose-response endpoint, resulting in significant losses for investors and a decline in market confidence.
- Future Development Plans: Despite the setback, Biogen intends to advance diranersen to registrational development based on biomarker and efficacy data, indicating the company's belief in the drug's long-term potential.
- Legal Investigation Initiated: Following the disappointing trial results, Levi & Korsinsky law firm has launched an investigation into Biogen, focusing on whether the company made misleading statements that could affect investors' legal rights.
- Investor Action Recommendations: Affected investors are encouraged to gather trading records and contact Levi & Korsinsky for a free evaluation to understand potential legal remedies, ensuring their rights are protected.
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Analyst Views on BIIB
Wall Street analysts forecast BIIB stock price to rise
26 Analyst Rating
11 Buy
14 Hold
1 Sell
Moderate Buy
Current: 196.390
Low
143.00
Averages
204.45
High
246.00
Current: 196.390
Low
143.00
Averages
204.45
High
246.00
About BIIB
Biogen Inc. is a biotechnology company. The Company is focused on discovering, developing and delivering therapies. It has a portfolio of medicines to treat Multiple Sclerosis (MS), has introduced an approved treatment for Spinal Muscular Atrophy (SMA), co-developed treatments to address a defining pathology of Alzheimer's disease and launched an approved treatment to target a genetic cause of Amyotrophic Lateral Sclerosis (ALS). It markets a drug approved in United States, European Union and certain international markets for the treatment of Friedreich Ataxia (FA) in adults and adolescents aged 16 years and older. It is focused on advancing its pipeline in neurology, specialized immunology and rare diseases. Its marketed products include VUMERITY, TYSABRI, TECFIDERA, AVONEX and PLEGRIDY for the treatment of MS; SPINRAZA for the treatment of SMA; SKYCLARYS for the treatment of FA, and QALSODY for the treatment of ALS. Its commercialized products also include EMPAVELI and SYFOVRE.
About the author
Emily J. Thompson
Emily J. Thompson, a Chartered Financial Analyst (CFA) with 12 years in investment research, graduated with honors from the Wharton School. Specializing in industrial and technology stocks, she provides in-depth analysis for Intellectia’s earnings and market brief reports.
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- Antitrust Action Details: Officials from Italy's antitrust authority and the Special Antitrust Unit of the Italian Financial Police conducted inspections at Biogen's Italian premises on Tuesday, reflecting the regulator's serious commitment to ensuring competition in the pharmaceutical market.
- Market Impact: Following Biogen's loss of exclusivity for Tysabri (natalizumab) in 2024, Sandoz introduced a low-cost biosimilar, with the regulator noting that Biogen's actions may have prevented Italy's National Health Service from realizing at least 20% in cost savings associated with biosimilars.
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- Market Reaction: Following the release of the CELIA trial data, Biogen's stock experienced a sharp decline on heavy trading volume, reflecting investor concerns about the company's future prospects, especially given management's previous confidence expressed during the Q1 2025 earnings call.
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- Market Dominance Investigation: The Italian Competition Authority has launched an investigation into Biogen (BIIB) for allegedly abusing its dominant position to hinder Sandoz (SDZXF) from selling a competing multiple sclerosis medication, raising concerns about unfair market practices.
- Antitrust Action Details: Officials from Italy's antitrust authority and the Special Antitrust Unit of the Italian Financial Police conducted inspections at Biogen's Italian premises on Tuesday, reflecting the regulator's serious commitment to ensuring competition in the pharmaceutical market.
- Market Impact: Following Biogen's loss of exclusivity for Tysabri (natalizumab) in 2024, Sandoz introduced a low-cost biosimilar, with the regulator noting that Biogen's actions may have prevented Italy's National Health Service from realizing at least 20% in cost savings associated with biosimilars.
- Cooperation Statement: Biogen stated it is
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- Trial Failure: On May 14, 2026, Biogen disclosed that its CELIA trial for diranersen failed to meet its primary dose-response endpoint, resulting in a 6.4% drop in stock price and billions in market value loss, indicating a market reassessment of the company's near-term pipeline value.
- Investor Losses: Many investors, particularly those who purchased Biogen shares at higher prices, are facing significant losses and may be eligible to participate in legal investigations aimed at recovering damages related to the trial's disappointing results.
- Market Reaction: Following the release of the CELIA trial data, Biogen's stock experienced a sharp decline on heavy trading volume, reflecting investor concerns about the company's future prospects, especially given management's previous confidence expressed during the Q1 2025 earnings call.
- Legal Investigation Initiated: The law firm Levi & Korsinsky has launched an investigation into whether Biogen made materially false or misleading statements regarding its pipeline prospects and the status of the CELIA trial, encouraging investors to gather trading records to participate in potential legal actions.
See More
Biogen and Denali Halt Development of Parkinson's Drug BIIB122
- Trial Setback: Biogen (BIIB) and Denali (DNLI) announced the discontinuation of BIIB122 after their Phase 2b LUMA study for early-stage Parkinson's disease failed to meet primary and secondary endpoints, marking a significant setback in their drug development efforts.
- Mechanism Exploration: BIIB122 was designed to inhibit the LRRK2 mutation associated with Parkinson's disease; despite the disappointing results, Denali's medical chief, Peter Chin, emphasized the need for further exploration of LRRK2 as a potential therapeutic target, indicating future research directions.
- Continued Research: Denali will proceed with its Phase 2a BEACON study for BIIB122 in LRRK2-associated Parkinson's disease, which is expected to generate data in H1 2027, potentially providing new insights into treatment options in this area.
- Market Reaction: Following the announcement, shares of Biogen and Denali fell in premarket trading on Friday, reflecting investor concerns about the companies' prospects in the neurodegenerative disease space, which may impact future funding and R&D investments.
See More
Biogen and Denali Discontinue BIIB122 for Parkinson's Disease
- Clinical Trial Results: Biogen and Denali's BIIB122 did not meet primary and secondary endpoints in the LUMA study, leading to the decision to discontinue its development for idiopathic Parkinson's disease, indicating the drug's ineffectiveness in slowing disease progression.
- Study Participation: The LUMA trial enrolled 648 adults aged 30 to 80 with early-stage Parkinson's disease, with participants receiving either BIIB122 or placebo for 48 to 144 weeks, designed to test whether LRRK2 inhibition could improve underlying disease biology.
- Biomarker Data: Despite the lack of clinical efficacy, exploratory biomarker data confirmed over 90% inhibition of peripheral LRRK2 activity and a 30% reduction in cerebrospinal fluid biomarkers in a sub-study, suggesting potential biological mechanisms for the drug.
- Future Research Directions: While BIIB122 will no longer be pursued for idiopathic Parkinson's disease, Denali will continue its independent Phase 2a BEACON study evaluating the same drug in individuals with pathogenic LRRK2 variants, with data expected in the first half of 2027.
See More
Biogen and Denali Halt Development of Parkinson's Drug BIIB122
- Clinical Trial Results: Biogen and Denali's LUMA study revealed that BIIB122 did not slow disease progression compared to placebo, with the primary endpoint failing to meet expectations, indicating significant shortcomings in the drug's therapeutic efficacy.
- Biomarker Analysis: Although exploratory biomarker data confirmed over 90% peripheral LRRK2 kinase inhibition, cerebrospinal fluid analysis showed only a 30% reduction in phosphorylated Rab10, failing to substantiate the drug's clinical effectiveness.
- Safety Assessment: BIIB122 maintained stable drug levels in blood and cerebrospinal fluid, and was generally well tolerated, with safety data indicating no severe adverse reactions during short-term use.
- Future Plan Adjustments: Based on the trial results, Biogen and Denali decided to discontinue further development of BIIB122 in idiopathic Parkinson's disease, while Denali will independently continue with the Phase 2a BEACON study targeting carriers of pathogenic LRRK2 variants.
See More
