- BIIB Advances Alzheimer's Disease Drug Despite Study Missing Main Goal
May 15, 2026
Shares of Biogen BIIB declined more than 6% yesterday after the company announced that it would move its experimental tau-targeting Alzheimer’s disease (AD) drug, diranersen, into late-stage development despite the phase II CELIA study missing its primary endpoint.
The primary endpoint of the CELIA study assessed the dose response for change from baseline at week 76 on the Clinical Dementia Rating–Sum of Boxes (CDR-SB) score, a widely used clinical scale that measures cognitive and functional decline in AD patients.
Although the study did not demonstrate the expected dose-dependent clinical benefit, pre-specified analyses of cognitive endpoints showed a reduction in clinical decline across all studied doses, particularly in participants receiving the lowest drug dose (60mg). Per Biogen, treatment with diranersen led to ‘robust reductions’ in both cerebrospinal fluid (CSF) tau and tau pathology across all studied doses, with reductions maintained throughout the dosing period. The drug’s safety profile was also consistent with findings from a previously conducted phase Ib study.
BIIB’s Stock Performance
While the biomarker and cognitive trends were viewed as encouraging by some investors despite the primary endpoint miss, the lack of detailed supporting data appeared to limit broader market enthusiasm. Investors were also disappointed that Biogen did not disclose a timeline for initiating the late-stage development program for diranersen.
Diranersen remains among the more advanced tau-targeting therapies currently in development for AD, an area many researchers believe could complement existing amyloid-focused treatments or potentially provide improved disease-modifying benefits.
Shares of Biogen have risen 9% year to date compared with the industry’s 1% growth.Zacks Investment Research
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Biogen Bets on Tau in Next Phase of AD Drug Development
Diranersen marks Biogen’s latest effort to expand its AD portfolio beyond amyloid-targeting therapies. This drug is being developed in collaboration with Ionis Pharmaceuticals IONS.
Biogen currently markets AD therapy Leqembi alongside Eisai and previously withdrew Aduhelm following controversy surrounding its regulatory approval and commercial rollout. Unlike those therapies, which target amyloid-beta plaques, diranersen is designed to reduce the production of tau, which is strongly linked to AD progression and cognitive decline.
Another marketed amyloid-targeting AD therapy is Eli Lilly’s LLY Kisunla. Eli Lilly is also developing experimental candidates targeting tau as interest in alternative AD mechanisms continues to grow across the industry.
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BIIB’s Zacks Rank
Biogen currently carries a Zacks Rank #3 (Hold). You can see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.
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- BIIB Advances Alzheimer's Disease Drug Despite Study Missing Main Goal
May 15, 2026 · zacks.com
Biogen advances Alzheimer's drug diranersen to late-stage trials after a phase II study misses its main goal but shows cognitive and biomarker gains.
- Biogen Is Celebrating A First In Alzheimer's Disease. But Investors Are Leery.
May 14, 2026
Biogen unveiled mixed results Thursday for its tau-targeting Alzheimer's treatment, leading the stock to drop.
Continue Reading
- Biogen Moves Alzheimer’s Drug to Late-Stage Trials. Wall Street Thinks It’s a Mistake.
May 14, 2026
Biogen’s diranersen showed ‘robust reductions’ in key biomarkers during a Phase 2 trial, the biotech said.
Continue Reading
- Ionis partner Biogen announces topline results from Phase 2 CELIA study of diranersen (BIIB080): first study to show reduction in tau pathology and cognitive benefit in patients with early Alzheimer’s disease
May 14, 2026
- Based on the strength of the biomarker and efficacy data, Biogen plans to advance diranersen to registrational development; CELIA did not meet its primary endpoint assessing dose response -
- Robust reductions in tau pathology were observed across all studied doses, with results generally consistent with those observed in the Phase 1b study -
- Pre-specified analyses of cognitive endpoints demonstrated slowing of clinical decline across all studied doses, particularly at the lowest dose -
- The safety and tolerability profile of diranersen was generally consistent with the Phase 1b study -
- Data will be presented at the Alzheimer’s Association International Conference (AAIC) 2026 and other upcoming scientific congresses -
CARLSBAD, Calif., May 14, 2026--(BUSINESS WIRE)--Ionis Pharmaceuticals, Inc. (Nasdaq: IONS) today announced that its partner, Biogen, shared compelling topline results from the Phase 2 CELIA study evaluating diranersen (IONIS-MAPTRx/BIIB080), an investigational antisense oligonucleotide (ASO) therapy targeting tau, in individuals with early Alzheimer’s disease (AD). The CELIA results provide the first evidence from a randomized Phase 2 study of a tau-directed therapy demonstrating both robust biomarker impact and cognitive benefit in early AD.
"We are highly encouraged by the topline results from CELIA, which underscore the potential of targeting tau to meaningfully impact patient outcomes in early Alzheimer’s disease," Holly Kordasiewicz, Ph.D., executive vice president, chief development officer, Ionis. "These findings represent an important advancement for the field and underscore the impact of Ionis’ growing neurology portfolio, which now includes 13 medicines in clinical development including six that are wholly owned. We’re proud to have discovered diranersen and are deeply grateful to everyone who made this research possible."
Pre-specified analyses of cognitive endpoints demonstrated slowing of clinical decline across all studied doses, particularly in participants receiving the lowest dose of diranersen, 60 mg administered every 24 weeks. Diranersen also demonstrated robust reductions in both cerebrospinal fluid (CSF) tau and tau pathology, as measured by positron emission tomography (PET), across all studied doses, with reductions maintained throughout the dosing period. CELIA did not meet its primary endpoint assessing dose response for change from baseline on the Clinical Dementia Rating–Sum of Boxes (CDR-SB) at Week 76.
"In CELIA, we believe we have seen an unprecedented and compelling confluence of efficacy and biomarkers results from a tau-directed agent in a randomized early Alzheimer’s disease study," said Priya Singhal, M.D., M.P.H., Executive Vice President and Head of Development at Biogen. "We are excited by these Phase 2 data, which give us the confidence to advance diranersen to registrational development. We look forward to engaging with regulators and the broader Alzheimer’s disease community on next steps. I would like to thank the patients, families, investigators, and study teams who participated in this pioneering study."
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The safety and tolerability profile of diranersen across all studied doses was generally consistent with the Phase 1b study and the known profile of diranersen to date. The incidence of adverse events (AEs) was comparable across dose groups, with a higher incidence of serious adverse events (SAEs) observed at the highest dose studied.
CELIA is a pioneering study evaluating diranersen, a first-in-class investigational ASO designed to reduce the production of tau protein at its source in early AD. While tau plays an important role in the normal function of brain cells, in AD, abnormal tau can accumulate and form intracellular tangles that contribute to neurodegeneration and cognitive decline. Unlike many investigational approaches that have focused on targeting extracellular tau, diranersen is designed to reduce both extracellular and intracellular tau.
About diranersen (IONIS-MAPTRx/BIIB080)
Diranersen (IONIS-MAPTRx/BIIB080) is an investigational antisense oligonucleotide (ASO) therapy designed to target microtubule-associated protein tau (MAPT) mRNA to reduce the production of tau protein. Abnormal accumulation of tau in the brain is a hallmark of Alzheimer’s disease (AD) associated with neurodegeneration and cognitive decline.
Diranersen is being investigated as a potential treatment for early AD. In 2025, the U.S. Food and Drug Administration (FDA) granted Fast Track designation to diranersen for the treatment of AD.
In December 2019, Biogen exercised a license option with Ionis Pharmaceuticals and obtained a worldwide, exclusive, royalty-bearing license to develop and commercialize diranersen. Diranersen was discovered by Ionis.
About the CELIA Study
CELIA is a global Phase 2 randomized, double-blind, placebo-controlled, dose-ranging study evaluating the efficacy, safety and tolerability of diranersen in individuals with early Alzheimer’s disease (AD). The study enrolled 416 participants with mild cognitive impairment due to AD or mild AD dementia. All participants enrolled in CELIA had not previously received anti-amyloid therapy.
The study evaluated three doses of diranersen administered intrathecally over a 76-week placebo-controlled treatment period: 60 mg every 24 weeks, 115 mg every 24 weeks and 115 mg every 12 weeks.
The primary endpoint of CELIA was assessment of dose response for change from baseline on the Clinical Dementia Rating–Sum of Boxes (CDR-SB) at Week 76. Secondary and exploratory endpoints included additional clinical, biomarker and imaging measures, including cerebrospinal fluid tau biomarkers and tau positron emission tomography (PET). Additional information on the CELIA study design is available in the ClinicalTrials.gov listing for the CELIA study.
An ongoing long-term extension (LTE) study is continuing to evaluate the long-term safety, tolerability and durability of diranersen in early AD.
About Ionis Neurology
Ionis has been at the forefront of discovering and developing leading neurological disease medicines, including SPINRAZA® (nusinersen), the first approved treatment for spinal muscular atrophy, WAINUA® (eplontersen), a medicine to treat hereditary transthyretin-mediated amyloid polyneuropathy (ATTRv-PN), and QALSODY® (tofersen) for SOD1-ALS. The clinical-stage portfolio includes 13 investigational medicines, of which six are wholly owned by Ionis. Ionis' investigational portfolio includes medicines for which there are few or no disease modifying treatments, such as rare diseases including Angelman syndrome, prion disease, multiple system atrophy, Huntington’s disease and Alexander disease, as well as more common conditions such as Alzheimer's disease.
About Ionis Pharmaceuticals, Inc.
For three decades, Ionis has invented medicines that bring better futures to people with serious diseases. Ionis currently has marketed medicines and a leading pipeline in neurology, cardiometabolic disease and select areas of high patient need. As the pioneer in RNA-targeted medicines, Ionis continues to drive innovation in RNA therapies in addition to advancing new approaches in gene editing. A deep understanding of disease biology and industry-leading technology propels our work, coupled with a passion and urgency to deliver life-changing advances for patients. To learn more about Ionis, visit Ionis.com and follow us on X (Twitter), LinkedIn and Instagram.
Ionis Forward-looking Statements
This press release includes forward-looking statements regarding Ionis' business and the therapeutic and commercial potential of diranersen (IONIS-MAPTRx/BIIB080), our commercial medicines, additional medicines in development and technologies and our expectations regarding development and regulatory milestones. Any statement describing Ionis' goals, expectations, financial or other projections, intentions or beliefs is a forward-looking statement and should be considered an at-risk statement. Such statements are subject to certain risks and uncertainties including those inherent in the process of discovering, developing and commercializing medicines that are safe and effective for use as human therapeutics, and in the endeavor of building a business around such medicines. Ionis' forward-looking statements also involve assumptions that, if they never materialize or prove correct, could cause its results to differ materially from those expressed or implied by such forward-looking statements. Although Ionis' forward-looking statements reflect the good faith judgment of its management, these statements are based only on facts and factors currently known by Ionis. Except as required by law, we undertake no obligation to update any forward-looking statements for any reason. As a result, you are cautioned not to rely on these forward-looking statements. These and other risks concerning Ionis' programs are described in additional detail in Ionis' annual report on Form 10-K and most recent Form 10-Q for the year ended December 31, 2025, which are on file with the Securities and Exchange Commission. Copies of these and other documents are available from the Company.
In this press release, unless the context requires otherwise, "Ionis," "Company," "we," "our" and "us" all refer to Ionis Pharmaceuticals and its subsidiaries.
Ionis Pharmaceuticals® is a trademark of Ionis Pharmaceuticals, Inc. SPINRAZA® and QALSODY® are registered trademarks of Biogen. WAINUA® is a registered trademark of the AstraZeneca group of companies.
View source version on businesswire.com: https://www.businesswire.com/news/home/20260514986673/en/
Contacts
Ionis Investor Contact:
D. Wade Walke, Ph.D.
IR@ionis.com 760-603-2331
Ionis Media Contact:
Hayley Soffer
media@ionis.com 760-603-4679
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- A Look At Ionis Pharmaceuticals (IONS) Valuation After Recent Share Price Moves
May 14, 2026
Find your next quality investment with Simply Wall St's easy and powerful screener, trusted by over 7 million individual investors worldwide.
How Ionis Pharmaceuticals Stock Has Been Trading
Ionis Pharmaceuticals (IONS) has drawn investor attention recently as the stock moved 2.3% in the latest session, with shorter term returns differing from its performance over the past 3 months and year to date.
See our latest analysis for Ionis Pharmaceuticals.
That latest move comes against a mixed backdrop, with the 30 day share price return of 3.54% contrasting with a 90 day share price return that is down 5.11%, while the 1 year total shareholder return of 138.04% points to strong longer term momentum.
If Ionis has you interested in healthcare and biotech, this could be a good time to broaden your watchlist with other potential ideas using the 33 healthcare AI stocks.
With Ionis posting a 1 year total shareholder return of 138.04% and trading at US$77.60, you have to ask: is the bulk of its future potential already reflected in the price, or is the market still underestimating what comes next?
Most Popular Narrative: 19.8% Undervalued
Compared with the latest close at $77.60, the most followed narrative pegs Ionis Pharmaceuticals' fair value meaningfully higher, which helps explain why some investors still see upside in the story.
The analysts have a consensus price target of $96.73 for Ionis Pharmaceuticals based on their expectations of its future earnings growth, profit margins and other risk factors.
However, there is a degree of disagreement amongst analysts, with the most bullish reporting a price target of $120.0, and the most bearish reporting a price target of just $47.0.
Read the complete narrative.
There is a detailed growth script sitting behind that fair value. It blends rapid revenue expansion, a swing from losses to profits, and a rich future earnings multiple. This perspective helps clarify which moving pieces may matter most over the next few years and how they could combine into that target price path.
Result: Fair Value of $96.73 (UNDERVALUED)
Have a read of the narrative in full and understand what's behind the forecasts.
However, there are still key watchpoints, including potential pricing pressure as Olezarsen targets broader populations and the risk that major FDA decisions are delayed or come back less favorable than hoped.
Find out about the key risks to this Ionis Pharmaceuticals narrative.
Another Angle On Valuation
The analyst narrative points to Ionis as about 19.8% undervalued at a fair value of $96.73, yet the current P/S of 12.1x tells a different story. That ratio sits well above the US Biotechs industry at 9.7x, peers at 4.4x, and even a fair ratio of 4.7x, which implies valuation risk if sentiment shifts.
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For a closer look at what this pricing gap could mean in practice, including how it lines up with cash flows, have a look at our valuation breakdown and then compare it with your own expectations before making any moves, See what the numbers say about this price — find out in our valuation breakdown.NasdaqGS:IONS P/S Ratio as at May 2026
Next Steps
With all this optimism on the table, does it match how you see Ionis today, or are expectations running ahead of reality? Take a moment to review the rewards investors are focusing on, starting with the 2 key rewards
Looking for more investment ideas?
If Ionis has sharpened your focus, do not stop here. Broaden your watchlist with other stocks that fit different goals before the crowd gets there first.
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This article by Simply Wall St is general in nature. We provide commentary based on historical data and analyst forecasts only using an unbiased methodology and our articles are not intended to be financial advice. It does not constitute a recommendation to buy or sell any stock, and does not take account of your objectives, or your financial situation. We aim to bring you long-term focused analysis driven by fundamental data. Note that our analysis may not factor in the latest price-sensitive company announcements or qualitative material. Simply Wall St has no position in any stocks mentioned.
Companies discussed in this article include IONS.
Have feedback on this article? Concerned about the content? Get in touch with us directly. Alternatively, email editorial-team@simplywallst.com
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- Ionis partner Biogen announces topline results from Phase 2 CELIA study of diranersen (BIIB080): first study to show reduction in tau pathology and cognitive benefit in patients with early Alzheimer's disease
May 14, 2026 · businesswire.com
CARLSBAD, Calif.--(BUSINESS WIRE)--Ionis Pharmaceuticals, Inc. (Nasdaq: IONS) today announced that its partner, Biogen, shared compelling topline results from the Phase 2 CELIA study evaluating diranersen (IONIS-MAPTRx/BIIB080), an investigational antisense oligonucleotide (ASO) therapy targeting tau, in individuals with early Alzheimer's disease (AD). The CELIA results provide the first evidence from a randomized Phase 2 study of a tau-directed therapy demonstrating both robust biomarker impac.
- IONIS PARTNER BIOGEN ANNOUNCES TOPLINE RESULTS FROM PHASE 2 CELIA STUDY OF DIRANERSEN (BIIB080): FIRST STUDY TO SHOW REDUCTION IN TAU PATHOLOGY AND COGNITIVE BENEFIT IN PATIENTS WITH EARLY ALZHEIMER'S DISEASE
May 14, 2026
CARLSBAD, CALIF.--(BUSINESS WIRE)--IONIS PHARMACEUTICALS, INC. (NASDAQ: IONS) TODAY ANNOUNCED THAT ITS PARTNER, BIOGEN, SHARED COMPELLING TOPLINE RESULTS FROM THE PHASE 2 CELIA STUDY EVALUATING DIRANERSEN (IONIS-MAPTRX/BIIB080), AN INVESTIGATIONAL ANTISENSE OLIGONUCLEOTIDE (ASO) THERAPY TARGETING TAU, IN INDIVIDUALS WITH EARLY ALZHEIMER'S DISEASE (AD). THE CELIA RESULTS PROVIDE THE FIRST EVIDENCE FROM A RANDOMIZED PHASE 2 STUDY OF A TAU-DIRECTED THERAPY DEMONSTRATING BOTH ROBUST BIOMARKER IMPAC.
- Oppenheimer Maintains an “Outperform Rating” on Pharmaceuticals, Inc. (IONS)
May 13, 2026
Ionis Pharmaceuticals, Inc. (NASDAQ:IONS) is one of the
8 Most Promising Biotech Stocks to Buy Now.
On April 30, Oppenheimer raised its price target on Ionis Pharmaceuticals, Inc. (NASDAQ:IONS) from $104 to $111. It maintained an “Outperform” rating on the stock while noting shares rose after first-quarter results and updated guidance.
On April 29, Ionis Pharmaceuticals, Inc. (NASDAQ:IONS) reported first-quarter 2026 results. Growing demand for TRYNGOLZA is driven by launch execution while raising full-year revenue guidance.
The company said the FDA accepted the olezarsen sNDA for priority review, with launch preparations for severe hypertriglyceridemia progressing, while growing peak net sales guidance for TRYNGOLZA to over $3 billion.Oppenheimer Maintains an “Outperform Rating” on Pharmaceuticals, Inc. (IONS)
The pipeline advanced. The firm said the FDA accepted the “zilganersen NDA” for priority review, positioning its first independent neurology launch.
CEO Brett Monia summed it up simply by stating that the business is performing well on both the commercial and R&D fronts. He noted future Phase 3 readouts and launches for olezarsen and zilganersen this year.
Ionis Pharmaceuticals, Inc. (NASDAQ:IONS) is a firm that develops and markets human therapeutic drugs using antisense technology. It is based in Carlsbad, California.
While we acknowledge the potential of IONS as an investment, we believe certain AI stocks offer greater upside potential and carry less downside risk. If you're looking for an extremely undervalued AI stock that also stands to benefit significantly from Trump-era tariffs and the onshoring trend, see our free report on the best short-term AI stock.
READ NEXT: 33 Stocks That Should Double in 3 Years and Cathie Wood 2026 Portfolio: 10 Best Stocks to Buy.
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- Ionis Pharmaceuticals, Inc. (IONS) Presents at Bank of America Global Healthcare Conference 2026 Transcript
May 12, 2026 · seekingalpha.com
Ionis Pharmaceuticals, Inc. (IONS) Presents at Bank of America Global Healthcare Conference 2026 Transcript
