Biogen Drops After Alzheimer’s Trial Setback News Update

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Alzheimer’s Update Jolts Biogen’s Risk-Reward Profile

The U.S. Food & Drug Administration (FDA) often shapes the risk and reward dynamics of biotechnology stocks, and the latest Alzheimer’s data from Biogen Inc. NASDAQ: BIIB illustrates how investor sentiment can shift rapidly.

Biogen entered May with positive momentum following a solid first-quarter earnings release and its proposed purchase of Apellis Pharmaceuticals NASDAQ: APLS for $41 per share. That deal would bring two marketed rare disease and immunology therapies into Biogen’s portfolio, along with a nephrology platform intended to support the launch of felzartamab.

The main catalyst, however, was anticipation around the Phase 2 CELIA data for diranersen, Biogen’s investigational tau-directed Alzheimer’s treatment.

When topline results were disclosed on May 14, the market reaction was mixed. The study did not achieve its primary endpoint – a dose response on the Clinical Dementia Rating-Sum of Boxes at Week 76 – and BIIB dropped more than 10%. Yet Biogen also reported encouraging biological and clinical findings, suggesting that the initial selloff may not reflect the full picture for diranersen or the company’s broader Alzheimer’s strategy.

Why Tau-Targeting Matters for Biogen

Diranersen is an antisense oligonucleotide (ASO) that targets tau, a protein responsible for stabilizing the internal transport system within neurons.

In Alzheimer’s disease, tau can undergo chemical changes, detach from its structural role, and form tangles inside neurons.

Together with amyloid plaques, these tangles are a hallmark of Alzheimer’s pathology, disrupting neuronal communication, contributing to cell death, and closely aligning with the cognitive decline seen in patients.

From an investment standpoint, tau is significant because it appears to be a key driver of symptoms. A therapy that reduces tau pathology, such as diranersen, could support an amyloid-plus-tau combination approach, which remains a central element of the long-term bullish narrative around Biogen’s Alzheimer’s pipeline.

CELIA Findings: Nuanced Trial Outcome for Diranersen

CELIA was the first randomized Phase 2 trial of a tau-focused therapy to show both biomarker changes and cognitive benefit in early Alzheimer’s disease.

Although the trial did not meet its primary endpoint, Biogen highlighted several positive topline outcomes. Across all doses, diranersen produced strong reductions in cerebrospinal fluid tau and tau pathology measured by PET, and these reductions persisted throughout the dosing period. Prespecified cognitive assessments also indicated a slowing of clinical decline across all evaluated doses, with the most notable effect at the lowest 60-milligram dose given every 24 weeks.

Biogen is moving diranersen forward in development. Given that CEO Chris Viehbacher has been pruning higher-risk research and development programs in recent years, analysts have interpreted the decision to advance diranersen as a meaningful internal endorsement of the data.

Even so, market observers are not treating CELIA as a straightforward success or failure. Analyst commentary has reflected a more complex read-through, balancing the primary endpoint miss with the biomarker and cognitive signals.

Street Targets Remain Above Current BIIB Levels

Analysts’ published price targets continue to imply room for upside in BIIB shares. The consensus target stands at $215.62, suggesting potential appreciation of about 14% from recent levels.

Individual firms have also reiterated constructive views:

• Guggenheim reaffirmed a Buy rating with a $260 price target.
• Oppenheimer raised its target to $300 while maintaining an Outperform rating.
• Mizuho kept an Outperform rating with a $236 target.

Leqembi and Apellis Acquisition Underpin Core Business

Over the trailing 12 months, Biogen’s revenue has been essentially flat but steady, a pattern that also holds for the company’s adjusted earnings per share (EPS).

Biogen currently has 10 commercialized products. For many investors, the flagship asset is Leqembi, the approved early Alzheimer’s treatment co-developed with Eisai. Leqembi is described as the only therapy with FDA-approved maintenance dosing options designed to continue slowing disease progression. By contrast, diranersen remains an experimental asset being tested in CELIA, a Phase 2 trial that concentrates on tau pathology.

Biogen’s recent earnings release showed that global in-market sales of Leqembi rose 74% year over year to $168 million. In addition, the FDA extended the review period for the Leqembi Iqlik subcutaneous starting dose Supplemental Biologics License Application (sBLA) by three months, moving the Prescription Drug User Fee Act (PDUFA) date to Aug. 24, 2026.

Analysts largely interpreted the extension as a matter of timing. Eisai indicated that the delay followed the submission of a major amendment, and that the FDA had not, to date, raised issues related to approvability.

Technical Picture: A Potential Entry Point Amid Volatility

From a technical perspective, BIIB’s longer-term trend remains constructive.

The stock advanced from the low $130s last summer to the high $180s, with the 50-day simple moving average (SMA) climbing in parallel and repeatedly providing support. Following the CELIA-driven decline, BIIB is now trading just above that 50-day SMA, which some investors may view as an encouraging sign given the recent pressure.

Shorter-term signals are more cautious. The MACD line has crossed below its signal line, and the MACD histogram has moved into negative territory, pointing to the possibility that the pullback has not fully played out. Trading volume during the May downturn has been elevated, a factor that bears watching.

For investors with a longer time horizon, the area around the 50-day SMA, near $185, presents a technically grounded potential entry zone. A sustained hold at that level – especially if the MACD starts to turn higher – would indicate that the broader uptrend is intact heading into the Leqembi Iqlik Aug. 24 PDUFA date.

Positioning BIIB Within Broader Stock Selection

Prospective investors are weighing whether to allocate fresh capital to Biogen following the Alzheimer’s trial selloff.

MarketBeat tracks the top-rated and best-performing research analysts and the stocks they recommend to clients frequently. According to that tracking, MarketBeat has identified five stocks that leading analysts are advising clients to accumulate before the broader market reacts – and Biogen did not appear on that list.

While Biogen currently carries a Moderate Buy rating from analysts overall, MarketBeat reports that top-rated analysts view those other five names as more attractive opportunities at this time.