Regeneron's Fianlimab Trial Fails to Meet Key Goals
Written by Emily J. Thompson, Senior Investment Analyst
Updated: May 16 2026
0mins
Source: stocktwits
- Trial Results: Regeneron's pivotal late-stage melanoma trial for its experimental drug fianlimab, combined with Libtayo, failed to meet its primary endpoint, as the fianlimab arm showed numerical improvement in progression-free survival but lacked statistical significance, leading to a slight decline in stock price during after-hours trading.
- Survival Data: In the high-dose arm, patients had a median progression-free survival of 11.5 months compared to 6.4 months for those on Keytruda alone, indicating a potential benefit but failing to meet clinical trial statistical requirements, highlighting challenges in market competition.
- Market Reaction: Despite 22 out of 29 analysts rating Regeneron stock as 'Buy' or higher, retail sentiment on Stocktwits remained bearish, reflecting concerns about the company's future performance, especially with the investigational status of the drug.
- Future Outlook: Regeneron is continuing a separate late-stage trial comparing the same combination against Bristol Myers Squibb’s Opdualag; although this trial's results are disappointing, the company is striving to establish a foothold in the rapidly growing melanoma immunotherapy market, with full results to be presented at an upcoming medical meeting.
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Analyst Views on REGN
Wall Street analysts forecast REGN stock price to rise
22 Analyst Rating
16 Buy
6 Hold
0 Sell
Moderate Buy
Current: 628.730
Low
637.00
Averages
808.50
High
1057
Current: 628.730
Low
637.00
Averages
808.50
High
1057
About REGN
Regeneron Pharmaceuticals, Inc. is a fully integrated biotechnology company. The Company invents, develops, manufactures, and commercializes medicines for people with serious diseases. Its products and product candidates in development are designed to help patients with eye diseases, allergic and inflammatory diseases, cancer, cardiovascular and metabolic diseases, neurological diseases, hematologic conditions, infectious diseases, and rare diseases. The Company is accelerating drug development using its proprietary technologies, such as VelociSuite, which produces optimized fully human antibodies and new classes of bispecific antibodies. VelociSuite consists of VelocImmune, VelociGene, VelociMouse, VelociMab, Veloci-Bi, VelociT, VelociHum, and other related technologies. Its marketed products include EYLEA (aflibercept); Dupixent (dupilumab); Libtayo (cemiplimab); Ordspono (odronextamab); Kevzara (sarilumab); Itepekimab; Lynozyfic, and others.
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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- Valuation Outlook: At the top of the IPO price range, Parabilis could achieve a valuation of up to $2.2 billion, establishing a strong market foundation for its future developments in cancer therapies.
- Collaboration Context: Regeneron has agreed to purchase approximately $75 million in company shares at a 10% discount, as part of a concurrent private placement linked to a research collaboration worth up to $2.3 billion, reflecting confidence in Parabilis's future potential.
See More
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- Funding Injection: CytomX will receive $37 million for nominating two additional targets selected by Regeneron for clinical development, which not only enhances its liquidity but also supports subsequent research efforts.
- Target Selection Opportunity: Regeneron will have the option to select up to six additional targets, a flexibility that could accelerate the development of new therapies, thereby enhancing CytomX's competitive position in the market.
- Potential Revenue: The expanded agreement includes payments linked to target nomination, clinical, and commercial milestones, and CytomX will also be eligible for tiered royalties based on global net sales, further strengthening its long-term profitability.
See More
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- Securities Fraud Investigation: Pomerantz LLP is investigating whether Regeneron and its executives have engaged in securities fraud or other unlawful business practices, raising serious concerns about corporate governance and investor rights.
- Poor Clinical Trial Results: On May 15, 2026, Regeneron announced that its Phase 3 trial of the LAG-3 inhibitor fianlimab in combination with the PD-1 inhibitor cemiplimab failed to achieve statistical significance for the primary endpoint of progression-free survival (PFS), indicating potential risks in its R&D direction.
- Significant Stock Price Drop: Following the trial results, Regeneron's stock price fell by $68.57, or 9.82%, closing at $629.68 on May 16, 2026, reflecting market concerns about the company's future prospects.
- Potential Legal Action: Due to the stock price decline, investors may face losses, prompting Pomerantz LLP to encourage affected investors to contact them to join the class action, indicating increasing legal risks for the company.
See More
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- Clinical Trial Recommendation: The WHO's Therapeutics Advisory Group has recommended Regeneron's Maftivimab for prioritized evaluation to address the Bundibugyo ebolavirus outbreak in the DRC and Uganda, highlighting the urgency of the public health crisis.
- Drug Background: Maftivimab is one of three antibodies in Inmazeb, the first FDA-approved treatment for infections caused by the Zaire ebolavirus, showing broad in-vitro activity against multiple Ebola species, although it has not yet been tested in vivo as a monotherapy.
- Patient Usage: Hundreds of patients have already received Maftivimab as part of Inmazeb, which has demonstrated an acceptable safety profile, indicating its potential in combating Ebola outbreaks.
- Company Coordination Efforts: Regeneron is closely coordinating with the U.S. Department of Health and Human Services and WHO as clinical evaluations progress, emphasizing its history of rapidly delivering medical solutions during global health crises, thereby enhancing its reputation in public health.
See More
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- Antibody Evaluation Approval: The World Health Organization has approved the evaluation of Regeneron Pharmaceuticals' antibody maftivimab as a potential treatment for the current Ebola outbreak, reflecting a proactive stance in combating the epidemic.
- Targeting Specific Virus: Maftivimab is one of the antibodies in the FDA-approved Inmazeb, primarily used for Orthoebolavirus zairen, with WHO recommending its prioritization for Bundibugyo ebolavirus to address the outbreaks in the Democratic Republic of the Congo and Uganda.
- Alternative Treatment Options: WHO also suggests evaluating Gilead Sciences' antiviral remdesivir and its experimental drug obeldesivir for post-exposure prophylaxis, aiming to enhance treatment options and response capabilities against the outbreak.
- Vaccine Usage Restrictions: Merck's Ervebo is the only licensed Ebola vaccine; however, WHO emphasizes that it should only be used in carefully designed research settings to assess its effectiveness against Bundibugyo ebolavirus, ensuring safety and efficacy.
See More
Regeneron Recommends Maftivimab for Ebola Treatment Trials
- WHO Recommendation: The World Health Organization has recommended prioritizing maftivimab for evaluation as a monotherapy against Bundibugyo ebolavirus, demonstrating broad in vitro activity against multiple Ebola species, potentially offering new treatment options for the current outbreak.
- Emergency Response Coordination: Regeneron is closely coordinating with the U.S. Department of Health and Human Services to prepare for clinical trials in the Democratic Republic of the Congo and Uganda, aiming to respond swiftly to WHO's declaration of the current Ebola outbreak as a public health emergency.
- Historical Contributions: Since 2018, Regeneron has provided Inmazeb to infected individuals under a compassionate use protocol, showcasing its rapid response capabilities during global health crises and solidifying its leadership in infectious disease treatment.
- Donations and Stockpiles: In September 2025, Regeneron donated 500 doses of Inmazeb to the WHO for exclusive use in low-income countries, enhancing global preparedness for Ebola outbreaks while also supplying stockpiles to the U.S. government to bolster national public health emergency readiness.
See More
