Sanofi phase 2 data highlight AATD drug advantage

Sanofi reported phase 2 ElevAATe data showing its investigational AATD therapy efdoralprin alfa outperformed standard plasma-derived augmentation in raising and sustaining functional alpha-1 antitrypsin (fAAT) levels in adults with AATD-related emphysema.

Accepted by SEC EDGAR 05/27/2026 - 10:31 AM EDT Learn about SEC filing dates

Rhea-AI Filing Summary

Sanofi reported phase 2 ElevAATe data showing its investigational AATD therapy efdoralprin alfa outperformed standard plasma-derived augmentation in raising and sustaining functional alpha-1 antitrypsin (fAAT) levels in adults with AATD-related emphysema.

Efdoralprin alfa given every three weeks achieved mean fAAT trough increases more than three times higher than weekly plasma-derived protein and met the primary endpoint with strong statistical significance (p<0.0001). All key secondary endpoints were also met. In the three‑week dosing arm, fAAT remained above the normal threshold of 23.8 µM for 100% of days over the 32‑week study versus 41% of days on standard therapy.

The safety profile was comparable to current treatment, with no treatment-emergent adverse events leading to permanent discontinuation and similar rates of common side effects such as COPD exacerbations, headache and COVID‑19 infection. Efdoralprin alfa has fast track and orphan drug designations in the US and orphan designation in the EU and remains in clinical development with ongoing long-term evaluation.

Key Figures

Patients randomized: 97 patients Study duration: 32 weeks Normal fAAT days on Q3W efdoralprin: 100% of days +5 more

8 metrics

Patients randomized 97 patients ElevAATe phase 2 AATD-related emphysema study population, randomized 2:2:1

Study duration 32 weeks Period during which fAAT levels were assessed in ElevAATe

Normal fAAT days on Q3W efdoralprin 100% of days Q3W arm kept fAAT above 23.8 µM throughout 32-week study

Normal fAAT days on standard therapy 41% of days Weekly plasma-derived augmentation arm with fAAT above 23.8 µM

Normal fAAT threshold 23.8 µM Threshold used to define normal functional AAT levels in ElevAATe

COPD exacerbations Q3W arm 34.1% Most common TEAE incidence in efdoralprin alfa every 3 weeks arm

Global AATD population 235,000 people Estimated number of people worldwide living with AATD

Undiagnosed AATD rate 90% Estimated proportion of individuals with AATD who are undiagnosed

Key Terms

alpha-1 antitrypsin deficiency, augmentation therapy, treatment-emergent adverse events, orphan drug designation, +2 more

6 terms

alpha-1 antitrypsin deficiency medical

"adult patients with alpha-1 antitrypsin deficiency (AATD)-related emphysema"

A genetic condition in which the body makes too little of a protective protein called alpha‑1 antitrypsin, leaving lungs and sometimes the liver vulnerable to damage; imagine a car missing some brake pads so wear and tear accelerates. It matters to investors because the condition defines a specific patient population, shapes demand for diagnostics and therapies, and concentrates regulatory, clinical trial and reimbursement risks and opportunities for companies developing treatments.

augmentation therapy medical

"superiority of efdoralprin alfa over a standard-of-care augmentation therapy"

treatment-emergent adverse events medical

"no participants experiencing treatment-emergent adverse events (TEAEs) leading to permanent discontinuation"

Events or symptoms that either appear for the first time or get worse after a patient starts a treatment; think of new or intensified side effects that show up once medicine or a medical device is used. Investors watch these closely because they affect whether a therapy can gain regulatory approval, be prescribed widely, or face legal and commercial setbacks—similar to how early customer complaints can sink a new product’s prospects.

orphan drug designation regulatory

"Efdoralprin alfa was granted fast track designation and orphan drug designation in the US"

Orphan drug designation is a special status given to medicines developed to treat rare diseases affecting only a small number of people. This status often provides benefits like faster approval processes and financial incentives, making it more attractive for companies to develop these drugs. For investors, it signals potential for exclusive market rights and reduced competition, which can impact the drug’s profitability.

fast track designation regulatory

"Efdoralprin alfa was granted fast track designation and orphan drug designation in the US"

Fast track designation is a status the U.S. Food and Drug Administration grants to drugs intended to treat serious conditions and address an unmet medical need. It gives the developer more frequent communication with the FDA and can allow parts of the application to be reviewed on a rolling basis, and it may pave the way to priority review or accelerated approval. It can shorten development timelines, though it does not guarantee approval.

open-label extension medical

"evaluated in the ElevAATe OLE phase 2 study"

An open-label extension is a continuation of a clinical trial where all participants and researchers know which treatment is being given, often after an initial blinded phase. It allows further study of a drug's long-term safety and effectiveness. For investors, it can indicate ongoing interest and confidence in a product's potential, influencing perceptions of its future value.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did Sanofi (SNY) announce about efdoralprin alfa in AATD?

Sanofi reported positive phase 2 data for efdoralprin alfa in AATD-related emphysema. The ElevAATe study showed the drug achieved higher and sustained functional alpha‑1 antitrypsin levels versus standard plasma-derived augmentation therapy, meeting its primary and all key secondary endpoints with strong statistical significance.

How did efdoralprin alfa perform versus standard augmentation therapy in ElevAATe?

Efdoralprin alfa outperformed weekly plasma-derived augmentation on key biomarker measures. Three‑weekly dosing produced mean functional AAT trough increases more than three times higher and kept levels above the normal 23.8 µM threshold for 100% of days over 32 weeks, compared with 41% on standard therapy.

What was the dosing schedule for efdoralprin alfa in Sanofi’s phase 2 ElevAATe trial?

Patients received efdoralprin alfa every three or four weeks. Ninety-seven patients with AATD-related emphysema were randomized 2:2:1 to efdoralprin alfa Q3W, efdoralprin alfa Q4W, or weekly plasma-derived augmentation therapy, allowing comparison of less frequent recombinant dosing against current standard care.

What safety profile did efdoralprin alfa show in the ElevAATe phase 2 study?

Efdoralprin alfa was well tolerated with a safety profile comparable to plasma-derived therapy. No participants discontinued treatment due to treatment-emergent adverse events. Common events included COPD exacerbations, headache, and COVID‑19 infection at similar rates across arms, and detected anti-drug antibodies were transient and non-neutralizing.

Does Sanofi’s efdoralprin alfa have any regulatory designations?

Efdoralprin alfa has multiple supportive regulatory designations. It received fast track and orphan drug designations in the United States and orphan designation in the European Union, reflecting its development for the rare genetic condition alpha‑1 antitrypsin deficiency-related emphysema.

What is alpha-1 antitrypsin deficiency (AATD) and how common is it?

AATD is a rare inherited disorder causing low or absent alpha‑1 antitrypsin. It can lead to progressive lung and liver damage, including emphysema. About 235,000 people worldwide, nearly 100,000 in the US, live with AATD, and an estimated 90% are believed undiagnosed.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of May 2026

Commission File Number: 001-31368

SANOFI

(Translation of registrant’s name into English)

46, avenue de la Grande Armée, 75017 Paris, FRANCE

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or Form 40-F.

Form 20-F ☒   Form 40-F ☐

In May 2026, Sanofi published the press release attached hereto as Exhibit 99.1 which is incorporated herein by reference.

Exhibit Index

Exhibit No.                               Description

Exhibit 99.1 Press Release dated May  18, 2026: ATS: phase 2 data demonstrate the superiority of efdoralprin alfa over a standard-of-care augmentation therapy in achieving higher fAAT levels in AATD.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Dated: May 27, 2026						SANOFI
				By		/s/ Alexandra Roger
						Name: Alexandra Roger Title: Head of Legal Corporate & Finance

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Exhibit 99.1

Press Release  

ATS: phase 2 data demonstrate the superiority of efdoralprin alfa over a standard-of-care augmentation therapy in achieving higher fAAT levels in AATD

• Data from the head-to-head study show efdoralprin alfa normalized and maintained functional AAT levels in people living with alpha-1 antitrypsin deficiency

• Efdoralprin alfa is a recombinant protein distinct from plasma-derived therapy, which has been the standard-of-care for nearly 40 years

Paris, May 18, 2026. Data from the global ElevAATe phase 2 study (clinical study identifier: NCT05856331) demonstrated superiority of investigational efdoralprin alfa over standard-of-care therapy in achieving and maintaining normalized functional alpha-1 antitrypsin (fAAT) levels in adult patients with alpha-1 antitrypsin deficiency (AATD)-related emphysema. These results are being presented today at the 2026 American Thoracic Society (ATS) International Conference in Orlando, FL, US.

Efdoralprin alfa, dosed every three weeks (Q3W), achieved mean increases in fAAT trough levels more than three times greater than plasma-derived protein (pdAAT) dosed weekly (Q1W), meeting the primary endpoint (p<0.0001). All key secondary endpoints in the study were also met (p<0.0001), highlighting the potential for efdoralprin alfa to be the first therapy to sustain normal fAAT levels for patients and do so with less frequent dosing. In patients dosed Q3W, fAAT levels remained above the normal threshold (23.8 µM) for 100% of days during the 32-week study compared to 41% of days in patients on a standard-of-care augmentation therapy.

AATD is an underdiagnosed, rare genetic condition that can cause considerable respiratory illness and is characterized by low levels or absence of AAT, a protein designed to protect the lungs from damaging inflammation. Without adequate fAAT levels, patients often experience progressive deterioration of the lung tissue and may develop emphysema, the most common form of chronic obstructive pulmonary disease (COPD), accounting for up to 72% of deaths in people with AATD. An estimated 90% of individuals with AATD are believed to be undiagnosed.

“AATD presents a persistent clinical challenge. Widespread lack of awareness of the condition as a genetic cause of some forms of COPD leaves many patients under-served. Without treatment to address the underlying AAT protein deficiency, these patients are unable to maintain protective protein levels and become vulnerable to progressive lung disease,” said Igor Barjaktarevic, MD, PhD, Associate Professor, David Geffen School of Medicine at UCLA, Los Angeles, CA, US and principal investigator on the ElevAATe phase 2 study. “The ElevAATE data suggest efdoralprin alfa, through its mechanism of action, may be able to restore normal AAT levels and keep patients in that range for longer than the standard-of-care therapy, helping to address an unmet need of this disease with a restorative recombinant approach.”

The ElevAATe phase 2 study

The ElevAATe phase 2 study was a double-blind, randomized study evaluating efdoralprin alfa versus a standard-of-care augmentation therapy in patients with AATD-related emphysema. Ninety-seven patients were randomized 2:2:1 to receive efdoralprin alfa every three or four weeks, or plasma-derived augmentation therapy once weekly.

The following results are being shared today:

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		Efdoralprin alfa Q3W		Efdoralprin alfa Q4W		Plasma-derived augmentation therapy Q1W
Primary endpoint
Mean change in average serum fAAT trough concentrations from baseline to steady state at week 32*		24.1µM [22.8µM, 25.3µM] p<0.0001		16.8µM [15.5µM, 18.1µM] p<0.0001		7.6µM [6.0µM, 9.3µM]
Key secondary endpoints
Mean change in serum fAAT average concentrations from baseline to steady state at week 32*		32.9µM [31.7µM, 34.2µM] p<0.0001		26.0µM [24.6µM, 27.3µM] p<0.0001		17.9µM [16.2µM, 19.6µM]
Percentage of days that steady state fAAT levels were above the lower limit of the normal range at week 32**		100% p<0.0001		89.3% p<0.0001		40.8%

*Least square mean change; [95% confidence interval].

** Normal range for functional AAT = 23.8-42.4 uM.

Q4W: every four weeks.

Efdoralprin alfa was well tolerated with a safety profile comparable to pdAAT, with no participants experiencing treatment-emergent adverse events (TEAEs) leading to permanent discontinuation of study intervention. The most common TEAEs in the efdoralprin alfa Q3W, efdoralprin alfa Q4W and pdAAT therapy arms were COPD exacerbations (34.1%, 42.1% and 44.4%, respectively), headache (19.5%, 13.2% and 11.1%, respectively), and COVID-19 infection (17.1%, 2.6% and 16.7%, respectively). Notably, the incidence of grade ≥2 COPD exacerbations, which were captured as an adverse event of special interest in the ElevAATe study, were numerically lower for the efdoralprin alfa Q3W arm (26.8%) versus the efdoralprin alfa Q4W (42.1%) and pdAAT (44.4%) arms. Efdoralprin alfa anti-drug antibodies were detected in two participants and were transient and non-neutralizing.

“The data demonstrate efdoralprin alfa, a restorative recombinant therapy designed to achieve a longer half-life than standard of care augmentation therapy, has the potential to raise and sustain fAAT levels within normal range with less frequent dosing. This could represent an important advancement in the treatment of AATD-related emphysema, offering patients new hope in a disease state where innovation has been limited over the past 40 years,” said Christopher Corsico, Global Head of Development at Sanofi.

Sanofi is engaging with global regulatory authorities on the appropriate next steps for efdoralprin alfa. Efdoralprin alfa was granted fast track designation and orphan drug designation in the US and orphan designation in the EU. Additional long-term safety and efficacy outcomes are being evaluated in the ElevAATe OLE phase 2 study (clinical study identifier: NCT05897424).

Efdoralprin alfa is currently in clinical development, and its safety and efficacy have not been evaluated by any regulatory authority.

About efdoralprin alfa

Efdoralprin alfa is a recombinant human AAT-Fc fusion protein being investigated as a restorative therapy in adults with AATD emphysema, with Q3W or Q4W dosing. This investigational treatment, designed to achieve a longer half-life than plasma-derived augmentation therapy, is

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being studied to restore and maintain fAAT levels to the normal range and inhibit neutrophil elastase and other proteases that can cause lung tissue damage in patients with AATD.

About AATD

AATD is a rare, inherited disorder characterized by low levels or absence of AAT, a protein produced by the liver that protects the lungs from inflammation and damage. The disease causes progressive deterioration of the tissue of the lungs and liver. Without adequate AAT levels, affected individuals often experience lung damage and develop COPD, including emphysema, and in severe forms of the disease patients can sometimes require lung transplantation. Plasma-derived therapies were introduced in 1987 to treat the condition but since then, no new treatment approaches have become available to patients. About 235,000 people worldwide live with AATD, with nearly 100,000 people in the US, but about 90% of individuals with AATD are likely undiagnosed.

About Sanofi

Sanofi is an R&D driven, AI-powered biopharma company committed to improving people’s lives and delivering compelling growth. We apply our deep understanding of the immune system to invent medicines and vaccines that treat and protect millions of people around the world, with an innovative pipeline that could benefit millions more. Our team is guided by one purpose: we chase the miracles of science to improve people’s lives; this inspires us to drive progress and deliver positive impact for our people and the communities we serve, by addressing the most urgent healthcare, environmental, and societal challenges of our time.

Sanofi is listed on EURONEXT: SAN and NASDAQ: SNY

Media Relations

Sandrine Guendoul | +33 6 25 09 14 25 | sandrine.guendoul@sanofi.com

Evan Berland | +1 215 432 0234 | evan.berland@sanofi.com

Léo Le Bourhis | +33 6 75 06 43 81 | leo.lebourhis@sanofi.com

Victor Rouault | +1 617 356 4751 | victor.rouault@sanofi.com

Timothy Gilbert | +1 516 521 2929 | timothy.gilbert@sanofi.com

Léa Ubaldi | +33 6 30 19 66 46 | lea.ubaldi@sanofi.com

Ekaterina Pesheva | +1 410 926 6780 | ekaterina.pesheva@sanofi.com

Investor Relations

Thomas Kudsk Larsen |+ 44 7545 513 693 | thomas.larsen@sanofi.com

Alizé Kaisserian | + 33 6 47 04 12 11 | alize.kaisserian@sanofi.com

Keita Browne | + 1 781 249 1766 | keita.browne@sanofi.com

Nathalie Pham | + 33 7 85 93 30 17 | nathalie.pham@sanofi.com

Nina Goworek | +1 908 569 7086 | nina.goworek@sanofi.com

Thibaud Châtelet | + 33 6 80 80 89 90 | thibaud.chatelet@sanofi.com

Yun Li | +33 6 84 00 90 72 | yun.li3@sanofi.com

Sanofi forward-looking statements

This press release contains forward-looking statements within the meaning of applicable securities laws, including the Private Securities Litigation Reform Act of 1995, as amended. Forward-looking statements are statements that are not historical facts. These statements include projections and estimates and their underlying assumptions, statements regarding plans, objectives, intentions, and expectations with respect to future financial results, events, operations, services, product development and potential, and statements regarding future events and economic performance. Words such as “expect,” “anticipate,” “believe,” “intend,” “estimate,” “plan,” “can,” “contemplate,” “could,” “is designed to,” “may,” “might,” “potential,” “objective,” “attempt,” “target,” “project,” “strategy,” “strive,” “desire,” “predict,” “forecast,” “ambition,” “guideline,” “seek,” “should,” “will,” “goal,” or the negative of these, and similar expressions are intended to identify forward-looking statements. Although Sanofi’s management believes that the expectations reflected in such forward-looking statements are reasonable, investors are cautioned that forward-looking information and statements are subject to various risks and uncertainties, many of which are difficult to predict and generally beyond the control of Sanofi, that could cause actual results and developments to differ materially from those expressed in, or implied or projected by, the forward-looking information and statements. These risks and uncertainties include among other things, the uncertainties inherent in research and development, future clinical data and analysis, including post marketing, decisions by regulatory authorities, such as the U.S Food and Drug Administration or the European Medicines Agency, regarding whether and when to approve any drug, device or biological application that may be filed for any such product candidates as well as their decisions regarding labelling and other matters that could affect the availability or commercial potential of such product candidates; the fact that product candidates if approved may not be commercially successful; unexpected regulatory actions or delays, or government regulation generally; authorities’ decisions regarding whether and when to approve a product candidate; political pressure in the United States to mandate lower drug prices including “most favored nation” pricing for State Medicaid programs; the future approval and commercial success of therapeutic alternatives; Sanofi’s ability to benefit from external growth opportunities, to complete related transactions and/or obtain regulatory clearances, including future clinical data and analysis of existing clinical data relating to the product, including post marketing, unexpected safety, quality or manufacturing issues, competition in general; risks associated with intellectual property and any related pending or future litigation and the ultimate outcome of such litigation; trends in exchange rates and prevailing interest rates, volatile economic and market conditions, cost containment initiatives and subsequent changes thereto, and the impact that global crises may have on us, our customers, suppliers, vendors, and other business partners, and the financial condition of any one of them, as well as on our employees and on the global economy as a whole. The risks and uncertainties also include the uncertainties discussed or identified in the public filings with the SEC and the French Markets Authority (AMF) made by Sanofi, including those listed under “Risk Factors” and “Cautionary Statement Regarding Forward-Looking Statements” in Sanofi’s annual

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report on Form 20-F for the year ended December 31, 2025 or contained in our periodic reports on Form 6-K. Other than as required by applicable law, Sanofi does not undertake any obligation to update or revise any forward-looking information or statements. In light of these risks, uncertainties and assumptions, you should not place undue reliance on any forward-looking statements contained herein.

All trademarks mentioned in this press release are the property of the Sanofi group.

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