Ionis Pharmaceuticals, Inc. (NASDAQ:IONS) announced today that Frank Bennett, Ph.D., executive vice president and chief scientific officer, will retire effective February 2027.

"As a founding scientist, Frank has been instrumental in shaping Ionis and advancing the entire field of RNA-targeted medicines," said Brett P. Monia, Ph.D., chief executive officer, Ionis. "Frank’s profound contributions include pioneering the use of antisense medicines in neurological disease. He led the discovery and development of the first approved medicines for spinal muscular atrophy and a genetic form of amyotrophic lateral sclerosis, which have transformed the lives of thousands of people. We are deeply grateful for Frank’s scientific leadership and unwavering dedication to the patients and communities that are counting on us."

Dr. Bennett joined Ionis as a founding scientist in 1989 and has pioneered the use of antisense oligonucleotides (ASOs) across multiple therapeutic disciplines. His research has focused on the basic mechanisms of ASOs, including pharmacokinetics, medicinal chemistry and cellular uptake. Notably, Dr. Bennett demonstrated that antisense drugs could spread broadly throughout the central nervous system when introduced directly into the cerebral spinal fluid.

As head of Ionis’ research programs, Dr. Bennett contributed to the discovery of more than fifty drug candidates, with seven receiving regulatory approval worldwide. He spearheaded the discovery and development of several Ionis medicines for neurological diseases, including SPINRAZA^® (nusinersen), the first approved treatment for spinal muscular atrophy (SMA), and QALSODY^® (tofersen), the first approved treatment for a genetic form of amyotrophic lateral sclerosis (ALS). In addition, Dr. Bennett led the discovery of several clinical-stage Ionis medicines for neurological diseases, including programs targeting additional genetic forms of ALS, Parkinson's disease, prion disease, Angelman syndrome, MECP2 duplication syndrome, as well as zilganersen, an investigational medicine for Alexander’s disease currently under review with the U.S. Food and Drug Administration. His work also extended to non-neurologic conditions, including bepirovirsen, an investigational medicine for chronic hepatitis B (CHB) currently under regulatory review with several global health authorities.

Dr. Bennett’s distinguished career has been recognized with several prestigious awards, including the 2019 Breakthrough Prize in Life Sciences in recognition of his work developing SPINRAZA, the inaugural 2019 Healey Center International Prize for Innovation in ALS, the 2021 Lifetime Achievement Award from the Oligonucleotide Therapeutics Society, the 2021 Gabbay Award and the 2023 Rainwater Prize for Outstanding Innovation in Neurodegenerative Disease Research. He has authored more than 240 peer-reviewed manuscripts and holds more than 200 issued U.S. patents.

Dr. Bennett will serve as a strategic consultant for a period after his retirement to support the transition. His responsibilities will be assumed by Eric Swayze, Ph.D., executive vice president, head of research.

About Ionis Pharmaceuticals, Inc.

For more than 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 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 for the year ended December 31, 2025 and most recent Form 10-Q, 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.

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Ionis Investor Contact:

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IR@ionis.com

760-603-2331

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