Ionis Pharmaceuticals, Inc.

Item 7.01 Regulation FD Disclosure. On June 24, 2026, Ionis Pharmaceuticals, Inc. (“Ionis”) issued a press release announcing that the U.S. Food and Drug Administration (“FDA”) has approved TRYNGOLZA® (olezarsen) as an adjunct to diet to reduce triglycerides (“TG”) and the risk of acute pancreatitis in adults with severe hypertriglyceridemia (“sHTG”: TG greater than or equal to 500 mg/dL). A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. The information in this Item 7.01 and the exhibit attached hereto shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, regardless of any general incorporation language in such filing.

Item 8.01 Other Events. On June 24, 2026, Ionis announced that the U.S. FDA has approved TRYNGOLZA® (olezarsen) as an adjunct to diet to reduce triglycerides and the risk of acute pancreatitis in adults with sHTG. TRYNGOLZA is available in a 50 mg or 80 mg dose and is self-administered once monthly via an autoinjector. sHTG is characterized by an increased risk of acute pancreatitis, which causes debilitating abdominal pain that often leads to repeated and prolonged hospitalization, permanent organ damage and can be life-threatening. The FDA approval was based on positive results from the Phase 3 CORE and CORE2 studies, which were published in The New England Journal of Medicine. In the CORE and CORE2 studies, TRYNGOLZA demonstrated rapid and consistent triglyceride control, lowering fasting triglyceride levels by up to 72% compared to placebo at six months and sustaining those reductions at 12 months. Additionally, TRYNGOLZA significantly reduced acute pancreatitis events by up to 91%. Among patients treated with TRYNGOLZA with baseline and 12-month data, 86% achieved triglyceride levels below 500 mg/dL, a critical threshold for reducing acute pancreatitis risk. The number needed to treat (“NNT”) over one year to prevent one episode of acute pancreatitis was 20 in the overall cohort and four in patients with triglycerides ≥880 mg/dL and a prior history of acute pancreatitis, indicating a strong clinical benefit across the spectrum of sHTG patients and an exceptional clinical benefit in the highest risk subgroup. Across the clinical program, TRYNGOLZA demonstrated a favorable safety and tolerability profile. The most common adverse reactions in patients with sHTG (incidence ≥2% higher than placebo) were injection site reactions and liver enzyme increases. TRYNGOLZA will be available for sHTG in the U.S. in July.