IONIS PHARMACEUTICALS INC 8-K

What Happened
On May 28, 2026, Ionis Pharmaceuticals filed an 8-K (Regulation FD / Other Events) to disclose that partner GSK reported positive pivotal results from two Phase 3 trials (B‑Well 1 and B‑Well 2) of bepirovirsen, an investigational antisense oligonucleotide for chronic hepatitis B (CHB). Pooled data showed a statistically significant functional cure rate of 19% vs 0% for placebo in patients with baseline HBsAg ≤3000 IU/mL (233 of 1,220 vs 0 of 614; p<0.001), and 26% vs 0% in the subgroup with HBsAg ≤1000 IU/mL (200 of 768 vs 0 of 393; p<0.001). Results were published in the New England Journal of Medicine and presented at EASL.

Key Details

• File date: May 28, 2026; press release furnished as Exhibit 99.1 to the 8‑K.
• Primary endpoint (Week 72, six months off treatment): 19% functional cure (233/1,220) vs 0/614 placebo for HBsAg ≤3000 IU/mL.
• Key secondary (≤1000 IU/mL): 26% functional cure (200/768) vs 0/393 placebo. Subgroup ~45% of diagnosed CHB cases globally.
• Additional outcomes: 49% of bepirovirsen recipients had qHBsAg ≤100 IU/mL one year after end of treatment (exploratory); sustained HBV DNA <LLOQ at week 72 in 23% overall (283/1,220) and 31% in ≤1000 IU/mL subgroup (237/768).
• Safety: acceptable and consistent with prior studies; most common AEs were injection site erythema, local pain, and temporary liver enzyme elevations.
• Regulatory/Commercial: Bepirovirsen under priority review by FDA (Breakthrough & Fast Track); reviews ongoing in EU, Japan (SENKU), and China (Breakthrough/Priority). GSK expects first regulatory decisions in Q3 2026. GSK licensed bepirovirsen from Ionis (2019); Ionis is eligible for milestone payments and tiered royalties of 10–12% on net sales.

Why It Matters
Positive Phase 3 data and imminent regulatory decisions could materially affect Ionis’ future revenue profile via milestone payments and royalties if GSK secures approvals and launches bepirovirsen. The reported functional cure rates (far above <1% with current standard of care) represent a potentially meaningful therapeutic advance for CHB patients. Investors should note the filing’s forward‑looking statements and the usual development, regulatory and commercial risks; the 8‑K is a disclosure of reported trial outcomes by GSK, not an FDA approval.