Arrowhead Pharmaceuticals (NASDAQ:ARWR) saw its stock price soar 23.4% to $91.96 during regular trading on July 22, 2026, following the release of positive Phase 3 data for its investigational therapy Plozasiran. The biotech sector, as measured by the SPDR S&P Biotech ETF (NYSEARCA:XBI), slipped 1.0% during the same period.
The SHASTA-3 and SHASTA-4 studies achieved all prespecified endpoints, demonstrating that Plozasiran lowered median triglyceride levels by 79% to 81% at 12 months, compared to a placebo reduction of approximately 27%. Additionally, the therapy reduced pancreatitis events by 78% across the pooled study population. The highest-risk subgroup treated with Plozasiran experienced zero pancreatitis events.
Arrowhead’s market capitalization increased by approximately $2.48 billion, reaching an estimated $13.09 billion. The gain represents 1.4 times the company’s cash holdings as of March 31, 2026, which stood at $1.78 billion. The company reported a net loss of $132.7 million for its fiscal second quarter.
CEO Christopher Anzalone highlighted the dosing advantage of Plozasiran, which requires only four injections per year compared to approximately 12 for Ionis Pharmaceuticals’ (NASDAQ:IONS) Tryngolza, representing a 67% reduction in injection frequency. Arrowhead plans to submit a supplemental new drug application in the U.S. by the end of 2026.
Ionis Pharmaceuticals, which already holds FDA approval for Tryngolza as of June 24, 2026, saw its stock trade mostly unchanged. The FDA broadened the label for Tryngolza, and Ionis announced the drug will be available in the U.S. starting in July. RBC Capital Markets analyst Luca Issi described the data as “a best-case scenario for ARWR.”
Despite the positive results, risks remain. Complete datasets have not been released, and comparing results across separate trials can be misleading. Regulators have not yet verified the broader efficacy claims. Comprehensive SHASTA results are scheduled for release on August 30 at the ESC Congress, which will provide further subgroup detail and safety data.
Arrowhead observed no notable changes in mean liver fat in the MRI subgroup and no clinically relevant alterations in liver enzymes. No new safety concerns were identified. The company’s market value advantage over Ionis has grown to approximately $4.30 billion, though both firms have wider pipelines that contribute to the valuation difference.
