Gene‑editing therapy cuts swelling attacks in late‑stage trial

Intellia Therapeutics said on Monday its experimental gene‑editing therapy reduced the frequency of swelling attacks in patients with a rare genetic disorder in a late‑stage trial, sending its shares up more than 5% in volatile premarket trading.The therapy, lonvoguran ziclumeran, is aimed at treating hereditary angioedema (HAE), an inherited disorder that causes recurring episodes of swelling in the limbs, face, gastrointestinal tract, and airways, with symptoms including abdominal pain, nausea, and vomiting.In a trial involving 80 patients, a one‑time infusion of the therapy reduced swelling episodes by 87% compared with placebo over six months, meeting the study’s primary endpoint.The therapy also helped 62% of patients remain attack‑free without regular preventive treatment during that period, compared with 11% in the placebo group, meeting the trial’s secondary goal.The company’s shares surged as much as 30% in premarket trading in anticipation of positive trial data before paring most of those gains.“The bar for lonvo‑z is high given its one‑time, high‑cost profile,” said analyst Debanjana Chatterjee of Jones Trading, adding that the muted stock reaction reflects misplaced expectations on Wall Street.Achieving best‑in‑class efficacy with a clean safety profile was always the realistic goal, and the therapy delivered on both, Chatterjee said.HAE affects about one in 50,000 people, according to the company, and can become life‑threatening when swelling affects the throat.The therapy is administered as a single intravenous infusion and is designed to disable a gene involved in producing kallikrein, a protein that plays a key role in triggering swelling attacks.Side effects observed by the data cut‑off were mild or moderate, with no serious adverse events reported in the treatment group, the company said.Intellia said it expects to complete its U.S. regulatory filing for the therapy in the second half of 2026, with a potential U.S. launch in the first half of 2027, pending approval.