Danny Cohn from the University of Amsterdam and colleagues from six countries reported the success of the second phase of clinical trials of in vivo CRISPR therapy for hereditary angioedema. The experimental drug NTLA-2002 contains components of the CRISPR/Cas9 system packaged in lipid nanoparticles, which, when introduced into the body, turn off the KLKB1 gene associated with the development of the disease (we wrote about its mechanism of action and trial design in detail earlier). A single administration should provide a lifelong effect. In the second phase of the trials, 10 patients were administered 25 milligrams of the drug, 11 patients - 50 milligrams, and six - a placebo. The results were published in The New England Journal of Medicine.
Compared with placebo, during the first 16 weeks, the frequency of attacks was reduced by an average of 75 percent at the 25-milligram dose and by 77 percent at the 50-milligram dose; plasma kallikrein levels were reduced by 55 and 86 percent from baseline. At these doses of active drug, 40 percent and 73 percent of patients, respectively, remained attack-free during the observation period without any additional therapy. The most common side effects of NTLA-2002 were headache, fatigue, and nasopharyngitis.