A single dose of the CRISPR-based gene-editing therapy NTLA-2002 has demonstrated a significant reduction in angioedema attacks and sustained reduction in total plasma kallikrein protein levels in patients with hereditary angioedema (HAE), according to results from a phase II randomized trial. The findings suggest a potential for long-term disease management with a single administration.
NTLA-2002 Efficacy
The trial, involving 27 patients, showed that from week 1 to week 16, the estimated mean monthly angioedema attack rate was 0.70 with 25 mg of NTLA-2002 and 0.65 with 50 mg, compared to 2.82 with placebo. This translates to an estimated difference in the mean monthly attack rate of -75% with the 25 mg dose and -77% with the 50 mg dose. Notably, four of the ten patients in the 25-mg group and eight of the eleven patients in the 50-mg group experienced a complete response, remaining 100% attack-free without any other treatments; this was not observed in any of the placebo patients. These results were presented at the American College of Allergy, Asthma & Immunology (ACAAI) annual meeting and published in the New England Journal of Medicine.
Mechanism of Action and Impact
NTLA-2002 works by inactivating the KLKB1 gene, which encodes for prekallikrein, a precursor to the kallikrein protein. By reducing kallikrein production and activity, as well as bradykinin levels, the therapy aims to decrease the risk of angioedema attacks. Hereditary angioedema is a rare genetic disease affecting approximately one in 50,000 people globally, characterized by severe swelling episodes that can affect the limbs, face, intestinal tract, and airway. These attacks are often unpredictable and can be life-threatening if they involve laryngeal edema.
Durable Therapeutic Effect
Updated data from the phase I portion of the trial, with a median follow-up of 20.1 months, indicated that reduced plasma kallikrein protein levels remained stable. The monthly attack rate had decreased by 98% from baseline, and eight of the ten patients have remained attack-free since the end of the primary observation period. According to Danny M. Cohn, MD, PhD, of Amsterdam University Medical Center, all patients experienced a clinically meaningful angioedema attack reduction following a single administration, most prominently in the 50 mg group, suggesting a potential for a permanent functional cure.
Safety Profile
The most common adverse events in the NTLA-2002 groups were headache (38%), fatigue (29%), and nasopharyngitis (29%). All adverse events were grade 1 or 2, except for a serious adverse event of grade 4 edema of the tongue with breathing impairment in a patient in the placebo group. No serious infusion-related events were reported.
Expert Commentary
In an accompanying editorial in the New England Journal of Medicine, Kiran Musunuru, MD, PhD, of the Perelman School of Medicine at the University of Pennsylvania, stated that the trial results provide unambiguous evidence that gene-editing therapies are helping patients. He anticipates that gene-editing treatments will have a transformative effect on the care of patients with a broad spectrum of diseases, with the durability of NTLA-2002 offering a truly 'one-and-done' proposition.
