Intellia Therapeutics Inc. (NASDAQ: NTLA) on Thursday released longer-term follow-up data from the ongoing Phase 1 study of investigational nexiguran ziclumeran (nex-z) for the treatment of hereditary ATTR amyloidosis with polyneuropathy (ATTRv-PN).

Results were presented at the International ATTR Amyloidosis Annual Meeting for Patients and Doctors. The results were simultaneously published in the New England Journal of Medicine.

Data

Deep, durable and consistent TTR reductions continue to be observed. Across patients who received a one-time dose of 0.3 mg/kg or higher (n=33), the mean serum TTR reduction at 24 months was 92% (corresponding mean absolute serum TTR level of 17.3 g/mL.

Among the 12 patients who had reached 36 months of follow-up, the mean serum TTR reduction was 90% (corresponding mean absolute serum TTR level of 20 g/mL.

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Favorable trends indicating stability or improvement were observed in most patients with ATTRv-PN after a single dose of nex-z.

Stability or improvement was based on evaluation of multiple clinical and biomarker measures, including Neuropathy Impairment Score (NIS), modified Neuropathy Impairment Score +7 (mNIS+7), modified body mass index (mBMI), Norfolk Quality of Life-Diabetic Neuropathy (QoL-DN) questionnaire, neurofilament light chain (NfL), and polyneuropathy disability (PND) score.

Among the 18 patients in whom a 24-month mNIS+7 assessment was completed by the data cutoff date (April 11, 2025), 13 (72%) showed improvements of a clinically meaningful threshold of ≥4 points, including most of the patients in the cohort who had progressed on Alnylam Pharmaceuticals, Inc.’s (NASDAQ: ALNY) Onpattro (patisiran).

Among all 36 patients enrolled in the Phase 1 trial, mean values of the secondary endpoints mBMI, QoL-DN and NfL all trended toward disease improvement, and 89% of patients showed improvement or stability in PND scores through 24 months compared to baseline.

Nex-z has been generally well tolerated as of the data cutoff date across all patients and at all dose levels tested.

The most commonly reported treatment-related adverse events were infusion-related reactions, which were mild or moderate and did not result in any discontinuations. Intellia began dosing patients in the Phase 3 MAGNITUDE-2 trial in April 2025.

What’s Next?

Patient screening is advancing rapidly, and enrollment completion is expected in the first half of 2026.

Intellia anticipates submitting a biologics license application (BLA) for ATTRv-PN by 2028.

Price Action: NTLA stock is down 4.42% at $16.98 at the last check on Thursday.

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