ECUR-506 - (OTC-HOPE)

August 27, 2026: iECURE reported updated data from the ongoing Phase 1/2 OTC-HOPE trial of ECUR-506 in male infants with neonatal-onset ornithine transcarbamylase deficiency, presented at the SSIEM Annual Symposium in Helsinki. Phase 1/2 dosing is complete across all three dose cohorts (nine participants total).

As of July 28, 2026, ECUR-506 was generally well tolerated across low, intermediate, and high doses, with no unexpected treatment-related safety events, no thrombotic microangiopathy, and no infusion reactions. Transient Grade 2-3 transaminitis resolved with reactive immunosuppression in seven of eight participants; one participant received prophylactic corticosteroids. One death from hypoxemic respiratory failure was deemed unrelated to ECUR-506 and attributed to underlying disease progression.

In the low-dose cohort, annualized hyperammonemic events fell 57% (p=0.02) and hyperammonemic crises fell 74% (p=0.01) versus pre-treatment. Two 24-week liver biopsies showed evidence of targeted hepatic editing, and reduced serum PCSK9 levels supported editing at the PCSK9 locus. One low-dose participant achieved a complete clinical response and stopped ammonia scavenger therapy and protein restriction; two others showed improvement, including one weaned from one of two scavengers. Biopsy analyses from intermediate- and high-dose cohorts are pending.