Ionis Pharmaceuticals, Inc. announced initiation of OASIS-HAE, the registrational study in the donidalorsen (formerly IONIS-PKK-LRx) Phase 3 clinical program. Donidalorsen is an investigational antisense medicine designed to reduce the production of prekallikrein, which plays a key role in the activation of inflammatory mediators associated with acute attacks of hereditary angioedema (HAE). Donidalorsen uses Ionis' LIgand-Conjugated Antisense, or LICA, technology. OASIS-HAE is a double-blind, randomized, placebo-controlled registrational study in up to 84 patients with hereditary angioedema, Types 1 and 2. Patients will be randomized to receive monthly or bi-monthly subcutaneous donidalorsen for 25 weeks. Following the placebo-controlled portion of the study, patients may enter the 52-week open-label extension study. New Phase 2 data recently presented at ACAAI highlighted an overall reduction in moderate to severe attacks, and a reduction in these attacks starting with the second dose. For the final month of the study, all donidalorsen treated patients were attack-free. In this study, donidalorsen was safe and well tolerated.