A Study to Assess the Clinical Efficacy of Donidalorsen (Also Known as IONIS-PKK-LRx and ISIS 721744) in Participants With Hereditary Angioedema

A Randomized, Double-Blind, Placebo-Controlled, Phase 2a Study to Assess the Clinical Efficacy of ISIS 721744, a Second-Generation Ligand-Conjugated Antisense Inhibitor of Prekallikrein, in Patients With Hereditary Angioedema

The purpose of this study was to evaluate the clinical efficacy, safety, and tolerability of donidalorsen in participants with hereditary angioedema (HAE) type 1 (HAE-1), HAE type 2 (HAE-2), or HAE with normal C1-inhibitor (C1-INH) and to evaluate the effect of donidalorsen on plasma prekallikrein (PKK) and other relevant biomarkers.

This was a randomized, double-blind, placebo-controlled study in 23 participants conducted concurrently in 2 parts (Part A and Part B); participants were allocated into Part A or Part B according to type of HAE (i.e., either HAE-1/HAE-2 in Part A or HAE-nC1-INH in Part B). Part A was randomized, double-blind, and placebo-controlled; and Part B was open-label. The length of participation in the study was approximately 8 months, which included an up to 8-week screening period, a 12-week treatment period, and a 13-week post-treatment period.

Inclusion Criteria:

• Documented diagnosis of HAE-1/HAE-2 (for inclusion in Part A) or HAE-nC1-INH (for inclusion in Part B)
• Participants must have experienced a minimum of 2 HAE attacks (assessed by the Angioedema Activity Score [AAS] and confirmed by the investigator) during the screening period
• Access to, and the ability to use, ≥ 1 acute medication(s) to treat angioedema attacks

Exclusion Criteria:

• Anticipated use of short-term prophylaxis for angioedema attacks for a pre-planned procedure during the screening or study periods

• Concurrent diagnosis of any other type of recurrent angioedema, including acquired or idiopathic angioedema

• Known history of or positive test for human immunodeficiency virus (HIV), hepatitis C, or chronic hepatitis B

• Malignancy within 5 years, except for basal or squamous cell carcinoma of the skin or carcinoma in situ of the cervix that has been successfully treated

• Treatment with another investigational drug or biological agent within 1 month or 5 half-lives, whichever is longer, of screening

• Exposure to any of the following medications:

  • Angiotensin-converting enzyme (ACE) inhibitors or any estrogen-containing medications with systemic absorption (such as oral contraceptive or hormonal replacement therapy) within 4 weeks prior to screening
  • Chronic prophylaxis with Lanadelumab within 10 weeks prior to screening
  • Oligonucleotides (including small interfering ribonucleic acid [RNA]) within 4 months of screening (if single dose received) or within 12 months of screening (if multiple doses received)