ADARx Pharmaceuticals Announces First Patient Dosed in Phase 3 STOP-HAE Clinical Trial and Orphan Drug Designation for ADX-324, a Long-Acting siRNA in Development for the Prophylactic Treatment of Hereditary Angioedema (HAE)

– Next-generation siRNA therapeutic candidate with the potential for twice-yearly dosing –

SAN DIEGO, Oct. 22, 2025 (GLOBE NEWSWIRE) -- ADARx Pharmaceuticals, Inc. (ADARx), a late-stage clinical biotechnology company developing next-generation RNA therapeutics, today announced that the first patient has been dosed in its Phase 3 STOP-HAE clinical trial evaluating ADX-324 in patients with hereditary angioedema (HAE). Additionally, ADARx announced that the U.S. Food and Drug Administration (FDA) has granted Orphan Drug Designation to ADX-324 for the treatment of patients with HAE.

“Despite advances in prophylactic therapy, most HAE patients remain at risk of breakthrough attacks and do not achieve sustained, long-term attack-free control. In addition, the currently approved prophylaxis treatments require monthly or more frequent injections. We believe the FDA’s Orphan Drug Designation for ADX-324 underscores the continued need for additional treatment options and highlights the potential of ADX-324 to provide extended attack-free periods with substantially reduced dosing frequency,” said Zhen Li, President and Chief Executive Officer of ADARx. “Dosing the first patient in our ADX-324 Phase 3 clinical trial is a significant milestone for ADARx and we look forward to advancing this program for the HAE community.”

The Phase 3 STOP-HAE clinical trial of ADX-324 is a randomized, double-blind, placebo-controlled study designed to evaluate the efficacy of ADX-324 in preventing HAE attacks in adults with Type I and Type II HAE. The trial will also assess safety, pharmacokinetics (PK), pharmacodynamics (PD), and patient reported health-related quality of life (HRQoL). Approximately 90 patients will be enrolled and randomized to receive either ADX-324 300 mg every 6 months, ADX-324 240 mg every 3 months, or placebo during the study. Patients completing the trial will be eligible to enroll in a long-term-open-label extension study.

Enrollment for this Phase 3 program follows positive Phase 1/2 data demonstrating that ADX-324 achieved significant and durable suppression of prekallikrein (PKK) protein levels with a favorable safety profile.

For more information about the clinical trial, visit https://stophae.com.

About HAE and ADX-324

HAE is a rare genetic disorder characterized by recurrent, unpredictable attacks of swelling that can be painful, disabling, and life-threatening. These attacks result from dysregulation of the kallikrein-kinin system (KKS), which regulates blood pressure, inflammation, coagulation and pain. PKK is a critical protein in the plasma kallikrein pathway that activates a second protein called kallikrein, which, if present, produces bradykinin, a potent vasodilator. A dysfunctional KKS leads to excessive release of bradykinin which causes the swelling attacks in HAE.

ADX-324 is an investigational siRNA therapy designed to inhibit PKK generation at the mRNA level and reduce the production of plasma PKK, thereby averting bradykinin generation and potentially preventing HAE attacks. Compared to currently approved prophylactic treatments, ADX-324 is expected to decrease PKK to a greater degree, offering the potential for greater and more durable control of kallikrein activity, which is expected to result in a higher proportion of patients remaining attack-free with a less frequent dosing regimen.

About ADARx Pharmaceuticals 

ADARx Pharmaceuticals is a late-stage clinical biotechnology company dedicated to transforming cutting-edge science into next-generation RNA medicines across a broad range of therapeutic areas. We have developed proprietary technology to control the expression of specific disease drivers with highly selective RNA targeted therapies with the goal of delivering life-changing treatments for patients with urgent unmet medical needs. ADARx is focused on advancing and expanding a deep pipeline of highly potent, durable and selective RNA-targeted therapeutic candidates, developing product candidates for the treatment of complement-mediated, genetic, cardiovascular, thrombotic, central nervous system and metabolic (obesity) diseases. In addition to our wholly-owned programs, we have entered into a collaboration and license option agreement with AbbVie to develop siRNA therapeutics across multiple disease areas, including neuroscience, immunology and oncology. Follow ADARx on LinkedIn.

Contacts

Investors: ir@adarx.com 

Media: teri@redhousecomms.com 

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