Detecting oral kallikrein-targeting therapy through triggered contact activation: A phase I study

Kallikrein inhibitors for angioedema: the progress of preclinical and early phase studies

INTRODUCTION

Hereditary angioedema (HAE) is a rare genetic disorder characterized by recurrent edema and predominantly caused by the dysregulation of the kinin-kallikrein system.

AREAS COVERED

This manuscript presents the results of preclinical and early clinical trials of newer drugs targeting the dysregulated kinin-kallikrein system. ATN-249 is an oral drug that has shown promising results in preclinical and Phase I studies, and good tolerability in the prophylactic treatment of attacks. KVD900 is also an oral agent developed for the on-demand treatment of HAE attacks. It has shown positive results in Phase I/II studies, with rapid absorption. The third drug, IONIS-PKKRx, is an antisense oligonucleotide targeting plasma prekallikrein mRNA. It has shown a dose-dependent reduction of plasma prekallikrein levels and proenzyme activation in Phase I/II studies, and has shown promising results. STAR-0215 is a long acting anti-activated kallikrein monoclonal antibody. A Phase 1a single ascending dose trial evaluated its safety, pharmacokinetics, and pharmacodynamics. Lastly, NTLA-2002 is an investigational gene-editing therapy.

EXPERT OPINION

The targeted treatment of the dysregulated kinin-kallikrein system with specific inhibitors is promising for the prevention of angioedema attacks. Ongoing phase III studies will provide further insight into the efficacy and long-term safety of these novel therapies, potentially expanding treatment options for HAE treatment.

Hereditary Angioedema: The Clinical Picture of Excessive Contact Activation

Hereditary angioedema is a rare, genetic disorder characterized by painful, debilitating and potentially life-threatening angioedema attacks in subcutaneous and submucosal tissue. While usually unpredictable, attacks can be provoked by a variety of triggers including physical injury and certain medication and are often preceded by prodromal symptoms. Hereditary angioedema has a profound influence on the patients' lives. The fundamental cause of hereditary angioedema in almost all patients is a mutation in the SERPING1 gene leading to a deficiency in C1-inhibitor. Subsequently, the contact activation cascade and kallikrein-kinin pathway are insufficiently inhibited, resulting in excessive bradykinin production triggering vascular leakage. While C1-inhibitor is an important regulator of the intrinsic coagulation pathway, fibrinolytic system and complement cascade, patients do not have an increased risk of coagulopathy, autoimmune conditions or immunodeficiency disorders. Hereditary angioedema is diagnosed based on C1-inhibitor level and function. Genetic analysis is only required in rare cases where hereditary angioedema with normal C1-inhibitor is found. In recent years, new, highly specific therapies have greatly improved disease control and angioedema-related quality of life. This article reviews the clinical picture of hereditary angioedema, the underlying pathophysiology, diagnostic process and currently available as well as investigational therapeutic options.

Specific Targeting of Plasma Kallikrein for Treatment of Hereditary Angioedema: A Revolutionary Decade

Hereditary angioedema (HAE) is a rare, chronic, genetic disease that presents with nonpruritic angioedema of the face, extremities, airway (can be life-threatening), genitourinary system, and abdomen. These symptoms can significantly impair daily activities. Hereditary angioedema is classified into HAE owing to a deficiency of functional C1INH (HAE-C1INH) or HAE with normal C1INH (HAE-nl-C1INH). Both type I and II HAE-C1INH result from inherited or spontaneous mutations in the SERPING1 gene, which encodes for C1INH. These mutations result in C1INH dysfunction, leading to uncontrolled plasma kallikrein activity with excessive bradykinin production. Bradykinin receptor activation leads to vasodilation, increased vascular permeability, and smooth muscle contractions, resulting in submucosal angioedema through fluid extravasation. Hereditary angioedema nl-C1INH is caused by either a known or unknown genetic mutation. The underlying mechanism of HAE-nl-C1INH is less well understood but is thought to be related to bradykinin signaling. Plasma kallikrein inhibitors have been developed to inhibit the kallikrein-kinin pathway to prevent (prophylactic) and treat on-demand (acute) HAE attacks. Several of these medications are delivered through subcutaneous or intravenous injection, although new and emerging therapies include oral formulations. This article provides a historical review and describes the evolving landscape of available kallikrein inhibitors to treat HAE-C1INH.

The contact activation system and vascular factors as alternative targets for Alzheimer's disease therapy

Alzheimer's disease (AD) is the most common neurodegenerative disease, affecting millions of people worldwide. Extracellular beta-amyloid (Aβ) plaques and neurofibrillary tau tangles are classical hallmarks of AD pathology and thus are the prime targets for AD therapeutics. However, approaches to slow or stop AD progression and dementia by reducing Aβ production, neutralizing toxic Aβ aggregates, or inhibiting tau aggregation have been largely unsuccessful in clinical trials. The contribution of dysregulated vascular components and inflammation is evident in AD pathology. Vascular changes are detectable early in AD progression, so treatment of vascular defects along with anti-Aβ/tau therapy could be a successful combination therapeutic strategy for this disease. Here, we explain how vascular dysfunction mechanistically contributes to thrombosis as well as inflammation and neurodegeneration in AD pathogenesis. This review provides evidence that addressing vascular dysfunction in people with AD could be a promising therapeutic strategy.