Escalating doses of C1 esterase inhibitor (CINRYZE) for prophylaxis in patients with hereditary angioedema

A Review of Randomized Controlled Trials of Hereditary Angioedema Long-Term Prophylaxis with C1 Inhibitor Replacement Therapy: Alleviation of Disease Symptoms Is Achievable

Through its fluctuating disease activity and unpredictable attacks, hereditary angioedema (HAE) imposes a substantial patient burden. To minimize HAE burden and improve quality of life, treatment should involve individualized management strategies that address on-demand therapy and short-term/long-term prophylaxis. Goals of long-term prophylaxis include reducing the number, severity, and burden of HAE attacks. The best characterized forms of HAE arise from deficiency or dysfunction of C1-inhibitor (C1-INH; types I/II), and C1-INH replacement therapy is a first-line intervention for on-demand (acute) treatment of HAE attacks, short-term prophylaxis before high-risk procedures, and long-term prophylaxis. Randomized, double-blind, placebo-controlled crossover trials have shown dose-dependent efficacy with plasma-derived C1-INH (pdC1-INH) 40-60 IU/kg subcutaneously, pdC1-INH 1000 U intravenously, and recombinant human C1-INH (rhC1-INH) 50 IU/kg (maximum 4200 IU) intravenously, all administered twice weekly, as long-term prophylaxis in patients with a history of 2 to ≥4 attacks/month. Overall, up to 83% (pdC1-INH 60 IU/kg) of patients experienced an HAE attack reduction threshold of ≥70%, and up to 58% (pdC1-INH 60 IU/kg) achieved an attack reduction threshold of ≥90%. Lower-dose intravenous pdC1-INH therapy (1000 U) was seemingly less effective, with 45% of 22 patients experiencing an HAE attack reduction threshold of ≥70%, and up to 23% achieving an attack reduction threshold of ≥90%. Higher-dose intravenous rhC1-INH 50 IU/kg (maximum, 4200 IU) twice weekly was of intermediate benefit. Despite a baseline mean attack frequency of 17.9 (during the 3 months prior to study treatment) and a mean attack frequency during a 4-week placebo period of 7.2, 52% of 23 patients experienced ≥70% reduction in attack frequency and 26% of 23 patients experienced ≥90% reduction in attack frequency. The increasing patient percentages treated with C1-INH replacement therapy as long-term prophylaxis meeting these high thresholds reinforces hopes and expectations that "attack freedom" is achievable, including for those with moderate or severe disease.

The international WAO/EAACI guideline for the management of hereditary angioedema - The 2021 revision and update

Hereditary Angioedema (HAE) is a rare and disabling disease for which early diagnosis and effective therapy are critical. This revision and update of the global WAO/EAACI guideline on the diagnosis and management of HAE provides up-to-date guidance for the management of HAE. For this update and revision of the guideline, an international panel of experts reviewed the existing evidence, developed 28 recommendations, and established consensus by an online DELPHI process. The goal of these recommendations and guideline is to help physicians and their patients in making rational decisions in the management of HAE with deficient C1-inhibitor (type 1) and HAE with dysfunctional C1-inhibitor (type 2), by providing guidance on common and important clinical issues, such as: 1) How should HAE be diagnosed? 2) When should HAE patients receive prophylactic on top of on-demand treatment and what treatments should be used? 3) What are the goals of treatment? 4) Should HAE management be different for special HAE patient groups such as children or pregnant/breast feeding women? 5) How should HAE patients monitor their disease activity, impact, and control? It is also the intention of this guideline to help establish global standards for the management of HAE and to encourage and facilitate the use of recommended diagnostics and therapies for all patients.

Attenuated androgen discontinuation in patients with hereditary angioedema: a commented case series

Background

Hereditary angioedema (HAE) is characterized by potentially severe and life-threatening attacks of localized swelling. Prophylactic therapies are available, including attenuated androgens. Efficacy of attenuated androgens has not been assessed in large, randomized, placebo-controlled trials and can be associated with frequent, and sometimes severe, side effects. As better tolerated targeted therapies become available, attenuated androgen withdrawal is increasingly considered by physicians and their patients with HAE. Attenuated androgens withdrawal has not been systematically studied in HAE, although examination of other disorders indicates that attenuated androgen withdrawal may result in mood disturbances and flu-like symptoms. Standardized protocols for attenuated androgen discontinuation that continue to provide control of attacks while limiting potential attenuated androgen withdrawal symptoms are not established as the outcomes of different withdrawal strategies have not been compared. We aim to describe the challenges of attenuated androgen discontinuation in patients with HAE and how these may continue into the post-androgen period.

Case presentation

We present a retrospective case series of 10 patients with confirmed type I HAE who have discontinued prophylactic treatment with attenuated androgens. The most common reason for attenuated androgen discontinuation was side effects. Attenuated androgens were either immediately withdrawn, tapered and/or overlapped with another treatment. The major challenge of discontinuation was the management of an increased frequency and severity of HAE attacks in some patients.

Conclusions

Healthcare teams need to undertake careful planning and monitoring after attenuated androgens discontinuation, and modify treatment strategies if HAE control is destabilized with an increased number of attacks. Discontinuation of attenuated androgens is definitively an option in an evolving HAE treatment landscape, and outcomes can be favourable with additional patient support and education.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13223-021-00644-0.

The international WAO/EAACI guideline for the management of hereditary angioedema-The 2021 revision and update

Hereditary angioedema (HAE) is a rare and disabling disease for which early diagnosis and effective therapy are critical. This revision and update of the global WAO/EAACI guideline on the diagnosis and management of HAE provides up-to-date guidance for the management of HAE. For this update and revision of the guideline, an international panel of experts reviewed the existing evidence, developed 28 recommendations, and established consensus by an online DELPHI process. The goal of these recommendations and guideline is to help physicians and their patients in making rational decisions in the management of HAE with deficient C1 inhibitor (type 1) and HAE with dysfunctional C1 inhibitor (type 2), by providing guidance on common and important clinical issues, such as: (1) How should HAE be diagnosed? (2) When should HAE patients receive prophylactic on top of on-demand treatment and what treatments should be used? (3) What are the goals of treatment? (4) Should HAE management be different for special HAE patient groups such as children or pregnant/breast-feeding women? and (5) How should HAE patients monitor their disease activity, impact, and control? It is also the intention of this guideline to help establish global standards for the management of HAE and to encourage and facilitate the use of recommended diagnostics and therapies for all patients.

A novel murine in vivo model for acute hereditary angioedema attacks

Hereditary Angioedema (HAE) is a rare genetic disease generally caused by deficiency or mutations in the C1-inhibitor gene, SERPING1, a member of the Serpin family. HAE results in acute attacks of edema, vasodilation, GI pain and hypotension. C1INH is a key inhibitor of enzymes controlling complement activation, fibrinolysis and the contact system. In HAE patients, contact system activation leads to uncontrolled production of bradykinin, the vasodilator responsible for the characteristic symptoms of HAE. In this study, we present the first physiological in vivo model to mimic acute HAE attacks. We evaluate hypotension, one of the many hallmark symptoms of acute HAE attacks using Serping1 deficient mice (serping1−/−) and implanted telemetry. Attacks were induced by IV injection of a silica nanoparticle (SiNP) suspension. Blood pressure was measured in real time, in conscious and untethered mice using implanted telemetry. SiNP injection induced a rapid, reversible decrease in blood pressure, in the presence of angiotensin converting enzyme (ACE) inhibition. We also demonstrate that an HAE therapeutic, ecallantide, can prevent HAE attacks in this model. The in vivo murine model described here can facilitate the understanding of acute HAE attacks, support drug development and ultimately contribute to improved patient care.

A small fragment of factor B as a potential inhibitor of complement alternative pathway activity

BACKGROUND

The complement system is a key player in innate immunity and a modulator of the adaptive immune system. Among the three pathways of complement, the alternative pathway (AP) accounts for most of the complement activation. Factor B (FB) is a major protease of the AP, making it a promising target to inhibit the AP activity in conditions of uncontrolled complement activation.

METHODS

Based on the data obtained from sequence analysis and conformational changes associated with FB, we expressed and purified a recombinant FB fragment (FBfr). We tested the inhibitory activity of the protein against the AP by in vitro assays.

RESULTS

FBfr protein was proven to inhibit the complement AP activity when tested by C3b deposition assay and rabbit erythrocyte hemolytic assay.

CONCLUSION

Our recombinant FBfr was able to compete with the native human FB, which allowed it to inhibit the AP activity. This novel compound is a good candidate for further characterization and testing to be used in complement diagnostic tests and as a drug lead in the field of complement therapeutics.

Advances in Hereditary Angioedema: The Prevention of Angioedema Attacks With Subcutaneous C1-Inhibitor Replacement Therapy

Supplemental Digital Content is Available in the Text.

Hereditary angioedema (HAE) is a debilitating condition caused by a functional C1-inhibitor (C1-INH) deficiency and characterized clinically by episodes of subcutaneous or submucosal swelling. C1-INH replacement is highly effective for preventing HAE attacks and can improve health-related quality of life. Once available only for intravenous use, C1-INH is now available as a subcutaneous formulation for self-administration, shown to provide sustained plasma levels of C1-INH and reducing the monthly median HAE attack rate by 95% versus placebo in the phase 3 COMPACT study. Subcutaneously administered C1-INH satisfies multiple unmet needs in the management of patients with HAE.

Immunological Basis of the Endometriosis: The Complement System as a Potential Therapeutic Target

Endometriosis (EM) is a chronic disease characterized by the presence and proliferation of functional endometrial glands and stroma outside the uterine cavity. Ovaries and pelvic peritoneum are the most common locations for endometrial ectopic tissue, followed by deep infiltrating EM sites. The cyclic and recurrent bleeding, the progressive fibrosis and the peritoneal adhesions of ectopic endometrial glands, may cause different symptoms depending on the origin involved. EM is a frequent clinical condition affecting around 10% of women of mainly reproductive age, as well as in post-menopausal women and adolescents, especially with uterine anomalies. The risk of developing EM depends on a complex interaction between genetic, immunological, hormonal, and environmental factors. It is largely considered to arise due to a dysfunction of immunological surveillance. In fact, women with EM exhibit altered functions of peritoneal macrophages, lymphocytes and natural killer cells, as well as levels of inflammatory mediators and growth factors in the peritoneal fluid. In EM patients, peritoneal macrophages are preponderant and highly active compared to healthy women. Peritoneal macrophages are able to regulate the events that determine the production of cytokines, prostaglandins, growth factors and complement components. Several studies have shown alteration in the regulation of the complement activation, leading to chronic inflammation characteristic of EM. Aberrant regulation/activation of the complement system has been observed in the peritoneal cavity of women affected by EM. Thus, complement inhibition may represent a new approach for the treatment of EM, given that a number of complement inhibitors are under pre-clinical and clinical development. Such an intervention may provide a broader therapeutic control of complement-mediated inflammatory damage in EM patients. This review will focus on our current understanding of the role of complement activation in EM and possible modalities available for complement-based therapy.

US HAEA Medical Advisory Board 2020 Guidelines for the Management of Hereditary Angioedema

Scientific and clinical progress together with the development of effective novel therapeutic options has engendered multiple important changes in the diagnosis and management of hereditary angioedema (HAE). We now update and extend the 2013 United States Hereditary Angioedema Association Medical Advisory Board guidelines for the treatment and management of HAE. The guidelines are based on a comprehensive literature review with recommendations indicating both the strength of our recommendation and the quality of the underlying evidence. Guidelines are provided regarding the classification, diagnosis, on-demand treatment, prophylactic treatment, special considerations for women and children, development of a comprehensive management and monitoring plan, and assessment of burden of illness for both HAE due to C1 inhibitor deficiency and HAE with normal C1 inhibitor. Advances in HAE treatment now allow the development of management plans that can help many patients with HAE lead a normal life. Achieving this goal requires that physicians be familiar with the diagnostic and therapeutic transformations that have occurred in recent years.

Thromboembolic Risk of C1 Esterase Inhibitors: A Systematic Review on Current Evidence

INTRODUCTION

The exact risk of developing a thromboembolic event (TEE) while using complement 1 esterase inhibitors (C1-INHs) is currently undetermined for patients with hereditary angioedema (HAE). This systematic review aimed to define the potential risk of TEEs from these agents.

AREAS COVERED

This evaluation covers publications examining or mentioning the risk of TEEs in association with C1-INHs. A systematic literature search was conducted utilizing PubMed, Scopus, and ProQuest. This review utilized search results through January 2020 and followed the PRISMA recommendations for a systematic review. Articles not available in English and animal or in-vitro studies were excluded. For inclusion, studies had to be open-label, randomized-controlled, cross-sectional, or clinical observational studies. A total of 13 studies met inclusion criteria and yielded 1716 patients receiving at least one dose of C1-INH, though only 41 incidences of thrombosis were documented.

EXPERT OPINION

Significant heterogeneity exists in the available literature concerning both study design and the reporting of data; therefore, interpretation of thrombotic risk is difficult. TEEs are rarely reported in the literature, and they seem unlikely to occur in patients without underlying risk factors. Important risk factors include those found in the prescribing information of C1-INHs.

Subcutaneous C1 inhibitor for prevention of attacks of hereditary angioedema: additional outcomes and subgroup analysis of a placebo-controlled randomized study

Background

Hereditary angioedema (HAE) is a debilitating disorder resulting from C1-esterase inhibitor (C1-INH) deficiency. In the COMPACT phase 3 study the prophylactic use of a subcutaneous C1 inhibitor (C1-INH [SC], HAEGARDA^®, CSL Behring) twice weekly significantly reduced the frequency of acute edema attacks. Analysis of treatment effects by subgroups, onset of effect, and other exploratory analysis have not been reported.

Methods

This is a post hoc exploratory analysis on data from the randomized, placebo-controlled COMPACT study. 90 patients with C1-INH-HAE were randomized to 1 of 4 treatment sequences: C1-INH (SC) 40 or 60 IU/kg of body weight twice weekly for 16 weeks, preceded or followed by a placebo period. The pre-specified primary efficacy endpoint was the time-normalized number of HAE attacks, and pre-specified secondary efficacy endpoints were the percentage of patients with a certain treatment response (≥ 50% reduction on C1-INH (SC) versus placebo in the time-normalized number of attacks) and the time-normalized number of use of rescue medication. Pre-specified exploratory endpoints included severity of attacks, alone and combined with rescue medication use. Post hoc analyses included exploration of onset of effect and clinical assessment of patients with < 50% of response.

Results

Subgroup findings by various patient characteristics showed a consistent preventive effect of C1-INH (SC). In a post hoc analysis of attacks, the onset of the preventive effect within the first 2 weeks after treatment initiation in COMPACT showed that 10/43 patients (23%) experienced attacks of any severity with 60 IU/kg versus 34/42 patients (81%) with placebo. The need for rescue medication was tenfold lower with 60 IU/kg (35 treated attacks) versus placebo (358 treated attacks). A qualitative analysis of the 4 patients treated with 60 IU/kg and with < 50% reduction of attacks demonstrated a reduction in severity of attacks, rescue medication use, and symptom days which was considered a clinically meaningful treatment effect.

Conclusions

C1-INH (SC) prophylaxis demonstrated a preventive treatment effect with evidence of benefit within 2 weeks. A consistent treatment effect at recommended C1-INH (SC) dosing was evident in all subgroups of patients with type I/II HAE and by various measures of disease and treatment burden.

Trial registration EU Clinical Trials Register, 2013-000916-10, Registered 10 December 2013, https://www.clinicaltrialsregister.eu/ctr-search/trial/2013-000916-10; ClinicalTrials.gov Register, NCT01912456, Registered 31 July 2013, https://clinicaltrials.gov/ct2/show/NCT01912456.

Update on the Use of C1-Esterase Inhibitor Replacement Therapy in the Acute and Prophylactic Treatment of Hereditary Angioedema

In the vast majority of patients with hereditary angioedema (HAE), angioedema attacks are due to the quantitative or functional deficiency of C1-esterase inhibitor (C1-INH), which leads to increased vascular permeability and unregulated release of bradykinin. Exogenous administration of C1-INH is a rational way to restore the concentration and functional activity of this protein, regulate the release of bradykinin, and attenuate or prevent subcutaneous and submucosal edema associated with HAE. Recent international guidelines for the management of HAE include C1-INH as an option for acute treatment of HAE. In addition, these guidelines recommend C1-INH as first-line treatment for long-term prophylaxis and as the therapy of choice for short-term/preprocedural prophylaxis. Several C1-INH products are available, with approved indications varying across regions. For the acute treatment of HAE, both plasma-derived and recombinant C1-INH formulations have been shown to be effective and well tolerated in adolescents and adults with HAE, with onset of relief within 30 min to a few hours. Plasma-derived C1-INH is approved for use in children, and recombinant C1-INH is being evaluated in this population. Intravenous (IV) and subcutaneous (SC) formulations of C1-INH have been approved for routine prophylaxis to prevent HAE attacks in adolescents and adults. Both formulations when administered twice weekly have been shown to reduce the frequency and severity of HAE attacks. The SC formulation of C1-INH obviates the need for repeated venous access and may facilitate self-administration of HAE prophylaxis at home, as recommended in HAE treatment guidelines. As with most rare diseases, the costs of HAE treatment are high; however, the development of additional acute and prophylactic medications for HAE may result in competitive pricing and help drive down the costs of HAE treatment.

Long-Term Outcomes with Subcutaneous C1-Inhibitor Replacement Therapy for Prevention of Hereditary Angioedema Attacks

BACKGROUND

For the prevention of attacks of hereditary angioedema (HAE), the efficacy and safety of subcutaneous human C1-esterase inhibitor (C1-INH[SC]; HAEGARDA, CSL Behring) was established in the 16-week Clinical Study for Optimal Management of Preventing Angioedema with Low-Volume Subcutaneous C1-Inhibitor Replacement Therapy (COMPACT).

OBJECTIVE

To assess the long-term safety, occurrence of angioedema attacks, and use of rescue medication with C1-INH(SC).

METHODS

Open-label, randomized, parallel-arm extension of COMPACT across 11 countries. Patients with frequent angioedema attacks, either study treatment-naive or who had completed COMPACT, were randomly assigned (1:1) to 40 IU/kg or 60 IU/kg C1-INH(SC) twice per week, with conditional uptitration to optimize prophylaxis (ClinicalTrials.gov registration no. NCT02316353).

RESULTS

A total of 126 patients with a monthly attack rate of 4.3 in 3 months before entry in COMPACT were enrolled and treated for a mean of 1.5 years; 44 patients (34.9%) had more than 2 years of exposure. Mean steady-state C1-INH functional activity increased to 66.6% with 60 IU/kg. Incidence of adverse events was low and similar in both dose groups (11.3 and 8.5 events per patient-year for 40 IU/kg and 60 IU/kg, respectively). For 40 IU/kg and 60 IU/kg, median annualized attack rates were 1.3 and 1.0, respectively, and median rescue medication use was 0.2 and 0.0 times per year, respectively. Of 23 patients receiving 60 IU/kg for more than 2 years, 19 (83%) were attack-free during months 25 to 30 of treatment.

CONCLUSIONS

In patients with frequent HAE attacks, long-term replacement therapy with C1-INH(SC) is safe and exhibits a substantial and sustained prophylactic effect, with the vast majority of patients becoming free from debilitating disease symptoms.

Indirect comparison of intravenous vs. subcutaneous C1-inhibitor placebo-controlled trials for routine prevention of hereditary angioedema attacks

Introduction

For prophylaxis of hereditary angioedema (HAE) attacks, replacement therapy with human C1-inhibitor (C1-INH) treatment is approved and available as intravenous [C1-INH(IV)] (Cinryze^®) and subcutaneous [C1-INH(SC)] HAEGARDA^® preparations. In the absence of a head-to-head comparative study of the two treatment modalities, an indirect comparison of data from 2 independent but similar clinical trials was undertaken.

Methods

Two similar randomized, double-blind, placebo-controlled, crossover studies were identified which evaluated either C1-INH(SC) (COMPACT; NCT01912456; 16 weeks) or C1-INH(IV) (CHANGE; NCT01005888; 14 weeks) vs. placebo (on-demand treatment only) for routine prevention of HAE attacks. Individual patient data from each trial were used to conduct an indirect comparison of treatment effects. Attack reductions (absolute and percent of mean/median number of monthly HAE attacks reduction over placebo) were compared between the two C1-INH formulations at approved/recommended doses: C1-INH(SC) 60 IU/kg twice weekly (n = 45) and 1000 U of C1-INH(IV) twice weekly (n = 22). Point estimates were adjusted using mixed and quantile regression models that controlled for study design.

Results

The absolute mean monthly numbers of HAE attack reductions were 3.6 (95% CI 2.9, 4.2) for C1-INH(SC) 60 IU/kg vs. placebo and 2.3 (1.4, 3.3) for C1-INH(IV) vs. placebo; between-product difference, 1.3 (0.1, 2.4; P = 0.034). The mean percent reduction in monthly attack rate was significantly greater with C1-INH(SC) as compared with C1-INH(IV) (84% vs. 51%; P < 0.001). The percentages of subjects experiencing ≥ 50%, ≥ 70%, and ≥ 90% reductions in monthly HAE attack rates versus placebo were significantly higher with C1-INH(SC) 60 IU/kg as compared to C1-INH(IV) 1000 U (≥ 50% reduction: 91% vs. 50%, odds ratio [OR] = 10.33, P = 0.003; ≥ 70% reduction: 84% vs. 46%, OR = 6.19, P = 0.005; ≥ 90% reduction: 57% vs. 18%, OR = 6.04, P = 0.007).

Conclusion

Within the limitations of an indirect study comparison, this analysis suggests greater attack reduction with twice-weekly C1-INH(SC) 60 IU/kg as compared to twice-weekly C1-INH(IV) 1000 U for the routine prevention of HAE attacks.

Training patients for self-administration of a new subcutaneous C1-inhibitor concentrate for hereditary angioedema

AIMS

The aim of this study was to provide recommendations for training patients with hereditary angioedema, based on nursing clinical trial experience, to self-administer subcutaneous C1-INH (C1-INH[SC]) used as routine prophylaxis.

BACKGROUND

A volume-reduced, subcutaneous C1-INH concentrate (C1-INH(SC); HAEGARDA®; CSL Behring) was recently FDA-approved for the routine prevention of hereditary angioedema attacks. Nurses will play an important role in patient training.

DESIGN

Review of a phase 3, randomized, placebo-controlled, double-blind, crossover trial of C1-INH(SC) (COMPACT) and summary of recommendations for training patients based on nurses' "hands-on experience."

METHODS

A panel of nurses with clinical trial experience provided recommendations for patient training.

RESULTS

Practical suggestions and guidelines were compiled regarding patient selection, product reconstitution and administration and patient follow-up. Successful patient self-administration of C1-INH(SC) can be greatly facilitated by qualified nursing intervention. The information provided in this paper will be useful to nurses anywhere who have an opportunity to interact with patients dealing with hereditary angioedema.

Effect of Lanadelumab Compared With Placebo on Prevention of Hereditary Angioedema Attacks: A Randomized Clinical Trial

IMPORTANCE

Current treatments for long-term prophylaxis in hereditary angioedema have limitations.

OBJECTIVE

To assess the efficacy of lanadelumab, a fully human monoclonal antibody that selectively inhibits active plasma kallikrein, in preventing hereditary angioedema attacks.

DESIGN, SETTING, AND PARTICIPANTS

Phase 3, randomized, double-blind, parallel-group, placebo-controlled trial conducted at 41 sites in Canada, Europe, Jordan, and the United States. Patients were randomized between March 3, 2016, and September 9, 2016; last day of follow-up was April 13, 2017. Randomization was 2:1 lanadelumab to placebo; patients assigned to lanadelumab were further randomized 1:1:1 to 1 of the 3 dose regimens. Patients 12 years or older with hereditary angioedema type I or II underwent a 4-week run-in period and those with 1 or more hereditary angioedema attacks during run-in were randomized.

INTERVENTIONS

Twenty-six-week treatment with subcutaneous lanadelumab 150 mg every 4 weeks (n = 28), 300 mg every 4 weeks (n = 29), 300 mg every 2 weeks (n = 27), or placebo (n = 41). All patients received injections every 2 weeks, with those in the every-4-week group receiving placebo in between active treatments.

MAIN OUTCOME AND MEASURES

Primary efficacy end point was the number of investigator-confirmed attacks of hereditary angioedema over the treatment period.

RESULTS

Among 125 patients randomized (mean age, 40.7 years [SD, 14.7 years]; 88 females [70.4%]; 113 white [90.4%]), 113 (90.4%) completed the study. During the run-in period, the mean number of hereditary angioedema attacks per month in the placebo group was 4.0; for the lanadelumab groups, 3.2 for the every-4-week 150-mg group; 3.7 for the every-4-week 300-mg group; and 3.5 for the every-2-week 300-mg group. During the treatment period, the mean number of attacks per month for the placebo group was 1.97; for the lanadelumab groups, 0.48 for the every-4-week 150-mg group; 0.53 for the every-4-week 300-mg group; and 0.26 for the every-2-week 300-mg group. Compared with placebo, the mean differences in the attack rate per month were -1.49 (95% CI, -1.90 to -1.08; P < .001); -1.44 (95% CI, -1.84 to -1.04; P < .001); and -1.71 (95% CI, -2.09 to -1.33; P < .001). The most commonly occurring adverse events with greater frequency in the lanadelumab treatment groups were injection site reactions (34.1% placebo, 52.4% lanadelumab) and dizziness (0% placebo, 6.0% lanadelumab).

CONCLUSIONS AND RELEVANCE

Among patients with hereditary angioedema type I or II, treatment with subcutaneous lanadelumab for 26 weeks significantly reduced the attack rate compared with placebo. These findings support the use of lanadelumab as a prophylactic therapy for hereditary angioedema. Further research is needed to determine long-term safety and efficacy.

TRIAL REGISTRATION

EudraCT Identifier: 2015-003943-20; ClinicalTrials.gov Identifier: NCT02586805.

The international WAO/EAACI guideline for the management of hereditary angioedema-The 2017 revision and update

Hereditary Angioedema (HAE) is a rare and disabling disease. Early diagnosis and appropriate therapy are essential. This update and revision of the global guideline for HAE provides up-to-date consensus recommendations for the management of HAE. In the development of this update and revision of the guideline, an international expert panel reviewed the existing evidence and developed 20 recommendations that were discussed, finalized and consented during the guideline consensus conference in June 2016 in Vienna. The final version of this update and revision of the guideline incorporates the contributions of a board of expert reviewers and the endorsing societies. The goal of this guideline update and revision is to provide clinicians and their patients with guidance that will assist them in making rational decisions in the management of HAE with deficient C1-inhibitor (type 1) and HAE with dysfunctional C1-inhibitor (type 2). The key clinical questions covered by these recommendations are: (1) How should HAE-1/2 be defined and classified?, (2) How should HAE-1/2 be diagnosed?, (3) Should HAE-1/2 patients receive prophylactic and/or on-demand treatment and what treatment options should be used?, (4) Should HAE-1/2 management be different for special HAE-1/2 patient groups such as pregnant/lactating women or children?, and (5) Should HAE-1/2 management incorporate self-administration of therapies and patient support measures?

Long-term prophylaxis therapy in patients with hereditary angioedema with C1 inhibitor deficiency

OBJECTIVE

To review the criteria for long-term prophylaxis therapy in patients with hereditary angioedema due to C1 inhibitor deficiency (C1-INH-HAE), describe how these criteria have evolved over time, and anticipate how criteria may change in the future with the availability of new C1-INH-HAE treatment options.

DATA SOURCES

Treatment guidelines, consensus statements, and expert reviews.

STUDY SELECTIONS

Manuscripts that described long-term prophylaxis therapy in patients with C1-INH-HAE were selected.

RESULTS

Historically, patients with C1-INH-HAE were considered to be candidates for long-term prophylaxis therapy if they had at least 1 attack per month, had at least 5 days of disability per month because of C1-INH-HAE, or did not sufficiently respond to on-demand treatment. More recently, guidelines and reviews state that thresholds of number of attacks or days of disability are arbitrary and that treatment plans should be individualized to the patient's needs. Furthermore, all patients should have a comprehensive management plan that is reviewed periodically and should have at least 2 doses of on-demand treatment available. Prophylaxis therapy should be discussed as a potential treatment option for each patient; however, the decision for its use will depend on the patient's individual needs and the course of their symptoms.

CONCLUSION

The criteria for long-term prophylaxis therapy in C1-INH-HAE have changed with the recognition that treatments should be individualized to the patient's needs and with the availability of new medications that have more favorable benefit-risk profiles, are easier to use, and improve patients' quality of life.

In Vitro Fertilization Using Luteinizing Hormone-Releasing Hormone Injections Resulted in Healthy Triplets without Increased Attack Rates in a Hereditary Angioedema Case

Hereditary angioedema due to C1-inhibitor deficiency (C1-INH-HAE) is a rare, autosomal dominant disorder. The management of pregnant patients with C1-INH-HAE is a challenge for the physician. Intravenous plasma-derived nanofiltered C1-INH (pdC1INH) is the only recommended option throughout pregnancy, postpartum, and breastfeeding period. In order to increase pregnancy rates, physicians use fertilization therapies increasing endogen levels of estrogens. Therefore, these techniques can provoke an increase in the number and severity of edema attacks in C1-INH-HAE. Our patient is a 32-year-old female, diagnosed with C1-INH-HAE type 1 since 2004. She had been taking danazol 50–200 mg/day for 9 years. Due to her pregnancy plans in 2013, danazol was discontinued. PdC1INH was prescribed regularly for prophylactic purpose. Triplet pregnancy occurred by in vitro fertilization using luteinizing hormone-releasing hormone (LHRH) injections. In our patient, LHRH injections were done four times without causing any severe attack during in vitro fertilization. Angioedema did not worsen during pregnancy and delivery due to the prophylactic use of intravenous pdC1INH in our patient. According to the attack frequency and severity, there was no difference between the three pregnancy trimesters. To our knowledge, this is the first published case of C1-INH-HAE receiving in vitro fertilization therapies without any angioedema attacks during pregnancy and delivery and eventually having healthy triplets with the prophylactic use of intravenous pdC1INH.

Health-Related Quality of Life with Subcutaneous C1-Inhibitor for Prevention of Attacks of Hereditary Angioedema

BACKGROUND

Hereditary angioedema with C1-inhibitor deficiency (C1-INH-HAE) impairs health-related quality of life (HRQoL).

OBJECTIVE

The objective of this study was to assess HRQoL outcomes in patients self-administering subcutaneous C1-INH (C1-INH[SC]; HAEGARDA) for routine prevention of HAE attacks.

METHODS

Post hoc analysis of data from the placebo-controlled, crossover phase III COMPACT study (Clinical Studies for Optimal Management of Preventing Angioedema with Low-Volume Subcutaneous C1-Inhibitor Replacement Therapy). Ninety patients with C1-INH-HAE were randomized to 1 of 4 treatment sequences: C1-INH(SC) 40 or 60 IU/kg twice weekly for 16 weeks, preceded or followed by 16 weeks of twice weekly placebo injections. All HAE attacks were treated with open-label on-demand treatment as necessary. HRQoL assessments at week 14 (last visit) included the European Quality of Life-5 Dimensions Questionnaire (EQ-5D-3L), the Hospital Anxiety and Depression Scale (HADS), the Work Productivity and Activity Impairment Questionnaire (WPAI), and the Treatment Satisfaction Questionnaire for Medication (TSQM).

RESULTS

Compared with placebo (on-demand treatment alone), treatment with twice weekly C1-INH(SC) (both doses combined) was associated with better EQ-5D visual analog scale general health, less HADS anxiety, less WPAI presenteeism, work productivity loss, and activity impairment, and greater TSQM effectiveness and overall treatment satisfaction. More patients self-reported a "good/excellent" response during routine prevention with C1-INH(SC) compared with on-demand only (placebo prophylaxis) management. For each HRQoL measure, a greater proportion of patients had a clinically meaningful improvement during C1-INH(SC) treatment compared with placebo.

CONCLUSIONS

In patients with frequent HAE attacks, a treatment strategy of routine prevention with self-administered twice weekly C1-INH(SC) had a greater impact on improving multiple HAE-related HRQoL impairments, most notably anxiety and work productivity, compared with on-demand treatment alone (placebo prophylaxis).

An open-label study to evaluate the long-term safety and efficacy of lanadelumab for prevention of attacks in hereditary angioedema: design of the HELP study extension

BACKGROUND

Hereditary angioedema (HAE) is characterized by recurrent attacks of subcutaneous or submucosal edema. Attacks are unpredictable, debilitating, and have a significant impact on quality of life. Patients may be prescribed prophylactic therapy to prevent angioedema attacks. Current prophylactic treatments may be difficult to administer (i.e., intravenously), require frequent administrations or are not well tolerated, and breakthrough attacks may still occur frequently. Lanadelumab is a subcutaneously-administered monoclonal antibody inhibitor of plasma kallikrein in clinical development for prophylaxis of hereditary angioedema attacks. A Phase 1b study supported its efficacy in preventing attacks. A Phase 3, randomized, double-blind, placebo-controlled, parallel-arm study has been completed and an open-label extension is currently ongoing.

METHODS/DESIGN

The primary objective of the open-label extension is to evaluate the long-term safety of repeated subcutaneous administrations of lanadelumab in patients with type I/II HAE. Secondary objectives include evaluation of efficacy and time to first angioedema attack to determine outer bounds of the dosing interval. The study will also evaluate immunogenicity, pharmacokinetics/pharmacodynamics, quality of life, characteristics of breakthrough attacks, ease of self-administration, and safety/efficacy in patients who switch to lanadelumab from another prophylactic therapy. The open-label extension will enroll patients who completed the double-blind study ("rollover patients") and those who did not participate in the double-blind study ("non-rollover patients"), which includes patients who may or may not be currently using another prophylactic therapy. Rollover patients will receive a single 300 mg dose of lanadelumab on Day 0 and the second dose after the patient's first confirmed angioedema attack. Thereafter, lanadelumab will be administered every 2 weeks. Non-rollover patients will receive 300 mg lanadelumab every 2 weeks regardless of the first attack. All patients will receive their last dose on Day 350 (maximum of 26 doses), and will then undergo a 4-week follow-up.

DISCUSSION

Prevention of attacks can reduce the burden of illness associated with HAE. Prophylactic therapy requires extended, repeated dosing and the results of this study will provide important data on the long-term safety and efficacy of lanadelumab, a monoclonal antibody inhibitor of plasma kallikrein for subcutaneous administration for the treatment of HAE. Trial registration NCT02741596.

Preventing Hereditary Angioedema Attacks in Children Using Cinryze®: Interim Efficacy and Safety Phase 3 Findings

BACKGROUND

Hereditary angioedema (HAE) is a rare genetic disease causing unpredictable and potentially life-threatening subcutaneous and submucosal edematous attacks. Cinryze® (Shire ViroPharma Inc., Lexington, MA, USA), a nanofiltered C1 inhibitor (C1-INH), is approved in Europe for the treatment, preprocedure prevention, and routine prophylaxis of HAE attacks, and for the routine prophylaxis of attacks in the USA. This phase 3 study assessed the safety and efficacy of 2 C1-INH doses in preventing attacks in children aged 6-11 years.

METHODS

A randomized single-blind crossover study was initiated in March 2014. Results for the first 6 patients completing the study are reported here. After a 12-week qualifying observation period, patients were randomly assigned to 1 of 2 C1-INH doses, 500 or 1,000 U, every 3-4 days for 12 weeks and crossed over to the alternative dose for a second 12-week period. The primary efficacy endpoint was the number of angioedema attacks per month.

RESULTS

Six females with HAE type I and a median age of 10.5 years received 2 doses of C1-INH (500 and 1,000 U). The mean (SD) difference in the number of monthly angioedema attacks between the baseline observation period and the treatment period was -1.89 (1.31) with 500 U and -1.89 (1.11) with 1,000 U. During the treatment periods, cumulative attack severity, cumulative daily severity, and the number of attacks needing acute treatment were lower. No serious adverse events or study drug discontinuations occurred.

CONCLUSIONS

Interim findings from this study indicate that routine prevention with intravenous administration of C1-INH is efficacious, safe, and well tolerated in children ≥6 years of age.

Prevention of Hereditary Angioedema Attacks with a Subcutaneous C1 Inhibitor

BACKGROUND

Hereditary angioedema is a disabling, potentially fatal condition caused by deficiency (type I) or dysfunction (type II) of the C1 inhibitor protein. In a phase 2 trial, the use of CSL830, a nanofiltered C1 inhibitor preparation that is suitable for subcutaneous injection, resulted in functional levels of C1 inhibitor activity that would be expected to provide effective prophylaxis of attacks.

METHODS

We conducted an international, prospective, multicenter, randomized, double-blind, placebo-controlled, dose-ranging, phase 3 trial to evaluate the efficacy and safety of self-administered subcutaneous CSL830 in patients with type I or type II hereditary angioedema who had had four or more attacks in a consecutive 2-month period within 3 months before screening. We randomly assigned the patients to one of four treatment sequences in a crossover design, each involving two 16-week treatment periods: either 40 IU or 60 IU of CSL830 per kilogram of body weight twice weekly followed by placebo, or vice versa. The primary efficacy end point was the number of attacks of angioedema. Secondary efficacy end points were the proportion of patients who had a response (≥50% reduction in the number of attacks with CSL830 as compared with placebo) and the number of times that rescue medication was used.

RESULTS

Of the 90 patients who underwent randomization, 79 completed the trial. Both doses of CSL830, as compared with placebo, reduced the rate of attacks of hereditary angioedema (mean difference with 40 IU, -2.42 attacks per month; 95% confidence interval [CI], -3.38 to -1.46; and mean difference with 60 IU, -3.51 attacks per month; 95% CI, -4.21 to -2.81; P<0.001 for both comparisons). Response rates were 76% (95% CI, 62 to 87) in the 40-IU group and 90% (95% CI, 77 to 96) in the 60-IU group. The need for rescue medication was reduced from 5.55 uses per month in the placebo group to 1.13 uses per month in the 40-IU group and from 3.89 uses in the placebo group to 0.32 uses per month in the 60-IU group. Adverse events (most commonly mild and transient local site reactions) occurred in similar proportions of patients who received CSL830 and those who received placebo.

CONCLUSIONS

In patients with hereditary angioedema, the prophylactic use of a subcutaneous C1 inhibitor twice weekly significantly reduced the frequency of acute attacks. (Funded by CSL Behring; COMPACT EudraCT number, 2013-000916-10 , and ClinicalTrials.gov number, NCT01912456 .).

Efficacy and safety of an intravenous C1-inhibitor concentrate for long-term prophylaxis in hereditary angioedema

BACKGROUND

The plasma-derived, pasteurized, nanofiltered C1-inhibitor concentrate (pnfC1-INH) is approved in the United States as an intravenous (IV) on-demand treatment for hereditary angioedema (HAE) attacks, and, in Europe, as on demand and short-term prophylaxis.

OBJECTIVE

This analysis evaluated Berinert Patient Registry data regarding IV pnfC1-INH used as long-term prophylaxis (LTP).

METHODS

The international registry (2010-2014) collected prospective and retrospective usage, dosing, and safety data on individuals who used pnfC1-INH for any reason.

RESULTS

The registry included data on 47 subjects (80.9% female subjects; mean age, 44.8 years), which reflected 4082 infusions categorized as LTP and a total of 430.2 months of LTP administration. The median absolute dose of pnfC1-INH given for LTP was 1000 IU (range, 500-3000 IU), with a median time interval between infusion and a subsequent pnfC1-INH-treated attack of 72.0 hours (range, 0.0-166.4 hours). Fifteen subjects (31.9%) had no pnfC1-INH-treated HAE attacks within 7 days after pnfC1-INH infusion for LTP; 32 subjects (68.1%) experienced 246 attacks, with rates of 0.06 attacks per infusion and 0.57 attacks per month. A total of 81 adverse events were reported in 16 subjects (34.0%) (0.02 events per infusion; 0.19 events per month); only 3 adverse events were considered related to pnfC1-INH (noncardiac chest pain, postinfusion headache, deep vein thrombosis in a subject with an IV port).

CONCLUSION

In this international registry, IV pnf-C1-INH given as LTP for HAE was safe and efficacious, with a low rate of attacks that required pnfC1-INH treatment, particularly within the first several days after LTP administration.

Prophylaxis in hereditary angioedema (HAE) with C1 inhibitor deficiency

Hereditary angioedema (HAE) is a rare congenital disorder characterized by recurrent episodes of subcutaneous or submucosal edema. Laryngeal manifestations can be life-threatening. In the majority of cases, the disease can be adequately treated with an on-demand approach--in some cases, however, short- or long-term prophylaxis is indicated. Attenuated androgens used to be the drugs of choice, but they are associated with considerable side effects and no longer commercially available in the German-speaking countries of the EU. They are currently being replaced by more effective and more tolerable agents such C1-inhibitors, the kallikrein inhibitor ecallantide, and the B2 receptor antagonist icatibant, which have recently obtained market authorization. These new drugs have had a major impact, especially on the indications and procedures for long-term prophylaxis. According to the most recent international consensus papers and our own experience, self-administered C1-inhibitors are now the first option for long-term prophylactic therapy. The decision for prophylaxis should no longer be based on single parameters such as the frequency of attacks but on adequate overall disease control including quality of life. More drugs are currently being developed, which may lead to further changes in the treatment algorithms of HAE.

Recombinant human C1 esterase inhibitor in the management of hereditary angioedema

Hereditary angioedema (HAE), a rare autosomal dominant genetic disorder, is caused by a deficiency in functional C1 esterase inhibitor (C1-INH). This potentially life-threatening condition manifests as recurrent attacks of subcutaneous and submucosal swelling of the skin, gastrointestinal tract and larynx. The management of HAE includes treatment of acute episodes, short-term prophylaxis in preparation for exposure to known triggers and long-term prophylaxis to decrease the incidence and severity of HAE attacks. Four products are approved in the USA for the treatment of acute attacks of HAE, including one human plasma-derived C1-INH therapy, a recombinant human C1-INH product (rhC1-INH), a plasma kallikrein inhibitor and a bradykinin B2 receptor antagonist. In addition, one human plasma-derived C1-INH therapy and danazol are approved for prophylaxis of HAE attacks. rhC1-INH, extracted from the milk of transgenic rabbits, is a glycoprotein of 478 amino acids with an identical amino acid sequence to the endogenous human C1-INH protein. Population pharmacokinetic analysis of rhC1-INH supports an intravenous dosing strategy of 50 U/kg (maximum 4200 U). The safety and efficacy of rhC1-INH in the treatment of acute attacks in patients with HAE were demonstrated in three randomized, double-blind, placebo-controlled studies and two open-label extension studies. In a pilot prophylaxis study, weekly administration of rhC1-INH 50 U/kg for 8 weeks reduced the incidence of HAE attacks and was well tolerated. Administration of rhC1-INH has not been associated with the development of anti-drug antibodies or antibodies to anti-host-related impurities.

Diagnostic and therapeutic management of hereditary angioedema due to C1-inhibitor deficiency: the Italian experience

PURPOSE OF REVIEW

Hereditary angioedema (HAE) due to C1-inhibitor (C1-INH) deficiency (C1-INH-HAE) is a rare disease, with a reported prevalence of about 1 : 50 000. C1-INH-HAE causes disabling symptoms, which may be life-threatening if swelling affects upper airways. Diagnostic procedures are now well established and the role of bradykinin as the main mediator of plasma outflow eliciting angioedema formation has been clearly elucidated.

RECENT FINDINGS

Increased understanding of the pathogenesis of C1-INH-HAE allowed in recent years the development of new drugs targeted to inhibit bradykinin synthesis (Ecallantide) or activity (Icatibant). At the same time, a recombinant C1-INH concentrate (Ruconest) was produced from the milk of transgenic rabbits and two plasma-derived C1-INHs (Berinert, Cinryze) underwent controlled trials to obtain marketing authorization. In 2012, an Italian network for C1-INH-HAE (ITACA) was established by physicians of 17 HAE reference centres to collect data from Italian patients and to homogenize and improve the diagnostic and therapeutic approach to the disease.

SUMMARY

Although there is a widespread agreement on therapeutic goals and treatment of C1-INH-HAE acute attacks, different approaches to prophylaxis are still present among HAE experts. The clinical experience of ITACA on a large population of C1-INH-HAE patients followed for several years may help in identifying the most effective strategies for the management of the disease.

Self-administered C1 esterase inhibitor concentrates for the management of hereditary angioedema: usability and patient acceptance

Hereditary angioedema (HAE) is a rare genetic disease characterized by episodic subcutaneous or submucosal swelling. The primary cause for the most common form of HAE is a deficiency in functional C1 esterase inhibitor (C1-INH). The swelling caused by HAE can be painful, disfiguring, and life-threatening. It reduces daily function and compromises the quality of life of affected individuals and their caregivers. Among different treatment strategies, replacement with C1-INH concentrates is employed for on-demand treatment of acute attacks and long-term prophylaxis. Three human plasma-derived C1-INH preparations are approved for HAE treatment in the US, the European Union, or both regions: Cinryze(®), Berinert(®), and Cetor(®); however, only Cinryze is approved for long-term prophylaxis. Postmarketing studies have shown that home therapy (self-administered or administered by a caregiver) is a convenient and safe option preferred by many HAE patients. In this review, we summarize the role of self-administered plasma-derived C1-INH concentrate therapy with Cinryze at home in the prophylaxis of HAE.

Overview of Laboratory Testing and Clinical Presentations of Complement Deficiencies and Dysregulation

Historically, complement disorders have been attributed to immunodeficiency associated with severe or frequent infection. More recently, however, complement has been recognized for its role in inflammation, autoimmune disorders, and vision loss. This paradigm shift requires a fundamental change in how complement testing is performed and interpreted. Here, we provide an overview of the complement pathways and summarize recent literature related to hereditary and acquired angioedema, infectious diseases, autoimmunity, and age-related macular degeneration. The impact of complement dysregulation in atypical hemolytic uremic syndrome, paroxysmal nocturnal hemoglobinuria, and C3 glomerulopathies is also described. The advent of therapeutics such as eculizumab and other complement inhibitors has driven the need to more fully understand complement to facilitate diagnosis and monitoring. In this report, we review analytical methods and discuss challenges for the clinical laboratory in measuring this complex biochemical system.

Complement, a target for therapy in inflammatory and degenerative diseases

Complement is a key component of immunity with crucial inflammatory and opsonic properties; inappropriate activation of complement triggers or exacerbates inflammatory disease.

Complement dysregulation is a core feature of some diseases and contributes to pathology in many others.

Approved agents have been developed for and are highly effective in some orphan applications, but their progress to use in more common diseases has been slow.

Numerous challenges, such as target concentration or high turnover, limit the efficacy of these agents in humans.

Numerous novel agents targeting different parts of the complement system in different ways are now emerging from pre-clinical studies and are entering Phase I/II trials; these agents bring the potential for more-effective and more-specific anti-complement therapies in disease.

Other agents, both biologic and small molecule, are in Phase II or III trials for both rare and common diseases — administration routes include localized (for example, intravitreal) and systemic routes.

There is an urgent need to develop biomarkers and imaging methods that enable monitoring of the effects and efficacy of anti-complement agents.

The complement cascade, a key regulator of innate immunity, is a rich source of potential therapeutic targets for diseases including autoimmune, inflammatory and degenerative disorders. Morgan and Harris discuss the progress made in modulating the complement system and the existing challenges, including dosing, localization of the drug to the target and how to interfere with protein–protein interactions.

The complement system is a key innate immune defence against infection and an important driver of inflammation; however, these very properties can also cause harm. Inappropriate or uncontrolled activation of complement can cause local and/or systemic inflammation, tissue damage and disease. Complement provides numerous options for drug development as it is a proteolytic cascade that involves nine specific proteases, unique multimolecular activation and lytic complexes, an arsenal of natural inhibitors, and numerous receptors that bind to activation fragments. Drug design is facilitated by the increasingly detailed structural understanding of the molecules involved in the complement system. Only two anti-complement drugs are currently on the market, but many more are being developed for diseases that include infectious, inflammatory, degenerative, traumatic and neoplastic disorders. In this Review, we describe the history, current landscape and future directions for anti-complement therapies.

A phase 1 study investigating DX-2930 in healthy subjects

BACKGROUND

DX-2930 is a human monoclonal antibody inhibitor of plasma kallikrein under investigation for long-term prophylaxis of hereditary angioedema.

OBJECTIVE

To assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of DX-2930 in healthy subjects.

METHODS

A single-center, double-blinded study was performed in 32 healthy subjects randomized 3:1 to receive a single subcutaneous administration of DX-2930 or placebo within 1 of 4 sequential, ascending dose cohorts (n = 8 each): 0.1, 0.3, 1.0, or 3.0 mg/kg.

RESULTS

No dose-limiting toxicity was observed. Headache was the most commonly reported treatment emergent adverse event (AE), occurring at a rate of 25% in the DX-2930- and placebo-treated groups; none were severe and all resolved. There were no serious AEs, discontinuations owing to an AE, or deaths. Two subjects had a severe AE reported as related to treatment by the blinded investigator; the 2 AEs were asymptomatic creatinine phosphokinase elevations of 902 U/L in 1 subject receiving 0.1 mg/kg DX-2930 and 1,967 U/L in 1 subject receiving placebo. For the 0.1-, 0.3-, 1.0-, and 3.0-mg/kg dose groups, respectively, mean maximum plasma concentrations were 0.6, 1.4, 5.6, and 14.5 μg/mL and mean elimination half-lives were 20.6, 16.8, 17.6, and 21.2 days. Exploratory biomarker assays, involving ex vivo activation of the kallikrein pathway, showed dose- and time-dependent inhibition of plasma kallikrein, with evidence of sustained bioactivity consistent with the pharmacokinetics profile.

CONCLUSION

A single administration of DX-2930 in healthy subjects up to doses of 3.0 mg/kg was well tolerated without dose-limiting toxicity. Pharmacokinetic and pharmacodynamic data provide evidence for a long-acting biological effect relevant to long-term prophylaxis for hereditary angioedema with C1-inhibitor deficiency.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01923207.