A phase 2 open-label extension study of prekallikrein inhibition with donidalorsen for hereditary angioedema

BACKGROUND

Hereditary angioedema (HAE) is a potentially fatal disease characterized by unpredictable, recurrent, often disabling swelling attacks. In a randomized phase 2 study, donidalorsen reduced HAE attack frequency and improved patient quality-of-life (ISIS721744-CS2, NCT04030598). We report the 2-year interim analysis of the phase 2 open-label extension (OLE) study (ISIS 721744-CS3, NCT04307381).

METHODS

In the OLE, the on-treatment study period consisted of fixed (weeks 1-13, donidalorsen 80 mg subcutaneously every 4 weeks [Q4W]) and flexible (weeks 17-105, donidalorsen 80 mg Q4W, 80 mg every 8 weeks [Q8W], or 100 mg Q4W) dosing periods. The primary outcome was incidence and severity of treatment-emergent adverse events (TEAEs). The secondary outcomes included efficacy, pharmacodynamic, and quality-of-life assessments.

RESULTS

Seventeen patients continued in the OLE study. No serious TEAEs or TEAEs leading to treatment discontinuation were reported. Mean monthly HAE attack rate was 96% lower than the study run-in baseline rate (mean, 0.06/month; 95% confidence interval [CI], 0.02-0.10; median, 0.04 on-treatment vs. mean, 2.70/month; 95% CI, 1.94-3.46; median, 2.29 at baseline). Mean monthly attack rate for Q8W dosing (n = 8) was 0.29 (range, 0.0-1.7; 95% CI, -0.21 to 0.79; median, 0.00). Mean plasma prekallikrein and D-dimer concentrations decreased, and Angioedema Quality of Life Questionnaire total score improved from baseline to week 105 with donidalorsen.

CONCLUSION

The 2-year interim results of this phase 2 OLE study of donidalorsen in patients with HAE demonstrated no new safety signals; donidalorsen was well tolerated. There was durable efficacy with a 96% reduction in HAE attacks.

The US Hereditary Angioedema Association Scientific Registry: hereditary angioedema demographics, disease severity, and comorbidities

BACKGROUND

Hereditary angioedema (HAE) and idiopathic nonhistaminergic angioedema (INHA) are ultra-rare diseases whose natural histories and comorbidities are incompletely understood.

OBJECTIVE

To develop a national patient-centric registry to address these deficiencies in our knowledge and improve our ability to assess the real-world impact of therapeutic interventions.

METHODS

Data from members of the US HAE Association were collected into an online registry between 2009 and April 7, 2021. Cohorts were categorized by reported physician diagnosis. Patient reported data were collected using a series of questionnaires. Demographic, natural history, and family history outcomes of the HAE due to C1 inhibitor deficiency (HAE-C1INH) participants were compared with those of the combined HAE with normal C1 inhibitor (HAE-nl-C1INH) plus INHA group. The prevalence of comorbid conditions in the HAE-C1INH group was compared with the general US population.

RESULTS

A total of 485 HAE-C1INH, 26 HAE-nl-C1INH, and 70 INHA participants were included in the analysis. Delay to diagnosis was shorter in HAE-C1INH (5 vs 11 years), but both had decreasing delays over time. Differences in attack frequency and location were found between the groups. Morbidity surrogates including emergency department visits, hospitalizations, unnecessary abdominal surgeries, and intubations were strikingly high as was mortality with 36.9% of HAE-C1INH and 15.4% of HAE-nl-C1INH participants reporting family members who died from a HAE attack. Females with HAE-C1INH had a significant increase in the prevalence of depression, sleep disorders, kidney disease, anemia, and hepatitis. Cardiovascular comorbidities were significantly reduced in the HAE-C1INH group.

CONCLUSION

The US HAEA Scientific Registry provides a mechanism to enhance our knowledge of HAE and INHA.

Lower serum 15-HETE level predicts nasal ILC2 accumulation during COX-1 inhibition in AERD

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) is associated with high levels of cysteinyl leukotrienes, prostaglandin D2, and low levels of prostaglandin E2. Further, 15-hydroxyeicosatetraenoic acid (15-HETE) levels may have predictive value in therapeutic outcomes of aspirin desensitization. Accumulation of nasal group 2 innate lymphoid cells (ILC2s) has been demonstrated during COX-1 inhibition in AERD, although the relationships between tissue ILC2 accumulation, reaction symptom severity, and novel lipid biomarkers are unknown.

OBJECTIVE

We sought to determine whether novel lipid mediators are predictive of nasal ILC2 accumulation and symptom scores during COX-1 inhibitor challenge in patients with AERD.

METHODS

Blood and nasal scraping samples from patients with AERD were collected at baseline and COX-1 inhibitor reaction and then processed for flow cytometry for nasal ILC2s and serum for lipidomic analysis.

RESULTS

Eight patients with AERD who were undergoing aspirin desensitization were recruited. Of the 161 eicosanoids tested, 42 serum mediators were detected. Baseline levels of 15-HETE were negatively correlated with the change in numbers of airway ILC2s (r = -0.6667; P = .0428). Docosahexaenoic acid epoxygenase metabolite 19,20-dihydroxy-4Z,7Z,10Z,13Z,16Z-docosapentaenoic acid (19,20-diHDPA) was positively correlated with both changes in airway ILC2s (r = 0.7143; P = .0305) and clinical symptom scores (r = 0.5000; P = .0081).

CONCLUSION

Low levels of baseline 15-HETE predicted a greater accumulation of airway ILC2s in patients with AERD who were receiving COX-1 inhibition. Further, increases in the cytochrome P pathway metabolite 19,20-dihydroxy-4Z,7Z,10Z,13Z,16Z-docosapentaenoic acid (19,20-diHDPA) were associated with increased symptoms and nasal ILC2 accumulation. Future studies to assess how these mediators might control ILC2s may improve the understanding of AERD pathogenesis.

Hereditary Angioedema: Impact of COVID-19 pandemic stress upon disease related morbidity and well-being

Background: Individuals with hereditary angioedema (HAE) experience stress-related sequelae, including enhanced disease morbidity and reduced quality of life. The pervasive societal strain that surround the coronavirus disease 2019 (COVID-19) pandemic may theoretically pose a disproportionate risk for patients with HAE. Objective: To dissect the interrelationship(s) among the COVID-19 pandemic, stress, and HAE disease-related morbidity and overall well-being. Methods: Subjects with HAE (either due to C1-inhibitor deficiency or with normal C1 inhibitor) as well as non-HAE household members (normal controls) completed online questionnaires that covered the impact of the COVID-19 pandemic on attack frequency, observed effectiveness of HAE medications, stress, and perceived quality of life and/or well-being. The subjects scored each of the questions to reflect their current status as well as their status before being aware of the pandemic. Results: Disease morbidity and psychologic stress outcomes were significantly worse in patients with HAE during the pandemic compared with before they were aware of the pandemic. A COVID-19 infection further increased attack frequency. Control subjects also experienced deterioration of well-being and optimism. A comorbid diagnosis of anxiety, depression, or posttraumatic stress disorder (PTSD) was generally associated with worse outcomes. Women consistently showed greater decrements in wellness during the pandemic compared with men. Women also reported higher levels of comorbid anxiety, depression, or PTSD than men and experienced a higher rate of job loss during the pandemic. Conclusion: The results implicated a deleterious impact of stress in the aftermath of COVID-19 awareness on HAE morbidity. The female subjects were universally more severely affected then were the male subjects. Overall well-being and/or quality of life, and optimism for the future deteriorated after awareness of the COVID-19 pandemic for the subjects with HAE and non-HAE household controls.

Therapeutic monoclonal antibodies with a focus on hereditary angioedema

Monoclonal antibodies (mAbs) have been shown to be effective and generally safe across a continually expanding list of therapeutic areas. We describe the advantages and limitations of mAbs as a therapeutic option compared with small molecules. Specifically, we discuss a novel mAb in the treatment of hereditary angioedema (HAE), a rare and potentially life-threatening condition characterized by recurrent unpredictable swelling attacks. HAE is mediated by dysregulation of plasma kallikrein activity leading to overproduction of bradykinin. Current prophylactic treatment for HAE includes androgens or replacement of the endogenous plasma kallikrein inhibitor, C1 inhibitor. However, there remains an unmet need for an effective, less burdensome treatment option. Lanadelumab is a fully human mAb targeting plasma kallikrein. Results from clinical trials, including a pivotal Phase 3 study and its ensuing open-label extension study, demonstrated that lanadelumab is associated with few treatment-related adverse events and reduced the rate of HAE attacks. This novel treatment option has the potential to significantly improve the lives of patients with HAE.

COVID-19 and hereditary angioedema: Incidence, outcomes, and mechanistic implications

Background: Patients with hereditary angioedema (HAE) have been postulated to be at increased risk for coronavirus disease 2019 (COVID-19) infection due to inherent dysregulation of the plasma kallikrein-kinin system. Only limited data have been available to explore this hypothesis. Objective: To assess the interrelationship(s) between COVID-19 and HAE. Methods: Self-reported COVID-19 infection, complications, morbidity, and mortality were surveyed by using an online questionnaire. The participants included subjects with HAE with C1 inhibitor (C1INH) deficiency (HAE-C1INH) and subjects with HAE with normal C1-inhibitor (HAE-nl-C1INH), and household controls (normal controls). The impact of HAE medications was examined. Results: A total of 1162 participants who completed the survey were analyzed, including: 695 subjects with HAE-C1INH, 175 subjects with HAE-nl-C1INH, and 292 normal controls. The incidence of reported COVID-19 was not significantly different between the normal controls (9%) and the subjects with HAE-C1INH (11%) but was greater in the subjects with HAE-nl-C1INH (19%; p = 0.006). Obesity was positively correlated with COVID-19 across the overall population (p = 0.012), with a similar but nonsignificant trend in the subjects with HAE-C1INH. Comorbid autoimmune disease was a risk factor for COVID-19 in the subjects with HAE-C1INH (p = 0.047). COVID-19 severity and complications were similar in all the groups. Reported COVID-19 was reduced in the subjects with HAE-C1INH who received prophylactic subcutaneous C1INH (5.6%; p = 0.0371) or on-demand icatibant (7.8%; p = 0.0016). The subjects with HAE-C1INH and not on any HAE medications had an increased risk of COVID-19 compared with the normal controls (24.5%; p = 0.006). Conclusion: The subjects with HAE-C1INH who were not taking HAE medications had a significantly higher rate of reported COVID-19 infection. Subcutaneous C1INH and icatibant use were associated with a significantly reduced rate of reported COVID-19. The results implicated potential roles for the complement cascade and tissue kallikrein-kinin pathways in the pathogenesis of COVID-19 in patients with HAE-C1INH.

Assessing the cost and quality-of-life impact of on-demand-only medications for adults with hereditary angioedema

Background: Novel subcutaneous (SC) prophylactic therapies are transforming the treatment landscape of hereditary angioedema (HAE). Although questions are being raised about their cost, little attention has been paid to the cost and quality of life (QoL) impact of using on-demand-only medications. Objective: We assessed the overall economic burden of on-demand-only treatment for HAE and compared patient QoL with patients who received novel SC prophylactic therapies. Methods: US Hereditary Angioedema Association members were invited to complete an anonymous online survey to profile attack frequency, treatment use, and the presence of comorbidities as well as economic and socioeconomic variables. We modeled on-demand treatment costs by using net pricing of medications in 2018, indirect patient and caregiver costs, and attack-related direct billed costs for emergency department admissions, physician office visits, and/or hospitalizations. QoL was assessed by using the Angioedema Quality of Life questionnaire. Results: A total of 1225 patients (31.4%) responded. Of these, 737 adults with HAE (type I or II) met the inclusion criteria and completed the survey. Per patient/year direct costs associated with modeled on-demand-only treatment totaled $363,795, with additional indirect socioeconomic costs of $52,576 per patient/year. The greatest improvement in QoL was seen in patients who used novel SC prophylactic therapies, with a 59.5% (p < 0.01) improvement in median impairment scores versus on-demand-only treatment. In addition, patients who used novel SC prophylactic therapies reported a 77% reduction in the number of attacks each year when compared with those who used on-demand-only treatment. Conclusion: Our real-world patient data showed the cost and QoL burden of HAE treatment with on-demand-only therapy. Use of novel SC prophylaxis can lead to sizeable reductions in attack frequency and statistically significant and clinically relevant improvements in QoL. These data could be useful to clinicians and patients as they consider therapy options for patients with HAE.

Intranasal ketorolac, diagnosis, and desensitization for aspirin-exacerbated respiratory disease

BACKGROUND

Intranasal ketorolac has been proposed as a diagnostic test for aspirin-exacerbated respiratory disease (AERD) and a faster, safer, and reliable addition to facilitating aspirin (ASA) desensitization.

OBJECTIVE

We conducted the first prospective study to dissect the impact of intranasal ketorolac incorporation during ASA desensitization vs standard oral protocols in concert with evaluating its diagnostic use for AERD.

METHODS

Patients with AERD were enrolled in a prospective open-label observational study between November 2006 and August 2013. Participants selected either one of the following desensitization protocols: intranasal ketorolac 1 day before oral ASA (group 1, combined) or ketorolac challenge with greater than 2 weeks elapsing until oral ASA (group 2, washout). All patients were on a leukotriene-modifying drug (montelukast) for at least 1 week before the challenge.

RESULTS

A total of 20 patients were enrolled: 13 in group 1 and 7 in group 2. No significant differences were seen for baseline symptom scores or forced expiratory volume in 1 second. Group 1 exhibited significant increases for the threshold dose of ASA (P = .009), the likelihood of having silent ASA desensitization (P = .01), and decreased reaction severity to oral ASA (P = .04). There were no significant differences in reaction forced expiratory volume in 1 second, the incidence of extrapulmonary symptoms, limited nasoocular reactions, rescue treatment requirements, or time to symptom resolution. There was 100% concordance between reactions to intranasal ketorolac and oral ASA for group 2, supporting its use as a diagnostic test for AERD.

CONCLUSION

Intranasal ketorolac is a useful diagnostic test and adjunct within the combined ketorolac/ASA protocol to achieve effective, efficient, and perhaps safer desensitization to ASA for patients with AERD.

Hereditary angioedema: On-demand treatment of angioedema attacks

The availability of effective acute treatment for angioedema has been fundamental in reducing the burden of illness for patients with hereditary angioedema (HAE). In building on the foundation of scientific advances that elucidate the pathomechanism(s) of attacks related to vascular permeability, novel targeted on-demand treatments have been developed and approved. These therapies have provided the means to arrest episodes of swelling, which, in the past, had the potential to inexorably lead to morbidity, and even mortality, for patients with HAE. Access to these medications, along with an emphasis on early administration and guidance that all attacks are candidates for treatment, has shifted the management paradigm for HAE. Although unmet needs remain, these acute therapies, coupled with advances in prophylactic treatment, have furthered the goal for all patients with HAE to live a normal life.

Lanadelumab demonstrates rapid and sustained prevention of hereditary angioedema attacks

Background

Lanadelumab demonstrated efficacy in preventing hereditary angioedema (HAE) attacks in the phase 3 HELP Study.

Objective

To assess time to onset of effect and long‐term efficacy of lanadelumab, based on exploratory findings from the HELP Study.

Methods

Eligible patients with HAE type I/II received lanadelumab 150 mg every 4 weeks (q4wks), 300 mg q4wks, 300 mg q2wks, or placebo. Ad hoc analyses evaluated day 0‐69 findings using a Poisson regression model accounting for overdispersion. Least‐squares mean monthly HAE attack rate for lanadelumab was compared with placebo. Intrapatient comparisons for days 0‐69 versus steady state (days 70‐182) used a paired t test for continuous endpoints or Kappa statistics for categorical endpoints.

Results

One hundred twenty‐five patients were randomized and treated. During days 0‐69, mean monthly attack rate was significantly lower with lanadelumab (0.41‐0.76) vs placebo (2.04), including attacks requiring acute treatment (0.33‐0.61 vs 1.66) and moderate/severe attacks (0.31‐0.48 vs 1.33, all P ≤ .001). More patients receiving lanadelumab vs placebo were attack free (37.9%‐48.1% vs 7.3%) and responders (85.7%‐100% vs 26.8%). During steady state, the efficacy of lanadelumab vs placebo was similar or improved vs days 0‐69. Intrapatient differences were significant with lanadelumab 300 mg q4wks for select outcomes. Lanadelumab efficacy was durable—HAE attack rate was consistently lower vs placebo, from the first 2 weeks of treatment through study end. Treatment emergent adverse events were comparable during days 0‐69 and 70‐182.

Conclusion

Protection with lanadelumab started from the first dose and continued throughout the entire study period.

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.

What is in your pantry? Entomologic anaphylaxis

Background: The booklouse, Liposcelis bostrychophila, is a potent environmental allergen clinically associated with rhinoconjunctivitis and asthma. Despite its known infestation of grain products, anaphylaxis from ingestion of this organism has, to our knowledge, not been previously reported. We present the case of a 44-year-old woman who developed anaphylaxis to ingested oats and rice shown to be contaminated with L. bostrychophila. Objective: The objective was to isolate a distinct antigen from L. bostrychophila implicated in a case of unexplained anaphylaxis. Methods: In vitro studies were obtained for relevant ingested materials and aeroallergens. Skin-prick testing (SPT) was performed with standard extracts, contaminated oats, fresh oats, and crushed L. bostrychophila. Western blots were conducted using subject and control serum to detect specific immunoglobulin E (IgE) against the grains and L. bostrychophila extract. Competitive inhibition immunoblotting was used to assess specificity of IgE binding. Results: In vitro studies and SPT were notable for positive responses to dust mite and flour contaminated by L. bostrychophila, along with contaminated oats. Testing results for fresh oat and rice were negative. Immunoblots that used the subject's serum revealed a strongly positive band in the contaminated oat and rice extracts at 24 kD, whereas dust-mite extract yielded a single 14-kD band. Isolated L. bostrychophila extract also yielded a 24-kD band. Competitive inhibition experiments demonstrated that the 24-kD band in the contaminated oat extract was immunologically distinct from the 14-kD dust-mite band. Conclusion: Our case highlights the importance of considering L. bostrychophila as a potential culprit for unexplained anaphylaxis due to ingested grain products. Given the ubiquitous presence of this insect, we suspect that this may be a more common problem than previously recognized.

Association Between Self-Reported Dental Hygiene Practices and Dental Procedure-Related Recurrent Angioedema Attacks in HAE Subjects: A Multicenter Survey

BACKGROUND

Hereditary angioedema (HAE) symptoms may be triggered by dental procedures, thereby complicating dental care in individuals affected by the condition.

OBJECTIVE

This study investigated the self-perceived dental care needs, perceived susceptibility to acute angioedema (AE) attacks after dental procedures, and dental care behavior of patients with HAE.

METHODS

A self-administered semistructured web-based questionnaire was distributed to 250 adult patients with HAE (type 1 or 2; 88% type 1) and 256 matched non-HAE controls. Data were analyzed using stratified χ² tests, logistic regression, and classification trees.

RESULTS

A total of 46.4% of HAE versus 55.5% of control patients had dental visits within 6 months (P = .04). Dental insurance was a barrier to seeking routine dental visits among both groups. However, significantly fewer patients with HAE had routine dental visits within 6 months despite having dental insurance compared with control patients (48% vs 60%, P = .01). Within the HAE group, a significantly greater number of patients with dental visits at intervals greater than 6 months had a history of recurrent postprocedural AE attacks (odds ratio [OR]: 3.9 [1.7, 8.8], P = .0005) and used antibacterial toothpaste more frequently than those without recurrent AE attacks (OR: 4.7 [1.5, 15.4], P = .005).

CONCLUSIONS

These data support the hypothesis that patients with HAE who are predisposed to having AE episodes in response to medical or physical trauma visit the dentist less and engage in specific oral hygiene practices more frequently than matched control patients and patients with HAE who reported that they were less likely to swell after a dental procedure.

Cost-Effectiveness of Prophylactic Medications for the Treatment of Hereditary Angioedema Due to C1 Inhibitor Deficiency: A Real-World U.S. Perspective

DISCLOSURES

No funding supported the writing of this commentary. The author reports personal fees from BioCryst, CSL Behring, Shire, and Pharming and grants from Ionis. He is chair of the US HAEA Medical Advisory Board and scientific advisor for HAE International.

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.

Detection and Quantitation of Cleaved and Uncleaved High Molecular Weight Kininogen in Plasma by Ligand Blotting with Radiolabeled Plasma Prekallikrein or Factor XI

A method for the quantitative assay of native single chain and kallikrein cleaved two-chain high molecular weight (HMW)-kininogen in plasma is described. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of whole plasma is followed by electrotransfer of the electropherogram to nitrocellulose membranes and detection of the blotted HMW-kininogen with its physiologic ligands, radiolabeled plasma prekallikrein or radiolabeled factor XI. Using unreduced SDS-PAGE cleaved two-chain HMW-kininogen (Mr ∼107,000 and 95,000), is elec-trophoretically separated from uncleaved single chain HMW-kininogen (Mr ∼150,000). Counting the radioactivity of the nitrocellulose pieces corresponding to cleaved HMW-kininogen permits its quantitative measurement by comparison with standards consisting of decreasing amounts of fully dextran sulfate activated normal human plasma. Single chain HMW-kininogen is similarly assayed using reduced SDS-PAGE and unactivated normal human plasma standards.

This technique is highly specific and sensitive to about 50 ng of either cleaved or uncleaved HMW-kininogen. Varying amounts of cleaved HMW-kininogen were found in a small series of plasmas from patients suffering from various inflammatory conditions. Higher levels of in vivo cleaved HMW-kininogen were observed during acute attacks of hereditary angioedema due to Cl-inhibitor deficiency. This technique may be useful for the assessment of the degree of in vitro or in vivo activation of the contact system.

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 .).

Anabolic androgen use in the management of hereditary angioedema: Not so cheap after all

BACKGROUND

Hereditary angioedema due to C1 inhibitor deficiency (HAE) is a rare, life-threatening disease that imposes a significant burden on affected patients. 17α-alkylated androgens (anabolic androgens) decrease attack frequency and severity but carry the risk of potentially serious dose-related adverse effects. Despite the emergence of targeted therapies for HAE, continued anabolic androgen use has been driven in part by their low cost.

OBJECTIVE

To examine the hidden cost of anabolic androgen use related to the risk of developing non-HAE comorbidities.

METHODS

Patients with HAE were identified in the Southern California Kaiser Permanente database using clinical and laboratory findings compatible with HAE. These patients were stratified into anabolic androgen exposed and nonexposed groups. Matched controls were selected from the Kaiser database who did not have HAE or anabolic androgen exposure. Using multivariate analysis, we determined the number of non-HAE comorbidities linked to anabolic androgen use. We next determined the association between dosing and increasing exposure to anabolic androgens and the likelihood of having various comorbidities.

RESULTS

Patients with HAE exposed to anabolic androgens had a 28% increase (P = .04) in non-HAE comorbidities when compared with their matched (nonexposed) controls. With each gram per month increase in exposure, a 12% increase in non-HAE comorbidities is observed (P < .01). The most commonly occurring non-HAE comorbidities were psychiatric, muscle cramps, obesity, and hyperlipidemia.

CONCLUSION

Our data suggest that long-term anabolic androgen use enhances the risk of developing comorbid health conditions, thus amplifying the cost of care. Our report provides additional support for the preferred use of newer, targeted therapies for the management of HAE.

Subcutaneous Icatibant for the Treatment of Hereditary Angioedema Attacks: Comparison of Home Self-Administration with Administration at a Medical Facility

BACKGROUND

Hereditary angioedema (HAE) is a life-threatening disorder characterized by recurrent angioedema. Icatibant, a subcutaneous bradykinin-B2-receptor antagonist, is an effective on-demand therapy. Data outside the United States suggest that self-administration is tolerated and patient-preferred compared with administration by health care professionals at medical facilities (HCP-administration).

OBJECTIVE

A prospective, multicenter study was conducted in the United States to compare icatibant self-administration and HCP-administration.

METHODS

Subjects 18 years or older with type I or II HAE were recruited. The first 2 HAE attacks after enrollment were treated at medical facilities. Subjects were instructed by a health care professional on self-administration during icatibant treatment for the second HAE attack. Icatibant was self-administered for all subsequent attacks. For each treated HAE attack, efficacy, safety, and tolerability data were recorded.

RESULTS

Nineteen patients with HAE received icatibant for 79 distinct HAE attacks. Mean attack duration was significantly shorter with self-administration (n = 50; 547 ± 510 minutes) than with HCP-administration (n = 29; 968 ± 717 minutes; P = .006). Mean time to treatment was significantly shorter with self-administration (143 ± 226 minutes) than with HCP-administration (361 ± 503 minutes; P < .0001). Shorter times to treatment were associated with shorter time from treatment to symptom resolution (r = 0.35; P = .02). Improvements in visual analog scale score and patient symptom score from pretreatment to 4 hours postinjection were comparable between self-administration and HCP-administration. There were no serious adverse events or discontinuations due to adverse events with self-administration or HCP-administration.

CONCLUSIONS

Icatibant self-administration shortened attack duration and time to treatment, with no difference in safety or local tolerability compared with HCP-administration. These findings support icatibant as an effective on-demand option for home-based treatment.

Pediatric Hereditary Angioedema: Onset, Diagnostic Delay, and Disease Severity

Hereditary angioedema (HAE) typically presents in childhood. Large gaps remain in our understanding of the natural history of HAE during childhood. We examined age of onset, delay in diagnosis, androgen exposure, and their influence on ultimate disease severity in a large cohort of patients with HAE. Median age of first swelling was 11 years with a median age at diagnosis of 19 years. Earlier onset of symptoms correlated with longer delays in diagnosis (P < .001) and predicted a more severe disease course, including increased number of attacks per year (P = .0009) and hospital admissions (P = .009). Earlier age of onset also significantly correlated with increased perceived HAE severity (P = .0002), negative overall life impact (P < .0001), and use of anabolic androgen. Our observations highlight the importance of early HAE diagnosis and suggest the necessity of a disease management plan once the diagnosis has been made.

Tolerability and Effectiveness of 17-α-Alkylated Androgen Therapy for Hereditary Angioedema: A Re-examination

BACKGROUND

Hereditary angioedema (HAE) is a genetic disorder clinically characterized by recurrent attacks of subcutaneous and mucosal swelling. 17-α-Alkylated androgens (AA) have been used prophylactically to reduce HAE severity, but there are many questions about the efficacy and tolerability of AA.

OBJECTIVE

The objective of this study was to investigate the tolerability and effectiveness of AA therapy in a large cohort of patients with HAE.

METHODS

We performed a retrospective cross-sectional study on 650 subjects with HAE utilizing a one time, anonymous, web-based survey. Based on an initial questionnaire, patients were routed to one of the following questionnaires: currently using AA, previously used but discontinued AA, or never used AA.

RESULTS

Statistical analysis revealed that androgens decreased attack frequency and severity in previous AA users (P < .0001) and current AA users (P < .0001). Substantial variability in the effectiveness was observed. Users who discontinued AA reported significantly lesser benefit. No dose effect was seen for the beneficial effect of AA; however, almost all users reported frequent side effects that were dose related and often severe.

CONCLUSIONS

AA therapy is usually effective for the treatment of HAE although a substantial fraction of patients with HAE do not achieve adequate benefit. In contrast, the side effects of AA are seen in almost all subjects who take the medicines. If used, AA should only be recommended in the lowest effective and tolerated dose for carefully selected patients.

Rhinovirus infection interferes with induction of tolerance to aeroantigens through OX40 ligand, thymic stromal lymphopoietin, and IL-33

BACKGROUND

Rhinovirus infection at an early age has been associated with development of asthma, but how rhinovirus influences the immune response is not clear.

OBJECTIVE

Tolerance to inhaled antigen is mediated through induction of regulatory T (Treg) cells, and we examined whether rhinovirus infection of the respiratory tract can block airway tolerance by modulating Treg cells.

METHODS

The immune response to intranasal ovalbumin in mice was assessed with concomitant infection with RV1B, and the factors induced in vivo were compared with those made by human lung epithelial cells infected in vitro with RV16.

RESULTS

RV1B infection of mice abrogated tolerance induced by inhalation of soluble ovalbumin, suppressing the normal generation of forkhead box protein 3-positive Treg cells while promoting TH2 cells. Furthermore, RV1B infection led to susceptibility to asthmatic lung disease when mice subsequently re-encountered aeroantigen. RV1B promoted early in vivo expression of the TNF family protein OX40 ligand on lung dendritic cells that was dependent on the innate cytokine thymic stromal lymphopoietin (TSLP) and also induced another innate cytokine, IL-33. Inhibiting each of these pathways allowed the natural development of Treg cells while minimizing TH2 differentiation and restored tolerance in the face of RV1B infection. In accordance, RV16 infection of human lung epithelial cells upregulated TSLP and IL-33 expression.

CONCLUSIONS

These results suggest that infection of the respiratory epithelium with rhinovirus can antagonize tolerance to inhaled antigen through combined induction of TSLP, IL-33, and OX40 ligand and that this can lead to susceptibility to asthmatic lung inflammation.

Current state of hereditary angioedema management: a patient survey

Hereditary angioedema (HAE) is a chronic disease with a high burden of disease that is poorly understood and often misdiagnosed. Availability of treatments, including C1 esterase inhibitor (C1INH) replacement, ecallantide, and icatibant, marks a significant advance for HAE patients. We aimed to better understand the current state of HAE care, from a patient perspective, after the introduction of several novel therapies. One session of the United States Hereditary Angioedema Association 2013 patient summit was devoted to data collection for this study. Patients attending the summit were self-selected, and HAE diagnosis was self-reported. Survey questions assessed patient characteristics, burden of disease, and treatment. Participant responses were captured using an audience response system. We surveyed 149 (80%) type I and II HAE (HAE-C1INH) and 37 (20%) HAE with normal C1INH (HAE-nlC1INH) patients. HAE-C1INH (72%) and HAE-nlCINH patients (76%) equally reported that HAE had a significant impact on quality of life (QOL). A third of HAE-C1INH patients were diagnosed within one year of their first HAE attack, but another third reported a delay of more than 10 years. Most HAE-C1INH (88%) and HAE-nlC1INH (76%) patients had on-demand treatment available. HAE-C1INH patients frequently had an individual treatment plan (76%) compared with 50% of HAE-nlC1INH patients. Most HAE-C1INH patients went to the emergency department (ED) or were hospitalized less than once every six months (80%). Our findings show that HAE management is improving with good access to on-demand and prophylactic treatment options. However, HAE patients still have a significant burden of disease and continued research and educational efforts are needed.

Before and after, the impact of available on-demand treatment for HAE

Availability of effective treatment for acute attacks is expected to transform the care of hereditary angioedema (HAE) patients. We felt that it would be of interest to test these assumptions by examining the perceptions of HAE patients regarding the impact that these therapies have had on their lives. Patients at a United States HAE Association summit meeting were asked to rate the burden of HAE currently and compare by recall with 2009 when these therapies were not available. Questions covered five domains: psychological/emotional status, ability to carry out daily activities, fear of suffocation, worry about their children inheriting HAE, and medication side effects. Data were analyzed using Wilcoxon signed-rank tests or analysis of variance. Responses were obtained from 134 self-identified HAE subjects: 85 type I, 21 type II, and 28 with normal C1 inhibitor (C1INH). Burden of disease showed significant improvement in all domains except worry about children inheriting HAE. With the introduction of newer therapies, subjects with the most severe burden of illness improved more than those with milder burdens. However, significant burden of illness remained. The availability of the current treatments has substantially improved the quality of life for HAE patients in the United States, similar to a survey of Danish HAE patients regarding the introduction of home treatment. Nevertheless, our study shows that a substantial burden of illness remains for HAE patients.

A consensus parameter for the evaluation and management of angioedema in the emergency department

Despite its relatively common occurrence and life-threatening potential, the management of angioedema in the emergency department (ED) is lacking in terms of a structured approach. It is paramount to distinguish the different etiologies of angioedema from one another and more specifically differentiate histaminergic-mediated angioedema from bradykinin-mediated angioedema, especially in lieu of the more novel treatments that have recently become available for bradykinin-mediated angioedema. With this background in mind, this consensus parameter for the evaluation and management of angioedema attempts to provide a working framework for emergency physicians (EPs) in approaching the patient with angioedema in terms of diagnosis and management in the ED. This consensus parameter was developed from a collaborative effort among a group of EPs and leading allergists with expertise in angioedema. After rigorous debate, review of the literature, and expert opinion, the following consensus guideline document was created. The document has been endorsed by the American College of Allergy, Asthma & Immunology (ACAAI) and the Society for Academic Emergency Medicine (SAEM).

Current update on cellular and molecular mechanisms of hereditary angioedema

OBJECTIVE

To provide an update on the molecular mechanisms of hereditary angioedema (HAE).

DATA SOURCES

MEDLINE and PubMed databases were searched to identify pertinent articles using the following key terms: hereditary angioedema, angioedema, C1 inhibitor, bradykinin, contact system, factor XII, mechanism, pathophysiology, severity, permeability, and estrogen.

STUDY SELECTIONS

Articles were selected based on their relevance to the subject matter.

RESULTS

Although the biochemical basis of "classic" HAE is known to result from C1 esterase inhibitor (C1INH) deficiency, a new form, HAE with normal C1INH, has been identified. HAE types I and II are caused by mutations in the SERPING1 gene that result in decreased plasma levels of functional C1INH. In HAE with normal C1INH, mutations in the F12 gene have been identified in a subset of individuals, but the genetic defect remains unknown in most patients. The primary mediator of swelling in HAE is bradykinin, a product of the plasma contact system that increases vascular permeability. HAE disease severity is highly variable and may be influenced by polymorphisms in other genes and other factors, such as hormones, trauma, stress, and infection.

CONCLUSION

Hereditary angioedema is a heterogeneous disorder with a complex pathophysiology. Implicated genes include SERPING1 and FXII in patients with HAE from C1INH deficiency and HAE with normal C1INH levels, respectively. Disease severity is highly variable.

Recognizing and managing hereditary angioedema

Hereditary angioedema is a rare but life-threatening disease characterized by recurring attacks of swelling of any part of the body, without hives. Prompt recognition is critical so that treatment can be started to minimize morbidity and the risk of death. Drugs have recently become available to prevent and treat acute attacks.