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Concept: Hereditary angioedema

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Hereditary angioedema (HAE) is a rare autosomal dominant disease that usually occurs in adolescence and early adulthood. It is characterized by recurrent non-pitting edema involving the skin and intestinal tract, especially the extremities and face. It is not associated with urticaria and pruritus. The cause is known to be the deficiency of C1 inhibitor. We herein report a 7-year-old girl with HAE who had recurrent episodes of swelling of the extremities and face without urticaria and pruritus. Her great grandmother had suffered from the same symptoms. The level of serum C4 was 8.01 mg/dL (normal: 10-40 mg/dL). The level of C1 inhibitor was 5.0 mg/dL (normal: 18-40 mg/dL). To our knowledge, this is the first pediatric case with typical clinical symptoms of HAE and C1 esterase inhibitor deficiency in Korea.

Concepts: Allergy, Gastroenterology, Angioedema, Hereditary angioedema, Urticaria, C1-inhibitor, Cetirizine

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Evidence on prehospital administration of the antifibrinolytic tranexamic acid (TXA) in civilian trauma populations is scarce. The aim was to study whether prehospital TXA use in trauma patients was associated with improved outcomes.

Concepts: Hereditary angioedema, Antifibrinolytics, Tranexamic acid, Antifibrinolytic

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Hereditary angioedema (HAE) is a disease characterized by recurrent tissue swelling affecting various body locations. Recent literature shows that patients with frequent attacks may benefit from long-term prophylaxis. This study evaluated the safety and prophylactic effect of weekly administrations of recombinant C1INH (rhC1INH).

Concepts: Angioedema, Hereditary angioedema, C1-inhibitor

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C1 inhibitor (C1INH) is a single-chain glycoprotein that inhibits activation of the contact system of coagulation and the complement system. C1INH isolated from human blood plasma (pd-hC1INH) is used for the management of hereditary angioedema (HAE), a disease caused by heterozygous deficiency of C1INH, and is a promise for treatment of ischemia-reperfusion injuries like acute myocardial or cerebral infarction. To obtain large quantities of C1INH, recombinant human C1INH (rhC1INH) was expressed in the milk of transgenic rabbits (12g/l) harboring genomic human C1INH sequences fused to 5' bovine αS(1) casein promoter sequences. Recombinant hC1INH was isolated from milk to a specific activity of 6.1U/mg and a purity of 99%; by size-exclusion chromatography the 1% impurities consisted of multimers and N-terminal cleaved C1INH species. Mass spectrometric analysis of purified rhC1INH revealed a relative molecular mass (M®) of 67,200. Differences in M® on SDS PAGE and mass spectrometric analysis between rhC1INH and pd-hC1INH are explained by differential glycosylation (calculated carbohydrate contents of 21% and 28%, respectively), since protein sequencing analysis of rhC1INH revealed intact N- and C-termini. Host-related impurity analysis by ELISA revealed trace amounts of rabbit protein (approximately 10ppm) in purified batches, but not endogenous rabbit C1INH. The kinetics of inhibition of the target proteases C1s, Factor XIIa, kallikrein and Factor XIa by rhC1INH and pd-hC1INH, indicated comparable inhibitory potency and specificity. Recently, rhC1INH (Ruconest(®)) has been approved by the European Medicines Agency for the treatment of acute attacks of HAE.

Concepts: Molecular biology, Blood, Coagulation, Complement system, Glycosylation, Angioedema, Hereditary angioedema, C1-inhibitor

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Edema is tissue swelling and is a common symptom in a variety of diseases. Edema form due to accumulation of fluids, either through reduced drainage or increased vascular permeability. There are multiple vascular signalling pathways that regulate vessel permeability. An important mediator that increases vascular leak is the peptide hormone bradykinin, which is the principal agent in the swelling disorder hereditary angioedema. The disease is autosomal dominant inherited and presents clinically with recurrent episodes of acute swelling that can be life-threatening involving the skin, the oropharyngeal, laryngeal, and gastrointestinal mucosa. Three different types of hereditary angiodema exist in patients. The review summarises current knowledge on the pathophysiology of hereditary angiodema and focuses on recent experimental and pharmacological findings that have led to a better understanding and new treatments for the disease.

Concepts: Disease, Skin, Angiotensin II receptor antagonist, Angioedema, Hereditary angioedema, ACE inhibitor, Bradykinin, Urticaria

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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 .).

Concepts: Pharmacology, Clinical trial, Crossover study, Type I and type II errors, Placebo, Randomness, Angioedema, Hereditary angioedema

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Conestat alfa, a recombinant human C1 inhibitor (rhC1-INH) is a novel therapeutic option for the acute treatment of hereditary angioedema due to C1-INH (HAE-C1-INH) deficiency. Our aim was to investigate the efficacy and safety profile of conestat alfa in patients with HAE-C1-INH, under real-life conditions. We analyzed 65 edematous episodes requiring acute treatment and occurring in two female HAE-C1-INH patients. The patients were treated at home with rhC1-INH per occasion. They recorded the time of rhC1-INH administration, the time to the onset of improvement, and time to the complete resolution of symptoms, as well as the side effects. Symptom severity and patient satisfaction were measured with a visual analog scale (VAS). Thirty-three HAE attacks occurred in submucosal tissue, 17 in subcutaneous tissue, and 15 had mixed locations. After the administration of rhC1-INH, clinical symptoms improved within 0.50 (0.17-4.50 hours) hours and resolved completely within 9.00 (1.67-58.75 hours) hours. The time between the onset of the attack and the administration of rhC1-INH was correlated with the time when the symptoms stopped worsening (R = 0.3212; p = 0.0096) and the time to complete resolution of the symptoms (R = 0.4774; p < 0.0001). The time to response to the drug differed with attack location. The efficacy and safety of rhC1-INH persisted after repeated use. None of the patients experienced a recurrence of the HAE attack or drug-related systemic adverse events. The mean VAS score of patient satisfaction was 93.14. Home treatment with rhC1-INH was an effective and well-tolerated therapy for all types of HAE attacks.

Concepts: Symptom, Attack, Angioedema, Hereditary angioedema, Attack!, C1-inhibitor

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Hereditary angioedema type III (HAEIII) is a rare inherited swelling disorder that is associated with point mutations in the gene encoding the plasma protease factor XII (FXII). Here, we demonstrate that HAEIII-associated mutant FXII, derived either from HAEIII patients or recombinantly produced, is defective in mucin-type Thr309-linked glycosylation. Loss of glycosylation led to increased contact-mediated autoactivation of zymogen FXII, resulting in excessive activation of the bradykinin-forming kallikrein-kinin pathway. In contrast, both FXII-driven coagulation and the ability of C1-esterase inhibitor to bind and inhibit activated FXII were not affected by the mutation. Intravital laser-scanning microscopy revealed that, compared with control animals, both F12-/- mice reconstituted with recombinant mutant forms of FXII and humanized HAEIII mouse models with inducible liver-specific expression of Thr309Lys-mutated FXII exhibited increased contact-driven microvascular leakage. An FXII-neutralizing antibody abolished bradykinin generation in HAEIII patient plasma and blunted edema in HAEIII mice. Together, the results of this study characterize the mechanism of HAEIII and establish FXII inhibition as a potential therapeutic strategy to interfere with excessive vascular leakage in HAEIII and potentially alleviate edema due to other causes.

Concepts: Gene, Mutation, Coagulation, Angioedema, Hereditary angioedema, Factor XII, Bradykinin, Serpin

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The clinical characteristics and icatibant-treatment outcomes of patients with hereditary angioedema with normal C1 inhibitor (HAE-nC1 INH) are limited.

Concepts: Angioedema, Hereditary angioedema, Bradykinin, Icatibant

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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.

Concepts: Allergy, Prevention, Angioedema, Hereditary angioedema, Urticaria and angioedema