Thomas Machnig

C1 esterase inhibitor concentrate in 1085 Hereditary Angioedema attacks – final results of the I.M.P.A.C.T.2 study

To cite this article: Craig TJ, Bewtra AK, Bahna SL, Hurewitz D, Schneider LC, Levy RJ, Moy JN, Offenberger J, Jacobson KW, Yang WH, Eidelman F, Janss G, Packer FR, Rojavin MA, Machnig T, Keinecke H‐O, Wasserman RL. C1 esterase inhibitor concentrate in 1085 Hereditary Angioedema attacks – final results of the I.M.P.A.C.T.2 study. Allergy 2011; 66: 1604–1611.

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.)

Effect of time to treatment on response to C1 esterase inhibitor concentrate for hereditary angioedema attacks.

BACKGROUND C1 esterase inhibitor (C1-INH) concentrate is well established as effective therapy for hereditary angioedema (HAE). It is thought that treatment of an acute HAE attack with C1-INH as early as possible improves efficacy, but there are limited data from prospective studies supporting this recommendation. OBJECTIVE To assess the effect of time to treatment (<6 vs ≥6 hours after start of an attack) with 20 U/kg of C1-INH concentrate on efficacy. METHODS A post hoc analysis of time to treatment after start of an attack was performed for 2 studies with C1-INH concentrate: International Multicenter Prospective Angioedema C1-INH Trial (IMPACT) 1 (randomized, placebo-controlled) and IMPACT 2 (open-label, uncontrolled extension). Because of differences in study design, the data sets were analyzed separately. IMPACT 1 data were analyzed using Cox regression with hazard ratios (HRs). For IMPACT 2 data, linear regression was applied to evaluate whether earlier treatment leads to faster recovery. Descriptive statistics for treatment response were calculated for both studies. RESULTS In IMPACT 1, treatment with C1-INH within less than 6 hours after start of an attack resulted in considerably shorter times to onset of symptom relief (HR, 3.36) and complete resolution (HR, 4.30) vs placebo. The benefit of C1-INH compared with placebo was reduced when administered after 6 or more hours (HRs, 1.18 for times to onset of symptom relief and 1.61 for complete resolution). Analysis of IMPACT 2 data indicated slower complete resolution of symptoms with later start of treatment. CONCLUSION Early treatment with C1-INH (<6 hours) provides a better treatment response than late treatment (≥6 hours), supporting the international recommendation to treat HAE attacks as early as possible. TRIAL REGISTRATION ClinicalTrials.gov Identifiers: NCT00168103 and NCT00292981.

C1-INH concentrate for treatment of acute hereditary angioedema: a pediatric cohort from the I.M.P.A.C.T. studies.

We analyzed the clinical response of pediatric and adolescent hereditary angioedema (HAE) patients to pdC1‐INH in the International Multicenter Prospective Angioedema C1‐INH Trials (I.M.P.A.C.T.) 1 and 2.

Safety of C1-Esterase Inhibitor in Acute and Prophylactic Therapy of Hereditary Angioedema: Findings from the Ongoing International Berinert Patient Registry

BACKGROUND The plasma-derived, pasteurized C1-inhibitor (C1-INH) concentrate, Berinert has a 4-decade history of use in hereditary angioedema (HAE), with a substantial literature base that demonstrates safety and efficacy. Thromboembolic events have rarely been reported with C1-INH products, typically with off-label use or at supratherapeutic doses. OBJECTIVES Active surveillance of safety and clinical usage patterns of pasteurized C1-inhibitor concentrate and the more recent pasteurized, nanofiltered C1-INH, with a particular interest in thromboembolic events. METHODS A registry was initiated in April 2010 at 27 US and 4 EU sites to obtain both prospective and retrospective safety and usage data on subjects who were administered C1-INH (Berinert). RESULTS As of May 10, 2013, data were available for 135 subjects and 3196 infusions. By subject, 67.4% were using C1-INH as on-demand therapy and 23.0% as both on-demand therapy and prophylactic administration. Approximately half of the infusions (49.5%) were administered for prophylaxis and >90% were given by the patient or a caregiver in the home setting. A total of 299 adverse events were reported, for an overall rate of 0.09 events per infusion with only 6 considered related to C1-INH. Two thromboembolic events were reported, both in patients with prothrombotic risk factors. CONCLUSION This large pool of real-world clinical usage data in HAE further supports the extensive safety profile of 2 Berinert formulations when used on demand and/or for prophylaxis in both home and health care settings. No evidence was found to suggest that Berinert is an independent, causative risk factor for thromboembolic events.

Treatment response after repeated administration of C1 esterase inhibitor for successive acute hereditary angioedema attacks.

Placebo-controlled studies established the efficacy of replacement therapy with C1 esterase inhibitor (C1-INH) concentrate for treating single acute hereditary angioedema (HAE) attacks, but only limited data from prospective studies are available on repeated treatment of successive HAE attacks. This study evaluates the association between repeated treatments with 20 U/kg of C1-INH concentrate (Berinert; CSL Behring, Marburg, Germany) for HAE attacks at any body location and treatment response. In a post hoc analysis of an open-label extension study (International Multicenter Prospective Angioedema C1-INH Trial [I.M.P.A.C.T.2]), the association between repeated treatment with C1-INH and times to onset of symptom relief and complete resolution of HAE symptoms was assessed in patients who were treated for at least 15 attacks by linear regression on the ordinal attack number. Eighteen patients received C1-INH concentrate for at least 15 HAE attacks over a mean duration of 34 months. Demographic and baseline characteristics of these patients were similar to those of all patients in the study. The distribution of body locations and the intensity of HAE attacks were similar for each of the first 15 attacks and subsequent attacks. The extent of previous use of C1-INH concentrate had no effect on the time to onset of symptom relief, the time to complete resolution of HAE symptoms, or the time between attacks treated with C1-INH concentrate; the median of individual linear regression coefficients was not statistically significantly different from 0. Treatment with 20 U/kg of C1-INH concentrate provided consistent treatment response in patients treated for multiple successive HAE attacks at any body location. (Clinicaltrials.gov identifier: NCT00292981).

Biochemical comparison of four commercially available C1 esterase inhibitor concentrates for treatment of hereditary angioedema

For safe and efficacious treatment of hereditary angioedema, C1 esterase inhibitor (C1‐INH) concentrates should have high purity and high amounts of functional protein. As no pharmacopoeia requirements exist for C1‐INH concentrate lot release, biochemical characteristics as declared by the manufacturers may not be compared directly. This study compared the characteristics and purity profiles of four commercially available C1‐INH concentrates.

Per-attack reporting of prodromal symptoms concurrent with C1-inhibitor treatment of hereditary angioedema attacks.

IntroductionProdromal symptoms commonly precede hereditary angioedema (HAE) attacks. There is continuing interest in evaluating prodromes as treatment indicators, but a paucity of relevant data. This study was designed to prospectively identify prodomal characteristics in patients voluntarily reporting such information around the time of seeking treatment for an acute HAE attack.MethodsTwenty-eight patients with HAE were enrolled in this survey, which was conducted in the context of an open-label study of treatment of HAE attacks with plasma-derived C1-inhibitor concentrate. At the time of treatment, patients were encouraged to answer survey questions about prodromal symptoms preceding that particular HAE attack.ResultsTwenty-one patients provided prodromal information for 253 treated HAE attacks. Seventy-one percent of patients (15/21) reported prodromes. Three patients accounted for approximately 80% of the attacks and 89% of the reported prodromal symptoms. Prodromes were experienced before 67.6% (171/253) of attacks, with a mean of 1.4 prodromes per attack. Fatigue was the most frequent prodrome (42% of attacks), followed by nausea (26%), and flu-like symptoms (22%). The median duration of a prodrome before an attack was 12 h (range, 0.33-24 h).ConclusionsDespite many limitations in the study design, these findings confirm that prodromes are frequently associated with HAE attacks in many patients and occur sufficiently early to allow time for treatment initiation. The frequency of “false positive” prodromal symptoms remains undetermined, and the authors captured data only on attacks severe enough to warrant treatment. Additional well-designed prospective studies are clearly needed to continue investigating the potential clinical relevance of prodromes.

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.

Assessment of inhibitory antibodies in patients with hereditary angioedema treated with plasma-derived C1 inhibitor

BACKGROUND Limited data are available regarding C1 inhibitor (C1-INH) administration and anti-C1-INH antibodies. OBJECTIVE To assess the incidence of antibody formation during treatment with pasteurized, nanofiltered plasma-derived C1-INH (pnfC1-INH) in patients with hereditary angioedema with C1-INH deficiency (C1-INH-HAE) and the comparative efficacy of pnfC1-INH in patients with and without antibodies. METHODS In this multicenter, open-label study, patients with C1-INH-HAE (≥12 years of age) were given 20 IU/kg of pnfC1-INH per HAE attack that required treatment and followed up for 9 months. Blood samples were taken at baseline (day of first attack) and months 3, 6, and 9 and analyzed for inhibitory anti-C1-INH antibody (iC1-INH-Ab) and noninhibitory anti-C1-INH antibodies (niC1-INH-Abs). RESULTS The study included 46 patients (69.6% female; mean age, 38.9 years; all white) who received 221 on-site pnfC1-INH infusions; most patients received 6 or fewer infusions. No patient tested positive (titer ≥1:50) for iC1-INH-Ab at any time during the study. Thirteen patients (28.2%) had detectable niC1-INH-Abs in 1 or more samples. Nine patients (19.6%) had detectable niC1-INH-Abs at baseline; 3 of these had no detectable antibodies after baseline. Of 10 patients (21.7%) with 1 or more detectable result for niC1-INH-Abs after baseline, 6 had detectable niC1-INH-Abs at baseline. Mean times to symptom relief onset and complete symptom resolution per patient were similar for those with or without anti-niC1-INH-Abs. CONCLUSION Administration of pnfC1-INH was not associated with iC1-INH-Ab formation in this population. Noninhibitory antibodies were detected in some patients but fluctuated during the study independently of pnfC1-INH administration and appeared to have no effect on pnfC1-INH efficacy. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01467947.