A randomized, placebo-controlled phase 3 trial of the PI3Kδ inhibitor leniolisib for activated PI3Kδ syndrome.

Activated phosphoinositide 3-kinase delta (PI3Kδ) syndrome (APDS) is an inborn error of immunity with clinical manifestations including infections, lymphoproliferation, autoimmunity, enteropathy, bronchiectasis, increased risk of lymphoma, and early mortality. Hyperactive PI3Kδ signaling causes APDS and is selectively targeted with leniolisib, an oral, small molecule inhibitor of PI3Kδ. Here, 31 patients with APDS aged ≥12 years were enrolled in a global, phase 3, triple-blinded trial and randomized 2:1 to receive 70 mg leniolisib or placebo twice daily for 12 weeks. Coprimary outcomes were differences from baseline in the index lymph node size and the percentage of naïve B cells in peripheral blood, assessed as proxies for immune dysregulation and deficiency. Both primary outcomes were met: the difference in the adjusted mean change (95% confidence interval [CI]) between leniolisib and placebo for lymph node size was -0.25 (-0.38, -0.12; P = .0006; N = 26) and for percentage of naïve B cells, was 37.30 (24.06, 50.54; P = .0002; N = 13). Leniolisib reduced spleen volume compared with placebo (adjusted mean difference in 3-dimensional volume [cm3], -186; 95% CI, -297 to -76.2; P = .0020) and improved key immune cell subsets. Fewer patients receiving leniolisib reported study treatment-related adverse events (AEs; mostly grades 1-2) than those receiving placebo (23.8% vs 30.0%). Overall, leniolisib was well tolerated and significant improvement over placebo was notable in the coprimary endpoints, reducing lymphadenopathy and increasing the percentage of naïve B cells, reflecting a favorable impact on the immune dysregulation and deficiency seen in patients with APDS. This trial was registered at www.clinicaltrials.gov as #NCT02435173.

Interim analysis: Open-label extension study of leniolisib for patients with APDS.

BACKGROUND: Activated phosphoinositide 3-kinase delta (PI3Kδ) syndrome (APDS; or p110δ-activating mutations causing senescent T cells, lymphadenopathy, and immunodeficiency) is an inborn error of immunity caused by PI3Kδ hyperactivity. Resultant immune deficiency and dysregulation lead to recurrent sinopulmonary infections, herpes viremia, autoimmunity, and lymphoproliferation. OBJECTIVE: Leniolisib, a selective PI3Kδ inhibitor, demonstrated favorable impact on immune cell subsets and lymphoproliferation over placebo in patients with APDS over 12 weeks. Here, we report results from an interim analysis of an ongoing open-label, single-arm extension study. METHODS: Patients with APDS aged 12 years or older who completed NCT02435173 or had previous exposure to PI3Kδ inhibitors were eligible. The primary end point was safety, assessed via investigator-reported adverse events (AEs) and clinical/laboratory evaluations. Secondary and exploratory end points included health-related quality of life, inflammatory markers, frequency of infections, and lymphoproliferation. RESULTS: Between September 2016 and August 2021, 37 patients (median age, 20 years; 42.3% female) were enrolled. Of these 37 patients, 26, 9, and 2 patients had previously received leniolisib, placebo, or other PI3Kδ inhibitors, respectively. At the data cutoff date (December 13, 2021), median leniolisib exposure was 102 weeks. Overall, 32 patients (87%) experienced an AE. Most AEs were grades 1 to 3; none were grade 4. One patient with severe baseline comorbidities experienced a grade 5 AE, determined as unrelated to leniolisib treatment. While on leniolisib, patients had reduced annualized infection rates (P = .004), and reductions in immunoglobulin replacement therapy occurred in 10 of 27 patients. Other observations include reduced lymphadenopathy and splenomegaly, improved cytopenias, and normalized lymphocyte subsets. CONCLUSIONS: Leniolisib was well tolerated and maintained durable outcomes with up to 5 years of exposure in 37 patients with APDS. CLINICALTRIALS: gov identifier: NCT02859727.

Population pharmacokinetics of recombinant human C1 esterase inhibitor in children with hereditary angioedema.

BACKGROUND: Recombinant human C1 esterase inhibitor (rhC1-INH) is indicated in the United States for the treatment of acute hereditary angioedema (HAE) attacks in adolescents and adults; it is also indicated in Europe for children aged 2 years and older. A need exists for further insight into potential pharmacokinetic (PK) differences in functional C1-INH levels by age (ie, children, adolescents, and adults). OBJECTIVE: To perform population PK modeling to predict C1-INH levels by age after by age rhC1-INH administration. METHODS: Data from a phase 2 pediatric trial (children aged 4-13 years at screening) were added to a database of 6 trials in adults and adolescents. An unpublished population PK model was refined and used to simulate C1-INH exposure. RESULTS: Analysis included 153 individuals (14 healthy volunteers; 139 patients with HAE) and 1788 functional C1-INH measurements (59 from 20 patients in the pediatric trial). Bodyweight (population weight, 16-128 kg) was a key predictor of C1-INH volume of distribution. Age was not a predictor of C1-INH PK after the inclusion of bodyweight in the model. Simulations of the recommended rhC1-INH dosing regimen (bodyweight <84 kg, 50 U/kg; ≥84 kg, 4200 U) revealed that overall C1-INH exposure was comparable among age groups. Predicted peak functional C1-INH concentrations were at or above the lower level of normal (≥0.7 U/mL) for 99.8% of adults (≥18 years), 99.8% of adolescents (14-17 years), and 96.0% of children (2-13 years). CONCLUSION: The analyses support the same weight-based rhC1-INH dosing for HAE attacks in children as currently recommended for adolescents and adults. These results support clinical trial data, which revealed similar safety and efficacy profiles across these age groups.

Recombinant human C1 esterase inhibitor treatment for hereditary angioedema attacks in children.

BACKGROUND: Attacks of hereditary angioedema (HAE) due to C1 esterase inhibitor deficiency (C1-INH-HAE) usually begin during childhood or adolescence. However, limited data are available regarding indications and modalities of treatment of children. This study evaluated recombinant human C1-INH (rhC1-INH) for HAE attacks in children. METHODS: This open-label, phase 2 study included children aged 2-13 years with C1-INH-HAE. Eligible HAE attacks were treated intravenously with rhC1-INH 50 IU/kg body weight (maximum, 4200 IU). The primary end-point was time to beginning of symptom relief (TOSR; ≥20 mm decrease from baseline in visual analog scale [VAS] score, persisting for two consecutive assessments); secondary end-point was time to minimal symptoms (TTMS; <20 mm VAS score for all anatomic locations). RESULTS: Twenty children (aged 5-14 years; 73 HAE attacks) were treated with rhC1-INH. Seventy (95.9%) of the attacks were treated with a single dose of rhC1-INH. Seven (35.0%) children were treated for four or more attacks. Overall, median TOSR was 60.0 minutes (95% confidence interval [CI], 60.0-65.0); data were consistent across attacks. Median TTMS was 122.5 minutes (95% CI, 120.0-126.0); data were consistent across attacks. No children withdrew from the study due to adverse events. No treatment-related serious adverse events or hypersensitivity reactions were reported; no neutralizing antibodies were detected. CONCLUSIONS: Recombinant human C1-INH was efficacious, safe, and well tolerated in children. Data support use of the same dosing regimen for HAE attacks in children (50 IU/kg; up to 4200 IU, followed by an additional dose, if needed) as is currently recommended for adolescents and adults.

Recombinant human C1 esterase inhibitor for prophylaxis of hereditary angio-oedema: a phase 2, multicentre, randomised, double-blind, placebo-controlled crossover trial.

BACKGROUND: Hereditary angio-oedema is a recurrent, oedematous disorder caused by deficiency of functional C1 inhibitor. Infusions of plasma-derived C1 esterase inhibitor deter attacks of hereditary angio-oedema, but the prophylactic effect of recombinant human C1 esterase inhibitor has not been rigorously studied. We aimed to assess the efficacy of recombinant human C1 esterase inhibitor for prophylaxis of hereditary angio-oedema. METHODS: We conducted this phase 2, multicentre, randomised, double-blind, placebo-controlled crossover trial at ten centres in Canada, the Czech Republic, Israel, Italy, Macedonia, Romania, Serbia, and the USA. We enrolled patients aged 13 years or older with functional C1-inhibitor concentrations of less than 50% of normal and a history of four or more attacks of hereditary angio-oedema per month for at least 3 months before study initiation. Patients were randomly assigned centrally (1:1:1:1:1:1), via an interactive response technology system with fixed allocation, to receive one of six treatment sequences. During each sequence, patients received intravenous recombinant human C1 esterase inhibitor (50 IU/kg; maximum 4200 IU) twice weekly, recombinant human C1 esterase inhibitor once weekly and placebo once weekly, and placebo twice weekly, each for 4 weeks with a 1 week washout period between crossover. All patients, investigators, and study personnel who participated in patient care were masked to group allocation during the study. The primary efficacy endpoint was the number of attacks of hereditary angio-oedema observed in each 4 week treatment period. Attack symptoms were recorded daily. The primary efficacy analysis was done in the intention-to-treat population. Safety was assessed in all patients who received at least one injection of study medication. This study is registered with ClinicalTrials.gov, number NCT02247739. FINDINGS: Between Dec 29, 2014, and May 3, 2016, we enrolled 35 patients, of whom 32 (91%) underwent randomisation (intention-to-treat population) and 26 (81%) completed the study. The mean number of attacks of hereditary angio-oedema over 4 weeks was significantly reduced with recombinant human C1 esterase inhibitor twice weekly (2·7 attacks [SD 2·4]) and once weekly (4·4 attacks [3·2]) versus placebo (7·2 attacks [3·6]), with mean differences of -4·4 attacks (p<0·0001) and -2·8 attacks (p=0·0004), respectively. We recorded adverse events in ten (34%) of 29 patients given twice-weekly recombinant human C1 esterase inhibitor, 13 (45%) of 29 patients given the once-weekly regimen, and eight (29%) of 28 patients given placebo. Headache (twice-weekly treatment) and nasopharyngitis (once-weekly treatment) were the most common adverse events. Two (7%) adverse events (fatigue and headache) were deemed possibly related to treatment with recombinant human C1 esterase inhibitor, but both resolved without additional treatment. No thrombotic or thromboembolic events, systemic allergic reactions (including anaphylaxis), or neutralising antibodies were reported. INTERPRETATION: Prophylaxis with recombinant human C1 esterase inhibitor provided clinically relevant reductions in frequency of hereditary angio-oedema attacks and was well tolerated. In view of the pharmacokinetic profile of recombinant human C1 esterase inhibitor, our results suggest that efficacy of C1-inhibitor replacement therapy might not be a direct function of plasma trough concentrations of C1 inhibitor. FUNDING: Pharming Technologies.

Efficacy of recombinant human C1 esterase inhibitor across anatomic locations in acute hereditary angioedema attacks.

BACKGROUND: Hereditary angioedema (HAE) may occur at or spread to multiple anatomic locations during an acute attack. Recombinant human C1 esterase inhibitor (rhC1-INH) is approved for treating acute HAE attacks. OBJECTIVE: To examine the time to the beginning of symptom relief with rhC1-INH by attack location. METHODS: Data for patients ≥12 years of age with an acute HAE attack who received rhC1-INH 50 IU/kg or placebo were pooled from two double-blind clinical trials with open-label extensions. The time to the beginning of symptom relief was defined as the first time point that the visual analog scale severity score at an attack location decreased by ≥20 mm versus baseline, with persistence. Data were reported as median time values (95% confidence interval [CI]). RESULTS: For abdominal attacks, the median time to the beginning of symptom relief was 60.0 minutes (95% CI, 47.0-62.0 minutes; n = 194 attacks) with rhC1-INH versus 240.0 minutes (95% CI, 45.0-720.0 minutes; n = 15 attacks) with placebo. The median time to the beginning of symptom relief for peripheral attacks was 105.0 minutes (95% CI, 90.0-120.0 minutes; n = 169 attacks) with rhC1-INH versus 303.0 minutes (95% CI, 180.0-720.0 minutes; n = 17 attacks) with placebo. For oro-facial-pharyngeal-laryngeal attacks or urogenital attacks, the median time to the beginning of symptom relief with rhC1-INH was 64.5 minutes (95% CI, 60.0-120.0 minutes; n = 36 attacks) and 119.0 minutes (95% CI, 40.0-270.0 minutes; n = 13 attacks), respectively, versus 306.0 minutes (95% CI, 30.0-495.0 minutes; n = 6 attacks) and 320.0 minutes (n = 1 attack) with placebo. CONCLUSION: In shortening the median time to the beginning of symptom relief of acute HAE attacks, rhC1-INH 50 IU/kg was efficacious, regardless of attack location.

Sustained response of recombinant human C1 esterase inhibitor for acute treatment of hereditary angioedema attacks.

BACKGROUND: Symptoms of hereditary angioedema (HAE) attacks can recur soon after initial treatment; the durability of response for recombinant human C1 esterase inhibitor (rhC1INH) treatment is unknown. OBJECTIVE: To examine the efficacy and durability of rhC1INH for acute HAE attacks. METHODS: In this pooled post hoc analysis of 2 trials, patients with type I or II HAE (functional C1INH levels <50% of normal) and a baseline visual analog scale score of at least 50 mm were included if they had received at least 1 intravenous dose of 50 IU/kg of rhC1INH. Response was defined as symptom relief within 4 hours after treatment with persistence (≥20-mm decrease in visual analog scale scores [0 mm {"no symptoms at all"} to 100 mm {"extremely disabling"}] at 2 consecutive time points) during the 4 hours. Durability was the response without an increase of at least 20 mm in the minimum post-treatment visual analog scale score up to 24 hours. Recurrence and new attack symptoms were determined for patients with 72-hour post-treatment data. RESULTS: Data were analyzed for 127 patients treated with 50 IU/kg of rhC1INH in 2 studies. Most attacks (90.7%) responded within 4 hours, with differences in response rates among attack locations (61.5%-94.4%). The median time to the beginning of symptom relief was 75.0 minutes (95% confidence interval 65.0-80.0). No relapse occurred during 24 hours for attacks that initially responded. Only 7.1% of attacks were associated with symptom recurrence within 72 hours of initial rhC1INH treatment. CONCLUSION: This integrated analysis supports the efficacy of rhC1INH for treatment of acute HAE across multiple attacks, with a sustained response for at least 3 days. TRIAL REGISTRATION: ClinicalTrials.gov Identifiers: NCT00225147 and NCT00262301.

Efficacy of recombinant human C1 esterase inhibitor for the treatment of severe hereditary angioedema attacks.

BACKGROUND: Severe attacks of hereditary angioedema (HAE) are debilitating and potentially life threatening, and can increase anxiety and the use of medical resources. OBJECTIVE: This post hoc assessment evaluated recombinant human C1 esterase inhibitor (rhC1-INH) used to treat acute severe HAE attacks. METHODS: In a double-blind, randomized-controlled trial (RCT), patients with an HAE attack (baseline visual analog scale score of ≥50 mm, with severe attacks defined as ≥75 mm) were randomly assigned to receive rhC1-INH (50 IU/kg for patients who weighed <84 kg; 4200 IU for patients who weighed ≥84 kg) or placebo. Also, in an open-label extension (OLE) study of rhC1-INH, oropharyngeal-laryngeal attacks were analyzed. Rescue therapy with rhC1-INH 50 IU/kg (≤4200 IU) was permitted after 4 hours or for life-threatening symptoms (in the RCT) or after 1 hour (in the OLE study). The primary end point measured the time to the beginning of symptom relief by using the Treatment Effects Questionnaire. RESULTS: Of 75 adults in the RCT, 43 had severe attacks and received either rhC1-INH (n = 24) or placebo (n = 19). The median (95% confidence interval) time to the onset of symptom relief totaled 90.0 minutes (95% confidence interval, 47.0-120.0 minutes) versus 334.0 minutes (95% confidence interval, 105.0 to not calculable minutes; hazard ratio, 2.5; p = 0.02), for rhC1-INH and placebo, respectively. Open-label rhC1-INH rescue therapy was administered to 1 of 24 in the rhC1-INH group (4.2%) and 10 of 19 in the placebo group (52.6%). During the OLE study, the median onset of symptom relief with rhC1-INH for eight oropharyngeal-laryngeal HAE attacks was 69.0 minutes (95% confidence interval, 59.0-91.0 minutes). CONCLUSION: In the current study, rhC1-INH was efficacious in resolving severe HAE attacks, including oropharyngeal-laryngeal attacks. The rhC1-INH rescue treatment rapidly improved symptoms for patients who received placebo and who experienced worsening or sustained symptoms.

Recombinant human C1 esterase inhibitor for acute hereditary angioedema attacks with upper airway involvement.

BACKGROUND: Recombinant human C1 esterase inhibitor (rhC1-INH) is approved for treatment of hereditary angioedema (HAE) in adolescents and adults. HAE attacks that involve the upper airway can be life threatening, and data on the administration of rhC1-INH for these types of attacks are currently limited. OBJECTIVE: To evaluate the efficacy and safety of rhC1-INH for treatment of acute HAE attacks with upper airway involvement. METHODS: A pooled analysis of data from three clinical trials with open-label extensions examined rhC1-INH for treatment of acute HAE attacks with upper airway involvement. Patients with functional plasma C1 esterase inhibitor <50% of normal who had experienced an acute upper airway HAE attack and received rhC1-INH were identified retrospectively based on severity of breathing or swallowing symptoms. The primary end point was the time to beginning of relief (time at which the overall visual analog scale score [0-100 mm] decreased from baseline by ≥20 mm for two consecutive time points [persistence]). RESULTS: Of 683 acute HAE attacks treated with rhC1-INH, data for 45 attacks with upper airway involvement were included. The median time to the beginning of symptom relief was 67 minutes (95% confidence interval, 60-120 minutes) and did not differ by attack number or by baseline breathing or swallowing symptom severity. Most attacks (91.1%) achieved the beginning of relief within 4 hours of rhC1-INH treatment. All attacks resolved without the need for any additional medication, and no patients required intubation or tracheostomy. Treatment with rhC1-INH was well tolerated, with no adverse events reported in more than one patient (except HAE reported as an adverse event [n = 2]). CONCLUSION: This pooled analysis of clinical trial data supports the efficacy of rhC1-INH for treatment of acute HAE attacks with upper airway involvement.

Angioedema attacks in patients with hereditary angioedema: Local manifestations of a systemic activation process.

Hereditary angioedema (HAE) caused by a deficiency of functional C1-inhibitor (C1INH) becomes clinically manifest as attacks of angioedema. C1INH is the main inhibitor of the contact system. Poor control of a local activation process of this system at the site of the attack is believed to lead to the formation of bradykinin (BK), which increases local vasopermeability and mediates angioedema on interaction with BK receptor 2 on the endothelium. However, several observations in patients with HAE are difficult to explain from a pathogenic model claiming a local activation process at the site of the angioedema attack. Therefore we postulate an alternative model for angioedema attacks in patients with HAE, which assumes a systemic, fluid-phase activation of the contact system to generate BK and its breakdown products. Interaction of these peptides with endothelial receptors that are locally expressed in the affected tissues rather than with receptors constitutively expressed by the endothelium throughout the whole body explains that such a systemic activation process results in local manifestations of an attack. In particular, BK receptor 1, which is induced on the endothelium by inflammatory stimuli, such as kinins and cytokines, meets the specifications of the involved receptor. The pathogenic model discussed here also provides an explanation for why angioedema can occur at multiple sites during an attack and why HAE attacks respond well to modest increases of circulating C1INH activity levels because inhibition of fluid-phase Factor XIIa and kallikrein requires lower C1INH levels than inhibition of activator-bound factors.

Allergenicity and safety of recombinant human C1 esterase inhibitor in patients with allergy to rabbit or cow's milk.

BACKGROUND: Recombinant human C1 inhibitor (rhC1INH) for on-demand treatment of hereditary angioedema is purified from milk of transgenic rabbits. It contains low amounts (<0.002%) of host-related impurities, which could trigger hypersensitivity reactions in patients with rabbit allergy (RA) and/or cow's milk allergy (CMA). OBJECTIVE: This study is an assessment of allergenicity and safety of rhC1INH in patients with RA and/or CMA. METHODS: Patients with CMA and/or RA underwent skin prick test (SPT), intracutaneous test (ICT), and, when results for both were negative, subcutaneous (SC) challenge with up to 2100U (14 mL) rhC1INH. The negative predictive value of the skin test protocol was calculated, defined as the ratio of patients without systemic symptoms of hypersensitivity following SC challenge, over the number of patients having tested negative for both the SPT and the ICT. Adverse events after exposure to rhC1INH were recorded. RESULTS: Twenty-six patients with RA and/or CMA were enrolled. Twenty-four had negative SPT and ICT results for rhC1INH, whereas 2 had negative SPT result but positive ICT result to rhC1INH (only the highest concentration). Twenty-two patients with negative SPT and ICT results underwent SC challenge. None developed allergic symptoms. Local treatment-emergent adverse events occurred in 7 patients (32%) after SC challenge. In 5 these were considered drug related. All were mild. CONCLUSIONS: None of the patients with negative SPT and ICT results for rhC1INH had allergic symptoms during rhC1INH challenge. The negative predictive value of the combination of SPT and ICT for the outcome of the SC challenge was 100% (95% CI, 84.6%-100%). SC administration of rhC1INH was well tolerated.

Recombinant human C1-esterase inhibitor relieves symptoms of hereditary angioedema attacks: phase 3, randomized, placebo-controlled trial.

BACKGROUND: Hereditary angioedema (HAE), caused by C1 inhibitor (C1INH) deficiency or dysfunction, is characterized by recurrent attacks of tissue swelling affecting multiple anatomic locations. Recombinant human C1INH (rhC1INH) has been shown effective for acute treatment of HAE attacks. OBJECTIVE: To evaluate the efficacy and safety of rhC1INH (50 IU/kg to maximum 4,200 IU/treatment) vs placebo in a larger HAE population. METHODS: Seventy-five patients experiencing peripheral, abdominal, facial, and/or oropharyngeal laryngeal attacks were randomized (3:2) to rhC1INH (n = 44) or placebo (saline; n = 31). Efficacy was assessed by patient responses on a Treatment Effect Questionnaire (TEQ) and visual analog scale (VAS). Safety also was evaluated. RESULTS: Median (95% confidence interval) time to beginning of symptom relief at the primary attack location was 90 minutes (61-150) in rhC1INH-treated patients vs 152 minutes (93, not estimable) in placebo-treated patients (P = .031) based on the TEQ and 75 minutes (60-105) vs 303 minutes (81-720, P = .003) based on a VAS decrease of at least 20 mm. Median time to minimal symptoms was 303 minutes (240-720) in rhC1INH-treated patients vs 483 minutes (300-1,440) in placebo-treated patients based on the TEQ (P = .078) and 240 minutes (177-270) vs 362 minutes (240, not estimable; P = .005), based on an overall VAS less than 20 mm. Overall, rhC1INH was safe and well tolerated; no thromboembolic events, anaphylaxis, or neutralizing antibodies were observed. CONCLUSION: Relief of symptoms of HAE attacks was achieved faster with rhC1INH compared with placebo as assessed by the TEQ and VAS, with a positive safety profile. Results are consistent with previous studies showing efficacy and safety of rhC1INH in patients with HAE.

Population pharmacokinetics of recombinant human C1 inhibitor in patients with hereditary angioedema.

AIMS: To characterize the pharmacokinetics (PK) of recombinant human C1 inhibitor (rhC1INH) in healthy volunteers and hereditary angioedema (HAE) patients. METHODS: Plasma levels of C1INH following 294 administrations of rhC1INH in 133 subjects were fitted using nonlinear mixed-effects modelling. The model was used to simulate maximal C1INH levels for the proposed dosing scheme. RESULTS: A one-compartment model with Michaelis-Menten elimination kinetics described the data. Baseline C1INH levels were 0.901 [95% confidence interval (CI): 0.839-0.968] and 0.176 U ml(-1) (95% CI: 0.154-0.200) in healthy volunteers and HAE patients, respectively. The volume of distribution of rhC1INH was 2.86 l (95% CI: 2.68-3.03). The maximal rate of elimination and the concentration corresponding to half this maximal rate were 1.63 U ml(-1) h(-1) (95% CI: 1.41-1.88) and 1.60 U ml(-1) (95% CI: 1.14-2.24), respectively, for healthy volunteers and symptomatic HAE patients. The maximal elimination rate was 36% lower in asymptomatic HAE patients. Peak C1INH levels did not change upon repeated administration of rhC1INH. Bodyweight was found to be an important predictor of the volume of distribution. Simulations of the proposed dosing scheme predicted peak C1INH concentrations above the lower level of the normal range (0.7 U ml(-1)) for at least 94% of all patients. CONCLUSIONS: The population PK model for C1INH supports a dosing scheme on a 50 U kg(-1) basis up to 84 kg, with a fixed dose of 4200 U above 84 kg. The PK of rhC1INH following repeat administration are consistent with the PK following the first administration.

Efficacy and safety of recombinant C1 inhibitor for the treatment of hereditary angioedema attacks: a North American open-label study.

BACKGROUND: The efficacy of recombinant human C1 inhibitor (rhC1INH) for the treatment of patients with acute hereditary angioedema (HAE) attacks has been demonstrated in 2 randomized, double-blind, placebo-controlled studies. OBJECTIVE: To assess the safety and efficacy of rhC1INH for repeated treatment of acute attacks of HAE. METHODS: In this open-label extension study, patients with eligible HAE attacks were treated with an intravenous 50-U/kg dose of rhC1INH with an option for an additional dose of 50 U/kg based on clinical response. Time to beginning of relief was assessed by patients using a 100-mm visual analogue scale (VAS). Safety evaluation was based on the clinical laboratory results and adverse events. RESULTS: Sixty-two patients were treated for 168 attacks (range, 1-8 attacks per patient). A total of 90% of the attacks were treated with a single 50-U/kg dose of rhC1INH. Median times to beginning of symptom relief for the first 5 attacks were 37 to 67 minutes. More than 90% of attacks responded within 4 hours after treatment with rhC1INH. There was no requirement for increased dosing with successive treatments. Thirty-nine patients (63%) reported at least 1 treatment-emergent adverse event, with most events rated mild to moderate. Seven severe treatment-emergent adverse events were reported, and all were considered to be unrelated to treatment with rhC1INH. CONCLUSION: The results of this open-label extension support continued efficacy of rhC1INH after repeated treatments for subsequent HAE attacks. There was no increase in adverse event reporting after repeated exposure to rhC1INH.

Recombinant human C1-inhibitor for the treatment of acute angioedema attacks in patients with hereditary angioedema.

BACKGROUND: Hereditary angioedema (HAE) results from a genetic deficiency of C1-inhibitor. Two similar independent, randomized, saline controlled, double-blind studies were conducted to evaluate the efficacy and safety of recombinant human C1-inhibitor (rhC1INH) as a treatment of acute angioedema attacks in patients with HAE. OBJECTIVE: Analysis of pooled study results. METHODS: Patients with an eligible attack were randomized to a single intravenous dose of rhC1INH or saline. Efficacy was assessed by using patient-reported visual analog scale outcomes, and safety was assessed by using adverse events and immunogenicity of rhC1INH. RESULTS: rhC1INH at 100 (n = 29) and 50 (n = 12) U/kg body weight resulted in a significant reduction for both the primary endpoint time to the beginning of relief of symptoms compared with saline (n = 29): median, 66 (95% CI, 61-122) minutes, 122 (72-136) minutes, and 495 (245-520) minutes, P < .001 and P = .013, respectively; and for the secondary endpoint time to minimal symptoms, median, 266 (242-490) minutes, 247 (243-484) minutes, and 1210 (970-1500) minutes, P < .001 and P = .001, respectively. Therapeutic failure occurred in 59% (17/29) of the saline group compared with 0% (0/12) of the 50 U/kg group and 10% (3/29) of the 100 U/kg group. Treatment-emergent adverse events were unremarkable and tended to be reported more frequently in the saline group. No postexposure antibody responses against rhC1INH or host-related impurities were observed. CONCLUSION: Administration of rhC1INH at 100 or 50 U/kg was highly effective as a treatment of acute attacks in patients with HAE and appeared to be safe and well tolerated.

Recombinant human C1 esterase inhibitor for hereditary angioedema attacks: A European registry.

BACKGROUND: Hereditary angioedema (HAE) due to C1 esterase inhibitor deficiency (C1-INH-HAE) is characterized by recurrent swelling attacks. A European treatment registry was established to review the adverse event profile and efficacy of recombinant human C1 esterase inhibitor (rhC1-INH) for HAE attacks. METHODS: Individuals with C1-INH-HAE were enrolled following a decision to treat with rhC1-INH and provision of written informed consent. Medical history and baseline HAE information were collected at screening. Healthcare providers entered data on HAE attacks, response to treatment, and adverse events using a web-based questionnaire. RESULTS: From July 1, 2011, through December 1, 2019, 71 patients with C1-INH-HAE (30 male/41 female; mean age, 47.3 years; age range, 19-78 years) in 9 countries reported 2356 attacks and were treated with rhC1-INH. Before registry entry, patients, including 20 (28.2%) who were on maintenance therapy/prophylaxis at registry enrollment, experienced a mean of 25 HAE attacks per year (median, 16 [range, 0-185]). Most treated HAE attacks were abdominal (46.1%), followed by peripheral (38.3%), oro-facial-pharyngeal (14.8%), urogenital (3.2%), and laryngeal (2.6%). The mean rhC1-INH dose was 3307 U (43.3 U/kg). Patients reported symptom improvement within 4 h for 97.8% of attacks (2305/2356) with rhC1-INH; most attacks (99.8%; 2351/2356) required only 1 dose. Five attacks were treated with a second dose (total rhC1-INH dose administered for attack, 4200 U). No hypersensitivity, thrombotic/thromboembolic events, or drug-related serious adverse events were reported. CONCLUSION: The rhC1-INH treatment registry provided real-world data on the treatment of 2356 HAE attacks that were consistent with clinical trial data of rhC1-INH in patients with C1-INH-HAE.

Modeling Cost-Effectiveness of On-Demand Treatment for Hereditary Angioedema Attacks.

BACKGROUND: Hereditary angioedema (HAE) is a rare C1-inhibitor (C1-INH) deficiency disease. Low levels of functional C1-INH can lead to recurrent attacks of severe swelling occurring in areas such as the limbs, face, gastrointestinal tract, and throat. These attacks are both painful and disabling and, if not treated promptly and effectively, can result in hospitalization or death. Agents targeting the specific physiologic pathway of HAE attacks can offer improved outcomes with limited side effects compared with nonspecific therapies. However, these treatments display varying efficacy in HAE patients, including the need to redose or seek additional care if the treatment does not resolve symptoms effectively. OBJECTIVE: To analyze the expected cost and utility per HAE attack when treated on-demand with HAE therapies indicated for the treatment of acute attacks. METHODS: A decision-tree model was developed using TreeAge Pro software. Four on-demand HAE treatments were included: ecallantide, icatibant, plasma-derived (pd)C1-INH, and recombinant human (rh)C1-INH. The model uses probabilities for redosing, self-administration versus health care provider administration, and risk of hospitalization. Costs within the model consisted of the HAE treatments and associated health care system expenses. Nonattack baseline utility and attack utility were implemented for effectiveness calculations; time to attack resolution was considered as well. Effectiveness and overall costs per attack were calculated and used to estimate cost per quality-adjusted life-year (QALY). Variability and ranges in cost-effectiveness were determined using probabilistic sensitivity analyses. Finally, a budget impact model for a health plan with 1 million covered lives was also developed. RESULTS: The base case model outputs show costs and calculated effectiveness per attack at $12,905 and 0.806 for rhC1-INH, $14,806 and 0.765 for icatibant, $14,668 and 0.769 for pdC1-INH, and $21,068 and 0.792 for ecallantide, respectively. Cost per QALY was calculated using 26.9 attacks per person-year, leading to results of $420,941 for rhC1-INH, $488,349 for icatibant, $483,892 for pdC1-INH, and $689,773 for ecallantide. Sensitivity analyses demonstrate that redose rates (from 3% for rhC1-INH to 44% for icatibant) are a primary driver of variability in cost-effectiveness. Annual health plan costs from the budget impact model are calculated as $6.94 million for rhC1-INH, $7.97 million for icatibant, $7.90 million for pdC1-INH, and $11.33 million for ecallantide. CONCLUSIONS: Accounting for patient well-being and additional cost components of HAE attacks generates a better estimation of cost-effectiveness than drug cost alone. Results from this model indicate that rhC1-INH is the dominant treatment option with lower expected costs and higher calculated effectiveness than comparators. Further analyses reinforce the idea that low redose rates contribute to improved cost-effectiveness. DISCLOSURES: Funding support was contributed by Pharming Healthcare. Relan and Adams are employed by Pharming Healthcare. Tyson and Magar are employed by AHRM, which received fees to perform the analysis and develop the manuscript. Bernstein reports grants, personal fees, and nonfinancial support from Shire, CSL Behring, and Pharming Healthcare; grants and personal fees from Biocryst; and nonfinancial support from HAEA, unrelated to this study.

Recombinant Human C1-Esterase Inhibitor to Treat Acute Hereditary Angioedema Attacks in Adolescents.

BACKGROUND: Recombinant human C1-esterase inhibitor (rhC1-INH) is efficacious and well tolerated for managing hereditary angioedema (HAE) attacks in adults. However, there are insufficient data on its efficacy and safety in adolescents. OBJECTIVE: To evaluate the efficacy and safety profiles of rhC1-INH for acute HAE attacks in adolescents. METHODS: Adolescents (aged 12-18 y) with HAE enrolled in 2 randomized controlled trials and 2 open-label extension trials were included and received intravenous rhC1-INH for acute attacks. Times to the beginning of sustained symptom relief (visual analog scale change from baseline ≥20 mm) and minimal symptoms (visual analog scale score of <20 mm across locations) were assessed. Safety parameters included hypersensitivity reactions, anti-rhC1-INH antibodies, and host-related impurities. RESULTS: Sixteen adolescents (50 attacks, aged 14-18 y) received rhC1-INH. Attacks were managed with single-dose rhC1-INH 50 U/kg (46.0%) and single-dose rhC1-INH 2100 U (16%), and 32.0% were treated with additional doses after receiving an initial rhC1-INH 2100 U dose (total dose, 4200-6300 U). Most attacks (88.0%) occurred at a single location; 59.1% (26 of 44) were abdominal. Across the first 5 attacks, median times to the beginning of symptom relief ranged from 19.0 to 78.5 minutes; median times to minimal symptoms ranged from 120 to 190 minutes. Pharmacokinetics showed that rhC1-INH restored functional plasma C1-esterase inhibitor levels to the normal (>70%) range for almost all evaluable patients. No severe or drug-related adverse events or hypersensitivity reactions occurred. No treatment-emergent antibodies to rhC1-INH or host-related impurities were observed. CONCLUSIONS: rhC1-INH is efficacious and well tolerated among adolescents with HAE.

Hereditary Angioedema Attacks: Local Swelling at Multiple Sites.

Hereditary angioedema (HAE) patients experience recurrent local swelling in various parts of the body including painful swelling of the intestine and life-threatening laryngeal oedema. Most HAE literature is about attacks located in one anatomical site, though it is mentioned that HAE attacks may also involve multiple anatomical sites simultaneously. A detailed description of such multi-location attacks is currently lacking. This study investigated the occurrence, severity and clinical course of HAE attacks with multiple anatomical locations. HAE patients included in a clinical database of recombinant human C1-inhibitor (rhC1INH) studies were evaluated. Visual analog scale scores filled out by the patients for various symptoms at various locations and investigator symptoms scores during the attack were analysed. Data of 219 eligible attacks in 119 patients was analysed. Thirty-three patients (28%) had symptoms at multiple locations in anatomically unrelated regions at the same time during their first attack. Up to five simultaneously affected locations were reported. The observation that severe HAE attacks often affect multiple sites in the body suggests that HAE symptoms result from a systemic rather than from a local process as is currently believed.