In vivo CRISPR base editing of PCSK9 durably lowers cholesterol in primates.

Gene-editing technologies, which include the CRISPR-Cas nucleases1-3 and CRISPR base editors4,5, have the potential to permanently modify disease-causing genes in patients6. The demonstration of durable editing in target organs of nonhuman primates is a key step before in vivo administration of gene editors to patients in clinical trials. Here we demonstrate that CRISPR base editors that are delivered in vivo using lipid nanoparticles can efficiently and precisely modify disease-related genes in living cynomolgus monkeys (Macaca fascicularis). We observed a near-complete knockdown of PCSK9 in the liver after a single infusion of lipid nanoparticles, with concomitant reductions in blood levels of PCSK9 and low-density lipoprotein cholesterol of approximately 90% and about 60%, respectively; all of these changes remained stable for at least 8 months after a single-dose treatment. In addition to supporting a 'once-and-done' approach to the reduction of low-density lipoprotein cholesterol and the treatment of atherosclerotic cardiovascular disease (the leading cause of death worldwide7), our results provide a proof-of-concept for how CRISPR base editors can be productively applied to make precise single-nucleotide changes in therapeutic target genes in the liver, and potentially in other organs.

Characterization of anaphylaxis after ecallantide treatment of hereditary angioedema attacks.

BACKGROUND: Ecallantide is a human plasma kallikrein inhibitor indicated for treatment of acute attacks of hereditary angioedema for patients 12 years of age and older. Ecallantide is produced in Pichia pastoris yeast cells by recombinant DNA technology. Use of ecallantide has been associated with a risk of hypersensitivity reactions, including anaphylaxis. OBJECTIVE: The objective of this detailed retrospective data review was to characterize anaphylaxis cases within the ecallantide clinical trials database. METHODS: Potential cases of hypersensitivity reactions in the ecallantide clinical development program were identified by examining reported adverse events. The National Institute of Allergy and Infectious Disease criteria were used to identify those events that were consistent with anaphylaxis; these cases were then reviewed in detail. Results from investigational antibody testing also were examined. RESULTS: Among patients who received subcutaneous ecallantide (n = 230 patients; 1045 doses of 30 mg ecallantide), 8 patients (3.5%) had reactions that met the National Institute of Allergy and Infectious Disease criteria for anaphylaxis; none occurred on first exposure to the drug. All 8 reactions had symptom onset within 1 hour of exposure and cutaneous manifestations commonly observed in type I hypersensitivity reactions. All the reactions responded to standard management of type I hypersensitivity reactions and resolved without fatal outcomes. IgE antibody testing to ecallantide or P pastoris was not consistently positive in patients who experienced apparent type I hypersensitivity reactions. CONCLUSION: Anaphylaxis episodes after subcutaneous ecallantide exposure have clinical features suggestive of type I hypersensitivity reactions. However, anti-ecallantide or anti-P pastoris IgE antibody status was not found to be reliably associated with anaphylaxis.

A phase 1 study investigating DX-2930 in healthy subjects.

BACKGROUND: DX-2930 is a human monoclonal antibody inhibitor of plasma kallikrein under investigation for long-term prophylaxis of hereditary angioedema. OBJECTIVE: To assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of DX-2930 in healthy subjects. METHODS: A single-center, double-blinded study was performed in 32 healthy subjects randomized 3:1 to receive a single subcutaneous administration of DX-2930 or placebo within 1 of 4 sequential, ascending dose cohorts (n = 8 each): 0.1, 0.3, 1.0, or 3.0 mg/kg. RESULTS: No dose-limiting toxicity was observed. Headache was the most commonly reported treatment emergent adverse event (AE), occurring at a rate of 25% in the DX-2930- and placebo-treated groups; none were severe and all resolved. There were no serious AEs, discontinuations owing to an AE, or deaths. Two subjects had a severe AE reported as related to treatment by the blinded investigator; the 2 AEs were asymptomatic creatinine phosphokinase elevations of 902 U/L in 1 subject receiving 0.1 mg/kg DX-2930 and 1,967 U/L in 1 subject receiving placebo. For the 0.1-, 0.3-, 1.0-, and 3.0-mg/kg dose groups, respectively, mean maximum plasma concentrations were 0.6, 1.4, 5.6, and 14.5 µg/mL and mean elimination half-lives were 20.6, 16.8, 17.6, and 21.2 days. Exploratory biomarker assays, involving ex vivo activation of the kallikrein pathway, showed dose- and time-dependent inhibition of plasma kallikrein, with evidence of sustained bioactivity consistent with the pharmacokinetics profile. CONCLUSION: A single administration of DX-2930 in healthy subjects up to doses of 3.0 mg/kg was well tolerated without dose-limiting toxicity. Pharmacokinetic and pharmacodynamic data provide evidence for a long-acting biological effect relevant to long-term prophylaxis for hereditary angioedema with C1-inhibitor deficiency. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01923207.

Abdominal attacks and treatment in hereditary angioedema with C1-inhibitor deficiency.

BACKGROUND: Hereditary angioedema (HAE) is characterized by unpredictable attacks of debilitating subcutaneous and mucosal edema. Gastrointestinal attacks are painful, of sudden onset and often mistaken for acute abdomen leading to unnecessary surgery. The purpose of this study was to analyze symptom presentation of gastrointestinal angioedema in pediatric and adult HAE patients. METHODS: Information collected during the clinical development of ecallantide for treatment of acute HAE attacks included affected anatomic location, accompanying symptoms, medical history, and pain assessments. Efficacy endpoints included Treatment Outcome Score (TOS, maximum score = 100; minimally important difference = 30), a point-in-time measure of treatment response, and time to treatment response. RESULTS: Forty-nine percent of 521 HAE attacks only involved abdominal symptoms. The most commonly reported abdominal symptoms were distension (77%), cramping (73%) and nausea (67%). The most common pain descriptors were tender, tiring-exhausting, aching, cramping and sickening. White blood cell counts were elevated (>10 × 10(9)/L) in 23% of attacks (mean ± SD: 15.1 ± 11.27 × 10(9)/L). A high proportion of patients reported a history of abdominal surgery, including appendectomy (23%), cholecystectomy (16.4%), and hysterectomy (8.2%). Mean TOS at 4 hours post ecallantide was 77 ± 33 versus 29 ± 65 for placebo. Median time to significant symptom resolution was 165 minutes (95% CI 136, 167) for ecallantide versus >4 hours (95% CI 161, >4 hours) for placebo. Anaphylactic reactions occurred in 6 of the 149 treated patients. CONCLUSIONS: HAE should be considered in the differential diagnosis of patients with recurrent discrete episodes of severe, unexplained crampy abdominal pain associated with nausea. TRIALS REGISTRATION: The data used in the analysis were gathered across multiple clinical trials conducted during the clinical development program for ecallantide. All of the studies were conducted using Good Clinical Practices (GCP) and in accordance with the ethical principles that have their origins in the Declaration of Helsinki. Each site that participated in the clinical trials obtained the appropriate IRB or Ethics Committee approval prior to enrolling any patients. All patients provided written informed consent prior to undergoing any study-related procedures. Pediatric patients provided written assent and their parents or guardians gave written informed consent.The following trials have been registered at http://www.clinicaltrials.gov: EDEMA2 (identifier NCT01826916); EDEMA3 (identifier NCT00262080); EDEMA4 (identifier NCT00457015); and DX-88/19 (identifier NCT00456508).

Use of ecallantide in pediatric hereditary angioedema.

OBJECTIVE: Hereditary angioedema (HAE) due to C1-inhibitor deficiency is a rare autosomal dominant disease that manifests as sudden unpredictable attacks of subcutaneous or submucosal edema affecting the skin, intestine, and upper airway. Ecallantide is a plasma kallikrein inhibitor indicated for treatment of HAE attacks in patients aged 16 years and older. This analysis examines safety and efficacy of ecallantide for treatment of HAE attacks in patients <18 years of age. METHODS: Data for patients aged 9 to 17 years treated subcutaneously with 30 mg ecallantide or placebo were pooled from 4 clinical studies (2 double-blind, placebo-controlled and 2 open-label). Efficacy end points included 2 HAE-specific patient-reported outcome measures: mean symptom complex severity (MSCS) score and treatment outcome score (TOS). Times to initial improvement, sustained improvement, and complete or near-complete symptom resolution were calculated. Treatment-emergent adverse events were examined. RESULTS: Overall, 29 pediatric patients were included; 25 of them received ecallantide for 62 total HAE attacks, and 10 received placebo for 10 total attacks. Ecallantide-treated attacks revealed clinically relevant reduction in symptom severity at 4 hours postdosing based on mean change in MSCS score (-1.4 ± 0.9 ecallantide versus -0.9 ± 0.6 placebo) and TOS (73.9 ± 35.50 ecallantide versus 45.0 ± 43.78 placebo). Patients treated with ecallantide showed rapid improvement in symptoms (median time to complete or near-complete symptom resolution: 181 minutes). No serious adverse events related to treatment were observed. CONCLUSIONS: Ecallantide appears effective for HAE attacks in adolescents, with rapid symptom improvement. No unexpected safety issues were identified.

Outcomes after ecallantide treatment of laryngeal hereditary angioedema attacks.

BACKGROUND: Hereditary angioedema (HAE) is a rare disorder associated with episodic attacks of well-demarcated angioedema. Attacks that affect the larynx can result in life-threatening airway obstruction. OBJECTIVES: To examine efficacy and safety of ecallantide treatment for laryngeal HAE attacks. METHODS: Data were combined from 4 clinical studies (EDEMA2, EDEMA3, EDEMA4, and DX-88/19) evaluating 30 mg of subcutaneous ecallantide for treatment of acute HAE attacks. Efficacy was assessed using 2 validated, HAE-specific, patient-reported outcome measures. The change in Mean Symptom Complex Severity (MSCS) score indicates change in symptom severity; a negative score indicates improvement. The calculated minimally important difference (MID) for change in severity is -0.30. The Treatment Outcome Score (TOS) measures treatment response. A positive score indicates improvement; the calculated MID is 30. RESULTS: Overall, 98 patients received ecallantide for 220 laryngeal attacks. The mean ± SD change in MSCS score was -1.1 ± 0.73 and -1.6 ± 0.68 at 4 and 24 hours, respectively. The mean ± SD TOS was 73.5 ± 35.8 and 85.5 ± 27.8 at 4 and 24 hours, respectively. Median time to significant improvement was 185 minutes (95% confidence interval, 167-226). One attack required intubation. Four treatment-emergent serious adverse events were reported, including 2 HAE attacks that resulted in hospitalization and 2 anaphylactic reactions. One of these reactions required treatment with epinephrine, but both patients recovered fully. There were no deaths. CONCLUSION: In this large attack series, ecallantide was effective for treatment of laryngeal HAE attacks. There is a risk of hypersensitivity, including anaphylaxis, consistent with product labeling. As such, ecallantide should be administered under the supervision of a health care professional. TRIAL REGISTRATION: clinicaltrials.gov Identifiers: not applicable for EDEMA2 (trial was conducted before implementation of registration requirements); NCT00262080 for EDEMA3, NCT00457015 for EDEMA4, and NCT00456508 for DX-88/19.

Efficacy and safety of ecallantide in treatment of recurrent attacks of hereditary angioedema: open-label continuation study.

Hereditary angioedema (HAE) is a rare disorder characterized by recurrent attacks of potentially life-threatening edema. The plasma kallikrein inhibitor ecallantide is approved for treatment of acute HAE attacks. This study evaluates the efficacy and safety of ecallantide for treatment of multiple HAE episodes in the DX-88/19 (continuation) study. Patients received 30 mg of subcutaneous ecallantide for acute HAE attack symptoms, with no limit on number of episodes treated. Primary end point was change in patient-reported mean symptom complex severity (MSCS) score at 4 hours. Additional end points included change in MSCS score at 24 hours, treatment outcome score (TOS) at 4 and 24 hours, and time to response. Safety parameters included adverse events. Statistical analyses were conducted on qualifying treatment episodes (those with ≥12 patients). One hundred forty-seven patients received treatment for 625 episodes; analyses were conducted through 13 treatment episodes. Across 13 episodes at 4 hours, mean change in MSCS score ranged from -1.04 to -1.36, and mean TOSs ranged from 56.2 to 79.8. Median time to onset of sustained improvement ranged from 59 to 113 minutes. There was no indication of reduced efficacy with repeated ecallantide use. No new safety signals were detected. Eight patients (5.4%) reported potential hypersensitivity reactions, six of whom met the definition of anaphylaxis based on National Institute of Allergy and Infectious Diseases criteria. Ecallantide is effective for acute recurrent HAE attacks and maintains its efficacy and safety during multiple treatment episodes in patients with HAE. Potential hypersensitivity reactions were consistent with prior reports.

Ecallantide for treatment of acute hereditary angioedema attacks: analysis of efficacy by patient characteristics.

Hereditary angioedema (HAE) is characterized by episodic attacks of edema. HAE is caused by low levels of the protein C1 esterase inhibitor, which inhibits plasma kallikrein, the enzyme responsible for converting high-molecular-weight kininogen to bradykinin. Unregulated production of bradykinin leads to the characteristic clinical symptoms of swelling and pain. Ecallantide is a novel plasma kallikrein inhibitor effective for treatment of acute HAE attacks. This study was designed to analyze the efficacy of ecallantide for treating HAE attacks by attack location, attack severity, patient gender, and body mass index (BMI). An analysis of integrated data from two double-blind, placebo-controlled trials of ecallantide for treatment of acute HAE attacks was undertaken. For the purpose of analysis, symptoms were classified by anatomic location and, for each location, by the patient-assessed severity of the attack. Efficacy versus placebo was examined using two validated patient-reported outcomes: treatment outcome score and mean symptom complex severity score. One hundred forty-three attacks were analyzed (73 ecallantide and 70 placebo). Ecallantide was equally effective in both male and female subjects. Ecallantide had decreased efficacy for patients with BMI > 30 kg/m(2). Ecallantide showed efficacy for treatment of severe and moderate attacks, and was effective for abdominal, internal head and neck, external head and neck, and cutaneous locations. In summary, ecallantide is effective for treatment of acute HAE attacks of different symptom locations and severity; outcomes were similar for men and women. However, the standard dose was less effective for obese patients.

Prospective, double-blind, placebo-controlled trials of ecallantide for acute attacks of hereditary angioedema.

Hereditary angioedema (HAE) is a rare genetic disorder characterized by unpredictable, episodic, incapacitating attacks of well-demarcated angioedema in the absence of urticaria and pruritus. HAE is due to deficient or dysfunctional C1-esterase inhibitor activity, which results in unopposed activation of plasma kallikrein, resulting in increased levels of bradykinin. Ecallantide is a potent and specific plasma kallikrein inhibitor approved for the treatment of acute attacks of HAE affecting any anatomic site. In Phase III clinical trials, subcutaneously administered ecallantide demonstrated significant, rapid and durable symptom relief. Ecallantide was effective for all attack types, including potentially life-threatening laryngeal attacks. The main safety concern is potentially serious hypersensitivity reactions, including anaphylaxis. Ecallantide represents an important treatment option for the management of acute attacks of HAE.

Off-label use: an industry perspective on expanding use beyond approved indications.

The use of a medical device outside of its approved label is commonly referred to as "off-label use." Off-label use arises when physicians see the opportunity to leverage an approved therapy for an unmet patient need. This practice typically occurs on a case by case basis without clear documentation of indication, frequency, or outcomes. Sponsors have a responsibility to consider formal indication expansion depending on the actual use, how well the therapy fits the unmet need, product iteration cycles, adoption speed, resource demands, and the clinical risk to benefit ratio. This responsibility is particularly relevant for breakthrough technologies where adoption patterns can span a variety of uses. For Boston Scientific's drug-eluting stent program, a surveillance program was developed in collaboration with the FDA to compile information on practice patterns and safety outcomes for the TAXUS Express2 Paclitaxel-Eluting Coronary Stent System. The ARRIVE program has used a Web-based format to collect real-time data on TAXUS stent use. This >7,000 patient registry documents both on-label and off-label use and key safety measures for the TAXUS stent. This real-world registry has successfully provided a data-driven approach to BSC's product development strategy, including the initiation of formal label expansion programs. For complex or combination products, more innovative ways of capturing risk to benefit data are needed to define off-label use and to maximize the potential therapeutic utility as supported by safety data.