Increased Response to Higher Dose Lanadelumab in Hereditary Angioedema Patients: Exploratory Findings From the HELP and HELP OLE Studies

Interventions for the long-term prevention of hereditary angioedema attacks

BACKGROUND

Hereditary angioedema (HAE) is a serious and potentially life-threatening condition that causes acute attacks of swelling, pain and reduced quality of life. People with Type I HAE (approximately 80% of all HAE cases) have insufficient amounts of C1 esterase inhibitor (C1-INH) protein; people with Type II HAE (approximately 20% of all cases) may have normal C1-INH concentrations, but, due to genetic mutations, these do not function properly. A few people, predominantly females, experience HAE despite having normal C1-INH levels and C1-INH function (rare Type III HAE). Several new drugs have been developed to treat acute attacks and prevent recurrence of attacks. There is currently no systematic review and meta-analysis that included all preventive medications for HAE.

OBJECTIVES

To assess the benefits and harms of interventions for the long-term prevention of HAE attacks in people with Type I, Type II or Type III HAE.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 3 August 2021.

SELECTION CRITERIA

We included randomised controlled trials in children or adults with HAE that used medications to prevent HAE attacks. The comparators could be placebo or active comparator, or both; approved and experimental drug trials were eligible for inclusion. There were no restrictions on dose, frequency or intensity of treatment. The minimum length of four weeks of treatment was required for inclusion; this criterion excluded the acute treatment of HAE attacks.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were 1. HAE attacks (number of attacks per person, per population) and change in number of HAE attacks; 2. mortality and 3. serious adverse events (e.g. hepatic dysfunction, hepatic toxicity and deleterious changes in blood tests). Our secondary outcomes were 4. quality of life; 5. severity of breakthrough attacks; 6. disability and 7. adverse events (e.g. weight gain, mild psychological changes and body hair). We used GRADE to assess certainty of evidence for each outcome.

MAIN RESULTS

We identified 15 studies (912 participants) that met the inclusion criteria. The studies included people with Type I and II HAE. The studies investigated avoralstat, berotralstat, subcutaneous C1-INH, plasma-derived C1-INH, nanofiltered C1-INH, recombinant human C1-INH, danazol, and lanadelumab for the prevention of HAE attacks. We did not find any studies on the use of tranexamic acid for prevention of HAE attacks. All drugs except avoralstat reduced the number of HAE attacks compared with placebo. For breakthrough attacks that occurred despite prophylactic treatment, intravenous and subcutaneous forms of C1-INH and lanadelumab reduced attack severity. It is not known whether other drugs have a similar effect, as the severity of breakthrough attacks in people taking drugs other than C1-INH and lanadelumab was not reported. For quality of life, avoralstat, berotralstat, C1-INH (all forms) and lanadelumab increased quality of life compared with placebo; there were no data for danazol. Four studies reported on changes in disability during treatment with C1-INH, berotralstat and lanadelumab; all three drugs decreased disability compared with placebo. Adverse events, including serious adverse events, did not occur at a rate higher than placebo. However, serious adverse event data and other adverse event data were not available for danazol, which prevented us from drawing conclusions about the absolute or relative safety of this drug. No deaths were reported in the included studies. The analysis was limited by the small number of studies, the small number of participants in each study and the lack of data on older drugs, therefore the certainty of the evidence is low. Given the rarity of HAE, it is not surprising that drugs were rarely directly compared, which does not allow conclusions on the comparative efficacy of the various drugs for people with HAE. Finally, we did not identify any studies that included people with Type III HAE. Therefore, we cannot draw any conclusions about the efficacy or safety of any drug in people with this form of HAE.

AUTHORS' CONCLUSIONS

The available data suggest that berotralstat, C1-INH (subcutaneous, plasma-derived, nanofiltered and recombinant), danazol and lanadelumab are effective in lowering the risk or incidence (or both) of HAE attacks. In addition, C1-INH and lanadelumab decrease the severity of breakthrough attacks (data for other drugs were not available). Avoralstat, berotralstat, C1-INH (all forms) and lanadelumab increase quality of life and do not increase the risk of adverse events, including serious adverse events. It is possible that danazol, subcutaneous C1-INH and recombinant human C1-INH are more effective than berotralstat and lanadelumab in reducing the risk of breakthrough attacks, but the small number of studies and the small size of the studies means that the certainty of the evidence is low. This and the lack of head-to-head trials prevented us from drawing firm conclusions on the relative efficacy of the drugs.

Lanadelumab for the prevention of attacks in hereditary angioedema

Introduction: Hereditary angioedema (HAE) with C1 esterase inhibitor deficiency (C1-INH-HAE) is a rare disease that manifests with cutaneous and/or submucosal swellings due to uncontrolled activation of the contact/kinin system. Attacks recur with unpredictable frequency and severity, laryngeal edema is potentially lethal, and the disease burden may severely disrupt patients' lives.Areas covered: This review provides an overview of lanadelumab, a human monoclonal antibody targeted against plasma kallikrein that was recently approved for prevention of symptoms in C1-INH-HAE.Expert opinion: The phase III HELP Study demonstrated the efficacy of lanadelumab in reducing HAE attacks. These positive results are being further confirmed in the open-label extension study. This agent addresses some of the limitations of existing prophylactic options as tolerability issues, the need for intravenous administration and frequent dosing. Therefore, lanadelumab can profoundly improve the quality of life of patients with C1-INH-HAE.

Lanadelumab for the treatment of hereditary angioedema

Introduction: Hereditary angioedema due to C1 inhibitor deficiency (C1-INH-HAE) is a rare yet still probably underdiagnosed clinical condition. Recurrent episodes of subcutaneous and sub-mucosal swelling may involve the skin, the gastrointestinal tract or even the upper airways, exposing the patients to the risk of death. With the aim of improving patients' quality of life, the therapeutic scenario has expanded over the years.Areas covered: The focus of the present review is lanadelumab, a fully human, κ-light-chain, monoclonal immunoglobulin G1 against plasma kallikrein, currently approved for long-term prophylaxis of C1-INH-HAE attacks in the USA and Canada and designated as an orphan drug by the European Medicines Agency.Expert opinion: Lanadelumab is able to inhibit plasma kallikrein with high selectivity and affinity. The subsequent phases of drug development and the ongoing open-label trial have proven its safety and efficacy. It overcomes some of the limitations of other drugs available for long-term prophylaxis, given the easy route of administration, the simple administration schedule and the possibility to tailor the treatment to each patient. Further studies are needed to test its efficacy also in other types of angioedema for which a central role of plasma kallikrein is envisaged.