Health status decline in α-1 antitrypsin deficiency: a feasible outcome for disease modifying therapies?

Antitrypsin deficiency: still more to learn about the lung after 60 years

The past 60 years have seen multiple publications related to lung disease in α1-antitrypsin deficiency largely reflecting the pathophysiology, biochemical effect and outcomes of augmentation therapy. However, the complexity of disease phenotype and the impact of the natural history presents problems of patient management, study design and hence interpretation of outcome. Although many national and some international registries exist, the lack of consistent in-depth assessment and importantly, the impact of augmentation therapy likely influences our perception of the true natural history. Development of new therapeutic strategies, and even assessment of the role and efficacy of augmentation, remain a challenge as powering such studies for conventional COPD outcomes is impractical due to relative rarity of the genetic condition and the presence of clinical phenotypic variation. The current review approaches these issues, discusses the nature and complexity of assessing patient variability, and provides guidance on further studies required to address them.

Assessing the efficacy of Alpha1-Proteinase inhibitor (human) augmentation therapy for Alpha1-Antitrypsin deficiency - Related emphysema: Challenges and opportunities

Clinical benefit of Alpha1-Proteinase Inhibitor (Human) (A1-PI) products for Alpha1-antitrypsin deficiency (AATD) is uncertain, based on a systematic review of observational studies and randomized controlled trials (RCTs) in AATD of Alpha1-Proteinase Inhibitor (Human) (A1-PI) products. At the recommended dose, A1-PI products raise its serum concentration but do not normalize levels. Observational studies suggest A1-PI might modestly slow progression of airflow limitation in patients with intermediate airflow obstruction, a finding not confirmed by three placebo-controlled RCTs of limited power, which showed non-significant rates of forced expiratory volume in 1 s (FEV1) change favoring placebo. These RCTs found trends favoring A1-PI in loss of high-resolution computerized tomographic (HRCT) lung density. While two meta-analyses of HRCT lung density change in RCTs achieved significance favoring A1-PI arms, clinical benefit remains uncertain. HRCT lung density measurements don't distinguish changes in measured density due to fluid shifts into and out of the lungs and changes in lung inflammation from those due to progressive loss of alveolar mass. A meta-analysis of RCTs found exacerbations significantly increased in A1-PI groups compared to placebo. No RCTs have shown favorable effects of A1-PI on mortality, FEV1, 6-min walking distance, quality of life, change in diffusion capacity of carbon monoxide (DLCO), or exacerbation frequency. A fourth RCT comparing two dose regimens of A1-PI is underway. RCTs have not provided evidence of clinical benefit in terms of how patients feel, function, or survive. Results have implications for the design of future clinical trials of A1-PI and potentially other products targeting AATD-associated emphysema.

Disease burden associated with alpha-1 antitrypsin deficiency: systematic and structured literature reviews

Alpha-1 antitrypsin deficiency (AATD) is a rare genetic disorder characterised by reduced levels of circulating alpha-1 antitrypsin and an increased risk of lung and liver disease. Recent reviews of AATD have focused on diagnosis, epidemiology and clinical management; comprehensive reviews examining disease burden are lacking. Therefore, we conducted literature reviews to investigate the AATD disease burden for patients, caregivers and healthcare systems. Embase, PubMed and Cochrane libraries were searched for AATD publications from database inception to June 2021, in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Most published AATD studies were small and short in duration, with variations in populations, designs, measures and outcomes, complicating cross-study comparisons. AATD was associated with significant pulmonary and hepatic morbidity. COPD, emphysema and bronchiectasis were common lung morbidities, where smoking was a key risk factor. Fibrosis and steatosis were the most common liver complications reported in patients with a PiZ allele. Health status analyses suggested a poorer quality of life for AATD patients diagnosed with COPD versus those with non-AATD-associated COPD. The burden for caregivers included loss of personal time due to caring responsibilities, stress and anxiety. AATD was also associated with high direct medical costs and healthcare resource utilisation.

Alpha 1 Antitrypsin Therapy in Patients with Alpha 1 Antitrypsin Deficiency: Perspectives from a Registry Study and Practical Considerations for Self-Administration During the COVID-19 Pandemic

Alpha 1 Antitrypsin deficiency (AATD) is a hereditary condition characterized by low serum Alpha 1 Antitrypsin (AAT) levels and a predisposition towards early-onset emphysema. Infusion of AAT is the only disease-modifying therapy that can sufficiently raise plasma AAT levels above the putative protective threshold and reduce the decline in lung density loss. Several randomized controlled trials (RCTs) and registry studies support the clinical efficacy of AAT therapy in slowing the progression of AATD-related emphysema and improving survival outcomes. The COVID-19 pandemic has prompted physicians to develop additional strategies for delivering AAT therapy, which are not only more convenient for the patient, but are “COVID-19 friendly”, thereby reducing the risk of exposing these vulnerable patients. Intravenous (IV) self-administration of AAT therapy is likely to be beneficial in certain subgroups of patients with AATD and can remove the need for weekly hospital visits, thereby improving independence and well-being. Increasing the awareness of self-administration in AATD through the development of formal guidelines and training programs is required among both physicians and patients and will play an essential role, especially post-COVID-19, in encouraging physicians to consider self-administration for AATD in suitable patients. This review summarizes the benefits of AAT therapy on the clinical endpoints of mortality and quality of life (QoL) and discusses the benefits of self-administration therapy compared with conventional therapy administered by a healthcare professional. In addition, this review highlights the challenges of providing AAT therapy during the COVID-19 pandemic and the potential considerations for its implementation thereafter.

Alpha-1 antitrypsin deficiency: an update on clinical aspects of diagnosis and management

Clinical heterogeneity has been demonstrated in alpha-1 antitrypsin deficiency (AATD), such that clinical suspicion plays an important role in its diagnosis. The PiZZ genotype is the most common severe deficiency genotype and so tends to result in the worst clinical presentation, hence it has been the major focus of research. However, milder genotypes, especially PiSZ and PiMZ, are also linked to the development of lung and liver disease, mainly when unhealthy behaviors are present, such as smoking and alcohol use. Monitoring and managing AATD patients remains an area of active research. Lung function tests or computed tomography (CT) densitometry may allow physicians to identify progressive disease during follow up of patients, with a view to decision making about AATD-specific therapy, like augmentation therapy, or eventually surgical procedures such as lung volume reduction or transplant. Different types of biological markers have been suggested for disease monitoring and therapy selection, although most need further investigation. Intravenous augmentation therapy reduces the progression of emphysema in PiZZ patients and is available in many European countries, but its effect in milder deficiency is less certain. AATD has also been suggested to represent a risk factor and trigger for pulmonary infections, like those induced by mycobacteria. We summarize the last 5-10 years' key findings in AATD diagnosis, assessment, and management, with a focus on milder deficiency variants.

Relationship of CT densitometry to lung physiological parameters and health status in alpha-1 antitrypsin deficiency: initial report of a centralised database of the NIHR rare diseases translational research collaborative

OBJECTIVES

To establish a database network for the study of alpha-1 antitrypsin deficiency (AATD) and compare the results to CT lung density as the most direct measure of emphysema.

DESIGN

A central electronic database was established to permit the upload of anonymised patient data from remote sites. Prospectively collected CT data were recorded onto disc, anonymised, analysed at the coordinating centre and compared with the clinical features of the disease.

SETTING

Tertiary referral centres with expertise in the management of AATD focused on academic Biomedical Research Units and Wellcome Clinical Research Facilities.

PARTICIPANTS

Data were collected from 187 patients over 1 year from eight UK academic sites. This included patient demographics, postbronchodilator physiology, health status and CT. Analysis was undertaken at the coordinating centre in Birmingham.

RESULTS

Patient recruitment in the 12 months reached 94% of target (set at 200) covering the whole spectrum of the disease from those with normal lung function to very severe chronic obstructive lung disease. CT scan suitable for analysis was available from 147 (79%) of the patients. CT density, analysed as the threshold for the lowest 15% of lung voxels, showed statistically significant relationships with the objective physiological parameters of lung function as determined by spirometric Global Initiative for Chronic Obstructive Lung Disease (GOLD) severity staging (p<0.001) and carbon monoxide gas transfer (p<0.01). Density also correlated with subjective measures of quality of life (p=0.02).

CONCLUSIONS

Establishment of the network for data collection and its transfer was highly successful facilitating future collaboration for the study of this rare disease and its management. CT densitometry correlated well with the objective clinical features of the disease supporting its role as the specific marker of the associated emphysema and its severity. Correlations with subjective measures of health, however, were generally weak indicating other factors play a role.

The importance of effective registries in pulmonary diseases and how to optimize their output

Randomized controlled trials (RCTs) are essential for the approval of new therapies; however, because of their design, they provide little insight concerning disease epidemiology/etiology and current clinical practice. Particularly, in lung disease, rigid inclusion/exclusion criteria can limit the generalizability of pivotal trial data. Noninterventional studies (NIS), conducted through the well-established mechanism of patient registries, are undervalued as a means to close data gaps left by RCTs by providing essential data that can guide patient care at different levels from clinical decision-making to health-care policy. While NIS contribute valuable data in all disease areas, their importance in rare diseases cannot be underestimated. In respiratory disease, registries have been essential in understanding the natural history and different phenotypes of rare conditions, such as alpha 1 antitrypsin deficiency, cystic fibrosis, and idiopathic pulmonary fibrosis. Importantly, additional therapeutic outcome data were generated. While measures for enhancing data quality in RCTs have evolved significantly, the approach and effectiveness of registries is variable. Within this article, we review the contribution of registries to pulmonary disease and make recommendations for their effective management. Additionally, we assess limitations of registry data as well as challenges to registry operation, including the impact of the European Union General Data Protection Regulation.

The Biological Effects of Double-Dose Alpha-1 Antitrypsin Augmentation Therapy. A Pilot Clinical Trial

Rationale: Augmentation therapy with intravenous AAT (alpha-1 antitrypsin) is the only specific therapy for individuals with pulmonary disease from AAT deficiency (AATD). The recommended standard dose (SD; 60 mg/kg/wk) elevates AAT trough serum levels to around 50% of normal; however, outside of slowing emphysema progression, its effects in other clinical outcomes have not been rigorously proven.

Objectives: To evaluate the biological effects of normalizing AAT trough levels with double-dose (DD) therapy (120 mg/kg/wk) in subjects with AATD already receiving SD therapy.

Methods: Clinically stable subjects were evaluated after 4 weeks of SD therapy, followed by 4 weeks of DD therapy, and 4 weeks after return to SD therapy. At the end of each phase, BAL fluid (BALF) and plasma samples were obtained.

Measurements and Main Results: DD therapy increased trough AAT levels to normal and, compared with SD therapy, reduced serine protease activity in BALF (elastase and cathepsin G), plasma elastase footprint (Aα-Val³⁶⁰), and markers of elastin degradation (desmosine/isodesmosine) in BALF. DD therapy also further downregulated BALF ILs and cytokines including Jak-STAT (Janus kinases–signal transducer and activator of transcription proteins), TNFα (tumor necrosis factor-α), and T-cell receptor signaling pathways, cytokines involved in macrophage migration, eosinophil recruitment, humoral and adaptive immunity, neutrophil activation, and cachexia. On restarting SD after DD treatment, a possible carryover effect was seen for several biological markers.

Conclusions: Subjects with AATD on SD augmentation therapy still exhibit inflammation, protease activity, and elastin degradation that can be further improved by normalizing AAT levels. Higher AAT dosing than currently recommended may lead to enhanced clinical benefits and should be explored further.

Clinical trial registered with www.clinicaltrials.gov (NCT 01669421).

Thresholds for clinically important deterioration versus improvement in COPD health status: results from a randomised controlled trial in pulmonary rehabilitation and an observational study during routine clinical practice

OBJECTIVES

Chronic Obstructive Pulmonary Disease (COPD) is a progressive disease. Preventing deterioration of health status is therefore an important therapy goal. (Minimal) Clinically Important Differences ((M)CIDs) are used to interpret changes observed. It remains unclear whether (M)CIDs are similar for both deterioration and improvement in health status. This study investigates and compares these clinical thresholds for three widely-used questionnaires.

DESIGN AND SETTING

Data were retrospectively analysed from an inhouse 3-week pulmonary rehabilitation (PR) randomised controlled trial in the German Klinik Bad Reichenhall (study 1), and observational research in Dutch primary and secondary routine clinical practice (RCP) (study 2).

PARTICIPANTS

Patients with COPD aged ≥18 years (study 1) and aged ≥40 years (study 2) without respiratory comorbidities were included for analysis.

PRIMARY OUTCOMES

The COPD Assessment Test (CAT), Clinical COPD Questionnaire (CCQ) and St George's Respiratory Questionnaire (SGRQ) were completed at baseline and at 3, 6 and 12 months. A Global Rating of Change scale was added at follow-up. Anchor-based and distribution-based methods were used to determine clinically relevant thresholds.

RESULTS

In total, 451 patients were included from PR and 207 from RCP. MCIDs for deterioration ranged from 1.30 to 4.21 (CAT), from 0.19 to 0.66 (CCQ), and from 2.75 to 7.53 (SGRQ). MCIDs for improvement ranged from -3.78 to -1.53 (CAT), from -0.50 to -0.19 (CCQ), and from -9.20 to -2.76 (SGRQ). Thresholds for moderate improvement versus deterioration ranged from -5.02 to -3.29 vs 3.89 to 8.14 (CAT), from -0.90 to -0.72 vs 0.42 to 1.23 (CCQ), and from -15.85 to -13.63 vs 7.46 to 9.30 (SGRQ).

CONCLUSIONS

MCID ranges for improvement and deterioration on the CAT, CCQ and SGRQ were somewhat similar. However, estimates for moderate and large change varied and were inconsistent. Thresholds differed between study settings.

TRIAL REGISTRATION NUMBER

Routine Inspiratory Muscle Training within COPD Rehabilitation trial: #DRKS00004609; MCID study: #UMCG201500447.