BackgroundPatients with ZZ (Glu342Lys) alpha-1-antitrypsin deficiency (ZZ-AATD) who received augmentation therapy with alpha-1-antitrypsin (AAT) in randomised controlled trials over 2–3 years, failed to show a significant reduction of the annual decline of FEV1.MethodsTo compare the trajectory of FEV1 change during 4 or more years in ZZ-AATD patients with emphysema receiving or not receiving intravenous augmentation therapy, a retrospective analysis of FEV1 values entered in the Alpha-1 International Registry (AIR) of ZZ-AATD patients from five different European countries: Germany, UK, Spain, Italy and The Netherlands was performed. The post-bronchodilator FEV1%predicted values for baseline and follow-up over time from patients were analysed using linear mixed effects models.ResultsData of 374 patients were analysed: 246 untreated and 128 treated with intravenous AAT augmentation therapy. The mean follow-up duration of the untreated group was 8.60 (sd±3.34) years and 8.59 (±2.62) years for the treated group. The mixed effects model analysis showed a mean FEV1 decline of −0.931% predicted per year (95% confidence interval −1.144 to −0.718) in the untreated group and a decline of −1.016% predicted per year (−1.319 to −0.7145) in the treated group. The likelihood ratio test showed no difference between the two groups (p=0.71).ConclusionIn our study population, we could not detect a significant difference in the annual decline of FEV1 by AAT augmentation treatment over an average period of 8.6 years. Other approaches are needed to validate any benefit of augmentation therapy.

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As a known genetic cause of chronic obstructive pulmonary disease (COPD), alpha1-antitrypsin deficiency (AATD) can cause severe respiratory problems at a relatively young age. These problems are caused by decreased or absent levels of alpha1-antitrypsin (AAT), an antiprotease which is primarily functional in the respiratory system. If the levels of AAT fall below the protective threshold of 11 µM, the neutrophil-derived serine proteases neutrophil elastase (NE) and proteinase 3 (PR3), which are targets of AAT, are not sufficiently inhibited, resulting in excessive degradation of the lung parenchyma, increased inflammation, and increased susceptibility to infections. Because other therapies are still in the early phases of development, the only therapy currently available for AATD is AAT augmentation therapy. The controversy surrounding AAT augmentation therapy concerns its efficiency, as protection of lung function decline is not demonstrated, despite the treatment’s proven significant effect on lung density change in the long term. In this review article, novel biomarkers of NE and PR3 activity and their use to assess the efficacy of AAT augmentation therapy are discussed. Furthermore, a series of seven synthetic NE and PR3 inhibitors that can be used to evaluate the specificity of the novel biomarkers, and with potential as new drugs, are discussed.

In alpha-1-antitrypsin deficiency (AATD), neutrophil serine proteases such as elastase and proteinase 3 (PR3) are insufficiently inhibited. A previous study in AATD patients showed a higher plasma level of the specific PR3-generated fibrinogen-derived peptide AαVal541, compared with healthy controls. Here, we analyzed the course of AαVal541 plasma levels during 4 weeks after a single iv dose of 240 mg/kg AAT in ten patients with genotype Z/Rare or Rare/Rare. To this end, we developed an immunoassay to measure AαVal541 in plasma and applied population pharmacokinetic modeling for AAT. The median AαVal541 plasma level before treatment was 140.2 nM (IQR 51.5–234.8 nM)). In five patients who received AAT for the first time, AαVal541 levels decreased to 20.6 nM (IQR 5.8–88.9 nM), and in five patients who already had received multiple infusions before, it decreased to 26.2 nM (IQR 22.31–35.0 nM). In 9 of 10 patients, AαVal541 levels were reduced to the median level of healthy controls (21.4 nM; IQR 16.7–30.1 nM). At 7–14 days after treatment, AαVal541 levels started to increase again in all patients. Our results show that fibrinopeptide AαVal541 may serve as a biochemical footprint to assess the efficacy of in vivo inhibition of PR3 activity in patients receiving intravenous AAT augmentation therapy.

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