Clinical Trial Design for Alpha-1 Antitrypsin Deficiency: A Model for Rare Diseases

Pharmacokinetics and Biochemical Efficacy of an α1-Proteinase Inhibitor (Aralast NP) in α1-Antitrypsin Deficiency: a Cross-Product Retrospective Comparability Analysis

INTRODUCTION

Augmentation therapy with plasma-derived α₁-proteinase inhibitor (A1PI) products is currently the only approved disease-specific therapy for α₁-antitrypsin deficiency (AATD), a genetic disorder associated with decreased levels of A1PI. Systemic trough levels of A1PI in plasma or serum are widely accepted as a biochemical efficacy endpoint in clinical trials for A1PI products.

METHODS

Retrospective analyses utilizing data from three clinical studies in patients with AATD were conducted to evaluate the pharmacokinetic(s) (PK) and biochemical efficacy comparability of Aralast NP and two other A1PI augmentation therapies, Aralast and Prolastin. All three A1PI products were administered as either single or multiple 60 mg/kg intravenous infusions. PK and biochemical efficacy comparability analyses were conducted by evaluating antigenic and functional A1PI serum or plasma concentration data from each of the three studies.

RESULTS

Comparable PK parameters were demonstrated between the three products for antigenic A1PI levels following a single infusion, with baseline-corrected and uncorrected geometric mean ratios for peak and systemic exposure ranging from 89.0% to 99.6%, with 90% confidence intervals within the 80-125% reference interval for bioequivalence. Biochemical efficacy comparability analyses of Aralast and Prolastin after multiple infusions at steady state showed geometric mean ratios for uncorrected and baseline-corrected antigenic and functional A1PI trough concentrations over weeks 8-11, and for individual weeks, that ranged from 75.8% to 106.6%, with the majority of the 90% confidence intervals falling either within the 80-125% interval or in proximity to it. Nonparametric superpositioning at steady state suggested that predicted trough concentrations for Aralast NP were comparable to the observed concentrations for Aralast and Prolastin.

CONCLUSION

These retrospective analyses provide robust evidence that Aralast NP has biochemical efficacy and PK comparable to that of Aralast and Prolastin, supporting the use of any of these A1PI products for the treatment of patients with AATD.

TRIAL REGISTRATION NUMBERS

ClinicalTrials.gov identifiers, NCT00242385 and NCT00396006.

Alpha-1 antitrypsin deficiency research and emerging treatment strategies: what's down the road?

Intravenous infusion of alpha-1 antitrypsin (AAT) was approved by the United States Food and Drug Administration (FDA) to treat emphysema associated with AAT deficiency (AATD) in 1987 and there are now several FDA-approved therapy products on the market, all of which are derived from pooled human plasma. Intravenous AAT therapy has proven clinical efficacy in slowing the decline of lung function associated with AATD progression; however, it is only recommended for individuals with the most severe forms of AATD as there is a lack of evidence that this treatment is effective in treating wild-type heterozygotes (e.g., PI*MS and PI*MZ genotypes), for which the prevalence may be much higher than previously thought. There are large numbers of individuals that are currently left untreated despite displaying symptoms of AATD. Furthermore, not all countries offer AAT augmentation therapy due to its expense and inconvenience for patients. More cost-effective treatments are now being sought that show efficacy for less severe forms of AATD and many new therapeutic technologies are being investigated, such as gene repair and other interference strategies, as well as the use of chemical chaperones. New sources of AAT are also being investigated to ensure there are enough supplies to meet future demand, and new methods of assessing response to treatment are being evaluated. There is currently extensive research into AATD and its treatment, and this chapter aims to highlight important emerging treatment strategies that aim to improve the lives of patients with AATD.

How will the field of gene therapy survive its success?

In August 2017, for the first time, a gene therapy was approved for market release in the United States. That approval was followed by two others before the end of the year. This article cites primary literature, review articles concerning particular biotechnologies, and press releases by the FDA and others in order to provide an overview of the current status of the field of gene therapy with respect to its translation into practice. Technical hurdles that have been overcome in the past decades are summarized, as are hurdles that need to be the subject of continued research. Then, some social and practical challenges are identified that must be overcome if the field of gene therapy, having survived past failures, is to achieve not only technical and clinical but also market success. One of these, the need for an expanded capacity for the manufacturing of viral vectors to be able to meet the needs of additional gene therapies that will be coming soon, is a challenge that the talents of current and future bioengineers may help address.

Accelerating Scientific Advancement for Pediatric Rare Lung Disease Research. Report from a National Institutes of Health-NHLBI Workshop, September 3 and 4, 2015

Pediatric rare lung disease (PRLD) is a term that refers to a heterogeneous group of rare disorders in children. In recent years, this field has experienced significant progress marked by scientific discoveries, multicenter and interdisciplinary collaborations, and efforts of patient advocates. Although genetic mechanisms underlie many PRLDs, pathogenesis remains uncertain for many of these disorders. Furthermore, epidemiology and natural history are insufficiently defined, and therapies are limited. To develop strategies to accelerate scientific advancement for PRLD research, the NHLBI of the National Institutes of Health convened a strategic planning workshop on September 3 and 4, 2015. The workshop brought together a group of scientific experts, intramural and extramural investigators, and advocacy groups with the following objectives: (1) to discuss the current state of PRLD research; (2) to identify scientific gaps and barriers to increasing research and improving outcomes for PRLDs; (3) to identify technologies, tools, and reagents that could be leveraged to accelerate advancement of research in this field; and (4) to develop priorities for research aimed at improving patient outcomes and quality of life. This report summarizes the workshop discussion and provides specific recommendations to guide future research in PRLD.