Palovarotene is an oral γ-selective retinoid agonist. In animal emphysema models, palovarotene reduced inflammation, promoted structural repair and functional improvement.REPAIR (Retinoid treatment of Emphysema in Patients on the α1-antitrypsin International Registry), was an investigator-initiated, double-blind, placebo-controlled randomised study to assess the safety and efficacy of 5 mg·day−1palovarotene given for 1 year to 262 patients with severe α1-antitrypsin deficiency and emphysema confirmed by computed tomography. Change in volume-adjusted 15th percentile point lung density from baseline in 1 year was the primary end-point; functional end-points were also regularly assessed.We randomly assigned 133 and 129 patients to placebo or palovarotene, respectively. Both groups were well matched for all baseline characteristics, including respiratory medications. 88% and 85% of patients completed 1 year of treatment with placebo and palovarotene, respectively. Palovarotene was generally well tolerated. In the study completers population, the placebo-corrected difference of lung density was -0.45 HU at week 28 (p=0.64) and -0.25 HU at week 52 (p=0.94). A nonsignificant treatment difference in most functional parameters of the lung in favour of the drug was observed over time suggesting potential pharmacological effects of palovarotene.Palovarotene 5 mg·day−1over 1 yr failed to show a significant benefit on lung density in moderate-to-severe emphysema secondary to severe α1-antitrypsin deficiency.

Background: Matrix metalloproteinase-9 (MMP-9) may be important in the progression of emphysema, but there have been few longitudinal clinical studies of MMP-9 including pulmonary status and COPD exacerbation outcomes. Methods: We utilized data from the placebo arm (n = 126) of a clinical trial of patients with alpha1-antitrypsin deficiency (AATD) and emphysema to examine the links between plasma MMP-9 levels, pulmonary status, and COPD exacerbations over a one year observation period. Pulmonary function, computed tomography lung density, incremental shuttle walk test (ISWT), and COPD exacerbations were assessed at regular intervals over 12 months. Prospective analyses used generalized estimating equations to incorporate repeated longitudinal measurements of MMP-9 and all endpoints, controlling for age, gender, race-ethnicity, leukocyte count, and tobacco history. A secondary analysis also incorporated highly-sensitive C-reactive protein levels in predictive models. Results: At baseline, higher plasma MMP-9 levels were cross-sectionally associated with lower FEV1 (p = 0.03), FVC (p < 0.001), carbon monoxide transfer factor (p = 0.03), resting oxygen saturation (p = 0.02), and ISWT distance walked (p = 0.02) but were not associated with radiographic lung density or total lung capacity (TLC). In longitudinal analyses, MMP-9 predicted a further decline in transfer factor (p = 0.04) and oxygen saturation (p < 0.001). MMP-9 also predicted worsening lung density (p = 0.003), increasing TLC (p = 0.02), and more frequent COPD exacerbations over follow-up (p = 0.003). Controlling additionally for hs-CRP levels did not substantively change the longitudinal associations between MMP-9 and these outcomes. Conclusions: Increased plasma MMP-9 levels generally predicted pulmonary status declines, including worsening transfer factor and lung density as well as greater COPD exacerbations in AATD-associated emphysema.

Emphysema is characterized by the destruction of alveolar wall and enlargement of alveolar airspaces, resulting in a reduction of the total lung gas exchange area, loss of lung elastic recoil and hyperinflation. The REPAIR study (Retinoid treatment of Emphysema in Patients on the Alpha-1 International Registry) is the first proof-of-concept study of a new potential disease-modifying drug, Palovarotene © , an orally active, gamma selective retinoid agonist in patients with emphysema secondary to alpha-1-antitrypsin deficiency (AATD) as a model population for the general smoke-induced emphysema population. This article describes the study design as well as the effectiveness of the quality control that was implemented on the key efficacy endpoints, based on data derived from the placebo-treated subjects. In this multicentre, multinational study the implementation of standardized procedures included: careful site selection, use of trained staff, regular monitoring and machine calibration, use of biological controls and regular feedback to sites by an independent quality control centre. All of these procedures resulted in high-quality measurements of lung density, spirometry, static lung volumes and gas transfer. It was also confirmed that CT lung density was the most sensitive endpoint followed by TLco, FEV 1 and RV measured by body box.

To guarantee the reliability of densitometric data in clinical trials on pulmonary emphysema a quality control procedure is presented, to prevent that a measured progression in lung density could be reflected by a gradual change in the maintenance of the computed tomographic scanner. For that purpose, a foam phantom has been developed, which mimicks the densities of emphysematous lung tissue, fixed in a sealed Perspex box. Analysis software was developed to automatically compare the density readings with a baseline reference. It was found that this quality control procedure can pick up subtle changes in the scanner of less than 1 hounsfield unit, due to changes in the X-ray tube, detectors, or reconstruction software, and can detect certain imaging artifacts. Therefore, it is recommended that this type of procedure be used to ensure the integrity of densitometric data in longitudinal studies.