From promising therapy… to proven results.
The recently completed Emphasys Bronchial Valve for Emphysema PalliatioN Trial (VENT Study) represents a landmark device trial in the field of pulmonary medicine. It is the largest and most rigorous evaluation of the Zephyr® Endobronchial Valve system conducted to date and is expected to set the standard for future research in the field of endobronchial valve therapy. Details of the VENT study are outlined below.
The VENT study design was based on input from a panel of expert clinicians convened by the FDA to help establish the appropriate clinical endpoints for bronchoscopic treatments for emphysema. This expert panel concluded that endpoints should include at least one physiologic, one exercise, and one quality of life outcome measure. Based on this input, the VENT trial included the following endpoints:
- Physiologic Improvement:
Forced expiratory volume, or FEV1, measures the volume of air forcefully exhaled by a patient over time. FEV1 is a commonly used and widely accepted endpoint in studies for COPD and is a key variable in measuring a patient’s pulmonary health. FEV1 was a co-primary endpoint of the study.
- Exercise Tolerance:
A patient’s exercise tolerance is used as a proxy for the patient’s ability to function on a daily basis. VENT used two tests of exercise tolerance. A co-primary endpoint of the study was the six-minute walk test, or 6MWT, which measures the distance a patient can walk in six minutes. Cycle ergometry, one of the secondary endpoints in VENT, measures the maximum workload exerted by a patient on a stationary bicycle.
- Quality of Life:
VENT used a standard, pulmonary-disease-specific questionnaire called the St. George’s Respiratory Questionnaire, or SGRQ, as a secondary endpoint in the study.
To measure patients’ breathlessness, VENT utilized a standard questionnaire called the modified Medical Research Council Dyspnea Scale, or mMRC, as a secondary endpoint.
- Oxygen consumption:
Many patients utilize supplemental oxygen to reduce their breathlessness. In the VENT trial, patients reported how much oxygen they consumed on a daily basis.
Other aspects of the VENT trial were drawn from the design of the National Emphysema Treatment Trial (NETT) which was a 1218 patient study supported by the National Heart Lung and Blood Institute (NHLBI) and the Center for Medicare and Medicaid services (CMS).
The VENT study also pioneered the use of a CT imaging core lab to analyze changes in lung volume before and after endobronchial valve therapy. Results from this portion of the study are expected to yield important new insights into regional lung physiology and breathing mechanics in patients with emphysema.
The VENT trial enrolled 321 patients at 31 centers in the United States. An additional 171 patients were enrolled in a parallel trial conducted in 23 centers in Europe. The treatment and control groups in both studies received optimal medical management treatment, including pulmonary rehabilitation. In the treatment cohorts, patients went on to receive endobronchial valve therapy with the Zephyr Endobronchial Valve.
Complete results of the VENT study have not yet been released outside major medical meetings to preserve the data for publication in a leading scientific journal. What has been released is that the VENT study met both its primary efficacy endpoints showing statistically significant improvements in lung function (p=0.0047) and exercise tolerance (p=0.0073).
The study also analyzed select patient subsets. In patients defined as having physiologically isolated target lung zones and correct Zephyr valve placement, FEV1 was increased by 21% (p<0.0001).
VENT showed the Zephyr Endobronchial Valve to have a favorable safety profile in terms of major complications between the treatment and control groups. At the six-month follow-up, protocol-defined major complications occurred in 5.9% of treated patients compared to 1.0% of control patients. The difference did not reach statistical significance.
Results from the VENT were used to support a pre-market approval (PMA) application which the company submitted to the FDA in September 2007.
A manuscript containing a complete analysis of the VENT study results is in preparation and will soon be submitted to a major medical journal for publication.
To learn more about other studies involving the Zephyr Endobronchial Valve system, click here.
Emphasys Medical, Inc.
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