What role will ensifentrine play in the future treatment of chronic obstructive pulmonary disease patients? Implications from recent clinical trials

Data from the phase III ENHANCE clinical trials provide compelling evidence that ensifentrine, an inhaled 'bifunctional' dual phosphodiesterase 3/4 inhibitor, can provide additional benefit to existing treatments in patients with chronic obstructive pulmonary disease and represents a 'first-in-class' drug having bifunctional bronchodilator and anti-inflammatory activity in a single molecule. Ensifentrine, generally well tolerated, can provide additional bronchodilation when added to muscarinic receptor antagonists or β2-agonists and reduce the exacerbation risk. This information allows us to consider better the possible inclusion of ensifentrine in the future treatment of chronic obstructive pulmonary disease. However, there is less information on whether it provides additional benefit when added to inhaled corticosteroid or 'triple therapy' and, therefore, when this drug is best utilized in clinical practice.Chronic obstructive pulmonary disease (COPD) is the name for a group of lung conditions that cause breathing difficulties/airflow limitations. The airflow limitation is not completely reversible and is associated with a state of chronic inflammation of lung tissue. Treatment of the disease is still heavily dependent on the use of medications called bronchodilators and corticosteroids. However, corticosteroids have little-to-no impact on the underlying inflammation in most COPD patients. Therefore, innovative anti-inflammatory approaches are required. In this context, single molecules that are capable of simultaneously inducing bronchodilation, relaxing the muscles in the lungs and widening the airways (bronchi), and anti-inflammatory activity are a highly intriguing possibility for treating COPD. One approach is to develop drugs that can simultaneously inhibit enzymes called phosphodiesterase (PDE)3 and PDE4. Enzymes are proteins that help speed up metabolism, or the chemical reactions in our bodies. PDE4 inhibitors are intracellular enzymes (work inside the cell) expressed in most inflammatory cells, even in neutrophils (a type of white blood cells), which are involved in the pathogenesis of COPD, where an infection turns into a disease. However, its inhibition does not produce severe bronchodilator effects, which is instead obtained by inhibiting PDE3, the PDE isoenzyme (a different form of the same enzyme) that is predominantly expressed in airway smooth muscle cells. A treatment called ensifentrine is a dual PDE3/4 inhibitor (inhibits both PDE3 and PDE4). Two recent phase III studies (ENHANCE-1 and ENHANCE-2) have shown that it induces significant bronchodilation and reduces the risk of COPD worsening, exerting an anti-inflammatory effect. Data from the ENHANCE studies also showed the benefit of adding ensifentrine to treatment with bronchodilators. Certainly, the drug represents a useful therapeutic option, but further clinical studies are needed to be able to correctly position ensifentrine in the context of regular COPD treatment.