Emerging targets for COPD therapy.

No currently available treatments reduce the progression of COPD or suppress the inflammation in small airways and lung parenchyma. However, several new treatments that target the inflammatory process are in clinical development. A group of specific therapies are directed against the influx of inflammatory cells into the airways and lung parenchyma that occurs in COPD; these include adhesion molecule and chemokine-directed therapy, as well as therapies to combat tumour necrosis factor-alpha and augment interleukin-10. Broad spectrum anti-inflammatory drugs are now in phase III development for COPD, and include phosphodiesterase-4 inhibitors. Other drugs that inhibit cell signalling include inhibitors of p38 mitogen-activated protein kinase, nuclear factor-kappaB and phosphoinositide-3 kinase-gamma. More specific approaches are to give antioxidants, inhibitors of inducible nitric oxide synthase, and leukotriene B4 receptor antagonists. Epidermal growth factor receptor kinase inhibitors and calcium-activated chloride channel inhibitors have potential to combat mucus overproduction. Therapy to inhibit fibrosis is being developed against transforming growth factor-beta1 and protease activated receptor-2. There is also a search for serine proteinase and matrix metalloproteinase inhibitors to prevent lung destruction and the development of emphysema, as well as drugs such as retinoids that may even reverse this process. Effective delivery of drugs to the sites of disease in the peripheral lung is an important consideration, and there is the need for validated biomarkers and monitoring techniques in early clinical studies with new therapies for COPD.