No TWEAK for COPD.

To the Editor: The therapy with the greatest functional benefit in chronic obstructive pulmonary disease (COPD) is pulmonary rehabilitation [1]; while the mode of action is probably multifactorial the functional benefit of pulmonary rehabilitation is associated with strength gain in the quadriceps [2]. This suggests that muscle hypertrophy, or countering atrophy, could be at least one of the mechanisms through which pulmonary rehabilitation is beneficial. However, despite the success of pulmonary rehabilitation, there are several occasions in which an effective adjunctive drug therapy might have a place in clinical practice; for example in patients who are too unwell to exercise, in patients unwilling or unable to complete pulmonary rehabilitation, or indeed to magnify or extend benefit in those who do. In order to conduct stratified medicine studies of future novel anabolic agents for skeletal muscle dysfunction in COPD, biomarkers to identify potential responders will be required. In particular, it is likely that such therapies may be aimed at subsets of patients with COPD rather than, as is the …