[Refractory heart failure. Antagonism of tumor necrosis factor alpha and endothelin in humans: 2 promises still to be honored].

Excessive biohumoral activation participates in the pathophysiology and progression of congestive heart failure (CHF). Pharmacological inhibition of the renin-angiotensin-aldosterone and beta-adrenergic systems improves the mortality and morbidity of this disease. Among other detrimental molecules, two local factors, tumor necrosis factor (TNF)-alpha and endothelin (ET) both contribute to the worsening of CHF. TNF-alpha can induce many of the cellular modifications typically associated with CHF, such as myocyte death, interstitial tissue derangement and negative inotropism. On the other hand ET promotes vasoconstriction, and cell growth and proliferation. On the premise of some favorable experimental studies, selective antagonism of TNF-alpha or ET has been tested in clinical trials in order to control the progression of or even reverse CHF. However, contrasting results have been obtained so far with either approach, in accordance with other unfavorable data from animal models of heart failure. Etanercept (Enbrel, a recombinant dimer of two p75sTNFR molecules fused to the Fc fragment of human IgG1) has proved to be useful and effective in basic and animal experiments, while contrasting data have been reported on humans. The Randomized EtaNErcept Worldwide evALuation (RENEWAL) trial has recently been prematurely stopped due to impossibility of showing statistically significant results with the pre-specified sample size. Results of phase II to III clinical trials on different ET receptor antagonists in CHF have yielded conflicting results, so that none of the agents of this class have been labeled for CHF. The mechanisms by which TNF-alpha and ET might exert their negative biological actions are discussed together with an analysis of the possible reasons why they have failed so far in human CHF.