Tumor necrosis factor (TNF) is an important mediator of cachexia, and its blockade prevents catabolism in animal models. However, little evidence shows that anti-TNF therapy is effective in treating cachexia in humans.
The main aim of this study was to investigate the effect of etanercept, a synthetic soluble TNF receptor, on body composition in patients with early rheumatoid arthritis (RA).
Twenty-six patients were randomly assigned to 24 wk of treatment with etanercept or methotrexate; the latter is the first-line therapy for RA. Body composition, physical function, disease activity, systemic inflammation, and the circulating insulin-like growth factor (IGF) system were measured at baseline (week 0) and at follow-up (weeks 12 and 24). Twelve patients in each treatment group (9 F, 3 M) completed the study.
Overall, no important changes in body composition were observed, despite a transient increase in IGF-I at week 12 (P < 0.01). However, the secondary analysis of those patients (6/treatment group) who gained weight during follow-up showed a significant effect of etanercept on the composition of the weight gained: 44% of weight gained in the etanercept group was fat-free mass, as compared with only 14% in the methotrexate group (P = 0.04). Etanercept and methotrexate were equally effective in controlling the disease and improving physical function.
Anti-TNF therapy with etanercept is not superior to that with methotrexate for the treatment of rheumatoid cachexia over a period of 6 mo. However, TNF blockade seems to normalize the anabolic response to overfeeding and, if these findings are confirmed, may be useful in conditions characterized by anorexia and weight loss.