[Nerve growth factor (NGF) in treatment of diabetic polyneuropathy. One hope less?]

Diabetic polyneuropathy (DPN) is by far the most common neuropathy in the western world. In Germany, some 3-4 million patients are afflicted. In the U.S., a large-scale multicenter trial was initiated to evaluate the efficacy and safety of recombinant human nerve growth factor (rhNGF) in the treatment of DPN. A total of 1019 patients were randomly assigned in this double-blind study to receive either rhNGF or placebo over a 48-week period. The rhNGF had no significant side effects apart from mild hyperalgesia at the injection site. However, the substance failed to show significant benefit on global assessment, neuropathic sypmtoms and signs or neurophysiological parameters of nerve function when compared to the placebo group. Possible reasons for the negative outcome of this trial are the small dosis of rhNGF used, choice of a study population different from those enrolled in earlier promising studies, and the multifactorial etiology of DPN, which poses significant difficulties to the design and evaluation of therapeutic trials.