The failure of Genentech Inc.'s recombinant human nerve growth factor to improve nerve function in patients with diabetic peripheral neuropathy provides further evidence that the application of endogenous growth factors to treat complex diseases is a risky proposition at best.

The Phase III trial in 1,019 Type I and II diabetic patients sought to demonstrate that a higher proportion of those given NGF would show improvements in nerve function versus placebo after 12 months, as measured by scores on the Neuropathy Impairment Score of the Lower Limbs. Although a six-month Phase II trial in 250 patients in1996 had shown "preliminary evidence of activity," according