Nerve growth factor improves HIV-associated sensory neuropathy

Nerve growth factor (NGF) significantly improves the pain symptoms of HIV-infected patients with sensory neuropathy, according to a report in the October 9th issue of Neurology.

The sensory neuropathy that affects as many as 35% of AIDS patients predominantly affects small-fibre sensory nerves, the activity of which is modulated to some degree by NGF, the authors explain.

Dr. Giovanni Schifitto, from the University of Rochester, New York, and colleagues studied the safety and effectiveness of recombinant human NGF for HIV-associated distal sensory polyneuropathy in 200 affected subjects.

Pain scores improved consistently in all patient groups (that is, patients receiving either 0.1 µg NGF per kg or 0.3 µg NGF per kg), with the higher-dose groups experiencing less pain and greater improvements than the lower-dose groups, the authors report.

Though there were trends towards improvement in cooling and vibratory sensation, the report indicates that only the higher-dose patients showed significantly improved pin sensitivity.

Thirty-four moderate or severe adverse events included 28 complaints of injection site discomfort, two cases of diarrhoea, and one report each of rash/urticaria, fatigue, impaired balance, and cough.

“Both the double-blind study and this open-label follow-up show symptomatic improvement in patients treated with NGF,” Dr. Schifitto said. “A phase III study in HIV sensory neuropathy would be needed to clearly define the efficacy of NGF in this population.”

Dr. Schifitto said that as far as he knows, South San Francisco, California-based biotechnology company Genentech Inc. “shelved NGF after the negative results of the diabetic neuropathy study.”

“The response to NGF in diabetic sensory neuropathy and HIV-associated sensory neuropathy are not necessarily comparable, because the pathological mechanisms involved may differ,” he said. “Therefore, the negative results of the phase III diabetic neuropathy study should not be extrapolated to HIV sensory neuropathy.”