Retinoic acid reduces chemotherapy-induced neuropathy in an animal model and patients with lung cancer

Objective: To evaluate the effect of all-trans retinoic acid (ATRA) as treatment for chemotherapy-induced peripheral neuropathy in an experimental animal model and in a randomized, double-blinded, controlled trial in patients with non-small-cell lung cancer (NSCLC). Methods: Forty male Wistar rats were randomized in 5 groups: group A, control; groups B and C, treated with cisplatin; and groups D and E, treated with paclitaxel. ATRA (20 mg/kg PO) was administered for 15 days in groups C and E. We evaluated neuropathy and nerve regeneration-related morphologic changes in sciatic nerve, the concentration of nerve growth factor (NGF), and retinoic acid receptor (RAR)-alpha and RAR-beta expression. In addition, 95 patients with NSCLC under chemotherapy treatment were randomized to either ATRA (20 mg/m(2)/d) or placebo. Serum NGF, neurophysiologic tests, and clinical neurotoxicity were assessed. Results: The experimental animals developed neuropathy and axonal degeneration, associated with decreased NGF levels in peripheral nerves. Treatment with ATRA reversed sensorial changes and nerve morphology; this was associated with increased NGF levels and RAR-beta expression. Patients treated with chemotherapy had clinical neuropathy and axonal loss assessed by neurophysiology, which was related to decreased NGF levels. ATRA reduced axonal degeneration demonstrated by nerve conduction velocity and clinical manifestations of neuropathy grades >= 2. Conclusions: ATRA reduced chemotherapy-induced experimental neuropathy, increased NGF levels, and induced RAR-beta expression in nerve. In patients, reduction of NGF in serum was associated with the severity of neuropathy; ATRA treatment reduced the electrophysiologic alterations.