Effects of topical treatment with fenretinide (4-HPR) and plasma vitamin A levels in patients with actinic keratoses.

Eighteen patients with facial actinic keratoses were treated with the retinoid fenretinide (4-HPR), applied topically twice-daily for 3 months. After 3 months of treatment, complete regression was observed in 56% and partial regression in 44% of cases. Eight patients relapsed within 3 months after drug discontinuation. Six months later, only two patients (11%) showed a treatment response (complete regression). Blood samples showed that 4-HPR was not absorbed and no local or distant adverse effects were observed. Baseline plasma retinol levels were lower than in healthy subjects, thus suggesting that reduced retinol levels might be involved in this pathology. These encouraging preliminary results suggest the need for further studies to evaluate the best dosage schedules and duration of 4-HPR topical application in actinic keratoses.