Lack of activity of betulin-based Oleogel-S10 in the treatment of actinic keratoses: a randomized, multicentre, placebo-controlled double-blind phase II trial.

Abstract

Betulinic acid and other triterpenes have shown strong antitumour activity in vitro and in vivo. A triterpene extract of birch bark formed the base of Oleogel-S10 and allowed topical application. Two previous trials have shown efficacy and tolerability in the treatment of actinic keratoses (AKs) with betulin-based Oleogel-S10. To confirm the efficacy and tolerability/safety of Oleogel-S10 in the treatment of AKs in a multicentre placebo-controlled study. Patients (n = 165) were treated topically for 3 months in a four-arm parallel study design, randomly allocated to A (n = 53) Oleogel-S10 once daily, B (n = 51) Oleogel-S10 twice daily, or C (n = 25) or D (n = 28) placebo (petroleum jelly) once or twice daily, respectively. Clinical efficacy in this double-blind study was assessed by the investigators. Final and baseline biopsies were evaluated by central histopathology. Complete clearance of the target lesions was seen in 4% of patients in group A and 7% in group B, but not in the placebo groups. A clearance rate of > 75% was seen for 15% and 18% of patients in groups A and B, respectively, and for 13% in the placebo groups. These differences were not statistically significant. Histopathologically, 43·9% of patients showed a downgrading or clearance of the marker AK with no significant differences between the groups. Treatment with Oleogel-S10 was well tolerated. The tolerability as assessed by the investigator was mostly 'very good' (78·8%), followed by 'good' (18·2%) and only 1·2% assessed it as 'intolerable'. Patient-assessed tolerability was graded mostly 'very good' (56·4%) or 'good' (34·5%). Treatment with Oleogel-S10 was well tolerated during a treatment period of 3 months, yet was no better than placebo in terms of efficacy in the treatment of AKs.