Efficacy of HP40
In two phase 3 trials with a total of 937 patients, four raised SKs per patient were treated with either HP40 or vehicle using the previously described method (Application and Mechanism). Three weeks later, residual SKs were re-treated. Pedunculated SKs or SKs in intertriginous areas, hair-bearing areas, or within 5 mm of the orbital rim were excluded. The therapeutic efficacy was assessed with a 4-point scale, Physician's Lesion Assessment (PLA), developed by the manufacturer where 0 is clear, 1 is nearly clear, 2 is a thin SK with a depth of 1 mm or less, and 3 is a thick SK with a depth greater than 1 mm. The primary endpoint was complete clearance (0 on PLA) of all four SKs.
The treatment and control groups had similar demographic characteristics, with an average age of 68.7 years, and the completion rate was nearly 100% for each trial (99%, 98% per trial). At the end of the study (day 106), HP40 resulted in a significantly higher rate of complete clearance of all four SKs than vehicle; however, the rate of clearance of all four SKs with HP40 was low overall (4%, 8% per study for HP40 versus 0% for both studies for vehicle). Post hoc, the authors also calculated the mean per-patient percentage of clear/nearly clear SKs, which was higher for HP40 than vehicle (47%, 54% versus 10%, 5%, respectively).
To examine the efficacy of HP40 by location, the percentage of clear/nearly clear SKs at day 106 for each anatomic site was calculated in another study. A total of 1,868 SKs were treated in the HP40 group and 1,880 SKs were treated in the vehicle group; 59% of SKs were on the trunk, 30% on the face, and 11% on the extremities. The highest rate of clearance/near-clearance with HP40 treatment was observed for the face (65%), followed by the trunk (46%), and then the extremities (38%). The authors theorized that these efficacy differences may be due to variations in skin topography, such as varying water or lipid content or SC thickness. For instance, the thin SC of the face may allow enhanced penetration of HP40 compared to other anatomical sites. Another explanation proposed by the authors was that the high exposure of the face to ultraviolet radiation may impair its ability to respond to H2O2-induced oxidative stress.
Skin Therapy Letter. 2020;25(1):1-4. © 2020 SkinCareGuide.com