Complete Clearance Is Sustained for at Least 12 Months After Treatment of Actinic Keratoses of the Face or Balding Scalp Via Daily Dosing With Imiquimod 3.75% or 2.5% Cream

February 2011 | Volume 10 | Issue 2 | Original Article | 165 | Copyright © February 2011


C. William Hanke MD,a Neil Swanson MD,b Suzanne Bruce MD,c
Brian Berman MD PhD,d James Kulp BS,e Sharon Levy MDe

aLaser and Skin Surgery Center, Carmel, IN
bDepartment of Dermatology, Oregon Health and Science University,
Portland, OR
cCenter for Skin Research, Houston, TX
d Department of Dermatology and Cutaneous Surgery, Miller School of Medicine, University of Miami, Miami, FL
e Product Development, Graceway Pharmaceuticals, LLC, Exton, PA

Abstract
Objective: Assess long-term, sustained, complete clearance of actinic keratoses after treatment with imiquimod 3.75% or 2.5% cream using two two-week or three-week cycles of daily dosing.
Methods: Adults with five to 20 baseline actinic keratoses who achieved complete clearance at the eight-week post-treatment visit in four phase 3 placebo-controlled treatment studies were followed for an additional 12 months.
Results: For imiquimod 3.75% and 2.5% cream, respectively, complete clearance was sustained for 12 months in 17/42 (40.5%) and 13/39 (33.3%) subjects from the two-week cycle studies, and in 23/48 (47.9%) and 16/37 (43.2%) subjects from the three-week cycle studies. There were no safety concerns during the follow-up.
Conclusion: In subjects with a median of eight to nine baseline actinic keratoses who achieved complete clearance after treatment of the full face or balding scalp with topical imiquimod 3.75% cream, complete clearance of all lesions (baseline, recurrent or new) was sustained in ≥40 percent of subjects for at least 14 months after the last dose. Clinicaltrials.gov identifier NCT00668733.

J Drugs Dermatol. 2011;10(2):165-170.

INTRODUCTION

Imiquimod 3.75% cream (Zyclaraâ„¢, Graceway Pharmaceuticals, LLC, Bristol, TN) is a new formulation of imiquimod recently approved by the U.S. Food and Drug Administration (FDA) to treat actinic keratoses (AK) on the face or balding scalp using a cyclical two week-on, two week-off, two week-on regimen of daily application.1 A topically active small molecule immune response modifier, imiquimod activates cells of the innate immune system via Toll-like receptor 7, initiating an immunologic cascade that includes production of cytokines, upregulation of antigen presentation, and secondary activation of the acquired immune system.2
A previously FDA-approved formulation, imiquimod 5% is an effective patient-applied, field-directed option for treating AKs; however, the labeled regimen of treating only a 25-cm2 area twice weekly (twice/week) for 16 weeks has limitations.3,4 AKs typically involve much larger areas of photodamaged skin than 25 cm2, and for some patients the dosing frequency is confusing and the treatment duration is too long to ensure adequate compliance.
To address these concerns, new formulations of imiquimod 3.75% and 2.5% cream were evaluated in four placebocontrolled, multi-center, phase 3 studies treating the full face or balding scalp using two two-week or three-week cycles of daily application.5,6 In the phase 3 studies of the new formulations, both imiquimod 3.75% and 2.5% creams were statistically superior to placebo cream with respect to complete clearance, reduction in AK counts, and photodamage scores.5,6 As AK is a chronic condition marked by recurrent or new lesions developing in the treated area even after effective therapy, examination of long-term treatment effects is warranted. In subjects who achieved complete clearance after treatment with imiquimod 5% twice/week for 16 weeks, thrice/week for 16 weeks or thrice/week for two four-week cycles, 43 percent, 24 percent and 39 percent were observed to have a recurrence, respectively, in the 25-cm2 treatment area after 12–18 months of follow-up.7,8 In order to obtain long-term clearance data on the new imiquimod formulations with their expanded field of treatment, we conducted a phase 3b, longitudinal, 12-month observational study fol-
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