Efficacy of imiquimod 3.75% from Lmax according to the number of actinic keratosis lesions

[Update in the diagnosis and treatment of actinic keratosis]

Actinic keratosis (AK) is among the most common conditions in dermatology in an increasingly aging population. However, the presence of severe field cancerization with large treatment fields showing multiple lesions with distinct features often poses a therapeutic challenge. The most accurate possible characterization of the treatment field, risk assessment concerning the occurrence of cutaneous squamous cell carcinoma, and knowledge of the efficacy and local side effects of the available interventions are of paramount importance for effective management and preventive efforts. This article summarizes current developments in the diagnosis and treatment of AK and discusses their application in everyday clinical practice. In particular, the focus is on the increasing value of non-invasive diagnostic techniques like "line-field" confocal optical coherence tomography, and the recently approved topical agents tirbanibulin 1% ointment and 5‑fluorouracil 4% cream, as well as current developments of photodynamic therapy and prevention.

[Actinic keratoses : Current guideline and practical recommendations]

The S3 guideline "Actinic keratosis and squamous cell carcinoma of the skin" was published on 30 June 2019. Subsequently, publications, reviews and meta-analyses appeared with new questions regarding the comparability of study data and heterogeneity of the evaluations, which are caused, among other things, by divergent measurement parameters as well as insufficient consideration of pretreatments and combined treatments. This concise overview was written in the context of criticism and in view of necessary developments and research. Topics include epidemiology, pathogenesis, prevention, clinical presentation, therapy and BK5103. Therapy is divided into local destructive procedures and topical applications. Recommendations with quotation marks are based on the actual guideline. Corresponding evidence levels are given. For the implementation in daily routine basic data, side effects and features of therapeutic options are mentioned. The current developments and questions concerning actinic keratoses become clear.

Treatment responder analysis in actinic keratosis: can it lead the way to individualized choice of treatment?

BACKGROUND

It is unclear if there are any distinct AK patient populations that might respond best to a given treatment.

OBJECTIVE

To identify if a distinct subgroup of patients with AK might respond better to treatment with ingenol mebutate (IngMeb) versus diclofenac sodium (DS).

METHODS

Complete clearance of AK and mean lesion reduction at end of first treatment course and week 17 were evaluated within subgroups.

RESULTS

502 patients (255 IngMeb; 247 DS) were included in the analysis. At week 17, complete clearance was achieved by more patients treated with IngMeb versus DS within the majority of patient subgroups, including patients with <6 lesions and ≥6 lesions at baseline, aged ≥65 years, males, females, Fitzpatrick skin types II and III, and facial lesions. Mean lesion reduction at week 17 was greater with IngMeb than DS within the same subgroups, and in patients with scalp lesions.

CONCLUSIONS

This responder analysis did not identify any distinct population that responded more optimally than others with IngMeb or DS. More patients achieved complete clearance and higher lesion reduction of AK with IngMeb compared with DS in most subgroups.

Imiquimod 3.75% for field-directed therapy of actinic keratosis: results of a prospective case-series study in Greece

Background

Imiquimod 3.75% is a field‐directed treatment for actinic keratosis that can detect and treat clinical and subclinical lesions across an entire sun‐exposed field. The detection of subclinical lesions is evidenced by an increase in lesions to the maximum lesion count during treatment (L_max). We report clinical outcomes for the first 15 patients treated with imiquimod 3.75% in daily clinical practice in Greece.

Methods

Fifteen patients with actinic keratosis lesions were treated with imiquimod 3.75% in an outpatient setting in two 2‐week treatment cycles separated by a 2‐week treatment‐free interval. Actinic keratosis lesions were counted before treatment, at the end of the first treatment cycle (Week 2; L_max), and 2 weeks after the second treatment cycle (Week 8). Local skin reactions (LSR) were also evaluated at Weeks 2 and 8.

Results

The median baseline actinic keratosis lesion count was 25, which increased to a median L_max of 29 at Week 2 and decreased to a median of 5 at Week 8. The median percentage and absolute reduction in actinic keratosis lesions from L_max to Week 8 were 87% and 23%, respectively. Most of the LSR were mild‐to‐moderate in intensity at Week 2 and had resolved by Week 8.

Conclusion

Imiquimod 3.75% effectively detected and cleared both the clinical and subclinical actinic keratosis lesions across the entire sun‐exposed field in this cohort of Greek patients. Treatment was well tolerated.

Low-level light-assisted photodynamic therapy using a wearable cap-like device for the treatment of actinic keratosis of the scalp

BACKGROUND

Daylight photodynamic therapy (dlPDT) is a painless and increasingly cost-effective treatment for actinic keratosis (AK). New protocols avoid incubation, minimizing pain and adverse events. However, it is time-consuming and dependent on specific weather conditions. In patients with AK of the scalp, we evaluated the efficacy of indoor photodynamic therapy (PDT) using a wearable low-level light therapy (LLLT) device, without pre-incubation with a photosensitizing agent.

METHODS

In this pilot study, 27 patients with thin and moderately thick AK (Olsen Grades I-II) underwent a single 15-minute session of LLLT using a wearable cap-like device immediately after application of methyl-aminolevulinate (MAL) cream, with no prior preparation of the affected area. Treatment efficacy was quantified by measuring the reduction in AK lesion number and the AK quality of life (AKQoL) score. All AK lesions were mapped at baseline for follow-up 2 months later. Paired pre/post scalp biopsies from 5 patients were analysed using histological and immunohistochemical techniques (p53, p27, cyclin D1, p63, and Ki67 expression). Data were analysed using the Wilcoxon signed-rank test.

RESULTS

In all patients we observed a global reduction in the number of AK lesions (71%; p < 0.0001) and AKQoL score (from 5.6 to 4.4; p = 0.034) 2 months after treatment. Histology and immunohistochemistry of skin biopsies from 5 patients also revealed marked improvements after LLLT. No patients reported any pain during treatment.

CONCLUSION

PDT using LLLT is a rapid, painless, and efficacious modality for the treatment of AK.

Imiquimod in dermatology: an overview

Imiquimod is an immune response modifier commercially available as a 3.75 and 5% cream. Topical imiquimod stimulates the innate and adaptive immune responses and induces cytokine production. This allows its use for the treatment of a wide variety of benign and malignant skin conditions due to its potential antiviral, antitumor, and immunoregulatory effects. Currently, topical imiquimod is US Food and Drug Administration (FDA)-approved for the treatment of anogenital warts, actinic keratosis, and superficial basal cell carcinomas. However, it has also shown a beneficial effect in the treatment of many other skin disorders. In this review, we describe existing evidence on the mechanism of action of topical imiquimod, its FDA-approved indications, off-label uses, and side effects.

Actinic keratosis and field cancerization

While actinic keratoses (AKs) have been considered precancerous until recently for being able to turn into squamous cell carcinomas (SCCs), it is now agreed that it would be more appropriate to call them cancerous. Although not all AKs turn into SCC and some of them may even have a spontaneous regression, there is an obvious association between SCC and AK. Approximately 90% of SCs have been reported to develop from AKs and AKs are the preinvasive form of SCCs. The presence of two or more AKs on a photodamaged skin is an indicator of field cancerization and represents an increased risk of invasive SCC. All lesions should be treated since it cannot be foreseen which of the lesions will regress and which will progress to SCC. AK can be a single lesion or it can involve multiple lesions in a field of cancerization; thus, AK treatment is grouped under two headings: (1) Lesion-specific treatment; and (2) Field-targeted treatment. Lesion-specific treatments are practicable in patients with a small number of clinically visible and isolated lesions. These treatments including cryotherapy, surgical excision, shave excision, curettage and laser are based on physical destruction of the visible lesions. Field-targeted treatments are effective in the treatment of visible lesions, subclinical lesions and keratinocyte changes in the areas surrounding the visible lesions. Field targeted treatment options are topical imiquimod cream, 5% 5-fluorouracil cream, ingenol mebutate, diclofenac gel, resimiquimod and photodynamic therapy.