5% KOH Solution vs. Placebo and Diclofenac Gel for the Treatment of Actinic Keratosis

The KOHDIAK study is a prospective, three-armed, randomised, double-blind study to evaluate the efficacy and safety of the treatment of mild and moderate actinic keratosis with a 5% potassium hydroxide solution (Solcera, medical device) versus placebo and investigator-blinded comparison with 3% diclofenac gel (Solaraze, medicinal product). It is performed in accordance with both the laws in force for clinical trials with medical devices and those with medicinal products.


Eligibility Criteria:
Inclusion Criteria:

* Age ≥ 18 years and \< 90 years
* Actinic keratosis grade I (mild) or II (moderate) according to the definition by Olsen with palpable or clinically/dermatoscopically apparent keratosis
* Either lesions being well accessible/treatable by the patient or presence of a second person to do the daily applications
* Written informed consent by the patient

Exclusion Criteria:

* Number of initial lesions to be treated ≥ 6
* Overall size of the area to be treated \> 25 cm2
* Size (maximum diameter) of single lesion to be treated \> 20 mm
* Lesions in close proximity to the eyes, eyelids, nostrils, mouth or mucosal tissue
* Need for topical treatment of cancerous area
* Presence of a relapsing, persistent, indurated, thickened, painful, bleeding, ulcerated and/or rapidly growing lesion
* Existing skin cancer (all forms of skin cancer incl. basal-cell carcinoma and squamous cell carcinoma) in the area to be treated in this study
* Dermal injuries, skin infection or exfoliative dermatitis in the area to be treated in this study
* Other skin diseases in the area to be treated in this study that affect the diagnostic assessment
* Pharmacological or physical local therapy of actinic keratosis (or application of the active ingredients used in the pharmacological therapy) in the area to be treated in this study during the last 4 weeks
* Primary or secondary immunodeficiency
* Treatment with interferons, interferon inducers, immunomodulators or systemic corticosteroids during the last 4 weeks
* Treatment with oral isotretinoin during the last 6 months
* Intracranial bleeding in the medical history or generally increased primary bleeding tendency
* Known intolerance/hypersensitivity to one of the ingredients of the investigational products, especially to diclofenac, parabens or benzyl alcohol as well as to NSAIDs, in particular acetylsalicylic acid
* Pregnancy and lactation
* Women of child-bearing potential either wishing to become pregnant or without effective contraception
* Other serious diseases, which are (according to the investigator's assessment) in conflict with the study participation (i.a. also in view of risk factors for a severe course of a potential COVID-19 disease in case of a SARS-CoV-2 infection)
* Obvious unreliability or lack of cooperation
* Known addiction to alcohol, medicinal products or drugs
* Dependency on the sponsor or an investigator
* Participation in a clinical trial during the last 30 days
* Previous participation in the present clinical trial
* Participation of a family member (in the same household) in the present clinical trial