The purpose of this study is to compare the efficacy of alitretinoin and azathioprine in the treatment of patients with severe chronic non-hyperkeratotic hand eczema.

Inclusion Criteria:

• Age ≥ 18 years and ≤ 75 years
• Severe or very severe chronic non-hyperkeratotic hand eczema for a minimum duration of 3 months as defined by a Physician Global Assessment (PGA) using a validated Photoguide
• Refractory to standard therapy, defined as:

Patients received treatment with topical corticosteroids of class II or higher for at least 8 weeks within 3 months before enrolment, with either no response or a transient response. Patients had also received standard skin care, including emollients and barrier protection as appropriate, without significant improvement. Patients had avoided irritants and allergens, if identified, without significant improvement.

• Women of childbearing potential are required to use at least two forms of contraception for at least 1 month before starting treatment, during treatment, and for at least 1 month after finishing treatment; these women are required to take monthly pregnancy tests
• Able to provide written Informed Consent
• Able to speak and read the Dutch language

Exclusion Criteria:

General criteria prior to randomization

• Treatment with alitretinoin or azathioprine in the previous 3 months
• Hyperkeratotic palmar eczema as defined by the Danish Contact Dermatitis Group
• Patients with predominantly atopic dermatitis, in which the hands are also involved. Patients with mild atopic dermatitis, in which the hands are mainly affected are eligible for inclusion.
• Psoriasis
• Active bacterial, fungal, or viral infection of the hands
• Pregnant/lactating or planning to become pregnant during the study period
• Treatment with systemic medication or UV radiation within the previous 4 weeks
• Mentally incompetent
• Immunocompromised status
• Known or suspected allergy to ingredients in the study medications
• Inclusion in a study of an investigational drug within 60 days prior to start of treatment
• Current malignancy (other than successfully treated non-metastatic cutaneous squamous cell or basal cell carcinoma and⁄or localized carcinoma in situ of the cervix)
• Current active pancreatitis
• Living vaccine (including bacillus Calmette-Guérin (BCG), varicella, measles, mumps, rubella, yellow fever, oral polio and oral typhoid) in the last 2 weeks or the planned application of such a vaccine during the study period
• Evidence of alcohol abuse or drug addiction
• Chronic or recurrent infectious diseases
• Contact sensitizations with clinical relevance to the hands, in which exposure to allergens is not avoided
• Hypervitaminosis A due to the use of vitamin A supplements containing >2000 IU
• Use of drugs with potential to change the effective dosis of study drugs within the previous 2 weeks

Laboratory exclusion criteria post randomization

• Alanine aminotransferase (ALAT) and ⁄or aspartate aminotransferase (ASAT) values > 200% of the upper limit of normal
• Impaired renal function as indicated by a clinically relevant abnormal creatinine value (to be determined by investigator or treating physician)
• Anemia as indicated by a clinically relevant lowered hemoglobin value (to be determined by investigator or treating physician)

Alitretinoin specific

• Triglycerides > 200% of the upper limit of normal,
• Cholesterol or low density lipoprotein (LDL) cholesterol values > 200% of the upper limit of normal
• Uncontrolled hypothyroidism (to be determined by investigator or treating physician)

Azathioprine specific

• Patients with low or absent thiopurine methyltransferase (TPMT) activity (defined in our center as <52 nmol/gHb/hour, combined with genotyping showing homozygous of compound heterozygous mutations) and a subsequent risk for life-threatening myelotoxicity

Data will be published anonymously and will not be possible to trace back to individual participants.