Efficacy and tolerance of tazarotene cream in lamellar ichthyosis (LI): a dose-finding study

INTERVENTION: Study treatments: Tazarotene cream 0.1% or 0.05% and vehicle. Dose: Period I (4 weeks): Patients will apply one of the two active test products and the vehicle on the lesions (except on face, scalp, neck and genital areas), on two randomly allocated sides (left side and right side of the body) once daily for 4 weeks (e.g., every evening). This will be associated with the daily application of a standard moisturiser (e.g., in the morning; including face and neck). An adjusted dosage to local tolerance of test products will be performed (no test product application on irritated areas on days when they are observed). Period II (8 weeks): No application of the test products for 8 weeks; application of the standard moisturiser only. Mode of administration: Topical CONDITION: Non Erythrodermic Autosomic Recessive Lamellar Ichthyosis (NEARLI) ; Not Applicable ; Congenital ichthyosis PRIMARY OUTCOME: Assessment of scaling and roughness by the investigator at each of the 10 visits (at screening, baseline, then on days 7, 14, 21, 28 [end of treatment, Period I], 42, 56, 70 and 84 [end of treatment‐free follow‐up, Period II]). SECONDARY OUTCOME: 1. Assessment of the relapse/rebound by the investigator during Period II; 2. Time‐course severity of each sign (scaling and roughness) during Periods I and II; 3. Separate assessment of the overall clinical severity of the lesions on palms and soles for each test side of the body at baseline and end of Period I; 4. Assessment of the severity of scaling at baseline and end of Period I; 5. Instrumental assessment of scaling on the two forearms using the D‐squame technique, at baseline and end of Period I; 6. Global local tolerance at end of Period I; 7. Overall acceptability by the patients at end of Period I; 8. Routine blood laboratory tests (hematology, chemistry) at baseline and at end of Period I; 9. Plasma monitoring of tazarotenic acid at baseline and at end of Period I; 10. Compliance; 11. Physical examination; 12. Adverse events INCLUSION CRITERIA: 1. Patients of both sexes of at least 8 years of age 2. Patients with a documented diagnosis of LI based on clinical signs and, if possible, pedigree analysis 3. Patients with both scaling and roughness of moderate to severe intensity on each side of the body 4. Patients or patient's parents/guardians able to understand and follow the study procedures 5. Written informed consent from the patients or parents/guardians 6. Patients or patients' parents/guardians affiliated to a healthcare security system