Timber Pharmaceuticals, Inc. announced that interim pharmacokinetic (PK) analyses from the Phase 3 ASCEND study indicate minimal systemic absorption of isotretinoin or its major metabolites in patients with moderate to severe forms of congenital ichthyosis (CI) who were treated with TMB-001 0.05% ointment. Full PK results will be presented during the Society for Pediatric Dermatology’s Annual Meeting to be held July 13-16, 2023, in Asheville, North Carolina. The Phase 3 ASCEND study is an ongoing double-blind, vehicle-controlled randomized 12-week study followed by 12 weeks of open label treatment of patients who are greater than 6 years of age with moderate to severe X-linked recessive CI (XLRI) or autosomal recessive CI (ARCI).

The primary endpoint is the difference in proportions of treated patients with 2-point Investigator's Global Assessment (IGA) scaling/fissuring score improvement from baseline at 12 weeks. A subset of patients is also participating in a 12-week open label Maximal Use Study (MuST) that includes the collection of PK data as well as safety and efficacy data. The interim PK analyses include the first nine patients who completed 15 days of the MuST study.

The results indicate minimal absorption of isotretinoin when TMB-001 0.05% is applied to 75-90% of the body surface area. The 9 subjects (7 ARCI, 2 XLRI; ages 12-62) demonstrated mean plasma concentrations (ng/mL) of isotretinoin at Day 14 of 4.83 (range: 1.46-16.59), 4-oxo-isotretinoin of 13.71 (6.52-47.86), tretinoin of 0.08 (0-0.66) and 4-oxo-tretinoin of 0.