Pharmacotherapeutic group: Retinoids for topical use in acne.
ATC code: D10AD06.
Pharmacology: Pharmacodynamics: Mechanism of action: Aklief cream contains 50 micrograms (mcg/g) (w/w) trifarotene, which is a chemically stable, terphenyl acid derivative with retinoid-like activity. It is a relatively potent RARγ agonist (retinoid acid receptor γ agonist), characterised by its high specificity to this receptor over RARα & RARβ (65- and 16-fold, respectively, with no Retinoid X Receptor (RXR) activity).
In addition, trifarotene modulates retinoid target genes (differentiation and inflammatory processes) in human immortalised keratinocytes and human reconstructed epidermis.
Pharmacodynamic effects: Trifarotene has demonstrated, in the Rhino-mouse model, marked comedolytic activity with the reduction in the comedone count and marked increased epidermis thickness. In this model, trifarotene produced the same comedolytic effect as other known retinoids.
Trifarotene has also shown anti-inflammatory and depigmenting activities.
Clinical trials: Aklief cream applied once daily in the evening was evaluated for 12 weeks in 2 randomised, multi-centre, parallel group, double-blind, vehicle-controlled studies of identical design. They were conducted in a total of 2420 patients aged, 9 years and older, with moderate facial and truncal acne vulgaris.
Acne severity was evaluated using the 5-point Investigator's Global Assessment (IGA) scale for the face and Physician's Global Assessment (PGA) for the trunk, with moderate acne vulgaris defined as a score of Grade 3-Moderate (see Table 1).
Click on icon to see table/diagram/image
There were three identical co-primary efficacy endpoints in both pivotal studies 1) the success rate based on the IGA and PGA outcome (percentage of subjects "clear" and "almost clear" and with at least a 2-grade change from baseline) and absolute and percentage change from baseline in 2) inflammatory and 3) non-inflammatory lesion counts at Week 12.
Overall, 87% of subjects were Caucasian and 55% were female. Thirty four (1.4%) subjects were 9 to 11 years of age, 1128 (47%) subjects were 12 to 17 years and 1258 (52%) subjects were 18 years and older. All patients had moderate acne vulgaris on the face and 99% on the trunk. At baseline subjects had between 7 and 200 (average 36) inflammatory lesions on the face and between 0 and 220 (average 38) on the trunk. Additionally subjects had 21 to 305 (average 52) non-inflammatory lesions on the face and 0 to 260 (average 46) on the trunk.
The IGA and PGA success rates, mean absolute, and percent reduction in acne lesion counts from baseline after 12 weeks of treatment are presented in the following tables: See Tables 2 and 3.
Click on icon to see table/diagram/image
Click on icon to see table/diagram/image
Paediatric population: Age group 12 to 17 years: In the phase 3 studies a total of 1128 children aged 12 to 17 years with moderate acne vulgaris were included: 573 of them in study 18251 and 555 children in study 18252.
Long-term efficacy: In Study 3, a one-year open label safety study of 435 patients, 12 years and older (210 children completed 52 weeks of the study), with moderate facial and truncal acne vulgaris, Aklief cream demonstrated a clinically meaningful improvement with IGA and PGA success rates increasing: from 26.3% at Week 12 visit to 65.9% at Week 52 visit for the face and from 38.9% at Week 12 visit to 67.1% at Week 52 visit for the trunk, respectively.
IGA and PGA success experienced by the same subject increased from 21.9% at Week 12 to 58.2% at Week 52.
Pharmacokinetics: Absorption: The absorption of trifarotene from Aklief cream was evaluated in adult and paediatric (10-17 years old) subjects with acne vulgaris. Subjects were treated once daily for 30 days with 2 grams/day of Aklief applied on the face, shoulders, chest, and upper back.
Overall, systemic exposure levels were low and similar between adults and paediatric populations.
After 4 weeks treatment, seven of nineteen (37%) adult subjects had quantifiable trifarotene plasma levels. C
max ranged from below the limit of quantification (LOQ <5 pg/mL) to 10 pg/mL and AUC
0-24h ranged from 75 to 104 pg.hr/mL.
Three of the seventeen (18%) of paediatric subjects presented quantifiable systemic exposure. C
max ranged from below the limit of quantification (LOQ <5 pg/mL) to 9 pg/mL and AUC
0-24h ranged from 89 to 106 pg.hr/mL.
Steady state conditions were achieved in both adult and paediatric subjects following 2 weeks of topical administration. No drug accumulation is expected with long-term use.
Distribution: Trifarotene penetrates into the skin with an exponential distribution from the stratum corneum to the epidermis and dermis.
An
in vitro study demonstrated that trifarotene is greater than 99.9% bound to plasma proteins. No significant binding of trifarotene to erythrocytes was observed.
Metabolism: In vitro studies using human hepatic microsomes and recombinant CYP450 enzymes have shown that trifarotene is primarily metabolised by CYP2C9 and to a lesser extent by CYP3A4, CYP2C8 and CYP2B6.
Excretion: In nonclinical studies, trifarotene is primarily excreted by the faeces.
Toxicology: Preclinical Safety Data: Genotoxicity: Based on the weight of evidence, Aklief cream was considered negative in an in vitro bacterial reverse mutation (Ames) assay, an in vitro mouse lymphoma assay with L5178Y/TK+/-cells and an in vivo micronucleus assay in rats. While an equivocal result was seen an in vitro micronucleus assay in primary human lymphocytes, the weight of evidence indicates a low genotoxic potential with trifarotene.
Carcinogenicity: Trifarotene was not carcinogenic when topically applied to mice daily for up to 24 months in the vehicle of Aklief cream at doses of up to 0.02 mg/kg (at a concentration of 0.001% w/w). Systemic exposure at the highest dose in mice was 90-fold greater than the anticipated maximum human exposure with Aklief cream. Trifarotene was also not carcinogenic when administered orally in a solution to rats daily for up to 24 months at doses of up to 0.75 mg/kg/day in males and 0.2 mg/kg/day in females. Systemic exposure at the highest dose in rats was 642-(males) and 1642-fold (females) times greater than the anticipated human exposure at the MRHD of Aklief cream.