Introduction � Many topical corticosteroids (CS) of differing potencies and formulations are available for treating psoriasis vulgaris � Topical CS potency can be assessed by the vasoconstriction assay (McKenzie-Stoughton), which is based on the blanching response of skin induced by topical CS application on healthy skin1 – This assay is recommended for topical CS potency ranking based on a correlation with clinical efficacy in psoriasis � A foam formulation of fixed-dose combination calcipotriol 50 µg/g (Cal) and betamethasone 0.5 mg/g (as dipropionate; BD) has been developed as a treatment option for patients with psoriasis – Clinical studies have demonstrated greater efficacy with Cal/BD foam versus the gel and ointment formulations 2-6 � The objective of this study was to compare the CS potency of BD in Cal/BD foam with existing CS-containing topical products Methods PATIENTS � The study enrolled healthy, non-smoking volunteers aged 18–50 years – All subjects were required to demonstrate adequate vasoconstriction prior to the study, defined as a visual skin blanching score of at least one unit following non-occlusive BD 0.05% ointment application for 4–6 hours � Subjects were excluded if they received systemic treatments or any medications that could interfere with the blanching reaction within 2 weeks, or had used topical CS on the test sites within 4 weeks prior to enrolment STUDY DESIGN � This was a Phase I, single-centre, investigator-blinded, vehicle-controlled, intra-individual comparison study (NCT02973776) � Each volunteer received a single application, under non-occlusive conditions of: Cal/BD foam, clobetasol propionate 0.05% cream (CP; very potent), BD 0.05% ointment (potent), mometasone furoate 0.1% cream (MF; potent), hydrocortisone-17-butyrate 0.1% ointment (HB; moderately potent) and foam vehicle to six circular test sites (each 2.2 cm in diameter) on the anterior forearms � After 16 hours of exposure, any remaining product was removed STUDY OBJECTIVES AND ASSESSMENTS � The primary objective was to compare the vasoconstriction potential of Cal/BD foam with the other treatments using the human skin blanching test (McKenzie-Stoughton vasoconstriction assay)1 � Skin blanching for each treatment was assessed 2 hours after the 16-hour application period by two independent, trained observers – Visual assessment of skin blanching was scored on a 9-point scale from 0–4 (0 = no change, 4 = maximal blanching; half-point scores were used for intermediate changes) � Local tolerability was assessed at the same time as skin blanching and at follow-up; safety was assessed throughout the study by evaluation of adverse events (AEs) STATISTICAL ANALYSIS � The mean of the two individual skin blanching visual scores were calculated for each treatment, and non-parametric tests were performed. Kruskal-Wallis test for the overall effect, and Wilcoxon Signed Rank test for the pairwise comparisons (Cal/BD foam vs other treatments) Results PATIENTS � A total of 36 healthy volunteers were randomized and analysed (Table 1) ASSESSMENT OF SKIN BLANCHING � All active treatments resulted in greater skin blanching compared with foam vehicle (Figure 1; Table 2) � Skin blanching with Cal/BD foam was significantly lower than with CP cream (P<0.001), similar to BD ointment and MF cream, and significantly higher than HB ointment and foam vehicle (P<0.001 for both) [Figure 1; Table 2] � No AEs were reported, and all subjects had a local tolerability score of 0 (ie, no reaction) Vasoconstrictor potency of fixed combination calcipotriol plus betamethasone dipropionate foam versus other corticosteroid psoriasis treatments Catherine Queille-Roussel,1 Jakob Nielsen2 1Centre de Pharmacologie Clinique Appliquée à la Dermatologie, Nice, France; 2LEO Pharma A/S, Ballerup, Denmark P1908 Poster presented at the 26th EADV Congress, Geneva, Switzerland, 13–17 September 2017 � Understanding topical CS potency is important to ensure the appropriate use of treatments for psoriasis: – The degree of skin blanching is used as a measure of the inherent potency of a CS, and its ability to diffuse into the skin � This study showed that, consistent with CS potency classifications, the steroid potency of Cal/BD foam was similar to BD ointment and MF cream, significantly stronger than that of HB ointment, but weaker than that of very potent CP cream � These findings expand on those from a previously reported Phase I study, which showed that Cal/BD foam was a more potent formulation than Cal/BD ointment7 Conclusions Acknowledgements � This study was sponsored by LEO Pharma. Medical writing support was provided by Andrew Jones, PhD, from Mudskipper Business Limited, funded by LEO Pharma References 1. McKenzie AW & Stoughton RB. Arch Dermatol 1962;86:608–10 2. Leonardi C et al. J Drugs Dermatol 2015;14:1468–77 3. Koo J et al. J Dermatolog Treat 2016;27:120–7 4. Paul C et al. J Eur Acad Dermatol Venereol 2017;31:119–26 5. Queille-Roussel C et al. Clin Drug Investig 2015;35:239–45 6. Stein GL et al. J Drugs Dermatol 2016;15:951–7 7. Queille-Roussel C et al. J Eur Acad Dermatol Venereol 2016;30:1951–6 Table 2. Skin blanching scores by treatment, assessed 2 hours after 16 hours of treatment application Treatment Mean (SD) Median (range) P value (v Cal/BD foam) Cal/BD foam 1.93 (0.56) 2.00 (0.75–3.00) – CP cream 3.09 (0.55) 3.00 (1.75–4.00) <0.001 BD ointment 1.85 (0.59) 1.75 (0.75–3.00) 0.30 MF cream 2.11 (0.59) 2.00 (1.00–3.75) 0.22 HB ointment 1.40 (0.66) 1.25 (0.50–3.00) <0.001 Foam vehicle 0.06 (0.13) 0 (0–0.50) <0.001 SD, standard deviation Table 2. Baseline demographic and characteristics of randomized subjects Subjects (n=36) Median age (range), years 34.5 (19–50) Males:Females, n (%) 14:22 (38.9:61.1) Race, n (%) White 36 (100.0) Fitzpatrick skin type, n (%) II 5 (13.9) III 30 (83.3) IV 1 (2.8) Median BMI (range), kg/m2 22.9 (16.2–34.5) BMI, body mass index Figure 1. Box plot showing visual assessment of skin blanching 2 hours after 16 hours of treatment application The horizontal line represents the median, and the circle represents the mean; the box represents the interquartile range (IQR), and the whiskers represent the range within 1.5 x IQR Cal/BD foam CP cream BD ointment MF cream HB ointment Vehicle Sk in b la nc hi ng 2 h ou rs a ft er pr od uc t r em ov al 4 3 2 1 0 pcg-workstation-2 Sticky Note Marked set by pcg-workstation-2 pcg-workstation-2 Sticky Note Marked set by pcg-workstation-2 pcg-workstation-2 Sticky Note Marked set by pcg-workstation-2 pcg-workstation-2 Sticky Note Marked set by pcg-workstation-2 pcg-workstation-2 Sticky Note Marked set by pcg-workstation-2 pcg-workstation-2 Sticky Note Marked set by pcg-workstation-2 pcg-workstation-2 Sticky Note Marked set by pcg-workstation-2 pcg-workstation-2 Sticky Note Marked set by pcg-workstation-2 pcg-workstation-2 Sticky Note Marked set by pcg-workstation-2 pcg-workstation-2 Sticky Note Marked set by pcg-workstation-2 pcg-workstation-2 Sticky Note Marked set by pcg-workstation-2 pcg-workstation-2 Sticky Note Marked set by pcg-workstation-2