Secukinumab (AIN457), a recombinant high-affinity fully human monoclonal antibody, selectively targets and neutralizes IL-17A. Secukinumab has been shown to be clinically effective 1, 2 with a rapid, strong and sustained efficacy and a favourable safety profile in patients with moderate-to-severe plaque psoriasis 3-5. Secukinumab is administered by subcutaneous injection, which is typical for the most recent antibody therapies. For psoriasis therapy, the distribution of secukinumab into lesional and non-lesional skin is of particular interest to provide local activity at the target site. Currently available methods to measure antibody concentrations in the skin (e.g. punch biopsies, suction blisters) can only be used for single time-point measurements as they are rather invasive and burdensome 6. Other methods such as dermal microdialysis are of limited use for large antibody molecules due to limited pore size of clinical membranes 7. Dermal open flow microperfusion (dOFM) offers an alternative sampling method characterized by minor invasiveness and the ability to continuously sample large and lipophilic molecules directly from the dermal interstitial fluid (dISF) (Fig. 1a) 8, 9. Calibration with a reference substance (e.g. sinistrin) or a reference-independent procedure (e.g. No-Net-Flux) allows absolute quantification (S10-12). We determined the concentration of secukinumab directly in the skin of healthy subjects and in lesional and non-lesional skin of plaque psoriasis subjects to assess the ability of a single 300 mg subcutaneous dose to neutralize its target, IL-17A, in the skin. This study (ClinicalTrials.gov: NCT01539213) was carried out at the Medical University of Graz, Austria. It was approved by the local ethics committee and the Austrian Agency for Health and Food Safety (AGES) and was conducted according to GCP and the Declaration of Helsinki. Written informed consent was obtained from each subject before study start. Eight healthy subjects and eight psoriasis subjects were included (Table S1). We first established the quantification of secukinumab with dOFM in the skin of healthy subjects using a No-Net-Flux procedure and sinistrin as an external reference substance, and by validating the quantification with suction blisters and punch biopsies. dOFM with sinistrin as a reference was then used for lesional and non-lesional skin in psoriasis subjects. At least three dOFM probes were inserted into the healthy skin of each subject on Days 1, 8 and 15 to collect dISF samples; additional probes were used in lesional psoriasis plaques (Fig. 1b). Sinistrin was administered as a primed-continuous intravenous infusion, and dOFM sampling was performed for up to 14 hours. Blood samples for secukinumab and sinistrin quantification in serum were collected at least hourly. After sampling on Day 1, each subject received a single subcutaneous dose of 300 mg secukinumab. Biopsy and suction blister samples were collected in healthy subjects on Day 15. Samples were analysed for secukinumab by a competitive ELISA and for sinistrin by a validated enzymatic method. Details can be found in Appendix S1. In healthy subjects, mean secukinumab serum concentrations were 36.1 ± 10.5 μg/ml (Day 8) and 35.0 ± 10.5 μg/ml (Day 15). Measured with sinistrin as reference, secukinumab concentrations in dISF were 7.8 ± 2.7 μg/ml (Day 8) and 8.0 ± 3.2 μg/ml (Day 15) (Fig. 2a). Punch biopsies and suction blisters yielded similar concentrations of 10.4 ± 4.0 μg/ml and 6.9 ± 2.3 μg/ml, respectively (P > 0.05) (Fig. 2b). In psoriasis subjects, the mean secukinumab serum concentrations were 21.1 ± 4.3 μg/ml (Day 8), 21.2 ± 4.9 μg/ml (Day 15) and 17.8 ± 5.1 μg/ml (Day 22). Secukinumab concentrations in dISF were 8.3 ± 3.4 μg/ml in non-lesional skin and 6.8 ± 2.7 μg/ml in lesional skin on Day 8 (P > 0.05) measured with sinistrin as reference. On Day 15, secukinumab concentrations were slightly lower, 6.4 ± 3.4 μg/ml in non-lesional skin and 5.7 ± 1.8 μg/ml in lesional skin (P > 0.05) (Fig. 2c). Tables S2/S3 show individual secukinumab concentrations, Appendix S1 and Fig. S1 show details of the sinistrin reference. Secukinumab No-Net-Flux data are shown in Figs S2 and S3. After a single dose of secukinumab 300 mg, the mean TSS (total sum score related to a single plaque) dropped significantly from 6.5 ± 0.8 to 2.6 ± 1.1 (P < 0.0001) from Day 1 to Day 22. The mean PASI (psoriasis area and severity index) decreased significantly by 58% from Day 1 to Day 22 (P < 0.0001). There were no serious adverse events. In this study, we found similar serum concentrations of secukinumab on Day 8 and Day 15 postdosing of secukinumab 300 mg on Day 1. Secukinumab concentrations in the skin were also relatively consistent over time. This suggests similar secukinumab pharmacokinetics in blood and skin without skin-specific retention. Overall, there were lower mean secukinumab serum concentrations in psoriasis subjects compared to healthy subjects which might have been caused by higher body weights with accompanying higher clearance (S13). Absolute secukinumab concentrations determined by suction blister and punch biopsy in healthy subjects corresponded to dOFM results. The 28% to 39% dISF secukinumab concentrations relative to serum in psoriasis subjects suggest a somewhat higher distribution of secukinumab in the skin of psoriasis subjects compared to 23% in healthy subjects. These concentrations in skin are consistent with tissue concentrations of other therapeutic antibodies, for example relative to plasma 28% of an antibody were found in the synovial fluid of patients with rheumatoid arthritis (S14). The clinical efficacy of the measured secukinumab concentrations is supported by a significant decrease in PASI as well as TSS of the target plaque. The mean secukinumab concentration (46 nM) measured on Day 8 in dISF from lesional skin indicates a clear molar excess of secukinumab molecules compared to the mean level of IL-17A molecules detected at baseline in the same plaques (0.31 pM, with a maximum of 2.28 pM) (S15). In summary, dOFM can readily be used to quantify dISF concentrations of therapeutic antibodies such as secukinumab in the skin of healthy subjects as well as psoriasis subjects. We were able to verify levels of secukinumab in the dISF of psoriasis subjects as early as one week after secukinumab injection in quantities that appear sufficient to completely neutralize IL-17A in skin. The authors thank Catherine Froeliger and Agnes Prasch for sample analysis; Sigrid Deller and Stefan Korsatko for their support with the clinical study; Beate Boulgaropoulos, Alison Green, Stephanie Harbers, Martin Kaul and Selma Mautner for editorial assistance with the manuscript. This study was funded by Novartis. FP, CC, RW, YC, CL and GB are employees and shareholders at Novartis. All other authors have no conflict of interest to disclose. CD, FP, MB, BA, RW, TRP, CL, FS and GB conceptualized and designed the study; CD, MB, BA, KIT and JKM performed the clinical experiments; CC and MR were in charge of sample analysis; CD, MB, YC and FS analysed the data; FP, RW, YC, CL and GB interpreted the data; CD drafted the manuscript; and all authors reviewed and revised the manuscript. Figure S1. Validation of sinistrin reference. Figure S2. Secukinumab No-Net-Flux in healthy subjects. Figure S3. Secukinumab No-Net-Flux in psoriasis subjects. Table S1. Study population - Demographic summary. Table S2. Subject individual secukinumab concentrations in healthy subjects. Table S3. Subject individual secukinumab concentrations in psoriasis subjects. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.
No takes yet. Share an insight, caveat, or question.
Dragatin et al. (2015) studied this question.