AIM:To develop and validate an ELISA method for the determination of secukinumab(SEC)in human plasma and apply it in psoriasis pa-tients.METHODS:A double-antibody sandwich ELI-SA was developed using anti-secukinumab anti-body as the capture antibody and biotin-labeled an-ti-secukinumab antibody as the detection antibody.The method was systematically validated.Nineteen patients with Psoriasis treated with standard dose of SEC were included.In order to determine trough concentrations of SEC,steady-state blood samples were collected after 24 weeks of treatment.Psoria-sis area and severity index score was used to evalu-ate the response.RESULTS:The SEC concentration showed a good concentration-response relation-ship within the range of 1.25 to 80.00 μg/mL.The intra-batch and inter-batch precision and accuracy were ≤ 15.00％,and there was no hook effect in the range of 1.25 to 1 000 μg/mL.The median trough concentrations of 19 patients was 33.56 μg/mL(IQR:32.55-45.98 μg/mL)with an inter-individu-al variation of 52.00％for body weight adjusted concentration of SEC.The SEC concentrations were not significantly different between the active group and remission group(P=0.92).CONCLUSION:We developed and validated a method for the determi-nation of SEC,which can be used for therapeutic drug monitoring in patients receiving SEC therapy.However the inter-individual variation is large.Fur-ther study is needed to explore the association of SEC levels with clinical response in Psoriasis.

AIM:To develop and validate an ELISA method for the determination of secukinumab(SEC)in human plasma and apply it in psoriasis pa-tients.METHODS:A double-antibody sandwich ELI-SA was developed using anti-secukinumab anti-body as the capture antibody and biotin-labeled an-ti-secukinumab antibody as the detection antibody.The method was systematically validated.Nineteen patients with Psoriasis treated with standard dose of SEC were included.In order to determine trough concentrations of SEC,steady-state blood samples were collected after 24 weeks of treatment.Psoria-sis area and severity index score was used to evalu-ate the response.RESULTS:The SEC concentration showed a good concentration-response relation-ship within the range of 1.25 to 80.00 μg/mL.The intra-batch and inter-batch precision and accuracy were ≤ 15.00％,and there was no hook effect in the range of 1.25 to 1 000 μg/mL.The median trough concentrations of 19 patients was 33.56 μg/mL(IQR:32.55-45.98 μg/mL)with an inter-individu-al variation of 52.00％for body weight adjusted concentration of SEC.The SEC concentrations were not significantly different between the active group and remission group(P=0.92).CONCLUSION:We developed and validated a method for the determi-nation of SEC,which can be used for therapeutic drug monitoring in patients receiving SEC therapy.However the inter-individual variation is large.Fur-ther study is needed to explore the association of SEC levels with clinical response in Psoriasis.