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.

Infliximab （IFX）， tumor necrosis factor-α inhibitor， is widely used in clinical practice for treating Crohn disease （CD）， but it is difficult to obtain the optimal therapeutic effect according to the conventional dose. It is recommended to perform therapeutic drug monitoring （TDM） for patients with poor therapeutic efficacy to guide clinical decisions. This paper reviews the pharmacokinetic characteristics of IFX， exposure-response relationship， the influencing factors of pharmacokinetic differences， and analytical methods in TDM. It is found that IFX doesn’t undergo liver or kidney metabolism， exhibits obvious exposure-response relationships in both the induction and maintenance phases of CD treatment； disease activity， albumin， antibodies to IFX （ATI） and other factors influence IFX’s exposure. It is recommended that trough concentration of IFX in the maintenance period should be kept above 3 μg/mL； the dose of IFX should be increased or medication interval should be shortened for patients with severe disease， low albumin levels and ATI formation， to promote therapeutic efficacy of IFX. It is suggested to use the same detection method for TDM of IFX in the same patient.