Clinical Significance And Monitoring Of Infliximab Trough Levels And Anti-infliximab Antibodies In Patients With Inflammatory Bowel Disease

Objective: To investigate the relationship between Infliximab serum trough levels(IFX-TLs),anti-IFX antibodies(ATI)and clinical effect of IFX in patients with inflammatory bowel disease(IBD),to analysis relevant factors of serum concentrations and ATI,and to explore the clinical significance.Methods: Seventeen patients with IBD who were treated with IFX from August 2016 to January 2018 were enrolled in this study.Each patient was tested for IFX trough levels and ATI before the infusion of IFX.Each patient continued to receive IFX treatment 1 to 6 times for a total of 40 IFX treatments,and 40 blood samples were obtained.The serum trough levels of IFX and ATI were measured by enzyme-linked immunosorbent assay(ELISA).C-reactive protein(CRP),erythrocyte sedimentation rate(ESR),serum albumin(ALB)and platelet(PLT)count were tested at the same time after drawing blood.All the ulcerative colitis(UC)Patients were evaluated by Mayo score while Crohn's disease(CD)patients by CDAI at every drawn blood point to assess efficacy of IFX.According to the consensus of diagnosis and treatment of inflammatory bowel disease(2012 Guangzhou),the 40 treatments were divided into treatment-effective group and treatment-ineffective group.The statistical software IBM SPSS 21.0 was used for statistical analysis.The measurement data were expressed as(`x±s).Independent data t-test was used to compare data sets.P <0.05 was considered statistically significant.Result: 1.A total of 17 active IBD patients were enrolled,including 9 males and 8 females.The ratio of male to female was 1.125: 1.The age was ranged between 17 to 60 years old with an average age being(37.53 ± 13.66)years old.There were 12 cases of UC patients,including 1 mild case(8.33%),2 moderate cases(16.67%)and 9 severe cases(75.0%).5 cases were CD patients,including 3 moderate cases(60.0%),2 severe cases(40.0%).2.The relationship between serum trough levels of IFX and efficacy: Among 40 times of IFX treatments,23 treatments were effective,the response rate to IFX was 57.5%.The IFX serum trough level in effective group was 0.1~19.81?g / mL,mean(4.16 ± 4.64)?g / m L.17 treatments were ineffective with the IFX-TLs being 0.05-4.3?g / m L,mean(1.38 ± 1.63)?g / mL was obviously lower than the effective group.The difference between the two groups was statistically significant(t = 2.355,P = 0.024).The IFX serum trough level was positively correlated with the effect of IFX.3.The relationship between ATI and efficacy: 40 serum samples were also tested ATI,the results showed that positive rate of antibodies to IFX was 17.5%(7/40),and the remaining 33 were negative.Six of seven patients with ATI positive antibody were ineffective of IFX.The levels of ATI in the effective group were significantly lower than those in the ineffective group(t =-2.162,P = 0.01).4.The comparison of related parameters between effective group and ineffective group: The IFX trough levels of effective group were significantly higher than the ineffective group(P = 0.024),while ATI of effective group was significantly lower than the ineffective group(P = 0.01).CRP and ESR of effective group were significantly lower than the ineffective group,the difference was statistically significant(P <0.05).However there was no significant difference about ALB snd PLT between two groups(P> 0.05).5.The comparison of related parameters about IFX-TLs: The positive rate of ATI in non-low IFX-TLs group was significantly lower than the low IFX-TLs group(3.45% vs.54.55%).The difference of ATI level was statistically significant(t = 4.629,P <0.001).There was negative correlation between ATI and IFX-TLs.Howerver,there was no correlation between IFX-TLs and CRP,ALB,ESR and PLT(P> 0.05).Conclusion: 1.Low IFX trough levels and positive ATI are relative risk factors for losing response of IFX in IBD patients,IFX trough levels and ATI can be used as important indicators to evaluate and predict IFX efficacy.2.In patients with IBD,the higher the ATI level is,the lower the IFX trough level will be.There is negative correlation between ATI and IFX-TLs.3.For patients with IBD,running tests for ATI and IFX-TLs have an important clinical significance on assessing the efficacy of IFX treatment as well as predicting the loss of response.