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P735 Immunogenicity differences between anti-TNF drugs

R. M. Gómez Espín*1, I. Nicolás de Prado1, C. Iniesta Navalón2, L. Rentero Redondo2, M. Gil Candel2, J. J. Martínez Crespo1

1HGU Reina Sofía, Gastroenterology, Murcia, Spain, 2HGU Reina Sofía, Pharmacology, Murcia, Spain

Background

The aim of this study was to determine the prevalence of immunogenicity in patients receiving anti-TNF drugs (infliximab and adalimumab) in our hospital and to analyse if there are differences in terms of immunogenicity between these drugs.

Methods

We conducted a retrospective observational study between May 2015 and October 2018, in a reference hospital area (330 beds). We included all patients diagnosed with inflammatory bowel disease that received treatment with infliximab or adalimumab and the serum levels of these drugs between May 2015 and October 2018. The variables studied were: sex, age, number of serum samples collected, main diagnosis, previous biologic therapy, serum drug concentrations and antibody levels. Antibody levels were performed in patients who had undetectable serum concentrations of the drug. We used χ² test to compare the association between categorical variables.

Results

We included 181 cases (151 patients), of which 62.5% were male, the mean age was 42.6 (SD: 14.5) years. 73.2% had Crohn’s disease. A total of 468 drug serum levels were collected, 61.1% infliximab (22.7% biosimilar) and 38.1% adalimumab. The adalimumab and originator infliximab mean serum trough level was 7.2 (SD: 4.3) μg/ml and 7.2 (SD:4.5) μg/ml, respectively, vs. 8.3 (SD: 7.8) μg/ml for biosimilar infliximab (p = 0.790). The prevalence of immunogenicity was 24/181 cases (13.3%). In terms of immunogenicity, no significant difference was found between infliximab vs. adalimumab (16% vs. 9.9%, respectively, p = 0.227). Similarly, there were no significant differences between originator infliximab vs. biosimilar infliximab (13.6% vs. 19.5%, respectively; p = 0.425). The median adalimumab antibody levels was 993.5 (DE:2199.4) AU/ml, 199.3 (DE:305.7) AU/ml for originator infliximab and 83.21 (78.9) AU/ml for biosimilar infliximab. The median time for antibodies appearance was 15.2 weeks (SD: 11.9) for adalimumab and 20.5 weeks (SD: 20.5) for infliximab, with no significant difference between them (p = 0.47).

Conclusion

The introduction of drug monitoring for anti-TNF drugs, including drug concentration and antidrug antibody level testing represents a fundamental mainstay for the optimisation of these treatments. In our study, we identified a similar anti-TNF antibody levels to other published series. There are no significant differences between both anti-TNF drugs in terms of immunogenicity. Furthermore, we found no significant difference in the mean concentration of the drug between originator infliximab and biosimilar infliximab nor a significant difference in terms of immunogenicity, suggesting that biosimilar infliximab is a cost-effective alternative to the reference product.