Background/Purpose: In patients affected by rheumatoid arthritis (RA), it has been studied a relation between high rheumatoid factor (RF) and a favorable response to anti-TNF therapy, regarding the presence of Fc region in the drug (1,2). Nonetheless, there is limited evidence about the therapeutic survival in function of the kind of anti-TNF and the levels of RF in these patients.The goal of this investigation is to analyze the survival and persistence of anti TNF drugs, depending on whether they have Fc region and the levels of RF in RA.

Methods: Observation cross-sectional study of anti-TNF treatments administered in RA patients between 2001 and 2022. We collected levels of RF and anti-citrullinated peptide antibodies (ACPAs) at start of medication, clinical activity, duration of treatment and withdrawal cause from the clinical record.

Results: We have included 377 anti-TNF treatments corresponding to 310 RA patients (79% female), with a mean age at diagnosis of 45 (13) years.Of 377 treatments, 87% were drugs with Fc region in their structure, 75% associated DMARD (mainly methotrexate) and 67% have not received prior biologic therapy. Mean time of evolution of RA until the start of anti-TNF was 110 (103) months and the mean duration of treatment was 75 (71) months, finalizing treatment 64,2%. When initiating therapy, 64% were RF positive (RF) and 72%, ACPA positive (table 1).We have classified patients according to the positivity of RF and the presence of Fc region in the therapy. We have observed a tendency towards discontinuing treatment in patients with high RF titers (P=0,06), which are treated mainly with an anti-TNF with Fc fraction (P=0,06).Finally, we have conducted a Kapplan-Meier analysis to evaluate the drug survival considering the presence of Fc region in the medication, with no observed differences between groups. We came up with the same result when comparing treatment regarding RF positivity at beginning of therapy. We classified patients combining the presence of Fc and RF positivity, discovering a greater therapeutic survival in treatments with Fc region and RF negativity (P=0,018). Furthermore, in treatments without Fc region, we report a tendency towards greater therapeutic survival in RF negative cases in comparison with RF positives (P=0,07) (view Image 1).

Conclusion: We report on a higher percentage of drug withdrawal in patients with RA and anti-TNF treatment with Fc region in their structure, as well as in those cases with higher titers of RF. In addition, we observed a greater therapeutic survival in treatments with low titers of RF and anti-TNF drug without Fc region than in other groups.

Table 1

Image 1

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/importance-of-fc-region-on-therapeutic-survival-in-rheumatoid-arthritis-patients-with-anti-tnf-therapy/