Early monitoring of anti-infliximab antibodies by drug-tolerant assay predicts later immunogenicity and drug survival in rheumatic diseases.

OBJECTIVES: To investigate the appearance of anti-drug antibodies (ADA) against infliximab (IFX) determined by drug-sensitive and drug-tolerant assays and their relationship with drug levels and drug survival. METHODS: This longitudinal observational study included 45 patients with rheumatoid arthritis (RA) and 61 with spondyloarthritis (SpA). Serum samples were obtained at weeks 2, 6, 12, 24, and 52. Serum IFX levels were measured by a capture enzyme-linked immunosorbent assay (ELISA) and ADA by an in-house drug-sensitive two-site (bridging) enzyme-linked immunosorbent assay (bELISA) and a commercially available drug-tolerant ELISA (IDK, Immundiagnostik, Germany). RESULTS: Anti-drug antibodies were detected earlier by IDK than by bELISA. Once ADA appeared, positivity persisted throughout the study period. Patients who were bELISA ADA+ had higher IDK ADA levels (than bELISA ADA- patients). Circulating IFX levels were detected in all patients except those found to be bELISA ADA+. Serum IFX levels were lower in IDK ADA+ than in IDK ADA-patients.Most patients (64%) discontinued due to inefficacy. The early onset of immunogenicity was related to IFX survival. Both in RA and SpA, the median survival (years) was shorter in patients with earlier development of ADA (IDK+ before or at week 24) than those who became IDK+ later (after week 24) or never developed ADA. CONCLUSION: A drug-tolerant assay detects ADA during IFX therapy earlier and more frequently than a drug-sensitive assay. The onset of immunogenicity detected by drug-tolerant assays is related to the subsequent detection of ADA by drug-sensitive assays and drug survival.

Circulating Tfh cells are differentially modified by abatacept or TNF blockers, and predict treatment response in Rheumatoid Arthritis.

OBJECTIVE: CD4+CXCR5+PD-1hi follicular helper T (Tfh) cells dwell in the germinal centers (GCs) of lymphoid organs and participate in Rheumatoid Arthritis (RA) pathogenesis; the frequency of their circulating counterparts (cTfh-frequency) is expanded in RA and correlates with the pool of GC Tfh cells. Our objective was to study the effect of abatacept (ABT) or TNF blockers (TNFb) on the cTfh-frequency in RA. METHODS: Peripheral blood was drawn from seropositive-longstanding RA patients chronically receiving csDMARDS (n = 45), TNFb (n = 59), or ABT (n = 34), and healthy controls (HC) (n = 137). Also, patients with an incomplete response to csDMARDS (n = 41) who initiated TNFb (n = 19) or ABT (n = 22), were studied at 0 and 12 months. The cTfh-frequency was examined by cytometry. RESULTS: As compared with HC, an increased cTfh-frequency was seen in seropositive-longstanding RA chronically receiving csDMARDs or TNFb but not ABT. After escalating from csDMARDs, the cTfh-frequency did not vary in patients who were given TNFb but decreased to HC levels in those given ABT. In the ABT group, the baseline cTfh-frequency was higher for patients who attained 12M remission (12Mr), vs those who remained active (12Ma): 0m cutoff for remission >0.38% (Sens. 92%, Sp. 90%), OR 25.3. Conversely, in the TNFb group, the baseline cTfh-frequency was lower for 12Mr vs 12Ma: 0m cutoff for non-remission >0.44% (Sens. 67%, Sp. 90%), OR 8.5. CONCLUSION: ABT but not TNFb, is able to curtail the cTfh-frequency in RA. A higher baseline cTfh-frequency predicts a good response to ABT but a poor response to TNFb.

Transiently increased circulating CD39+FoxP3+ Treg cells predict the clinical response to Methotrexate in Early Rheumatoid Arthritis.

OBJECTIVES: A subset of human circulating FoxP3+ regulatory T cells expresses CD39 (cTreg39+) and hydrolyses pro-inflammatory adenine nucleotides released at inflammatory foci, rendering the anti-inflammatory agent adenosine. Methotrexate (MTX), inhibiting ATIC, enhances the extrusion of adenine nucleotides and may help Treg39+ cells control inflammation. Therefore, we examined the relation of cTreg39+ cells with the effect of MTX in early Rheumatoid Arthritis (eRA). METHODS: Freshly isolated peripheral blood lymphocytes from 98 untreated eRA patients and 98 healthy controls (HC) were examined by cytometry. Twelve months (12m) after initiating MTX, 82 patients were clinically re-evaluated and cytometry was repeated in 40 of them. The effect of MTX on Treg cell potency was assessed in Treg/Tresp cocultures. RESULTS: The baseline (0m) cTreg39+ cell frequency was elevated in eRA above HC levels. Patients who reached low disease activity at 12 months (12m-LDA, DAS28-ESR≤ 3.2, n = 51) had presented with a significantly higher 0m cTreg39+ frequency vs those who did not (n = 31). The 0m cTreg39+ cutoff for attaining 12 m-LDA was 42.0% (Sensitivity=90.4%/Specificity=96.8%). At 12m, the cTreg39+ frequency was no longer elevated but its association with disease activity remained: it was still significantly higher in patients who had reached LDA vs those who had not. In vitro, MTX augmented the Treg39+ cell potency but had no effect on Treg39- cells. CONCLUSION: MTX cooperates with Treg39+ cells and the baseline cTreg39+ frequency predicts the response to MTX in eRA. In addition, the transiently elevated baseline cTreg39+ frequency in eRA may provide a slot for prompt MTX initiation.

Subsequent biologic and targeted synthetic disease modifying anti rheumatic drugs after fulfilling difficult-to-treat rheumatoid arthritis criteria: a survival analysis.

OBJECTIVES: To evaluate the survival of different biologic or targeted-synthetic disease-modifying antirheumatic drugs (b/tsDMARD) administered after fulfilling difficult-to-treat rheumatoid arthritis (D2TRA) criteria, and to assess factors related to treatment discontinuation. METHODS: Retrospective study including D2TRA patients. Drug retention of the b/tsDMARD administered after fulfilling D2TRA was assessed by Kaplan-Meier plots and the log-rank test. Cox hazard models were used to identify factors affecting treatment discontinuation. RESULTS: Of the 122 patients included, 75 maintained active treatment (61.5%) with a subsequent line after D2T compared to 47 (38.5%) who discontinued and required more successive lines of b/tsDMARDs. The median survival of the treatments was 78.3(7.6) months and the treatment after D2T with the better rate of survival was rituximab, followed by JAKi and IL6Ri, while worse survival rates were associated with abatacept and TNFi. Significant differences were noted among b/tsDMARDs (log-rank p < 0.01) and to evaluate these differences, a Cox regression was performed, taking each b/tsDMARD as a reference and comparing it with the others. DAS28 values 6-months after initiation of treatment were higher in those patients who discontinued treatment [4.4(1.2) vs 3.5(1.3), p = 0.01]. The multivariate cox regression model revealed that treatment choice after D2T [HR = 1.26(95%CI 1.06-1.05)] and lower DAS28 values at 6 months [HR = 1.49(95%CI 1.16-1.52)] were independent risk factors associated with treatment discontinuation. CONCLUSIONS: Once patients met the D2TRA criteria, the subsequent line of b/tsDMARDs with the best survival rates were rituximab, JAKi and IL6Ri. Moreover, DAS28 at 6-months of treatment after D2T was an independent risk factor for drug discontinuation. Key Points • Rituximab, IL6Ri and JAKi have better retention rates in patients after fulfilling D2TRA criteria • Clinical disease activity in the first six months after fulfillment of D2TRA criteria is an independent risk factor of subsequent treatment survival.