The effect of certolizumab drug concentration and anti-drug antibodies on TNF neutralisation.

OBJECTIVES: Tumour necrosis factor (TNF) inhibitors like certolizumab, elicit an immunogenic response leading to the formation of anti-drug antibodies (ADAs). We sought to mechanistically investigate the relationship between certolizumab concentrations, ADAs, and the effective TNF neutralising capacity in sera of rheumatoid arthritis (RA) patients. TNF neutralising capacity of certolizumab was compared to the neutralising capacity of adalimumab. METHODS: Serum samples were collected from 40 consecutive certolizumab-treated RA patients at baseline and 4, 16, 28 and 52 weeks after treatment initiation [Dutch Trial Register NTR (Nederlands Trial Register) Trial NL2824 no. 2965]. Certolizumab concentration and ADA titre were measured with a certolizumab bridging enzyme-linked immunosorbent assay (ELISA) and a drug-tolerant radioimmunoassay (RIA), respectively. TNF neutralisation by certolizumab and adalimumab, in presence or absence of ADAs, was analysed with the TNF-sensitive WEHI bioassay. RESULTS: Despite a high incidence of ADAs during one year of follow-up (65%; 26/40 patients), certolizumab levels of >10 µg/ml were measured in most patients. The capacity for TNF neutralisation highly correlated with certolizumab serum concentration, whereas no association with ADAs was observed. Similar results were obtained for adalimumab. The relative in vitro neutralising potency was higher for certolizumab compared to adalimumab. CONCLUSIONS: Anti-certolizumab antibodies were detected in a large proportion of patients, but in most cases where ADAs were detected, certolizumab was also present in high concentrations, directly correlating with in vitro neutralising capacity. These results indicate that measurement of certolizumab drug levels, rather than ADAs, have direct clinical significance.

The effect of methotrexate on tumour necrosis factor concentrations in etanercept-treated rheumatoid arthritis patients.

OBJECTIVES: Recently, we demonstrated that early low concentrations of circulating, adalimumab-bound TNF in RA patients treated with adalimumab was associated with future anti-drug antibody formation. Furthermore, low TNF was associated with less frequent baseline MTX use. This is remarkable, because of the anti-inflammatory effects of MTX and a potential inhibiting effect on cytokine production. We hypothesized an indirect effect of non-MTX use on low TNF concentrations via immunogenicity. To investigate the effect of MTX on TNF concentrations independent of anti-drug antibody formation, we measured TNF in RA patients treated with etanercept, a drug with low immunogenicity. METHODS: TNF was quantified in 186 consecutive etanercept-treated RA patients at baseline and at weeks 4, 16 and 28. The dynamics of TNF during etanercept treatment were compared with dynamics recently published for adalimumab. RESULTS: We demonstrated that TNF concentrations at week 4 did not associate with baseline MTX or remission after 28 weeks. Furthermore, median (interquartile range) TNF increased from <112 (<112-<112) pg/ml at baseline to 548 (344-688) pg/ml at week 4 and remained stable at week 16 and 28 [598 (442-756) and 568 (444-755) pg/ml, respectively]. CONCLUSION: Circulating TNF did not associate with MTX usage in etanercept-treated patients. This implies that MTX does not have a direct effect on TNF concentrations in circulation and that the association between early low TNF and non-use of MTX for adalimumab is thus most likely due to anti-drug antibody formation.

Long-term treatment response in rheumatoid arthritis patients starting adalimumab or etanercept with or without concomitant methotrexate.

OBJECTIVES: To observe long-term clinical response and drug survival in a prospective two-year cohort study in rheumatoid arthritis (RA) patients starting adalimumab or etanercept treatment, with or without methotrexate (MTX), after failure of conventional DMARD therapy, including MTX. METHODS: Disease activity score of 28 joints (DAS28) and Health Assessment Questionnaire (HAQ) were collected of 873 consecutive RA patients, treated with adalimumab or etanercept, prospectively at baseline, 4, 16, 28, 40, 52, 78 and 104 weeks of biological therapy. Sustained minimal disease activity (MDA), DAS28 <2.6 for at least 24 consecutive weeks, biological discontinuation, ΔHAQ and ΔDAS28 were compared between patients treated with or without concomitant MTX for etanercept and adalimumab separately. RESULTS: More patients treated with adalimumab and MTX (42%) achieved sustained MDA than patients without MTX (18%). The hazard ratio (HR) was 2.3 [1.4-3.9]. No significant difference was found in etanercept treatment (with MTX 33% vs. 28% without MTX), HR 1.1 [0.8-1.6]. More patients treated without MTX discontinued treatment than patients with MTX co-treatment in adalimumab (HR 2.1 [1.5-3.0]) and etanercept (HR 1.9 [1.0-3.4]). The mean decrease in DAS28 over time was higher for patients treated with MTX in adalimumab (regression coefficient (RC): 0.57, p<0.001), but was not significantly different in etanercept treatment (RC 0.05, p=0.427). No significant differences were found in ΔHAQ. CONCLUSIONS: Treatment discontinuation is lower in patients treated with MTX in both adalimumab and etanercept treatment. However, considering good clinical response, in contrast to etanercept, a synergetic effect of MTX is observed only in adalimumab treatment.

Comparing a tapering strategy to the standard dosing regimen of TNF inhibitors in rheumatoid arthritis patients with low disease activity.

OBJECTIVES: The aim of this study is to compare clinical outcomes, incidence of flares and administered drug reduction between rheumatoid arthritis (RA) patients under TNF inhibitors (TNFi) tapering strategy and RA patients on standard regimen. METHODS: Two groups of RA patients on TNFi with DAS28<3.2 were compared: the tapering group (TG: 67 pts from Spain) and the control group with standard therapy regimen (CG: 77 pts from the Netherlands). DAS28 was measured at different time points: visit 0 (prior starting TNFi), visit 1 (prior to start tapering in TG and with DAS28<3.2 in TG and CG), visit 2 (6 months after visit 1), visit 3 (1 year after visit 1), visit 4 (the last visit available after visit 1) and visit-flare (visit with the worst flare between visit 1 and visit 4). RESULTS: Despite the reduction of administered drug at visit 4 in the TG (interval elongation of 32.8% in infliximab, 52.9% in adalimumab and 52.6% in etanercept), the DAS28 remained similar between groups at the end of the study (DAS28: 2.7±0.9 in TG vs. 2.5±1 in CG, p=0.1). No differences were seen in the number of patients with flares [26/67 (38.9%) in the TG vs. 30/77 (39%) in the CG, p=0.324] and only nineteen out of 136 patients (14%) had anti-drug antibodies at the end of the study. CONCLUSIONS: The tapering strategy of TNFi in RA patients result in a reduction of the drug administered, while the disease control is not worse than patients on the standard regimen.

Comparing Tapering Strategy to Standard Dosing Regimen of Tumor Necrosis Factor Inhibitors in Patients with Spondyloarthritis in Low Disease Activity.

OBJECTIVE: To compare clinical outcomes, incidence of flares, and administered drug reduction between patients with spondyloarthritis (SpA) under TNF inhibitor (TNFi) tapering strategy with patients receiving a standard regimen. METHODS: In this retrospective study, 74 patients with SpA from Spain on tapering strategy (tapering group; TG) were compared with 43 patients from the Netherlands receiving a standard regimen (control group; CG). The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) was measured at visit 0 (prior to starting the TNFi), visit 1 (prior to starting tapering strategy in TG and at least 6 months with BASDAI < 4 after starting the TNFi in the TG and CG), visit 2 (6 mos after visit 1), visit 3 (1 year after visit 1), and visit 4 (the last visit available after visit 1). RESULTS: An overall reduction of the administered drug was seen at visit 4 in the TG [dose reduction of 22% for infliximab (IFX) and an interval elongation of 28.7% for IFX, 45.2% for adalimumab, and 51.5% for etanercept] without significant differences in the BASDAI between the groups at visit 4 (2.15 ± 1.55 in TG vs 2.11 ± 1.31 in CG, p = 0.883). The number of patients with flares was similar in both groups [22/74 (30%) in the TG vs 8/43 (19%) in the CG, p = 0.184]. CONCLUSION: The tapering strategy in SpA results in an important reduction of the drug administered, and the disease control remains similar to that of the patients with SpA receiving the standard regimen.

Key findings towards optimising adalimumab treatment: the concentration-effect curve.

OBJECTIVE: To determine a concentration-effect curve of adalimumab in rheumatoid arthritis (RA) patients taking into account the effect of methotrexate (MTX) on concentration and effect and to identify a therapeutic range for adalimumab concentrations. METHODS: In a prospective observational cohort study, 221 consecutive patients with RA were treated with 40 mg adalimumab subcutaneously every other week. The relationship between adalimumab trough level and clinical efficacy after 28 weeks of follow-up was determined in a concentration-effect curve. A receiver-operator characteristics (ROC) curve established a therapeutic cut-off concentration. The effect of MTX on adalimumab trough levels was shown by dividing patients that are and are not concomitantly using MTX in the concentration-effect curve and a concentration table. RESULTS: Clinical efficacy improved with increasing adalimumab concentration and reached a maximum (mean disease activity score in 28 joints improvement of 2) with levels between 5-8 µg/mL. Levels exceeding 8 µg/mL were illustrated to have no additional beneficial effect on disease activity. The ROC curve showed an area under the curve of 0.695 (95% CI 0.626 to 0.764) for European League Against Rheumatism response and adalimumab levels: good responders versus non-responders and moderate responders. A cut-off of 5 µg/mL had a sensitivity of 91% and a specificity of 43%. Adalimumab levels are influenced by concomitant MTX use: patients on adalimumab monotherapy had a median adalimumab level of 4.1 µg/mL (IQR 1.3-7.7), whereas patients concomitantly taking MTX had a median level of 7.4 µg/mL (IQR 5.3-10.6, p<0.001). CONCLUSIONS: Adalimumab trough levels in a range of 5-8 µg/mL are sufficient to reach adequate clinical response. These levels are influenced substantially by concomitant MTX use.

Immunogenicity, adalimumab levels and clinical response in ankylosing spondylitis patients during 24†weeks of follow-up.

BACKGROUND: Immunogenicity influences adalimumab levels and therefore clinical response in patients with rheumatic diseases. OBJECTIVES: To study the relationship between clinical response, adalimumab levels and antidrug antibodies (ADAb) in ankylosing spondylitis (AS). METHODS: Observational cohort study of 115 consecutive AS patients treated with adalimumab in the Netherlands (n=85) and Taiwan (n=30), monitored during 24 weeks. Adalimumab levels and ADAb titres were determined using an ELISA and an antigen binding test (ABT), respectively, designed by Sanquin Research, Amsterdam. Response to adalimumab treatment was defined as a Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) response, and disease activity was measured using the Ankylosing Spondylitis Disease Activity Score using C-reactive protein (CRP) (ASDAS). RESULTS: At baseline, median BASDAI (IQR) was 6.4 (4.5-7.6) and mean ASDAS (SD) was 3.5 (1.0). After 24 weeks, 49 (42.6%) patients were BASDAI50 responders and mean ASDAS (SD) for responders was 1.5 (1.0) vs 2.6 (1.0) for non-responders (p<0.001). Thirty-one (27.0%) patients had detectable ADAb. After 24 weeks, adalimumab levels (mg/L) (IQR) were significantly higher in ADAb-negative patients than in ADAb-positive patients (12.7 (8.2-18.0) vs 1.2 (0.0-2.0), (p<0.001)). A significant association was demonstrated between adalimumab levels and ASDAS (p=0.02; RC -1.1; 95% CI -2.0 to -0.2). Eleven (9.6%) patients had no detectable adalimumab levels and high detectable ADAb titres (>100 AU/mL). In these patients, CRP and erythrocyte sedimentation rate remained elevated during treatment. CONCLUSIONS: Adalimumab levels are related to clinical response in AS patients measured with ASDAS and are influenced by ADAb detectable with an ABT.

Anti-adalimumab antibodies and adalimumab concentrations in psoriatic arthritis; an association with disease activity at 28 and 52 weeks of follow-up.

OBJECTIVES: To investigate the relationship between antidrug antibodies (ADA), adalimumab concentrations and clinical response in patients with psoriatic arthritis (PsA) during 52 weeks of follow-up. METHODS: This prospective cohort study included 103 consecutive patients with PsA. Disease Activity Score of 28 joints (DAS28), Erythrocyte Sedimentation Rate, C reactive protein and Psoriasis Area and Severity Index were assessed. Adalimumab concentrations and ADA were measured in serum trough samples, using an ELISA and a radio immunoassay, respectively. RESULTS: Adalimumab concentrations were significantly lower at 28 and 52 weeks in patients with detectable ADA compared with patients without detectable ADA (at week 28: 1.3 mg/L (IQR 0.0-3.2) versus 8.7 mg/L (IQR 5.7-11.5), p<0.001; at week 52: 0.9 mg/L (IQR 0.0-2.9) vs 9.4 mg/L (IQR 5.7-12.1), p=0.0001). DAS28 at 28 weeks (2.16 vs 2.95, p=0.023) and 52 weeks (2.19 vs 2.95, p=0.024) showed a significant difference; patients with detectable ADA had a poorer clinical outcome than patients without. CONCLUSIONS: Patients with detectable ADA had lower adalimumab concentrations and a significantly poorer clinical outcome compared with patients in whom ADA were not detected.

[TNF inhibitors: the role of drug levels]. / TNF-blokkers: de rol van medicijnconcentraties.

There is a variation in the pharmacokinetics of TNF inhibitors. Measurement of drug levels may help to identify patients in whom treatment can be optimised. Various factors influence the pharmacokinetics of TNF inhibitors; one of the most important factors is immunogenicity. There is inter-patient variation in the TNF inhibitor dose needed to achieve clinical effectiveness, as well as variation in the dose needed to maintain clinical effectiveness. Immunosuppressive co-medication plays an important role in the optimisation of TNF inhibitor therapy via an effect on inflammation and immunogenicity.

Long-term measurement of anti-adalimumab using pH-shift-anti-idiotype antigen binding test shows predictive value and transient antibody formation.

BACKGROUND AND OBJECTIVES: Therapeutic monoclonal antibodies are effective drugs for many different diseases. However, the formation of anti-drug antibodies (ADA) against a biological can result in reduced clinical response in some patients. Measurement of ADA in the presence of (high) drug levels is difficult due to drug interference in most assays, including the commonly used antigen binding test (ABT). METHODS: We recently published a novel method which enables the measurement of complexed antibodies against adalimumab (an anti-TNF antibody) in the presence of drug. Here we use this pH-shift-anti-idiotype ABT (PIA) to measure anti-adalimumab antibodies (AAA) in 99 rheumatoid arthritis (RA) patients treated for up to 3 years with adalimumab. RESULTS: 53 out of 99 RA patients produced AAA. In 50 of these PIA positive patients, AAA could be detected within the first 28 weeks of treatment. Patients in which AAA could be detected in the PIA after 28 weeks of treatment were more prone to declining adalimumab levels (<5 µg/ml) (p<0.01) and high AAA levels which could be detected in the ABT (p<0.05) at later time points. We observed transient AAA formation in 17/53 patients. CONCLUSIONS: Results show that AAA develop early in treatment. However, levels that completely neutralise the drug may be reached much later in treatment. Furthermore, the patients positive for PIA at 28 weeks have an increased chance to develop clinical non-response due to immunogenicity. In some of the patients, AAA formation is transient.

Changes in bone mineral density during long-term treatment with adalimumab in patients with rheumatoid arthritis: a cohort study.

OBJECTIVE: To investigate the effect of long-term adalimumab treatment on BMD of the lumbar spine, total hip and hands in patients with RA. METHODS: In 184 established RA patients treated with adalimumab for at least 1 year, BMD measurements of the total hip and lumbar spine were performed using dual-energy X-ray absorptiometry. Metacarpal cortex BMD was measured using digital X-ray radiogrammetry. RESULTS: After 1 year of treatment, BMD of the hip and lumbar spine remained stable, while BMD of the hands decreased significantly by -1.41% (P < 0.0001). After a mean follow-up of 4.0 (s.d. 1.0) years, mean BMD change per year was -0.58% and 0.07% for the hip and lumbar spine, respectively (overall P-value of hip was <0.0001 and spine was 0.67). Predictors for BMD loss of the hip were anti-CCP positivity, non-use of bisphosphonates at baseline and BMI. In European League Against Rheumatism (EULAR) non-responders at 52 weeks, BMD change of the hip and spine was -1.25% and 1.08%, respectively, for moderate responders -0.61% and -1.87%, respectively, and in EULAR good responders, BMD remained stable: -0.02% and 0.06%, respectively. BMD of the hands decreased in non-, moderate and good responders (-2.85%, -1.47% and -1.26%, respectively). CONCLUSION: In patients with severe, established RA, loss of BMD in the spine was arrested over 4 years of adalimumab treatment, whereas BMD of the hands and hip continued to decrease after 1 and 4 years, respectively. The changes in BMD are related to disease activity, underlining the importance of monitoring disease activity.

Biologicals and bone loss.

Inflammatory joint diseases are associated with extra-articular side effects including bone involvement.There is an increased risk of osteoporotic fractures. The pathogeneses of local and generalized bone loss share a common pathway. Early and active rheumatoid arthritis is associated with longitudinal observed bone loss and fracture rate is of vertebral and nonvertebral fractures is doubled compared with matched healthy controls. Lowering disease activity with TNF inhibitors or is associated with stabilisation of bone mineral density by counteracting elevated bone resorption.

Comparison of long-term clinical outcome with etanercept treatment and adalimumab treatment of rheumatoid arthritis with respect to immunogenicity.

OBJECTIVE: To compare rates of sustained low and minimal disease activity and remission according to the American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) criteria during 3-year followup in rheumatoid arthritis (RA) patients treated with etanercept and adalimumab in routine care. METHODS: Four hundred seven RA patients previously unexposed to tumor necrosis factor antagonists were treated with etanercept (n = 203) or adalimumab (n = 204) and assessed at 3- and later 6-month intervals. Treatment allocation was at the discretion of the treating rheumatologist. Clinical parameters were measured at each time point, as were anti-adalimumab antibodies in adalimumab-treated patients. Achievement of clinical outcome was defined as the occurrence of sustained (at least 12 consecutive months) low disease activity (28-joint Disease Activity Score [DAS28] <3.2), minimal disease activity (DAS28 <2.6), or ACR/EULAR remission based on the Simplified Disease Activity Index (SDAI). Non-overlapping response rates were calculated. RESULTS: Among the adalimumab group, 13% reached sustained low disease activity but not sustained minimal disease activity, 15% reached sustained minimal disease activity but not sustained remission according to the SDAI, and 16% reached sustained ACR/EULAR remission. In the etanercept group the corresponding rates were 16%, 11%, and 12%, respectively (P = 0.42, overall test for linear trend). Adalimumab-treated patients without anti-adalimumab antibodies (n = 150 [74%]) had the best outcomes, and adalimumab-treated patients with anti-adalimumab antibodies the worst, with outcomes in etanercept-treated patients in between (P < 0.0001). Differences were most apparent in the sustained SDAI remission and sustained minimal disease activity categories. For example, 40% of anti-adalimumab antibody-negative patients, 23% of etanercept-treated patients, and 4% of anti-adalimumab antibody-positive patients achieved at least sustained minimal disease activity. CONCLUSION: Overall, etanercept and adalimumab treatment appear similar in inducing a good long-term clinical outcome. However, in the case of adalimumab this is strongly dependent on the presence or absence of anti-adalimumab antibodies.

IgG4 production against adalimumab during long term treatment of RA patients.

PURPOSE: A substantial part of rheumatoid arthritis (RA) patients is chronically treated with adalimumab. Some of these patients produce antibodies against adalimumab, which correlate with lower serum drug levels and reduced clinical response. Long term exposure to antigens may result in antigen specific IgG4 production as was demonstrated in studies on prolonged exposure to antigens such as different allergens, Factor VIII and IFN-ß. Here, we investigate whether long term treatment of RA patients with the therapeutic monoclonal antibody adalimumab leads to the production of specific IgG4 antibodies. METHODS: We developed radio immunoassays to detect total IgG or IgG4 against adalimumab and applied these in a cohort of 271 consecutive RA patients during 3 years of adalimumab treatment. RESULTS: In 32 % of the 271 patients antibodies against adalimumab were detectable. IgG4 antibodies were detected in 29 % of the patients. The proportion IgG4 of total IgG against adalimumab varies widely between patients, and IgG4 was found to contribute significantly to the anti drug antibody (ADA) response in some patients. CONCLUSION: In the immune response against adalimumab in adalimumab-treated RA patients a considerable part of the ADA is IgG4. Although IgG4 is often considered to be harmless due to its lack of effector function, neutralization of adalimumab by IgG4 antibodies will lead to a reduced clinical response.

Are we ready for therapeutic drug monitoring of biologic therapeutics?

In the previous issue of Arthritis Research & Therapy, Ducourau and colleagues report that they retrospectively detected anti-infliximab antibodies in 21% of patients with rheumatic diseases. Patients with anti-infliximab antibodies had lower serum drug concentrations. These findings contribute to the existing evidence of immunogenicity of biologicals and its clinical relevance. We argue for therapeutic drug monitoring to optimize treatment response.

Development of antidrug antibodies against adalimumab and association with disease activity and treatment failure during long-term follow-up.

CONTEXT: Short-term data on the immunogenicity of monoclonal antibodies showed associations between the development of antidrug antibodies and diminished serum drug levels, and a diminished treatment response. Little is known about the clinical relevance of antidrug antibodies against these drugs during long-term follow-up. OBJECTIVE: To examine the course of antidrug antibody formation against fully human monoclonal antibody adalimumab and its clinical relevance during long-term (3-year) follow-up of patients with rheumatoid arthritis (RA). DESIGN, SETTING, AND PATIENTS: Prospective cohort study February 2004-September 2008; end of follow-up was September 2010. All 272 patients were diagnosed with RA and started treatment with adalimumab in an outpatient clinic. MAIN OUTCOME MEASURES: Disease activity was monitored and trough serum samples were obtained at baseline and 8 time points to 156 weeks. Serum adalimumab concentrations and antiadalimumab antibody titers were determined after follow-up. Treatment discontinuation, minimal disease activity, and clinical remission were compared for patients with and without antiadalimumab antibodies. RESULTS: After 3 years, 76 of 272 patients (28%) developed antiadalimumab antibodies--51 of these (67%) during the first 28 weeks of treatment. Patients without antiadalimumab antibodies had much higher adalimumab concentrations (median, 12 mg/L; IQR, 9-16 mg/L) compared with patients with antibody titers from 13 to 100 AU/mL (median, 5 mg/L; IQR, 3-9 mg/L; regression coefficient, -4.5; 95% CI, -6.0 to -2.9; P < .001) and also those greater than 100 AU/mL (median, 0 mg/L; IQR, 0-3 mg/L; regression coefficient, -7.1; 95% CI, -8.4 to -5.8; P < .001). Patients with antiadalimumab antibodies more often discontinued participation due to treatment failure (n = 29 [38%]; hazard ratio [HR], 3.0; 95% CI, 1.6-5.5; P < .001) compared with antiadalimumab antibody-negative ones (n = 28 [14%]). Ninety-five of 196 patients (48%) without antiadalimumab antibodies had minimal disease activity vs 10 of 76 patients (13%) with antiadalimumab antibodies; patients with antiadalimumab antibodies less often had sustained minimal disease activity score in 28 joints (DAS28) (< 3.2; HR, 3.6; 95% CI, 1.8-7.2; P < .001) compared with antiadalimumab antibody-negative ones. Three of 76 patients (4%) with antiadalimumab antibodies achieved sustained remission compared with 67 of 196 (34%) antiadalimumab antibody-negative ones; patients with antiadalimumab antibodies less often achieved remission (DAS28 < 2.6; HR, 7.1; 95% CI, 2.1-23.4; P < .001) compared with antiadalimumab antibody-negative ones. CONCLUSION: Among outpatients with RA in whom adalimumab was started over 3 years, the development of antidrug antibodies was associated with lower adalimumab concentration and lower likelihood of minimal disease activity or clinical remission.