Obesity decreases clinical efficacy and levels of adalimumab in patients with ankylosing spondylitis

OBJECTIVES

Obesity can be a factor that affects response to anti-TNF drugs. However, studies on patients with ankylosing spondylitis (AS) are rare. We aimed to determine whether obesity affects serum levels of adalimumab (ADL), and immunogenicity and clinical efficacy of the drug in patients with AS.

METHODS

A cross-sectional study on 57 patients with axial AS receiving ADL was conducted. They received DMARD per standard of care at their rheumatologist's discretion. Patients' body mass index (BMI) was obtained when ADL treatment began. Clinical response was evaluated using the Spanish versions of the BASDAI index and the ASDAS ESR index. Serum concentrations of free ADL (trough level) and anti-ADL antibodies were measured using Promonitor-ADL and Promonitor Anti-ADL ELISA kits (Progenika Grifols SA, Spain), just prior to the next subcutaneous injection of ADL.

RESULTS

Patients with BMI >30 kg/ m2 (obese) as opposed to BMI <25 kg/ m2 (normal), presented lower blood ADL levels [5.0 (5.52) vs. 9.14 (4.3), p=0.032], increased ASDAS scores (2.58 [0.79] vs. 1.9 [0.83], p=0.03), and shorter ADL treatment time: 1.01 [0.84] vs. (1.85 [1.65]; p=0.08]), and increased BASDAI results (5.04 [2.5] vs. 3.5 [1.88]; p=0.06). Obese patients showed a lower probability of clinical response to ADL versus non-obese patients with regard to achieving BASDAI ≤4 (OR: 3.5, 95%CI: 0.84-17.19; p=0.05) or ASDAS ≤2.1 (OR: 4.64, 95%CI: 1.02-24.13; p=0.02).

CONCLUSIONS

Of the AS patients receiving treatment with ADL, those that are obese had significantly lower serum ADL levels and decreased clinical response without an increase in immunogenicity.

Antibodies to infliximab in Remicade-treated rheumatic patients show identical reactivity towards biosimilars

OBJECTIVES

The aim of this study was to determine whether antibodies to infliximab (IFX) in Remicade-treated patients cross-react with the biosimilar CT-P13.

METHODS

250 consecutive patients with rheumatic diseases under Remicade and 77 controls were retrospectively selected for the study. Anti-IFX antibodies at drug through levels were measured in parallel with three different bridging ELISA assays: Promonitor-ANTI-IFX kit, which uses Remicade to detect antibodies, and two more assays that use either Inflectra or Remsima with the same format. Correlation and association between each assay was studied.

RESULTS

50.4% of patients were tested positive with Promonitor-ANTI-IFX. All were antibodies to IFX (ATI)-positive when either Inflectra or Remsima assays were used. In all comparisons positive and negative percentage agreements were 100%, and correlation coefficients were ≥0.995. No differences between rheumatoid arthritis and spondyloarthritis, or between concomitant immunosuppressives, were observed.

CONCLUSIONS

Anti-IFX antibodies of Remicade-treated patients cross-react with either Inflectra or Remsima. Although additional epitopes may be present in the biosimilar, results suggest that epitopes influencing the immune response to IFX are also present in the biosimilar. Antibody-positive patients treated with Remicade should not be switched to the biosimilar, since antibodies will interact with the new drug and potentially lead to loss of response. This finding supports the utility for therapeutic drug monitoring before a switching strategy is considered.

Clinical relevance of monitoring serum levels of adalimumab in patients with rheumatoid arthritis in daily practice

OBJECTIVES

The aim of this paper is to assess the usefulness of measuring serum levels of adalimumab (ADL) and anti-ADL antibodies in 57 patients with rheumatoid arthritis (RA) treated with ADL for at least 3 months in daily practice.

METHODS

All patients received concomitant disease-modifying anti-rheumatic drug (DMARD). Receiver-operator characteristics (ROC) analysis was used to obtain the cut-off value of ADL for low disease activity (DAS28-ESR ≤3.2).

RESULTS

Anti-ADL antibodies were detected in 4 (7%) patients with a mean (SD) DAS28 score of 4.6 (0.9). Patients with positive anti-ADL antibodies had significantly lower levels of ADL and higher DAS28 scores than those with negative antibodies. Patients with DAS28 ≤3.2 as compared with patients with DAS28 >3.2 showed significantly better SDAI score, higher serum concentrations of ADL and none of them showed anti-ADL antibodies. The cut-off of serum level of ADL for DAS28 <3.2 was 4.3 mg/L. According to serum levels of ADL, patients were grouped into group 1 (low level) <5.5 mg/L, group 2 (medium level) 5.5-11.3 mg/L and group 3 (high level) >11.3 mg/L. Patients in the medium group were closed to clinical remission (median DAS28 2.7) and patients in the high group were on clinical remission (DAS28 2.1).

CONCLUSIONS

Serum levels of ADL should be maintained >4.3 mg/L. In patients with ADL levels >11.3 mg/L, a decrease of the dose of ADL or an increase in the interval between doses may be planned. The presence of anti-ADL antibodies was associated with a loss of clinical efficacy of ADL.

Monitoring trough plasma concentrations of mycophenolate mofetil in patients with uveitis

BACKGROUND

Mycophenolate mofetil (MMF) has been used successfully in patients with various forms of uveitis not responsive to other immunosuppressants. Nevertheless, for these patients neither recommendations for optimal dosage of MMF nor data concerning drug exposure of MMF are available.

OBJECTIVE

To describe the results of the therapeutic drug monitoring (TDM) of MMF trough concentrations in a cohort of patients with uveitis, with the aim of optimizing the dosage of this drug, by maintaining a target concentration to achieve adequate immunosuppression with a minimal risk of therapeutic failure or toxicity.

PATIENTS AND METHODS

This study describes the results of monitoring trough plasma concentrations of MMF in 12 patients with uveitis during a mean period of 21.4 months. Patients included one with Stevens-Johnson syndrome, one with Graves-Basedow's disease, one with Behcet's disease, one with idiopathic thrombocytopenic purpura and the rest with idiopathic uveitis. All patients were treated with steroids and additional therapy prior to treatment with MMF.

RESULTS

Pharmacokinetic monitoring of mycophenolic acid (MPA) was performed with 108 trough plasma samples using an EMIT assay. Mean daily MMF dose was 24.5 +/- 6.3 mg/kg and mean trough MPA concentration was 2.9 +/- 1.9 microg/mL. Therapy was effective in 10 patients (83%). There were few side-effects: diarrhoea, excitement, agitation and cough that disappeared with daily dose reduction of MMF.

CONCLUSIONS

MMF was effective in the majority of patients with uveitis with an acceptable profile of side-effects. TDM of MMF in patients with uveitis is clinically practicable and may help to optimize individual immunosuppressive therapy. We estimated that MMF dosages in the range of 0.5-1.5 g/day might be sufficient for treating uveitis and we recommend an initial target range of 2-4 microg/mL, which included 50% of our results. Randomized controlled trials are essential to confirm the efficacy of MMF in uveitis.