Formation and clearance of TNF-TNF inhibitor complexes during TNF inhibitor treatment.

BACKGROUND AND PURPOSE: Millions of patients with inflammatory diseases are treated with tumour necrosis factor (TNF) inhibitors (TNFi). Individual treatment response varies, in part related to variable drug clearance. The role of TNF-TNFi complexes in clearance of the different TNFi is controversial. Moreover, mechanistic insight into the structural aspects and biological significance of TNF-TNFi complexes is lacking. We hypothesized a role for Fc-mediated clearance of TNF-TNFi immune complexes. Therefore, we investigated circulating TNF-TNFi complexes upon treatment with certolizumab-lacking Fc tails-in comparison with adalimumab, golimumab, infliximab and etanercept. EXPERIMENTAL APPROACH: Drug-tolerant ELISAs were developed and used to quantify TNF during adalimumab, golimumab, etanercept, certolizumab and infliximab treatment in patients with inflammatory arthritis or ulcerative colitis for a maximum follow-up of 1 year. Effects on in vitro TNF production and Fc-mediated uptake of TNF-TNFi complexes were investigated for all five TNFi. KEY RESULTS: Circulating TNF concentrations were >20-fold higher during certolizumab treatment compared with adalimumab, reaching up to 23.1 ng·ml-1 . Internalization of TNF-TNFi complexes by macrophages depended on Fc valency, with efficient uptake for the full antibody TNFi (three Fc tails), but little or no uptake for etanercept and certolizumab (one and zero Fc tail, respectively). TNF production was not affected by TNFi. Total TNF load did not affect clearance rate of total TNFi. CONCLUSIONS AND IMPLICATIONS: Differences in TNFi structure profoundly affect clearance of TNF, while it is unlikely that TNF itself significantly contributes to target-mediated drug disposition of TNFi.

Long-Term Treatment With TNF-Alpha Inhibitors Improves Bone Mineral Density But Not Vertebral Fracture Progression in Ankylosing Spondylitis.

The aim of this cohort study was to evaluate the long-term effects of TNF inhibitors (TNFis) on BMD and the incidence of vertebral fractures (VFxs) in patients with ankylosing spondylitis (AS). Consecutive patients with active AS with TNFi treatment duration up to 4 years with available DXA scans and spine X-rays were included. BMD (classified according to the WHO criteria for osteoporosis) of the hip and lumbar spine, the VFx (classified as a Genant score >1/>20% height loss), and radiological progression (modified stoke ankylosing spondylitis spinal score [mSASSS]) scores were obtained at baseline and at 4 years of TNFi treatment. Overall, 135 AS patients were included. At baseline, 40.1% of patients had low BMD of the hip and 40.2% of the lumbar spine. This decreased to 38.1% (p = 0.03) with low hip BMD and 25.3% (p < 0.001) of the lumbar spine BMD after 4 years of TNFi treatment. VFxs were present at baseline in 11.1% of the 131 patients, which increased to 19.6% after 4 years of TNFi treatment. A Genant score ≥2, was found at baseline in 3 out of 14 VFx (21.4%) patients, which increased to 7 out of 27 VFx (25.9%) patients after 4 years. All disease activity parameters-the ankylosing spondylitis disease activity scale, the C-reactive protein, the erythrocyte sedimentation rate, and the bath ankylosing spondylitis disease activity index-decreased significantly (p < 0.001). The mean radiological progression (n = 80) increased significantly from a median mSASSS of 4.0 (1.5 to 16.0) at baseline to 6.5 (2.1 to 22.9) after 4 years of TNFi treatment (p < 0.001). Despite the improvement in BMD and the decrease in disease activity, we still found new VFxs, an increase in severity in the number and grade of VFxs, and radiographic progression during 4 years of treatment with TNFis in AS patients with long disease duration. © 2019 American Society for Bone and Mineral Research.