Tocilizumab (Roactemra¬ģ) - Therapeutic Drug Monitoring (TDM)

Tocilizumab is a humanized IgG1 monoclonal antibody against the human interleukin-6 (IL-6) receptor produced in Chinese hamster ovary (CHO) cells by recombinant DNA technology. Tocilizumab binds specifically to both soluble and membrane-bound IL-6 receptors (sIL-6R and mIL-6R), thereby inhibiting sIL-6R and mIL-6R-mediated signaling. IL-6 is produced by a variety of cell types including T- and B-cells, monocytes and fibroblasts and involved in diverse physiological processes such as T-cell activation, induction of immunoglobulin secretion, induction of hepatic acute phase protein synthesis and stimulation of hemopoiesis. IL-6 is thought to play a role in the pathogenesis of various diseases including inflammatory diseases, osteoporosis and neoplasia.

Clinical Use

In Europe, tocilizumab is indicated to treat:

  • adults with severe rheumatoid arthritis that is getting worse in methotrexate-naive patients
  • adults with moderate to severe active rheumatoid arthritis whose previous treatments with disease modifying antirheumatic drugs have not worked well or were not tolerated
  • children from 2 years of age with active systemic juvenile idiopathic arthritis in whom other anti-inflammatory treatments have not worked well enough
  • children from 2 years of age with juvenile idiopathic polyarthritis in whom treatment with methotrexate has not worked well enough.

Testing tocilizumab concentration:

The assay is performed using Enzyme Linked Immunosorbent Assay (ELISA). The limit of quantification (LOQ) for tocilizumab in serum is 0.2 ¬Ķg/mL.

Testing tocilizumab anti-drug antibodies (ADA):

The assay is performed using radioimmunoassay (RIA). The limit of quantification (LOQ) for ADA is 12 AU/mL.

Clinical Relevance

No response or loss of response of treatment with tocilizumab.

During treatment, some patients may develop antibodies to tocilizumab; anti-drug antibodies (ADA).

With level testing of biologics, efficacy of therapy can be improved, as treatment decisions may need to be adapted depending on the test results in conjunction with clinical responses to treatment.

Data and interpretation of tocilizumab ADA and its serum levels are still very limited.

Personalized Medicine

Monitoring biologic levels in individual patients allows optimization of treatment efficacy by adjusting therapy depending on the specific response of the patient. When drug levels are decreased in a non-responder, this may reflect formation of inactivating antibodies directed to the biologic treatment. Immunogenicity testing identifies presence or absence of inactivating antibodies, which guides the next treatment decision ‚Äď switch to other biological treatment, lowering of dose or intensify dosing. Reducing drug dosage in well-responding patients with relatively high drug levels cuts down cost. A personalized approach can improve therapy efficacy and quality of life.

Read more on the following pages:

Order of test: Print and complete the request form and send it together with the sample.

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