Eculizumab (Soliris¬ģ) - Therapeutic Drug Monitoring (TDM)

Eculizumab is a humanised monoclonal (IgG2/4?) antibody produced in NS0 cell line by recombinant DNA technology that preventing generation of the terminal complement complex by inhibiting cleavage of complement protein C5.

Eculizumab specifically binds to the complement protein C5 with high affinity, thereby inhibiting its cleavage to C5a and C5b and preventing the generation of the terminal complement complex C5b-9. Upon administration of eculizumab, the early components of complement activation that are essential for opsonization of microorganisms and clearance of immune complexes are preserved.

In PNH patients, treatment with eculizumab blocks complement-mediated intravascular haemolysis and in aHUS patients it inhibits complement- mediated thrombotic microangiopathy. Chronic administration of eculizumab in refractory gMG patients results in immediate, complete, and sustained inhibition of terminal complement activity, which would lead to membrane attack complex (MAC)-dependent lysis and C5a-dependent inflammation at the neuromuscular junction.

Clinical Use

In Europe, eculizumab (Soliris¬ģ) is used to treat:

  • adults and children with paroxysmal nocturnal haemoglobinuria (PNH)
  • adults and children withatypical haemolytic uraemic syndrome (aHUS)
  • adults with myasthenia gravis, in whom other medicines do not work and who are positive for AChR antibody.
Because these conditions are rare diseases, Soliris was designated an ‚Äėorphan medicine‚Äô for PNH, aHUS and for myasthenia gravis.

Testing eculizumab concentration:

The assay is performed using Enzyme Linked Immunosorbent Assay (ELISA). The limit of quantification (LOQ) for eculizumab in serum is not yet defined but is approx. 0.001 ¬Ķg/mL.

Testing eculizumab anti-drug antibodies (ADA):

Not available

Clinical Relevance

No response or loss of response of treatment with eculizumab.

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 eculizumab 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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