UNIVERSAL ASSAY FOR DETERMINING THE QUANTITY OF TNFa INHIBITORY DRUGS AND THEIR CORRESPONDING ANTI-DRUG-ANTIBODIES

A method for determining the presence and quantity of one or more different TNF-α inhibitor drug antibodies in one or more biological samples each comprising less than 20 μl, the method comprising the steps of:

• a. providing a first TNF-α conjugate comprising TNF-α and a first conjugated moiety,
• b. providing a second TNF-α conjugate comprising TNF-α and a second conjugated moiety, said second moiety being capable of generating or ameliorating a detectable signal in the presence of a molecular complex comprising a TNF-α inhibitor and the first TNF-α conjugate and the second TNF-α conjugate,
• c. providing a reaction liquid comprising the first and the second TNF-α conjugates and a spike containing a known amount of the TNF-α inhibitor, and contacting the sample with the reaction liquid, whereby a detection liquid comprising the sample potentially comprising the TNF-α inhibitor drug antibody, the spike amount of the TNF-α inhibitor and the first and the second TNF-α conjugates is formed,
• d. detecting the change in signal following step c, and
• e. determining the quantity of the TNF-α inhibitor by comparing the obtained results with an internal standard, and
• f. determining the presence or absence of the TNF-α inhibitor anti-body by comparing the obtained results with an internal standard.