MabTrack Adalimumab Level: A rapid, precise ELISA test for measuring adalimumab in plasma and serum.

Identification of drug levels can be important for patient adjusted treatment schedules, as low drug levels are frequently an indication for antibody formation against adalimumab. In addition, low drug levels may be a sign of ineffectiveness of adalimumab before rebound of clinical symptoms. Alternatively, it is proposed that in patients that respond well to adalimumab, the dosing of adalimumab can be reduced according to serum concentrations. Drug level tests can therefore help to adapt patient medication or to switch to an alternative TNF inhibitor.

By closely monitoring drug levels and antibody formation in combination with disease activity, it is possible for the physician to objectively determine the drug activity in an individual patient and to design patient specific treatment schedules. The therapeutic antibody adalimumab affects tumour necrosis factor (TNF) and is frequently administered to patients who suffer from rheumatic arthritis, intestinal disorders, dermatological diseases and cancer. TNF plays an important role in inflammation, it may cause pain, swollen joints and stiffness in rheumatoid arthritis patients and ulcers in patients with intestinal bowel disease. Inhibition of TNF is therefore believed to relieve some of these symptoms and thus to improve quality of life of patients. Plasma and serum levels of TNF inhibitors are highly variable between patients, and clearly correlate to the clinical symptoms in patients. In approximately 25 to 30% of the rheumatoid arthritis patients treated with adalimumab, antibodies are formed directed towards the idiotype of adalimumab. This can hamper the function of the TNF inhibitor and can cause a reduction in plasma concentration of the TNF inhibitor.

For professional use only

The MabTrack level adalimumab ELISA is a “sandwich-type” of enzyme immunoassay. In the microtiter plates, TNF is captured by monoclonal antibodies coated to polystyrene microtiter wells. The adalimumab, present in the patient sample, the calibrator or the controls, binds to the TNF on the microtiter plate. Non-bound material is then removed by washing. Subsequently, a horseradish peroxidase-labeled monoclonal anti-drug antibody is added. This antibody binds to the adalimumab/TNF/anti-TNF complex present in the microtiter well. After removal of non-bound HRP conjugate by washing, substrate solution is added to the wells. A coloured product is formed in proportion to the amount of adalimumab present in the sample, calibrator and controls. After the reaction has been terminated by the addition of a stop solution, absorbance is measured in a microtiter plate reader. From the absorbance of samples and those of the calibrator curve, the concentration of adalimumab can be determined by interpolation with the calibrator curve.

Clinical optimal ranges, e.g. therapeutic ranges, were determined at Sanquin Diagnostic Services with the adalimumab ELISA for rheumatoid arthritis: 5–8 µg/mL (Pouw et al.) and in dermatology (Psoriasis): 3.5–7 µg/mL (Menting et al.). The Mabtrack level adalimunab kit is calibrated on the WHO International Standard sold by the National Institute for Biological Standards and Control (#17/263).

After opening, all reagents and the microtiter plate strips may be used for ≤ 6 weeks if stored at 2–8 °C.

– The flat-bottom microtiter plate consists of 12 strips of 8 wells ready for use. All the wells are coated with TNF-specific mouse monoclonal antibody and recombinant TNF. The microtiter plate is vacuum sealed in a plastic pouch containing desiccant. The kit provides the flexibility to use the microtiter plate on separate occasions. Determine the number of strips required to test the desired number of samples plus 8 wells needed for running calibrators and controls. Remove strips that will not be used from the microtiter plate-frame and re-pack them in the plastic pouch containing the desiccant.

– After opening, all reagents and the microtiter plate strips may be used for ≤ 6 weeks if stored at 2–8 °C.

– Consult the enclosed information leaflet for the kit specific adalimumab concentrations in calibrator 1-6 and in control 1 and control 2.

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