Serum Control for Therapeutic Antibody and IgE during Treatment - PowerPoint PPT Presentation

International Conference Advances in Pneumology Bonn 2011 Serum Control for Therapeutic Antibody and IgE during Treatment with Omalizumab Dr. Gunther Becher, BecherConsult GmbH Dr. Pavel Strohner, BioTeZ Berlin-Buch GmbH

Target is not measurable by traditional antibody based tests in presence of a therapeutic antibody Because components of test system are already in the sample! New immunoassay for antibody therapies developed: recovery ELISA 5

Comparison of IgE determinations during Omalizumab therapy In presence of therapeutic antibody, conventional Sandwich ELISA systematically measures false high levels of IgE. 8

Comparison of IgE determination during Omalizumab therapy The efficiency of Omalizumab therapy can not be controlled by conventional tests; they rarely measure the goal of therapy (< 50 ng IgE / mL). 9

There is no correlation between concentration of target antigen and therapeutic antibody in serum, also not with respect to initial values 8 .

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c) Function 3: Recovery curve (main result of assay) rec = 1 / (1+k1*q1) + NSB Basis: b1 = q1*p/(1/k1+q1) Binding rate of target protein:b1/p=q1/(1/k1+q1) Recovery of free target protein: rec = 1 – b1/p = 1 – q1/(1/k1+q1) 13

Recovery of IgE after TAb addition in relation to reference curve without TAb Calculation of IgE from O.D. with inverse of function 1 for spiked samples Slope of lines = Recovery (rec) 15

Function 3: Recovery curve: Y = 1 / (1 + 2,7628 * X) + 2,0753E-04 Y = rec; X = TAb It shows the neutralization rate of target protein dependent on TAb. Higher the TAb lower the neutralization of added TAb. 16

recovery ELISA avoids massive interference of conventional tests in samples during antibody therapy recovery ELISA measures 3 parameters for a sample:  Free antigen (target protein), if available in serum  Available therapeutic antibody (TAb) in serum  Effective interaction between antigen and TAb (binding / neutralization rate of target protein) 17

Comparative studies from the example IgE / Omalizumab show: • Conventional immunoassays are not suitable for measurement of antigen during antibody therapies • Traditional assays are massively disrupted by the presence of therapeutic antibodies in the sample recovery ELISA provides the solution 21

Taking the general assumption in account, we could establish the following recovery ELISAs which allow to analyze the interaction between target protein and therapeutic antibody. 1. IgE / Omalizumab „RIO“ - Registered IVD 2. TNF-  / Adalumimab - For research use only Further recovery ELISAs in progress (in-house versions available) : 3. TNF-  / Infliximab 4. TNF-  / Eternacept 5. Her2 / Trastuzumab 6. VEGF / Bevacizumab 22