Patent ID: 8445219

Claim:
A method for determining the degree of receptor binding saturation effected by a monoclonal antibody of interest (Ab1) by means of a first (Ab1A) and a second (Ab2) monoclonal antibody each provided with an individual detection system, wherein Ab1 specifically binds to an epitope (E1) of a receptor domain in a tissue sample, Ab1A recognizes and binds to the same epitope E1 of the receptor domain, and Ab2 binds to an epitope (E2) of the same receptor domain that is different from E1, and said binding of Ab2 does not interact with binding of Ab1 or Ab1A to E1, the method comprising the steps: (i) applying antibody Ab2 to a tissue sample of an individual in an amount which is sufficient to achieve receptor binding saturation towards E2 and determining the signal strength provided by the individual detection system associated with antibody Ab2, (ii) applying antibody Ab1A to a tissue sample of the same individual that was treated before with said antibody Ab1, in an amount which is sufficient to bind to receptor epitope E1 not already bound by antibody Ab1, and determining the signal strength provided by the individual detection system associated with antibody Ab1A, and (iii) calculating from the difference of the signal strength obtained by steps (i) and (ii), the amount of receptor domains which can still bind antibody Ab1, thus determining the degree of receptor binding saturation effected by antibody Ab1.