An in vitro method for determining the presence or absence of an anti-drug antibody in a minipig sample by a sandwich assay, wherein the drug is a human or humanized antibody the method comprising: a) contacting the sample with an excess amount of a drug to which the ADA binds to form drug/ADA complexes, wherein subsequently the drug/ADA complexes are contacted with an antibody specifically binding to human IgG, wherein the antibody specifically binding to human IgG is immobilized on a support, thereby immobilizing the drug/ADA complexes on the support, b) contacting the immobilized drug/ADA complexes with a monoclonal antibody specifically binding minipig IgG selected from an antibody comprising i. a CDR1 of the heavy chain of SEQ ID NO: 3, a CDR2 of the heavy chain of SEQ ID NO: 4, and a CDR3 of the heavy chain of SEQ ID NO: 5, a CDR1 of the light chain of SEQ ID NO: 6, a CDR2 of the light chain of SEQ ID NO: 7, and a CDR3 of the light chain of SEQ ID NO: 8; ii. a CDR1 of the heavy chain of SEQ ID NO: 19, a CDR2 of the heavy chain of SEQ ID NO: 20, and a CDR3 of the heavy chain of SEQ ID NO: 21, a CDR1 of the light chain of SEQ ID NO: 22, a CDR2 of the light chain of SEQ ID NO: 23, and a CDR3 of the light chain of SEQ ID NO: 24; or iii. a CDR1 of the heavy chain of SEQ ID NO: 27, a CDR2 of the heavy chain of SEQ ID NO: 28, and a CDR3 of the heavy chain of SEQ ID NO: 29, a CDR1 of the light chain of SEQ ID NO: 30, a CDR2 of the light chain of SEQ ID NO: 31, and a CDR3 of the light chain of SEQ ID NO: 32; and wherein the antibody specifically binding to minipig IgG does not bind to human IgG, and c) determining the binding of the antibody specifically binding to minipig IgG to the drug/ADA complexes to determine whether ADA is present in the sample. a) contacting the sample with an excess amount of a drug to which the ADA binds to form drug/ADA complexes, wherein subsequently the drug/ADA complexes are contacted with an antibody specifically binding to human IgG, wherein the antibody specifically binding to human IgG is immobilized on a support, thereby immobilizing the drug/ADA complexes on the support, b) contacting the immobilized drug/ADA complexes with a monoclonal antibody specifically binding minipig IgG selected from an antibody comprising i. a CDR1 of the heavy chain of SEQ ID NO: 3, a CDR2 of the heavy chain of SEQ ID NO: 4, and a CDR3 of the heavy chain of SEQ ID NO: 5, a CDR1 of the light chain of SEQ ID NO: 6, a CDR2 of the light chain of SEQ ID NO: 7, and a CDR3 of the light chain of SEQ ID NO: 8; ii. a CDR1 of the heavy chain of SEQ ID NO: 19, a CDR2 of the heavy chain of SEQ ID NO: 20, and a CDR3 of the heavy chain of SEQ ID NO: 21, a CDR1 of the light chain of SEQ ID NO: 22, a CDR2 of the light chain of SEQ ID NO: 23, and a CDR3 of the light chain of SEQ ID NO: 24; or iii. a CDR1 of the heavy chain of SEQ ID NO: 27, a CDR2 of the heavy chain of SEQ ID NO: 28, and a CDR3 of the heavy chain of SEQ ID NO: 29, a CDR1 of the light chain of SEQ ID NO: 30, a CDR2 of the light chain of SEQ ID NO: 31, and a CDR3 of the light chain of SEQ ID NO: 32; and wherein the antibody specifically binding to minipig IgG does not bind to human IgG, and i. a CDR1 of the heavy chain of SEQ ID NO: 3, a CDR2 of the heavy chain of SEQ ID NO: 4, and a CDR3 of the heavy chain of SEQ ID NO: 5, a CDR1 of the light chain of SEQ ID NO: 6, a CDR2 of the light chain of SEQ ID NO: 7, and a CDR3 of the light chain of SEQ ID NO: 8; ii. a CDR1 of the heavy chain of SEQ ID NO: 19, a CDR2 of the heavy chain of SEQ ID NO: 20, and a CDR3 of the heavy chain of SEQ ID NO: 21, a CDR1 of the light chain of SEQ ID NO: 22, a CDR2 of the light chain of SEQ ID NO: 23, and a CDR3 of the light chain of SEQ ID NO: 24; or iii. a CDR1 of the heavy chain of SEQ ID NO: 27, a CDR2 of the heavy chain of SEQ ID NO: 28, and a CDR3 of the heavy chain of SEQ ID NO: 29, a CDR1 of the light chain of SEQ ID NO: 30, a CDR2 of the light chain of SEQ ID NO: 31, and a CDR3 of the light chain of SEQ ID NO: 32; and c) determining the binding of the antibody specifically binding to minipig IgG to the drug/ADA complexes to determine whether ADA is present in the sample.