592830 Disclosed is a process of improving the antagonistic activity of a monoclonal antibody directed against a specific target molecule, or a divalent functional fragment or derivative thereof, said antibody being capable of inhibiting one or more of the biological activities of said target molecule, wherein said process comprises a stage of reconfiguration of the hinge region consisting of a modification of the amino acid sequence of said hinge region by the deletion, the addition or the substitution of at least one amino acid and wherein said reconfigured hinge region has a sequence selected from the group consisting of PRDCGCKPCICT, PKSCGCKPCICT, PKSCGCKPCICP, PRDCGCKPCPPCP, PRDCGCHTCPPCP, PKSCDCHCPPCP, RKCCVECPPCP, CKSCDKTHTCPPCP, PCSCDKTHTCPPCP, PKCCDKTHTCPPCP, PKSCCKTHTCPPCP, PKSCDCTHTCPPCP, PKSCDKCHTCPPCP, PKSCDKTCTCPPCP, PKSCDKTHCCPPCP, PSCDKTHTCPPCP, PKSCDTHTCPPCP, PKSCDKTHCPPCP, KCDKTHTCPPCP, PSCKTHTCPPCP, PKSCDTHCPPCP, PKSCTHTCPPCP, PKSCDKTHCPPC, PKSCDCHTCPPCP, PKSCDCTHCPPCP, PCSCKHTCPPCP, PSCCTHTCPPCP, PSCDKHCCPPCP, PKSTHTCPPCP, PKSCTCPPCP and PKSCDKCVECPPCP Further disclosed are monoclonal antibodies according the above process, characterized in that it comprises an amino acid sequence selected from the group consisting of PKSCGCKPCICT, PKSCGCKPCICP, PRDCGCKPCPPCP, PRDCGCHTCPPCP, PKSCDCHCPPCP, CKSCDKTHTCPPCP, PCSCDKTHTCPPCP, PKCCDKTHTCPPCP, PKSCCKTHTCPPCP, PKSCDCTHTCPPCP, PKSCDKTCTCPPCP, PKSCDKTHCCPPCP, PSCDKTHTCPPCP, PKSCDTHTCPPCP, PKSCDKTHCPPCP, KCDKTHTCPPCP, PSCKTHTCPPCP, PKSCDTHCPPCP, PKSCTHTCPPCP, PKSCDKTHCPPC, PKSCDCHTCPPCP, PKSCDCTHCPPCP, PCSCKHTCPPCP, PSCCTHTCPPCP, PSCDKHCCPPCP, PKSTHTCPPCP, PKSCTCPPCP and PKSCDKCVECPPCP
