Targeting of saporin to Hodgkin's lymphoma cells by anti-CD30 and anti-CD25 bispecific antibodies.
CD25 and CD30 represent suitable target molecules for bispecific antibody (bimAb)-driven toxin delivery to lymphoid tumour cells. We describe two new anti-CD30/anti-saporin bimAbs (termed CD30 x sap1 and CD30 x sap2), produced by hybrid hybridomas, which react against non-cross-reactive epitopes of the saporin molecule, and compared their effect with a bimAb reacting with saporin and with CD25 (CD25 x sap1). In a protein synthesis inhibition assay these bimAbs were able to enhance saporin toxicity (IC50 = 8.5 x 10(-9) M in the absence of mAbs) with a similar activity: in the presence of 10(-9) M CD30 x sap1 bimAb the IC50 was 2.75 x 10(-11) M, whereas with CD30 x sap2 bimAb the IC50 was 6.5 x 10(-11) M and CD25 x sap1 bimAb displayed an IC50 of 3 x 10(-11) M (as saporin). The combined use of the two anti-CD30 bimAbs further increased cytotoxicity by 100-fold, resulting in an IC50 of 1.9 x 10(-13) M. A slightly less efficient improvement was obtained by combining the CD25 x sap1 bimAb with the CD30 x sap2 bimAb directed against a different toxin epitope (saporin IC50 to 7 x 10(-13) M). In contrast, no synergistic effect was observed using the combination of the anti-CD25 bimAb with the anti-CD30 bimAb reacting with the same epitope of saporin (IC50 = 4.5 x 10(-11) M). Analysis of FITC-saporin binding to L540 cells by flow cytometry demonstrated that the appropriate combinations of the two anti-CD30/anti-saporin bimAbs or of the anti-CD30/anti-saporin and anti-CD25/anti-saporin bimAbs had a cooperative effect on the binding of the ribosome-inactivating protein (RIP) to the cells, when compared with single bimAbs.
Sforzini
S
S
Istituto Nazionale per la Ricerca sul Cancro, Centro di Biotecnologie Avanzate, Genova, Italy.
de Totero
D
D
Gaggero
A
A
Ippoliti
R
R
Glennie
M J
MJ
Canevari
S
S
Stein
H
H
Ferrini
S
S
D018033:Antibodies, Bispecific / Q000096:biosynthesis / Q000276:immunology; D000951:Antigens, Neoplasm / Q000276:immunology; D000972:Antineoplastic Agents, Phytogenic / Q000276:immunology / Q000493:pharmacokinetics* / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006689:Hodgkin Disease / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D006825:Hybridomas / Q000276:immunology; D000922:Immunotoxins / Q000493:pharmacokinetics*; D017730:Ki-1 Antigen / Q000276:immunology; D009699:N-Glycosyl Hydrolases; D009363:Neoplasm Proteins / Q000096:biosynthesis; D010940:Plant Proteins / Q000276:immunology / Q000493:pharmacokinetics* / Q000494:pharmacology; D015375:Receptors, Interleukin-2 / Q000276:immunology; D054789:Ribosome Inactivating Proteins, Type 1; D000076985:Saporins; D014407:Tumor Cells, Cultured
D018033:Antibodies, Bispecific; D000951:Antigens, Neoplasm; D000972:Antineoplastic Agents, Phytogenic; D000922:Immunotoxins; D017730:Ki-1 Antigen; D009363:Neoplasm Proteins; D010940:Plant Proteins; D015375:Receptors, Interleukin-2; D054789:Ribosome Inactivating Proteins, Type 1; D009699:N-Glycosyl Hydrolases; D000076985:Saporins