Differential sensitivity of CD30+ neoplastic cells to gelonin delivered by anti-CD30/anti-gelonin bispecific antibodies.
Lymphocyte activation antigens, such as CD30, represent suitable target molecules for antibody-driven drug delivery in haemopoietic malignancies. A ribosome-inactivating protein (RIP) type 1 of potential interest for mAb targeting is gelonin, which displays a lower toxicity, as compared to other RIPs. In this study, two anti-CD30/antigelonin bispecific monoclonal antibodies (bimAbs), secreted by hybrid hybridomas, were used to deliver this RIP to CD30+ tumour cells. The two bimAbs, termed D4 and A18, were produced using the same anti-CD30 mAb and two anti-gelonin mAbs, directed to unrelated epitopes of the gelonin molecule. These bimAbs enhanced gelonin toxicity (IC50 5 x 10(-8) M, in the absence of mAbs) against the CD30+ L540 Hodgkin's lymphoma cell line in a protein synthesis inhibition assay. Thus, in the presence of 10(-9) M D4 bimAb, protein synthesis was inhibited with an IC50 of 5 x 10(-10) M as gelonin, whereas with A18 bimAb the IC50 was 8 x 10(-11) M. More interestingly, the combined use of the two bimAbs had a synergistic effect, since the IC50 of gelonin reached 6 x 10(-12) M. Among CD30 tumour cell lines, the Hodgkin's lymphoma L428 was also sensitive to gelonin delivered by bimAbs (IC50 6 x 10(-11) M), whereas the COLE Hodgkin's cell line and the T-ALL Jurkat were completely resistant to the toxic effect of gelonin and bimAbs. COLE and Jurkat cells were also resistant to a gelonin/anti-CD30 conventional immunotoxin, whereas they were sensitive to a saporin/anti-CD30 immunotoxin. This suggests that the resistance to gelonin is not related to a lack of internalization through the CD30 molecule but is associated with some property of the RIP.
Sforzini
S
S
Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy.
Bolognesi
A
A
Meazza
R
R
Marciano
S
S
Casalini
P
P
Dürkop
H
H
Tazzari
P L
PL
Stein
H
H
Stirpe
F
F
Ferrini
S
S
D018033:Antibodies, Bispecific / Q000008:administration & dosage*; D003602:Cytotoxicity, Immunologic; D004306:Dose-Response Relationship, Immunologic; D004351:Drug Resistance; D006689:Hodgkin Disease / Q000188:drug therapy* / Q000276:immunology; D006801:Humans; D000922:Immunotoxins / Q000627:therapeutic use; D017730:Ki-1 Antigen / Q000276:immunology*; D010940:Plant Proteins / Q000008:administration & dosage* / Q000276:immunology / Q000627:therapeutic use; D054789:Ribosome Inactivating Proteins, Type 1; D014407:Tumor Cells, Cultured
D018033:Antibodies, Bispecific; D000922:Immunotoxins; D017730:Ki-1 Antigen; D010940:Plant Proteins; D054789:Ribosome Inactivating Proteins, Type 1; C025674:GEL protein, Gelonium multiflorum