Antibody-penicillin-V-amidase conjugates kill antigen-positive tumor cells when combined with doxorubicin phenoxyacetamide.
The two monoclonal antibodies (mAb), L6 (anti-carcinoma), and 1F5 [anti-(B-cell-lymphoma)], were chemically linked to the enzyme penicillin-V amidase (PVA), which hydrolyzes phenoxyacetamides, to explore the potential of using mAb-enzyme conjugates for the localization of chemotherapeutic drugs at tumor cells. The phenoxyacetamide derivatives of doxorubicin and melphalan were prepared, yielding the less toxic amides, doxorubicin-N-p-hydroxyphenoxyacetamide (DPO) and melphalan-N-p-hydroxyphenoxyacetamide (MelPO). These were hydrolyzed by PVA to doxorubicin and melphalan respectively. In vitro studies with the L6-positive lung carcinoma cell line, H2981, and the 1F5-positive B-cell lymphoma line, Daudi, showed that DPO was 80-fold less toxic to H2981 cells and 20-fold less toxic to Daudi cells than doxorubicin, and its toxicity was substantially increased when the H2981 cells were pretreated with L6-PVA or the Daudi cells were pretreated with 1F5-PVA. The cytotoxic effect was antigen-specific, since only the binding mAb-enzyme conjugate increased the cytotoxicity of the prodrug. MelPO was more than 1000-fold less toxic than melphalan to H2981 cells and more than 100-fold less toxic than melphalan to Daudi cells. Pretreatment with the mAb-PVA conjugates did not enhance the toxicity of MelPO in either cell line, because PVA hydrolyzes the phenoxyacetamide bond of MelPO too slowly to generate a toxic level of melphalan.
Kerr
D E
DE
Oncogen, Seattle, WA 98121.
Senter
P D
PD
Burnett
W V
WV
Hirschberg
D L
DL
Hellström
I
I
Hellström
K E
KE
D000581:Amidohydrolases / Q000494:pharmacology*; D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm / Q000276:immunology; D002277:Carcinoma / Q000188:drug therapy / Q000276:immunology / Q000473:pathology; D004317:Doxorubicin / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology / Q000627:therapeutic use; D006801:Humans; D000922:Immunotoxins / Q000138:chemical synthesis / Q000494:pharmacology*; D008223:Lymphoma / Q000188:drug therapy / Q000276:immunology / Q000473:pathology; D008558:Melphalan / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D010399:Penicillin Amidase / Q000494:pharmacology*; D010404:Penicillin V / Q000494:pharmacology; D011355:Prodrugs / Q000378:metabolism / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000187:drug effects*
D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D000922:Immunotoxins; D011355:Prodrugs; C065207:doxorubicin-N-4-hydroxyphenoxyacetamide; C065216:melphalan-N-4-hydroxyphenoxyacetamide; D004317:Doxorubicin; D000581:Amidohydrolases; D010399:Penicillin Amidase; D008558:Melphalan; D010404:Penicillin V