The novel melphalan prodrug J1 inhibits neuroblastoma growth in vitro and in vivo.
Neuroblastoma is the most common extracranial solid tumor of childhood. The activity of J1 (l-melphalanyl-p-l-fluorophenylalanine ethyl ester), an enzymatically activated melphalan prodrug, was evaluated in neuroblastoma models in vitro and in vivo. Seven neuroblastoma cell lines with various levels of drug resistance were screened for cytotoxicity of J1 alone or in combination with standard cytotoxic drugs, using a fluorometric cytotoxicity assay. J1 displayed high cytotoxic activity in vitro against all neuroblastoma cell lines, with IC(50) values in the submicromolar range, significantly more potent than melphalan. The cytotoxicity of J1, but not melphalan, could be significantly inhibited by the aminopeptidase inhibitor bestatin. J1 induced caspase-3 cleavage and apoptotic morphology, had additive effects in combination with doxorubicin, cyclophosphamide, carboplatin, and vincristine, and synergistically killed otherwise drug-resistant cells when combined with etoposide. Athymic rats and mice carrying neuroblastoma xenografts [SH-SY5Y, SK-N-BE(2)] were treated with equimolar doses of melphalan, J1, or no drug, and effects on tumor growth and tissue morphology were analyzed. Tumor growth in vivo was significantly inhibited by J1 compared with untreated controls. Compared with melphalan, J1 more effectively inhibited the growth of mice with SH-SY5Y xenografts, was associated with higher caspase-3 activation, fewer proliferating tumor cells, and significantly decreased mean vascular density. In conclusion, the melphalan prodrug J1 is highly active in models of neuroblastoma in vitro and in vivo, encouraging further clinical development in this patient group.
Wickström
Malin
M
Division of Clinical Pharmacology, Department of Medical Sciences, Entrance 61, 4th Floor Uppsala University Hospital, 75185 Uppsala, Sweden. Malin.Wickstrom@medsci.uu.se
Johnsen
John Inge
JI
Ponthan
Frida
F
Segerström
Lova
L
Sveinbjörnsson
Baldur
B
Lindskog
Magnus
M
Lövborg
Henrik
H
Viktorsson
Kristina
K
Lewensohn
Rolf
R
Kogner
Per
P
Larsson
Rolf
R
Gullbo
Joachim
J
D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D016190:Carboplatin / Q000008:administration & dosage; D045744:Cell Line, Tumor / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004151:Dipeptides / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000008:administration & dosage; D004354:Drug Screening Assays, Antitumor; D005047:Etoposide / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008558:Melphalan / Q000008:administration & dosage; D051379:Mice; D015394:Molecular Structure; D009389:Neovascularization, Pathologic; D009447:Neuroblastoma / Q000098:blood supply / Q000188:drug therapy* / Q000378:metabolism; D011355:Prodrugs / Q000494:pharmacology*; D051381:Rats; D011923:Rats, Nude; D014407:Tumor Cells, Cultured; D014750:Vincristine / Q000008:administration & dosage
D004151:Dipeptides; C482580:L-melphalanyl-p-L-fluorophenylalanine ethyl ester; D011355:Prodrugs; D014750:Vincristine; D005047:Etoposide; D004317:Doxorubicin; D016190:Carboplatin; D008558:Melphalan