Preclinical activity of 17 beta-[N-[N'-(2-chloroethyl)-N'-nitrosocarbamoyl]-L-alanyl]-5 alpha-dihydrotestosterone (E91) against tumour colony forming units and haematopoietic progenitor cells.
E91 (17 beta-[N-[N'-(2-chloroethyl)-N'-nitrosocarbamoyl]-L-alanyl]-5 alpha-dihydrotestosterone) (CNC-ala-DHT) is a newly synthesised alkylating compound consisting of N-[N'-(2-chloroethyl)-N'-nitrosocarbamoyl]-L-alanine (CNC-ala) as the alkylating moiety and of 5 alpha-dihydrotestosterone (DHT) as a steroid carrier molecule. We studied the antitumour activity of E91 (final concentrations: 0.1, 1, 10 and 30 mumol/l) against freshly explanted human tumours, using an in vitro soft agar cloning system. A total of 54 tumour samples was evaluated using 1 h-exposure and 51 tumour specimens were studied using a continuous exposure for 21-28 days. In addition, the compound's activity was compared with other clinically used anticancer agents. After short-term exposure, 49 of 53 evaluable specimens (92%) had adequate colony formation, as compared with 49 of 50 (98%) after long-term exposure. After short-term exposure, E91 exhibited only marginal antitumour activity. However, in long-term exposure experiments, E91 had marked and concentration-dependent antitumour activity (P < 0.001). At concentrations of > 10 mumol/l, E91 was as active as the other clinically used antineoplastic agents and at 30 mumol/l, E91 was significantly more active than 5-fluorouracil (P = 0.041). E91 showed activity against a wide spectrum of tumour types. The highest activity was observed against colorectal carcinomas (3/4 tumour specimens inhibited at 30 mumol/l). Sensitivity was also high remarkable in breast cancer specimens with 3/6 specimens inhibited at 30 mumol/l. In vitro myelotoxicity was less than that of doxorubicin. At 30 mumol/l, E91 induced a reduction of colony forming units-granulocyte macrophage (CFU-GM) to only 53% of control and of CFU-GEMM to 20% of control. We conclude that because of broad activity and reduced myelotoxicity further clinical development of E91 appears warranted.
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Technische Universität München, Klinikum Rechts der Isar, Germany.
Peter
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Depenbrock
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Eisenbrand
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G
Schmid
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Pitzl
H
H
Hanauske
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AR
D000970:Antineoplastic Agents / Q000627:therapeutic use*; D002455:Cell Division / Q000187:drug effects; D013196:Dihydrotestosterone / Q000031:analogs & derivatives* / Q000627:therapeutic use; D006412:Hematopoietic Stem Cells / Q000187:drug effects*; D006801:Humans; D009369:Neoplasms / Q000188:drug therapy* / Q000473:pathology; D009588:Nitrogen Mustard Compounds / Q000627:therapeutic use*; D009607:Nitrosourea Compounds / Q000627:therapeutic use*; D013739:Testosterone / Q000031:analogs & derivatives* / Q000627:therapeutic use; D014407:Tumor Cells, Cultured; D014410:Tumor Stem Cell Assay
D000970:Antineoplastic Agents; C104207:N-(N'-(2-chloroethyl)--N'-nitrosocarbamoyl)methionine-dihydrotestosterone-17-ester; D009588:Nitrogen Mustard Compounds; D009607:Nitrosourea Compounds; D013196:Dihydrotestosterone; D013739:Testosterone; C065508:2-chloroethylnitrosocarbamoylalanine 17-dihydrotestosterone ester