Comparative in vitro cytotoxicity of cyclophosphamide, its major active metabolites and the new oxazaphosphorine ASTA Z 7557 (INN mafosfamide)

David S Alberts, Janine G Einspahr, Robert Struck, Gary Bignami, Laurie Young, Earl A. Surwit, Sydney E. Salmon

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Cyclophosphamide (CPA), the most commonly used alkylating agent in the treatment of a wide variety of hematologic and solid tumors, requires oxidation by hepatic microsomal enzymes to its active alkylating species. A number of alternative methods exist to simulate the in vitro cytotoxicity of CPA against animal and human tumors, including the co-incubation of CPA with the S-9 fraction of rat liver homogenates (S-9) and the use of either 4-hydroperoxy CPA (a stabilized form of a major blood-borne metabolite of CPA), phosphoramide mustard (PM, considered to be the ultimate intracellular alkylating metabolite of CPA), or ASTA Z 7557 [4-(2-sulfonatoethylthio)-CPA, a new oxazaphosphorine compound which after dissolution undergoes rapid spontaneous hydrolysis in vitro with liberation of 4-hydroxy-CPA]. Using a human tumor clonogenic assay (HTCA) we have quantitated the median molar inhibitory dose 50 (ID50) concentrations of S-9 activated-CPA, 4-hydroperoxy-CPA, PM, and ASTA Z 7557 against 107 previously untreated tumors, as well as determining the in vitro biological stability of the former three CPA metabolite preparations. 4-Hydroperoxy-CPA proved the most consistently cytotoxic (median molar ID50=5.77×10-5M) compound, followed by ASTA Z 7557, S-9 activated-CPA and PM in that order. Of additional interest S-9 activated CPA and PM proved relatively unstable biologically when frozen at -120°C, whereas 4-hydroperoxy-CPA lost none of its cytotoxicity over a 36 day period during freezing. On the basis of these data 4-hydroperoxy-CPA appears the compound of choice for use in vitro to evaluate the activity that CPA is likely to express clinically against solid tumors. Since 4-hydroperoxy-CPA is not available for clinical use, ASTA Z 7557, which was slightly less cytotoxic to ovarian cancers and a wide variety of other tumors in the HTCA, appears an attractive agent to develop further clinically, especially for regional chemotherapy (e.g., intraperitoneal and intra-arterial treatment) of solid tumors.

Original languageEnglish (US)
Pages (from-to)141-148
Number of pages8
JournalInvestigational New Drugs
Volume2
Issue number2
DOIs
StatePublished - Jun 1984

Fingerprint

Cyclophosphamide
Neoplasms
mafosfamide
In Vitro Techniques
Alkylating Agents
Liver
Ovarian Neoplasms
Freezing
Inhibitory Concentration 50

Keywords

  • ASTA Z 7557
  • cyclophosphamide
  • oxazaphosphorine

ASJC Scopus subject areas

  • Pharmacology
  • Molecular Medicine

Cite this

Comparative in vitro cytotoxicity of cyclophosphamide, its major active metabolites and the new oxazaphosphorine ASTA Z 7557 (INN mafosfamide). / Alberts, David S; Einspahr, Janine G; Struck, Robert; Bignami, Gary; Young, Laurie; Surwit, Earl A.; Salmon, Sydney E.

In: Investigational New Drugs, Vol. 2, No. 2, 06.1984, p. 141-148.

Research output: Contribution to journalArticle

@article{ae7553d845934ae483d9fdc8993a5bce,
title = "Comparative in vitro cytotoxicity of cyclophosphamide, its major active metabolites and the new oxazaphosphorine ASTA Z 7557 (INN mafosfamide)",
abstract = "Cyclophosphamide (CPA), the most commonly used alkylating agent in the treatment of a wide variety of hematologic and solid tumors, requires oxidation by hepatic microsomal enzymes to its active alkylating species. A number of alternative methods exist to simulate the in vitro cytotoxicity of CPA against animal and human tumors, including the co-incubation of CPA with the S-9 fraction of rat liver homogenates (S-9) and the use of either 4-hydroperoxy CPA (a stabilized form of a major blood-borne metabolite of CPA), phosphoramide mustard (PM, considered to be the ultimate intracellular alkylating metabolite of CPA), or ASTA Z 7557 [4-(2-sulfonatoethylthio)-CPA, a new oxazaphosphorine compound which after dissolution undergoes rapid spontaneous hydrolysis in vitro with liberation of 4-hydroxy-CPA]. Using a human tumor clonogenic assay (HTCA) we have quantitated the median molar inhibitory dose 50 (ID50) concentrations of S-9 activated-CPA, 4-hydroperoxy-CPA, PM, and ASTA Z 7557 against 107 previously untreated tumors, as well as determining the in vitro biological stability of the former three CPA metabolite preparations. 4-Hydroperoxy-CPA proved the most consistently cytotoxic (median molar ID50=5.77×10-5M) compound, followed by ASTA Z 7557, S-9 activated-CPA and PM in that order. Of additional interest S-9 activated CPA and PM proved relatively unstable biologically when frozen at -120°C, whereas 4-hydroperoxy-CPA lost none of its cytotoxicity over a 36 day period during freezing. On the basis of these data 4-hydroperoxy-CPA appears the compound of choice for use in vitro to evaluate the activity that CPA is likely to express clinically against solid tumors. Since 4-hydroperoxy-CPA is not available for clinical use, ASTA Z 7557, which was slightly less cytotoxic to ovarian cancers and a wide variety of other tumors in the HTCA, appears an attractive agent to develop further clinically, especially for regional chemotherapy (e.g., intraperitoneal and intra-arterial treatment) of solid tumors.",
keywords = "ASTA Z 7557, cyclophosphamide, oxazaphosphorine",
author = "Alberts, {David S} and Einspahr, {Janine G} and Robert Struck and Gary Bignami and Laurie Young and Surwit, {Earl A.} and Salmon, {Sydney E.}",
year = "1984",
month = "6",
doi = "10.1007/BF00232343",
language = "English (US)",
volume = "2",
pages = "141--148",
journal = "Investigational New Drugs",
issn = "0167-6997",
publisher = "Kluwer Academic Publishers",
number = "2",

}

TY - JOUR

T1 - Comparative in vitro cytotoxicity of cyclophosphamide, its major active metabolites and the new oxazaphosphorine ASTA Z 7557 (INN mafosfamide)

AU - Alberts, David S

AU - Einspahr, Janine G

AU - Struck, Robert

AU - Bignami, Gary

AU - Young, Laurie

AU - Surwit, Earl A.

AU - Salmon, Sydney E.

PY - 1984/6

Y1 - 1984/6

N2 - Cyclophosphamide (CPA), the most commonly used alkylating agent in the treatment of a wide variety of hematologic and solid tumors, requires oxidation by hepatic microsomal enzymes to its active alkylating species. A number of alternative methods exist to simulate the in vitro cytotoxicity of CPA against animal and human tumors, including the co-incubation of CPA with the S-9 fraction of rat liver homogenates (S-9) and the use of either 4-hydroperoxy CPA (a stabilized form of a major blood-borne metabolite of CPA), phosphoramide mustard (PM, considered to be the ultimate intracellular alkylating metabolite of CPA), or ASTA Z 7557 [4-(2-sulfonatoethylthio)-CPA, a new oxazaphosphorine compound which after dissolution undergoes rapid spontaneous hydrolysis in vitro with liberation of 4-hydroxy-CPA]. Using a human tumor clonogenic assay (HTCA) we have quantitated the median molar inhibitory dose 50 (ID50) concentrations of S-9 activated-CPA, 4-hydroperoxy-CPA, PM, and ASTA Z 7557 against 107 previously untreated tumors, as well as determining the in vitro biological stability of the former three CPA metabolite preparations. 4-Hydroperoxy-CPA proved the most consistently cytotoxic (median molar ID50=5.77×10-5M) compound, followed by ASTA Z 7557, S-9 activated-CPA and PM in that order. Of additional interest S-9 activated CPA and PM proved relatively unstable biologically when frozen at -120°C, whereas 4-hydroperoxy-CPA lost none of its cytotoxicity over a 36 day period during freezing. On the basis of these data 4-hydroperoxy-CPA appears the compound of choice for use in vitro to evaluate the activity that CPA is likely to express clinically against solid tumors. Since 4-hydroperoxy-CPA is not available for clinical use, ASTA Z 7557, which was slightly less cytotoxic to ovarian cancers and a wide variety of other tumors in the HTCA, appears an attractive agent to develop further clinically, especially for regional chemotherapy (e.g., intraperitoneal and intra-arterial treatment) of solid tumors.

AB - Cyclophosphamide (CPA), the most commonly used alkylating agent in the treatment of a wide variety of hematologic and solid tumors, requires oxidation by hepatic microsomal enzymes to its active alkylating species. A number of alternative methods exist to simulate the in vitro cytotoxicity of CPA against animal and human tumors, including the co-incubation of CPA with the S-9 fraction of rat liver homogenates (S-9) and the use of either 4-hydroperoxy CPA (a stabilized form of a major blood-borne metabolite of CPA), phosphoramide mustard (PM, considered to be the ultimate intracellular alkylating metabolite of CPA), or ASTA Z 7557 [4-(2-sulfonatoethylthio)-CPA, a new oxazaphosphorine compound which after dissolution undergoes rapid spontaneous hydrolysis in vitro with liberation of 4-hydroxy-CPA]. Using a human tumor clonogenic assay (HTCA) we have quantitated the median molar inhibitory dose 50 (ID50) concentrations of S-9 activated-CPA, 4-hydroperoxy-CPA, PM, and ASTA Z 7557 against 107 previously untreated tumors, as well as determining the in vitro biological stability of the former three CPA metabolite preparations. 4-Hydroperoxy-CPA proved the most consistently cytotoxic (median molar ID50=5.77×10-5M) compound, followed by ASTA Z 7557, S-9 activated-CPA and PM in that order. Of additional interest S-9 activated CPA and PM proved relatively unstable biologically when frozen at -120°C, whereas 4-hydroperoxy-CPA lost none of its cytotoxicity over a 36 day period during freezing. On the basis of these data 4-hydroperoxy-CPA appears the compound of choice for use in vitro to evaluate the activity that CPA is likely to express clinically against solid tumors. Since 4-hydroperoxy-CPA is not available for clinical use, ASTA Z 7557, which was slightly less cytotoxic to ovarian cancers and a wide variety of other tumors in the HTCA, appears an attractive agent to develop further clinically, especially for regional chemotherapy (e.g., intraperitoneal and intra-arterial treatment) of solid tumors.

KW - ASTA Z 7557

KW - cyclophosphamide

KW - oxazaphosphorine

UR - http://www.scopus.com/inward/record.url?scp=0021187591&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0021187591&partnerID=8YFLogxK

U2 - 10.1007/BF00232343

DO - 10.1007/BF00232343

M3 - Article

VL - 2

SP - 141

EP - 148

JO - Investigational New Drugs

JF - Investigational New Drugs

SN - 0167-6997

IS - 2

ER -