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Preclinical efficacy of the bioreductive alkylating agent RH1 against paediatric tumours.

Hussein D, Holt SV, Brookes KE, Klymenko T, Adamski JK, Hogg A, Estlin EJ, Ward T, Dive C, Makin GW - Br. J. Cancer (2009)

Bottom Line: In acute viability assays against neuroblastoma, osteosarcoma, and Ewing's sarcoma cell lines RH1 IC(50) values ranged from 1-200 nM and drug potency correlated both with DTD levels and drug-induced apoptosis.However, synergy between RH1 and cisplatin or doxorubicin was only seen in low DTD expressing cell lines.In clonogenic assays RH1 IC(50) values ranged from 1.5-7.5 nM and drug potency did not correlate with DTD level.

View Article: PubMed Central - PubMed

Affiliation: Clinical and Experimental Pharmacology Group, Paterson Institute for Cancer Research, Manchester, UK.

ABSTRACT

Background: Despite substantial improvements in childhood cancer survival, drug resistance remains problematic for several paediatric tumour types. The urgent need to access novel agents to treat drug-resistant disease should be expedited by pre-clinical evaluation of paediatric tumour models during the early stages of drug development in adult cancer patients.

Methods/results: The novel cytotoxic RH1 (2,5-diaziridinyl-3-[hydroxymethyl]-6-methyl-1,4-benzoquinone) is activated by the obligate two-electron reductase DT-diaphorase (DTD, widely expressed in adult tumour cells) to a potent DNA interstrand cross-linker. In acute viability assays against neuroblastoma, osteosarcoma, and Ewing's sarcoma cell lines RH1 IC(50) values ranged from 1-200 nM and drug potency correlated both with DTD levels and drug-induced apoptosis. However, synergy between RH1 and cisplatin or doxorubicin was only seen in low DTD expressing cell lines. In clonogenic assays RH1 IC(50) values ranged from 1.5-7.5 nM and drug potency did not correlate with DTD level. In A673 Ewing's sarcoma and 791T osteosarcoma tumour xenografts in mice RH1 induced apoptosis 24 h after a single bolus injection (0.4 mg/kg) and daily dosing for 5 days delayed tumour growth relative to control.

Conclusion: The demonstration of RH1 efficacy against paediatric tumour cell lines, which was performed concurrently with the adult Phase 1 Trial, suggests that this agent may have clinical usefulness in childhood cancer.

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Induction of apoptosis in paediatric tumour xenografts. (A) Analysis of cells staining for cleaved caspase 3 in A673 tumour xenografts in nude mice 24 h after a single intraperitoneal dose of RH1. (B) Analysis of cells staining for cleaved caspase 3 in 791T xenografts in nude mice 24 h after a single intraperitoneal dose of RH1.
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fig4: Induction of apoptosis in paediatric tumour xenografts. (A) Analysis of cells staining for cleaved caspase 3 in A673 tumour xenografts in nude mice 24 h after a single intraperitoneal dose of RH1. (B) Analysis of cells staining for cleaved caspase 3 in 791T xenografts in nude mice 24 h after a single intraperitoneal dose of RH1.

Mentions: A single i.p. dose of 0.4 mg kg−1 RH1 was sufficient to induce apoptosis in A673 Ewing's sarcoma grown as s.c. xenografts in nude mice. Figure 4A shows immunostaining for cleaved caspase 3 (CC3) in A673 xenografts with a clear increase in the proportion of cells expressing CC3 24 h after RH1 dosing (Figure 4B), although this increase was not maintained at later time points. In 791T osteosarcoma xenografts, however, no increase in percentage of cells with CC3 was observed at two time points (24 and 48 h) after RH1 treatment, although in these cells the background level of apoptosis in sham-treated tumours was relatively high and may have masked any RH1-induced effect (Figure 4B).


Preclinical efficacy of the bioreductive alkylating agent RH1 against paediatric tumours.

Hussein D, Holt SV, Brookes KE, Klymenko T, Adamski JK, Hogg A, Estlin EJ, Ward T, Dive C, Makin GW - Br. J. Cancer (2009)

Induction of apoptosis in paediatric tumour xenografts. (A) Analysis of cells staining for cleaved caspase 3 in A673 tumour xenografts in nude mice 24 h after a single intraperitoneal dose of RH1. (B) Analysis of cells staining for cleaved caspase 3 in 791T xenografts in nude mice 24 h after a single intraperitoneal dose of RH1.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2713707&req=5

fig4: Induction of apoptosis in paediatric tumour xenografts. (A) Analysis of cells staining for cleaved caspase 3 in A673 tumour xenografts in nude mice 24 h after a single intraperitoneal dose of RH1. (B) Analysis of cells staining for cleaved caspase 3 in 791T xenografts in nude mice 24 h after a single intraperitoneal dose of RH1.
Mentions: A single i.p. dose of 0.4 mg kg−1 RH1 was sufficient to induce apoptosis in A673 Ewing's sarcoma grown as s.c. xenografts in nude mice. Figure 4A shows immunostaining for cleaved caspase 3 (CC3) in A673 xenografts with a clear increase in the proportion of cells expressing CC3 24 h after RH1 dosing (Figure 4B), although this increase was not maintained at later time points. In 791T osteosarcoma xenografts, however, no increase in percentage of cells with CC3 was observed at two time points (24 and 48 h) after RH1 treatment, although in these cells the background level of apoptosis in sham-treated tumours was relatively high and may have masked any RH1-induced effect (Figure 4B).

Bottom Line: In acute viability assays against neuroblastoma, osteosarcoma, and Ewing's sarcoma cell lines RH1 IC(50) values ranged from 1-200 nM and drug potency correlated both with DTD levels and drug-induced apoptosis.However, synergy between RH1 and cisplatin or doxorubicin was only seen in low DTD expressing cell lines.In clonogenic assays RH1 IC(50) values ranged from 1.5-7.5 nM and drug potency did not correlate with DTD level.

View Article: PubMed Central - PubMed

Affiliation: Clinical and Experimental Pharmacology Group, Paterson Institute for Cancer Research, Manchester, UK.

ABSTRACT

Background: Despite substantial improvements in childhood cancer survival, drug resistance remains problematic for several paediatric tumour types. The urgent need to access novel agents to treat drug-resistant disease should be expedited by pre-clinical evaluation of paediatric tumour models during the early stages of drug development in adult cancer patients.

Methods/results: The novel cytotoxic RH1 (2,5-diaziridinyl-3-[hydroxymethyl]-6-methyl-1,4-benzoquinone) is activated by the obligate two-electron reductase DT-diaphorase (DTD, widely expressed in adult tumour cells) to a potent DNA interstrand cross-linker. In acute viability assays against neuroblastoma, osteosarcoma, and Ewing's sarcoma cell lines RH1 IC(50) values ranged from 1-200 nM and drug potency correlated both with DTD levels and drug-induced apoptosis. However, synergy between RH1 and cisplatin or doxorubicin was only seen in low DTD expressing cell lines. In clonogenic assays RH1 IC(50) values ranged from 1.5-7.5 nM and drug potency did not correlate with DTD level. In A673 Ewing's sarcoma and 791T osteosarcoma tumour xenografts in mice RH1 induced apoptosis 24 h after a single bolus injection (0.4 mg/kg) and daily dosing for 5 days delayed tumour growth relative to control.

Conclusion: The demonstration of RH1 efficacy against paediatric tumour cell lines, which was performed concurrently with the adult Phase 1 Trial, suggests that this agent may have clinical usefulness in childhood cancer.

Show MeSH
Related in: MedlinePlus