PRECLINICAL STUDIES: |
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IN VITRO |
VFL vs VRL |
- mechanism of action3,17
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equal |
- radiosensitising effect |
equal |
- cell cycle effect |
equal |
- cross-resistance to other MDR-inducing drugs41
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VFL: least cross-resistant |
- inducer of drug resistance15,20
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VFL far less potent than VRL at 2 × IC50: resistance after 8 months instead of within 2 weeks for VRL |
- combination with other chemotherapeutic agents42
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VFL: high level of synergy |
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IN VIVO |
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- efficacy against a series of murine and human tumour experimental models15,16
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VFL definite superiority to VRL |
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VFL: high or moderate activity in 64% (7 of 11) |
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VRL: moderate activity in 27% (3 of 11) |
- inducer of drug resistance20
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VFL far less readily than VRL |
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10 mg/kg vs 2.5 mg/kg – P388: complete resistance after 22 weeks instead of after 5 weeks |
- tolerance15,43,44
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VFL: high level, superior to VRL |
- anti-vascular effects44,45
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VFL: at doses much lower (5-fold) than the MTD |
- anti-angiogenic effects45
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VFL: at doses below the optimum effective single dose (40-20-fold lower than its MTD) |
- activity against metastases45
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VFL: significant effects at low doses (16-fold lower than the MTD) |
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CLINICAL IMPLICATIONS: |
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- neurotoxicity5,6,17,18,46
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VFL: reduced relative to VRL |
- therapeutic window6,16,45,47
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VFL: presumed to be wider than VRL |