Increasing the Tumoricidal Activity of Daunomycin-pHPMA Conjugates Using Vitamin B12 as a Targeting Agent

Many different types of tumour have previously been shown to over-express cell-surface receptors involved in the uptake of Vitamin B12 (VB12). We have examined the potential of using VB12 as a targeting agent for the delivery of pHPMA-conjugated daunomycin in four murine tumour models. VB12-targeted-duanomycin-HPMA conjugates were found to increase both the number of survivors and the survival time of tumour-bearing mice. The data indicate that VB12 may be highly effective in enhancing the efficacy of polymer-bound cytotoxins, particularly in those tumours that over- express receptors involved in vitamin B12 uptake.