In addition, more soluble derivatives of CB1954 that cause more effective tumour regression have recently been described (Wilson et al, 2002) and since 5-FU and CB1954 have been shown to act synergistically (Palmer et al, 2003), the combinatorial use of prodrug activating enzymes (CDase and NTR) might be a promising option for CDEPT. Here, NTSR1 is linked to neoplasm.