A G-quadruplex-binding compound showing anti-tumour activity in an in vivo model for pancreatic cancer

We report here that a tetra-substituted naphthalene-diimide derivative (MM41) has significant in vivo anti-tumour activity against the MIA PaCa-2 pancreatic Cancer xenograft model. IV administration with a twice-weekly 15 mg/kg dose produces CA 80% tumour growth decrease in a group of tumour-bearing Animals. Two Animals survived tumour-free after 279 days. High levels of MM41 are rapidly transported into cell nuclei and were found to accumulate in the tumour. MM41 is a quadruplex-interactive compound which binds strongly to the quadruplexes encoded in the promoter sequences of the Bcl-2 and K-Ras genes, both of which are dis-regulated in many human pancreatic cancers. Levels of Bcl-2 were reduced by CA 40% in tumours from MM41-treated Animals relative to controls, consistent with Bcl-2 being a target for MM41. Molecular modelling suggests that MM41 binds to a Bcl-2 quadruplex in a manner resembling that previously observed in co-crystal structures with human telomeric quadruplexes. This supports the concept that MM41 (and by implication Other quadruplex-targeting small molecules) can bind to quadruplex-forming promoter regions in a number of genes and down-regulate their transcription. We suggest that quadruplexes within those master genes that are up-regulated drivers for particular cancers, may be selective targets for compounds such as MM41.