Anti-tumour drug more potent with light-directed delivery

PCI Biotech's light-activated delivery system significantly enhances the effects of tumour-targeting drugs in mice, according to a new study.

The researchers at the Norwegian Radium Hospital in Oslo say this dual therapy approach could be employed to increase the effect and lower the side effects of anti-cancer drugs in humans.

They tested the approach on mice with human non-pigmented melanoma skin cancer grafts, using a drug consisting of a very potent toxin fused to an antibody fragment that recognises a protein commonly found on the cancer cells, but not on normal ones. This allowed them specifically to target the tumour cells. While drug therapy alone did not significantly slow growth of the tumours, using PCI to enhance the delivery process substantially improved the results.

In mice treated with both PCI and the tumour-targeting drug, half of the animals did not reach the defined end point for tumour growth, even after 110 days (the end of the study). By contrast, all the mice receiving the drug alone had reached the end point after 40 days, which was not significantly different from what was seen in untreated control animals. There were also no adverse effects on the mice, indicating that PCI technology can allow the use of drug doses so low that unwanted side effects in humans could be substantially reduced.

The study, carried out by the Norwegian team and researchers from the M D Anderson Cancer Center in Houston, Texas, is published in the journal PLoS ONE.

Dr Pal Selbo, lead author of the study, said: "In this study we have used an advanced biotechnological drug that consists of a protein toxin fused to a cancer-targeting moiety. The combination of the tumour targeting by the antibody and the light-directed drug delivery achieved by PCI gives extraordinarily specific therapy."

Per Walday, ceo of PCI Biotech, of Norway, added: "These results clearly demonstrate that PCI as a modality may greatly improve the efficacy of cell-targeted therapeutic agents. Our main priority going forward is to move the PCI technology into the clinic, to prove its safety and efficacy in man."