Light-activated delivery system enhances anti-tumour drug potency

The effects of tumour-targeting drugs in mice are significantly enhanced by PCI Biotech's light-activated delivery system, a new study shows. Researchers say this dual therapy approach could be employed to increase the effect and lower the side effects of anti-cancer drugs in humans.

The researchers 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 recognizes a protein commonly found on the cancer cells, but not on normal cells. This allowed them to target the tumour cells specifically. Whilst drug therapy alone did not significantly slow growth of the tumours, using PCI to enhance the delivery process substantially improved the results.

Thus, 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 by the end of the study (after 110 days). By contrast, all the mice receiving the drug alone had reached the endpoint after just 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, by researchers at the Norwegian Radium Hospital in Oslo, Norway, and the M.D. Anderson Cancer Center in Houston, Texas, is published in the journal PLoS ONE.

Lead author of the study, Dr. Pal K. Selbo, comments: "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, effectively combining two different principles for specifically targeting the tumour cells. The increased delivery efficiency offered by the PCI technology makes it possible to achieve very good therapeutic effects with drug doses substantially lower than what is necessary without the help of PCI. The study demonstrates the excellent effect of the PCI technology with a very promising class of anticancer drugs, and could pave the way for the efficient and safe use of such drugs in humans."

Per Walday, CEO of PCI Biotech, adds: "This study further demonstrates the potential of the PCI technology in combination with important new classes of therapies. 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."