New drug delivery device 'could transform cancer treatment'

A new device that delivers cancer drugs directly into tumors without relying on perfusion via the bloodstream, could increase life expectancy for patients with pancreatic, breast and other solid cancers, say researchers.

Pancreatic cancer is difficult to treat surgically because usually the tumor is entwined with major organs.

The new device uses a method called "iontophoresis" where an electrical field drives chemotherapy drugs directly into the tumor, preventing their growth, and in some cases, even shrinking them, says the team from the University of North Carolina (UNC) at Chapel Hill.

The electrical field is conveyed via electrodes either implanted internally - for example to treat a pancreatic tumor - or applied externally to the skin - for example to treat an underlying breast tumor.

The UNC researchers describe the iontophoretic device and how they tested it on human pancreatic tumors grafted into mice and dogs, in the journal Science Translational Medicine.

Pancreatic cancer is relatively rare, however it is the fourth leading cause of cancer-related death in the US where estimates suggest in 2014 more than 46,000 people were diagnosed with the disease and nearly 40,000 died of it.

Limits of current methods

The main reason three quarters of people who develop pancreatic cancer do not survive more than 12 months after diagnosis - a statistic that has not changed in 40 years - is because by the time the cancer is found, it is at an advanced stage and difficult to treat.

Unfortunately, while surgery is the best option for curing pancreatic cancer, not many patients can have it because by the time their tumor is detected it has entwined itself with major organs and blood vessels.

Current ways of delivering chemotherapy are also limited because the pancreatic cancer cells are well-protected by a fortress of tissue that impedes the perfusion of drugs that could otherwise shrink the tumor or stop it growing.

Also, pancreatic cancer tumors do not have a good blood supply, thus limiting the effectiveness of drug delivery via the bloodstream. Increasing the dose is not an option because it increases toxicity to the rest of the body.

The new device delivered drugs into tumors more effectively than IV

In their study, the team showed that the iontophoretic device delivered chemotherapy drugs into the tumors much more effectively than the conventional intravenous (IV) method, and also achieved higher concentrations of the drugs in the tumor without increasing toxicity to the rest of the body.

For example, noting the result of one test, the authors write:

"Device delivery of gemcitabine in dogs resulted in more than 7-fold difference in local drug concentrations and 25-fold lower systemic drug levels than the IV treatment."

"Once this goes to clinical trials, it could shift the paradigm for pancreatic cancer treatments - or any other solid tumors where standard IV chemotherapy drugs are hard to get to."

Funds for the study came from the University Cancer Research Fund and the National Institutes of Health.

References:

1.  Local iontophoretic administration of cytotoxic therapies to solid tumors, James D. Byrne et al., Sci Transl Med, doi:10.1126/scitranslmed.3009951, published online 4 February 2015, abstract.
2.  The University of North Carolina at Chapel Hill news release, accessed 6 February 2015.
3.  National Cancer Institute snapshot of pancreatic cancer, accessed 6 February 2015.