A group of researchers from the United States and the United Kingdom has created a new cancer drug delivery system that builds on a new approach known as "metronomic dosage regimen," which uses significantly lower doses of chemotherapeutic drugs but at more frequent time intervals.

"Our goal is to significantly reduce tumors, slow or stop their regrowth, and allow a person's body and immune system time to recover its health and natural abilities to fight cancer," Adam Alani, an associate professor in the Oregon State University (OSU)/Oregon Health & Science University College of Pharmacy, and lead author on a new study published in Chemistry of Materials, was quoted as explaining in a news release from OSU.

"I'm very optimistic this is possible, and that it could provide an entirely new approach to cancer treatment", said Alani.

While the approach has multiple goals of killing cancer cells, creating a hostile biological environment for their growth, reducing toxicity from the drug regimen and avoiding the development of resistance to the cancer drugs being used, the new system is designed to dramatically slow and control tumors on a long-term, sustained basis, not necessarily aiming for their complete elimination.

"This new system takes some existing cancer therapy drugs for ovarian cancer, delivers both of them at the same time and allows them to work synergistically," said Alani.

"Imagine if we could manage cancer on a long-term basis as a chronic condition, like we now do high blood pressure or diabetes. This could be a huge leap forward."

Most conventional cancer chemotherapy is based on the use of "maximum tolerable doses" of a drug, in an attempt to completely eliminate cancer or tumors. In some cases such as ovarian cancer, however, drug-free intervals are needed to allow patient recovery from side effects, during which tumors can sometimes begin to grow again or develop resistance to the drugs being used.

The types of cancers the "metronomic dosage regimen" may best lend itself to are those that are quite complex and difficult to treat with conventional regimens based on "maximum tolerable dose." This includes ovarian, sarcoma, breast, prostate, and lung cancers.

One example of the new approach, now in trial stages, is use of two drugs already common in ovarian cancer treatment, paclitaxel and rapamycin, but at levels a tenth to a third of the maximum tolerable dose. One drug attacks cancer cells; the other inhibits cancer cell formation and the growth of blood vessels at tumor sites.

The system developed in the research takes the process a step further. It attaches these drugs to polymer nanoparticles that migrate specifically into cancer cells and are designed to release the drugs at a particular level of acidity that is common to those cells. The low doses, careful targeting of the drugs and their ability to work in synergy at the same time appeared to greatly increase their effectiveness, while almost completely eliminating toxicity.

Source : XINHUA