Recent research suggests that a novel material called nanosponge could be up to five times more effective at reducing tumor growth than direct injection. The drug delivery system is likened to filling virus-sized sponges with an anti-cancer drug, attaching chemical linkers that bond to a feature on the surface of tumor cells, then injecting the sponges into the body. When the sponges come into contact with a tumor cell, they either attach to the surface or are sucked into the cell, where they offload their deadly contents in a predictable and controlled manner.

The research team was led by Eva Harth, assistant professor of chemistry at Vanderbilt University, and Dennis E. Hallahan from the Washington University School of Medicine. "Effective targeted drug delivery systems have been a dream for a long time now but it has been largely frustrated by the complex chemistry that is involved," said Harth. "We have taken a significant step toward overcoming these obstacles."

Delivery systems such as these are advantageous because the drug is released directly at the site of the tumor rather than circulating through the body, thus it should be more effective for a given dosage. In addition, there could be less harmful side effects because smaller quantities of the drug have contact with healthy tissue.

Additionally, the nanosponge particles are soluble in water, so the hydrophobic drugs that do not dissolve readily in water can be encapsulated within the nanosponge. Currently these drugs need to be mixed with a chemical called an adjuvant reagent, which can cause adverse side-effects and reduce the efficacy.

Research has shown that drug delivery systems work best when they are smaller than 100 nanometers, and in this study the nanosponge particles were 50 nanometers in size. The beauty of the nanosponge particles is that they can be made smaller or larger by varying the proportion of cross-linker to polymer. "The relationship between particle size and the effectiveness of these drug delivery systems is the subject of active investigation," said Harth.

The system also uses simple, high-yield chemistry, so it will be relatively easy to scale-up for commercial production.

The next step is an experiment with repeated injections, to determine if the nanosponge system can stop and reverse tumor growth. The scientists also plan on performing more comprehensive toxicity studies on the nanosponge delivery system, that are required before it can be used in clinical trials.

The research was published this month in the journal Cancer Research.