If a patient with ovarian cancer or mesothelioma develops metastases that spread to the abdominal cavity, her chances of survival past five years goes down to less than 40 percent, even after the tumor is removed. A research team at Boston University has one solution--a drug-loaded nanoparticle that responds to the acidic pH inside tumor cells by expanding and releasing the anticancer agent paclitaxel slowly over a period of 24 hours. The nanoparticles not only decreased tumor growth, but prevented new tumors from implanting themselves in the abdominal cavity.
The goal was to create a nanoparticle that would release paclitaxel only when taken up by tumors, release drug slowly to maximize the number of dividing cells exposed to the drug, and remain in the vicinity of the tumors while it released the drug. In tests, the paclitaxel-loaded nanoparticles released about 4 percent of their drug load each hour for 24 hours, creating a sustained load of drug in the vicinity of the nanoparticle. When added to mesothelioma cells growing in culture, the drug-loaded nanoparticles killed a substantial number of cells.
Next, they tried it on mice that had an aggressive form of mesothelioma. The results looked good. Tumor size was reduced with the expandable nanoparticles, and the mice treated lived nearly twice as long as those who were given paclitaxel without the nanoparticles.