Paclitaxel particles extend life threefold in mouse bladder cancer

By delivering paclitaxel in nanoparticles directly to the tumors, researchers have been able to deliver three times the normal dose in mice with advanced bladder cancer. This could mean better control of late-stage cancer with fewer side effects.

Bladder cancer is the fourth most common cancer in men. It is very treatable at its early stages, but as it advances, the outcome becomes less good, and the prognosis for the disease has changed little in three decades. Paclitaxel (Taxol), developed by Bristol-Myers Squibb ($BMY), is a standard treatment for this and many other cancers. However, its side effects can range from simply unpleasant to quite dangerous, such as increased risk of infection and potentially life-threatening allergic reactions to the carrier oil.

The nanoparticle delivery system, developed at the University of California at Davis, is based on tiny bubbles, known as micelles, which have molecules on their surface that can target the tumor cells, and payloads of paclitaxel in their hollow centers.

Mice with highly aggressive bladder cancers were dosed with the delivery system equivalent to the standard dose of paclitaxel, or at three times the standard dose. Those that got the normal levels of paclitaxel had lower levels of tumor growth and better survival than untreated mice.

The mice given the higher dose took longest to develop tumors and had more days of tumor control, and they survived three times longer than mice treated with standard doses of paclitaxel (without the delivery system). There were fewer side effects in the mice getting the drug with the delivery system, and no deaths.

When the mice were given bladder cancer homing micelles loaded with imaging agents, the researchers could see that these were targeting the bladder cancer cells rather than the human cells, and showed that the same technology could be used to diagnose bladder cancer, or monitor its progress.

"We have developed a novel, multifunctional nanotherapeutics platform that can selectively and efficiently deliver both diagnostic and therapeutic agents to bladder tumors," said Chong-Xian Pan of UC Davis.

This is very early-stage research, and more animal studies and human studies are needed before it could reach the market, but it could be a small step forward for a hard to treat disease.

- read the press release