With the new method, the test dose predicted the patients' blood levels of the drug with less than 10 percent variability.
In a separate study using a test dose and the standard intermittent delivery method, the patients metabolized the drug more slowly as the intermittent doses continued. By the 13th and final dose, on average the variability between the test-dose prediction and the actual levels had grown to more than 20 percent.
The new method may prevent side effects and increase effectiveness by maintaining a more consistent level of drug in the blood and avoiding extreme highs and lows, Shea said. "We hope this novel delivery method will be safer, and we hope it will allow us to give more total drug, which will do a better job by killing more cancer cells."
In the patients' studied, side effects were similar to those seen in current treatment. "This prolonged infusion looks like it's at least as safe as what we've been doing before," Shea said.
Because patients appear to metabolize busulfan more predictably when receiving it by continuous infusion, doctors may be able to more effectively tailor doses to individuals. "This novel delivery method may give us a new opportunity for consistent and targeted dosing for individual patients," Shea said.
Shea and his colleagues are developing a study of such tailored dosing and hope to open a clinical trial by the end of the summer.