Promising drug cuts tumor metabolism. (Drug Research).

Early safety trials of an experimental medicine suggest that it could be used for treating several serious cancers.

Gastrointestinal stromal tumor, or GIST, is an unusual but highly lethal form of cancer. Two years ago, George Demetri of the Dana-Farber Cancer Institute in Boston and his colleagues demonstrated that the drug imatinib, also called Gleevec, can dramatically shrink tumors in people with GIST (SN: 5/26/01, p. 328). That drug has since become standard therapy for people with the disease. After treatment for an average of about 18 months, however, GIST becomes resistant to imatinib and tumor growth accelerates.

Lately, Demetri has been testing a new experimental drug, called SU11248, against imatinib-resistant GIST. SU11248 has been tested in mice, but its safety and effectiveness in people haven't been established.

Demetri's team gave varying doses of SU11248 to 45 GIST patients whose cancers either never responded to imatinib or had become resistant to the drug.

Aberrant metabolic activity that supports tumor growth dropped off in nearly three-quarters of the people taking the experimental drug, Demetri and his colleagues found. Positron-emission tomography images taken after patients began receiving SU11248 showed reduced tumor metabolism, compared with images taken prior to treatment.

In other recent experiments with SU11248, Jean-Pierre Armand of the Institut Gustave Roussv in Villejuif, France, and his colleagues report preliminary data suggesting that the drug might also work against kidney cancers and neuroendocrine tumors, which can arise in various parts of the body.

Both Armand and Demetri found fatigue to be the most common side effect that caused patients to discontinue treatment with SU11248. Other side effects, which will have to be monitored as trials continue, include damage to bone marrow and gastrointestinal bleeding.--B.H.