By Wendy Diller
Looking for early evidence that its key cancer drug imatinib mesylate (Gleevec) was effective in patients with inoperable gastrointestinal stromal tumors (GIST), Novartis AG tried a somewhat novel approach: using PET imaging and FDG contrast agent to visualize changes in the tumor. Within an hour of administering the drug to patients in a Phase I study, the tumors exhibited metabolic changes, converting from FDG positive to FDG negative. The alterations themselves didn't get Novartis researchers excited. Rather, they were struck by the correlation between those changes and subsequent alterations in the anatomical structure of the tumor, which became apparent only months after treatment