Imatinib, known commercially as Gleevec, worked best when
combined with the chemotherapy paclitaxel to slash the incidence
of bone metastases and the size of tumors in mice injected with
a multiple-drug resistant form of prostate cancer. Tumors were
found in only 4 of 18 mice treated with the combination, median
tumor weight was one tenth of a gram, and the cancer spread to
the lymph nodes in three cases. Tumors grew in all 19 control
mice, their median tumor weight was 1.3 grams, and all
metastasized to the lymph nodes. This extremely drug-resistant
form of the cancer, designed by the research team to emulate the
grim clinical reality of prostate cancer that has spread into
the bone, successfully warded off the combined medications in
lab experiments, said Isaiah J. Fidler, D.V.M., Ph.D., chair of
the Department of Cancer Biology and director of the Cancer
Metastasis Research Center at M. D. Anderson. "Why, then, did it
work so well in the animal? Because we didn't attack the tumor,
we attacked the blood ves