Efficacy and safety of imatinib mesylate in advanced gastrointestinal stromal tumors.
BACKGROUND
Constitutive activation of KIT receptor tyrosine kinase is critical in the pathogenesis of gastrointestinal stromal tumors. Imatinib mesylate, a selective tyrosine kinase inhibitor, has been shown in preclinical models and preliminary clinical studies to have activity against such tumors.


METHODS
We conducted an open-label, randomized, multicenter trial to evaluate the activity of imatinib in patients with advanced gastrointestinal stromal tumor. We assessed antitumor response and the safety and tolerability of the drug. Pharmacokinetics were assessed in a subgroup of patients.


RESULTS
A total of 147 patients were randomly assigned to receive 400 mg or 600 mg of imatinib daily. Overall, 79 patients (53.7 percent) had a partial response, 41 patients (27.9 percent) had stable disease, and for technical reasons, response could not be evaluated in 7 patients (4.8 percent). No patient had a complete response to the treatment. The median duration of response had not been reached after a median follow-up of 24 weeks after the onset of response. Early resistance to imatinib was noted in 20 patients (13.6 percent). Therapy was well tolerated, although mild-to-moderate edema, diarrhea, and fatigue were common. Gastrointestinal or intraabdominal hemorrhage occurred in approximately 5 percent of patients. There were no significant differences in toxic effects or response between the two doses. Imatinib was well absorbed, with pharmacokinetics similar to those reported in patients with chronic myeloid leukemia.


CONCLUSIONS
Imatinib induced a sustained objective response in more than half of patients with an advanced unresectable or metastatic gastrointestinal stromal tumor. Inhibition of the KIT signal-transduction pathway is a promising treatment for advanced gastrointestinal stromal tumors, which resist conventional chemotherapy.
Demetri
George D
GD
Dana-Farber Cancer Institute and Harvard Cancer Center, Boston, MA 02115, USA.
von Mehren
Margaret
M
Blanke
Charles D
CD
Van den Abbeele
Annick D
AD
Eisenberg
Burton
B
Roberts
Peter J
PJ
Heinrich
Michael C
MC
Tuveson
David A
DA
Singer
Samuel
S
Janicek
Milos
M
Fletcher
Jonathan A
JA
Silverman
Stuart G
SG
Silberman
Sandra L
SL
Capdeville
Renaud
R
Kiese
Beate
B
Peng
Bin
B
Dimitrijevic
Sasa
S
Druker
Brian J
BJ
Corless
Christopher
C
Fletcher
Christopher D M
CD
Joensuu
Heikki
H
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D001549:Benzamides; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000188:drug therapy* / Q000473:pathology; D006801:Humans; D000068877:Imatinib Mesylate; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics; D011743:Pyrimidines / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D012074:Remission Induction; D015398:Signal Transduction / Q000187:drug effects; D017154:Stromal Cells / Q000473:pathology; D016019:Survival Analysis
D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D011743:Pyrimidines; D000068877:Imatinib Mesylate; D011505:Protein-Tyrosine Kinases; D019009:Proto-Oncogene Proteins c-kit