A prospective, multicenter, phase 2 study of imatinib mesylate in korean patients with metastatic or unresectable gastrointestinal stromal tumor.
OBJECTIVE
This prospective, multicenter, phase 2 study evaluated the efficacy and safety of imatinib mesylate and assessed KIT and PDGFRA gene mutation status in Korean patients with gastrointestinal stromal tumors (GISTs).


METHODS
Forty-seven patients with pathologically proven KIT-positive metastatic or unresectable GISTs were accrued from eight institutions in Korea. Imatinib was administered orally at 400 mg once daily. In case of disease progression, the dose was escalated to 600 mg once daily, then 400 mg twice daily. KIT and PDGFRA mutations were analyzed in 29 of the 47 patients.


RESULTS
Imatinib produced partial responses in 30 patients (63.8%; 95% confidence interval, 50.1-77.6%) and stable disease in 13 patients (27.7%). The median time to response was 2.6 months (range, 1.0-6.2 months). With a median follow-up of 62 months (range, 32-67 months), 4-year progression-free survival and overall survival rates were 50 and 65%, respectively. The most common adverse events were anemia, neutropenia, edema, and skin rash (predominantly of grade 1-2). There were no treatment-related deaths. In the subset evaluated for mutational status, 24 patients (82.8%) had KIT exon 11 mutations and 1 (3.4%) had a KIT exon 9 mutation.


CONCLUSIONS
Imatinib is effective and safe in Korean patients with metastatic or unresectable GIST.
Ryu
Min-Hee
MH
Department of Internal Medicine, Division of Oncology, Asan Medical Center, Songpa-Gu, Seoul, Korea.
Kang
Won Ki
WK
Bang
Yung-Jue
YJ
Lee
Kyung Hee
KH
Shin
Dong Bok
DB
Ryoo
Baek-Yeol
BY
Roh
Jae Kyung
JK
Kang
Jin-Hyoung
JH
Lee
Hyoungnam
H
Kim
Tae Won
TW
Chang
Heung Moon
HM
Park
Joon Oh
JO
Park
Young Suk
YS
Kim
Tae-You
TY
Kim
Min Kyoung
MK
Lee
Woon Kee
WK
Kang
Hye Jin
HJ
Kang
Yoon-Koo
YK
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001549:Benzamides; D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D005838:Genotype; D006801:Humans; D000068877:Imatinib Mesylate; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D010879:Piperazines / Q000627:therapeutic use*; D011110:Polymorphism, Genetic; D011379:Prognosis; D011446:Prospective Studies; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000378:metabolism; D011743:Pyrimidines / Q000627:therapeutic use*; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000235:genetics / Q000378:metabolism; D012074:Remission Induction; D012307:Risk Factors; D015996:Survival Rate; D016896:Treatment Outcome
D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D011743:Pyrimidines; D000068877:Imatinib Mesylate; D011505:Protein-Tyrosine Kinases; D019009:Proto-Oncogene Proteins c-kit; D020796:Receptor, Platelet-Derived Growth Factor alpha