A phase II study of imatinib in patients with advanced anaplastic thyroid cancer.
BACKGROUND
Currently, there is no standard treatment for metastatic anaplastic thyroid cancer (ATC). DNA microarray analysis has shown platelet-dervived growth factor receptor (PDGFR) overexpression in ATC relative to well-differentiated thyroid cancer. In p53-mutated/deficient ATC cell lines, cABL is overexpressed, and selective inhibition of cABL results in a cytostatic effect. Imatinib inhibits tyrosine kinase activity of Bcr-ABL and PDGF. We hypothesize that patients with ATC that over-expresses PDGF receptors or cABL will respond to imatinib.


METHODS
Patients with histologically confirmed ATC who had measurable disease and whose disease expressed PDGF receptors by immunohistochemistry were eligible for study. Imatinib was administered at 400 mg orally twice daily without drug holiday. Response to treatment was assessed every 8 weeks. Patients with complete response, partial responses, or stable disease were treated until disease progression. The study was terminated early due to poor accrual.


RESULTS
From February 2004 to May 2007, 11 patients were enrolled and were started on imatinib. At baseline, 4/11 had locoregional disease, 5/11 had distant metastases, and 2/11 had both. Nine of 11 had prior chemoradiation, and 7/11 had thyroidectomy. Eight of 11 were evaluable for response; 4 were excluded for lack of follow-up with radiologic evaluation. The overall response rates at 8 weeks were complete response 0/8, partial response 2/8, and stable disease 4/8. The median time to follow-up was 26 months (ranges 23-30 months). The rate of 6-month progression-free survival was 36% (95% confidence interval, 9%-65%). The rate of 6-month overall survival was 45% (95% confidence interval, 16%-70%). The most common grade 3 toxicity was edema in 25%; other grade 3 toxicities included fatigue and hyponatremia (12.5% each). There were no grade 4 toxicities or treatment related deaths.


CONCLUSIONS
Imatinib appears to have activity in advanced ATC and is well tolerated. Due to difficulty of accruing patients with a rare malignancy at a single institution, further investigation of imatinib in ATC may be warranted in a multi-institutional setting.
Ha
Huan T
HT
Division of Hematology/Oncology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA.
Lee
Julia S
JS
Urba
Susan
S
Koenig
Ronald J
RJ
Sisson
James
J
Giordano
Thomas
T
Worden
Francis P
FP
D000368:Aged; D000970:Antineoplastic Agents / Q000009:adverse effects / Q000627:therapeutic use*; D001549:Benzamides; D002277:Carcinoma / Q000188:drug therapy* / Q000532:radiotherapy; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D000068877:Imatinib Mesylate; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000009:adverse effects / Q000627:therapeutic use*; D047428:Protein Kinase Inhibitors / Q000009:adverse effects / Q000627:therapeutic use*; D011743:Pyrimidines / Q000009:adverse effects / Q000627:therapeutic use*; D017479:Receptors, Platelet-Derived Growth Factor / Q000032:analysis / Q000037:antagonists & inhibitors; D013964:Thyroid Neoplasms / Q000188:drug therapy*
D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D000068877:Imatinib Mesylate; D017479:Receptors, Platelet-Derived Growth Factor