Molecular targeting of platelet-derived growth factor B by imatinib mesylate in a patient with metastatic dermatofibrosarcoma protuberans.
OBJECTIVE
Dermatofibrosarcoma protuberans is caused by activation of the platelet-derived growth factor B (PDGFB) receptor, a transmembrane tyrosine kinase. We investigated the response of dermatofibrosarcoma protuberans to the tyrosine kinase inhibitor imatinib mesylate.


METHODS
A patient with unresectable, metastatic dermatofibrosarcoma protuberans received imatinib mesylate (400 mg bid). Response to therapy was assessed by [18F]fluorodeoxyglucose (FDG) positron emission tomography, magnetic resonance imaging, and histopathologic and immunohistochemical evaluation.


RESULTS
The patient was treated for 4 months with imatinib mesylate. The hypermetabolic uptake of FDG fell to background levels within 2 weeks of treatment, and the tumor volume shrank by over 75% during the 4 months of therapy, allowing for resection of the mass. There was no residual viable tumor in the resected specimen, indicating a complete histologic response to treatment with imatinib mesylate.


CONCLUSIONS
Imatinib mesylate is highly active in dermatofibrosarcoma protuberans. The dramatic response seen in this patient demonstrates that inhibition of PDGFB receptor tyrosine kinase activity can significantly impact viability of at least one type of solid tumor.
Department of Pathology, University of Washington Medical Center, Seattle, WA 98195, USA. bprubin@u.washington.edu
Brian P
BP
Rubin
Scott M
SM
Schuetze
Janet F
JF
Eary
Thomas H
TH
Norwood
Sohail
S
Mirza
Ernest U
EU
Conrad
James D
JD
Bruckner
D000328:Adult; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001549:Benzamides; D018223:Dermatofibrosarcoma / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000473:pathology; D006801:Humans; D000068877:Imatinib Mesylate; D008297:Male; D010879:Piperazines / Q000627:therapeutic use*; D020574:Proto-Oncogene Proteins c-sis / Q000037:antagonists & inhibitors*; D011743:Pyrimidines / Q000627:therapeutic use*; D011877:Radionuclide Imaging; D012878:Skin Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000473:pathology; D013120:Spinal Cord Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000556:secondary
D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D020574:Proto-Oncogene Proteins c-sis; D011743:Pyrimidines; D000068877:Imatinib Mesylate