Imatinib mesylate in advanced dermatofibrosarcoma protuberans: pooled analysis of two phase II clinical trials.
OBJECTIVE
Dermatofibrosarcoma protuberans (DFSP) is a dermal sarcoma typically carrying a translocation between chromosomes 17 and 22 that generates functional platelet-derived growth factor B (PDGFB).


METHODS
Two distinct phase II trials of imatinib (400 to 800 mg daily) in patients with locally advanced or metastatic DFSP were conducted and closed prematurely, one in Europe (European Organisation for Research and Treatment of Cancer [EORTC]) with 14-week progression-free rate as the primary end point and the other in North America (Southwest Oncology Group [SWOG]) with confirmed objective response rate as the primary end point. In the EORTC trial, confirmation of PDGFB rearrangement was required, and surgery was undertaken after 14 weeks if feasible. The SWOG study confirmed t(17;22) after enrollment.


RESULTS
Sixteen and eight patients were enrolled onto the EORTC and SWOG trials, respectively. Tumor size ranged from 1.2 to 49 cm. DFSP was located on head/neck, trunk, and limb in seven, 11, and six patients, respectively, and was classic, pigmented, and fibrosarcomatous DFSP in 13, one, and nine patients, respectively. Metastases were present in seven patients (lung involvement was present six patients). Eleven patients (4%) had partial response as best response, and four patients had progressive disease as best response. Median time to progression (TTP) was 1.7 years. Imatinib was stopped in 11 patients because of progression, one patient because of toxicity, and two patients after complete resection of disease. Median overall survival (OS) time has not been reached; 1-year OS rate was 87.5%.


CONCLUSIONS
Imatinib is active in DFSP harboring t(17;22) including fibrosarcomatous DFSP, with objective response rate approaching 50%. Response rates and TTP did not differ between patients taking 400 mg daily versus 400 mg twice a day.
Rutkowski
Piotr
P
Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Roentgena 5, 02-781 Warsaw, Poland. rutkowskip@coi.waw.pl
Van Glabbeke
Martine
M
Rankin
Cathryn J
CJ
Ruka
Wlodzimierz
W
Rubin
Brian P
BP
Debiec-Rychter
Maria
M
Lazar
Alexander
A
Gelderblom
Hans
H
Sciot
Raf
R
Lopez-Terrada
Dolores
D
Hohenberger
Peter
P
van Oosterom
Allan T
AT
Schuetze
Scott M
SM
D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000009:adverse effects / Q000627:therapeutic use*; D001549:Benzamides; D017322:Clinical Trials, Phase II as Topic; D018223:Dermatofibrosarcoma / Q000188:drug therapy* / Q000401:mortality; D004334:Drug Administration Schedule; D057239:Early Termination of Clinical Trials; D005260:Female; D006801:Humans; D000068877:Imatinib Mesylate; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D011743:Pyrimidines / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*
D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D011743:Pyrimidines; D000068877:Imatinib Mesylate