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Published on: April 3, 2026
Imatinib mesylate as a preoperative therapy in dermatofibrosarcoma: results of a multicenter phase II study on 25
Delphine Kérob1, Raphael Porcher, Olivier Vérola
1AP-HP Department of Dermatology, Hôpital Saint-Louis, Universite Paris 7 Denis Diderot, Paris, France. delphine.kerob@sls.aphp.fr
Aims:
The treatment of dermatofibrosarcoma protuberans (DFSP) involves wide local excision with frequent need for reconstructive surgery. A t(17;22) translocation resulting in COL1A1-PDGFB fusion is present in >95% of cases. Certain patient observations and a report on nine patients suggest that imatinib mesylate, targeting platelet-derived growth factor receptor beta, has clinical potential in DFSP. The primary aim of this phase II multicenter study was to define the percentage of clinical responders (Response Evaluation Criteria in Solid Tumors) to a 2-month preoperative daily administration of 600 mg of imatinib mesylate before wide local excision. The secondary aims were to determine tolerance, objective response from imaging results (ultrasound and magnetic resonance imaging), and pathologic responses observed in sequential tissue specimens.
Patients And Methods:
A two-stage flexible design was used with interim analysis after the recruitment of six patients. Twenty-five adults suffering from primary or recurrent DFSP were included from July 2004 to May 2006.
Results:
The COL1A1-PDGFB fusion gene was detected in 21 out of 25 patients following fluorescence in situ hybridization analysis (two cases were noninformative). A clinical response was achieved in nine (36%) patients (95% confidence interval, 18.9-57.5). The median relative tumoral decrease was 20.0% (range, -12.5 to 100). Apart from expected grade 1 or 2 side effects, we observed one grade 3 neutropenia, one grade 3 maculopapular rash, and one grade 4 transient transaminitis.
Conclusion:
Our results support the use of imatinib in a neoadjuvant setting in nonresectable DFSP, or when surgery is difficult or mutilating. These results will be useful for setting hypotheses in the evaluation of new drugs to treat primary or secondary resistance to imatinib.
Insights
Imatinib mesylate showed clinical response in 36% of dermatofibrosarcoma protuberans (DFSP) patients. This study supports imatinib
Area of Science:
- Oncology
- Medical Research
- Pharmacology
Background:
- Dermatofibrosarcoma protuberans (DFSP) treatment typically requires wide local excision and reconstructive surgery.
- A specific genetic translocation, t(17;22) leading to COL1A1-PDGFB fusion, is found in over 95% of DFSP cases.
- Preclinical data and case reports suggest imatinib mesylate, a platelet-derived growth factor receptor beta inhibitor, has potential in DFSP treatment.
Purpose of the Study:
- To evaluate the clinical response rate of imatinib mesylate in patients with DFSP.
- To assess the safety and tolerability of neoadjuvant imatinib mesylate therapy.
- To determine objective and pathologic responses to imatinib mesylate prior to surgery.
Main Methods:
- A phase II multicenter study involving 25 adult patients with primary or recurrent DFSP.
- Patients received 600 mg of imatinib mesylate daily for 2 months preoperatively.
- Response Evaluation Criteria in Solid Tumors (RECIST) criteria were used to assess clinical response; imaging and tissue analysis were also performed.
Main Results:
- The COL1A1-PDGFB fusion gene was detected in 21 of 25 patients.
- A clinical response was observed in 36% of patients (95% CI, 18.9-57.5), with a median tumor decrease of 20%.
- Adverse events were mostly grade 1 or 2, with some grade 3 or 4 events including neutropenia, rash, and transaminitis.
Conclusions:
- Imatinib mesylate demonstrates clinical efficacy in the neoadjuvant treatment of DFSP, particularly for nonresectable or surgically challenging cases.
- The findings provide a basis for future research into imatinib resistance and novel therapeutic strategies for DFSP.
- Neoadjuvant imatinib offers a potential option to improve surgical outcomes in DFSP.
