Control of aggressive fibromatosis by treatment with imatinib mesylate. A case report and review of the literature

There has been only one report available that focuses on the treatment with imatinib mesylate of two individual persons with aggressive fibromatosis. The authors concluded that after long-term treatment, for 9 and 11 months, with imatinib mesylate, both patients demonstrated radiographic and clinical responses. The novel therapy should be considered as salvage in patients with aggressive fibromatosis expressed platelet-derived growth factor receptor—alfa, beta (PDGFR-alfa, PDGFR-beta), and/or c-kit, whose tumors are uncontrollable by the standard management. On the other hand, the number of kinases blocked by imatinib mesylate is notching up, for instance the tyrosine kinase, which is associated with macrophage-colony stimulating factor receptor (M-CSFR).

The patient was suffering from aggressive fibromatosis after prior therapy including surgery (R2), radiotherapy, and systemic treatment with combination of tamoxifen and sulindac. The tumor specimen was immunostained for PDGFR-beta and c-kit (CD117), and PDGFR-alfa and cytokines platelet-derived growth factor-alfa and beta were not assessed. The tests for both assessed molecules revealed negative results. In spite of this, the patient underwent a unique treatment with imatinib mesylate at the dose of 400 mg orally once daily for 3 years and 2 months.

After three months of the therapy, radiographic (met criteria of SD but small decrease of the tumor was noted) and clinical responses were recorded for the first time. The same was seen after 6 and 13 months of therapy continuation with imatinib mesylate. Currently, the patient is treated with imatinib mesylate (400 mg orally once daily) without any toxicity effects. The last MRI revealed readily a smaller tumor (35 × 20 mm) after such a therapy lasted more than 3 years.

Treatment with imatinib mesyalte has been a well-accepted therapy for chronic myelagenous leukemia (CML) and gastrointestinal stromal tumors (GIST). There have been established four kinases (p210^bcr/abl, c-kit, PDGFR-alfa, PDGFR-beta) suggested as the target for imatinib mesylate. Other potential targets will be discovered as it has lately been determined that M-CSFR kinase activity was blocked by imatinib mesylate. The salvage therapy for aggressive fibromatosis with imatinib mesylate seems to be an attractive opportunity for patients with the advanced disease, whose prior therapy failed.