Response of imatinib-resistant extra-abdominal aggressive fibromatosis to sunitinib: Case report and review of the literature on response to tyrosine kinase inhibitors

Purpose: Aggressive fibromatosis (AF) is usually a slowly growing locally invasive tumor, but may exhibit a much more aggressive phenotype. The role of chemotherapy in AF is not well defined, but can be useful in some cases. We examined the response of a case to both imatinib and sunitinib. Methods: We report a case of an aggressive multicentric extra-abdominal AF that was responsive to sunitinib, but resistant to imatinib. Results: A 23-year-old woman developed painful multifocal AF of both legs and gluteal muscles that progressed after surgery and treatment with methotrexate/vinblastine and pegylated-liposomal doxorubicin. She received six cycles of ifosfamide/etoposide (IMV), and obtained a good response with elimination of pain. After 5 months, she developed progression and again received six cycles of IMV, with cessation of symptoms. After 13 months, tumors recurred. Although the AF was symptomatic and progressing, she was hesitant to receive chemotherapy and began treatment with sunitinib 50 mg/day for 28 days of a 42-day cycle. At 4 months, she could walk on her heels without pain. After 13 months of sunitinib, therapy was changed to imatinib 400 mg/day; after 7 days she noticed increasing pain in the AF lesions and decreased knee flexibility. Imatinib was continued, but after 2 months of imatinib, she could only walk a few steps due to pain. Sunitinib was reinstituted at 37.5 mg/day and symptoms improved within 1.5 weeks, with a marked reduction of symptoms at 1 month. She was doing well with a normal activity level, 32 months after initially beginning sunitinib. Conclusions: We conclude that sunitinib may be useful in some cases of AF.