Imatinib mesylate treatment of recurrent meningiomas in preselected patients: a retrospective analysis.

Some unresectable and symptomatic meningiomas recur after conventional radiation therapy or stereotactic radiosurgery and are a therapeutic challenge. Evidence-based data from medical therapy for patients with recurrent meningioma can be deemed insufficient. Because of the prevalent expression of PDGF receptors in meningiomas, the tyrosine kinase imatinib mesylate has attracted interest as a treatment option for this patient group. In this retrospective study we analyzed 18 patients with recurrent meningiomas who were treated at our institution between 1996 and 2008. Nine patients with positive immunohistochemical staining of at least one of the PDGF receptors were given a daily oral dose of 400 mg imatinib mesylate as first, second, or third-line systemic therapy. Immunohistochemical staining was performed on formalin-fixed and paraffin-embedded tumor tissue with antibodies against PDGFR-α and β, c-Kit, Arg, and c-Abl. Imatinib mesylate at a dose of 400-800 mg/day was well tolerated. Of nine patients treated with imatinib, seven had stable disease and two had progressed at the first scan after three months. We observed no complete or partial responses, although prolonged disease stabilization with progression-free survival of 66.7 % at six months was observed. Overall median progression-free survival was 16 months. We conclude that single-agent imatinib mesylate might be a well-tolerated therapeutic option with high achievement of disease stabilization for preselected patients with recurrent meningiomas. Because of the small cohort, non-randomized design, and highly diverse patient population, we propose future prospective studies to validate our results.