Combination of Hydroxyurea and Verapamil for Refractory Meningiomas

Meningiomas account for 20% of primary adult brain tumors, occurring at an annual incidence of 6 per 100,000 (Louis, Scheithauer et al. 2000). Complete surgical resection is the treatment of choice but may not possible when the tumor invades critical structures (e.g., skull base, sagittal sinus) (Mirimanoff, Dosoretz et al. 1985; al-Rodhan and Laws 1990; Al-Rodhan and Laws 1991; Newman 1994; De Monte 1995; Levine, Buchanan et al. 1999; Barnett, Suh et al. 2000; Ragel and Jensen 2003). Up to 20% of meningiomas exhibit a more aggressive phenotype that does not respond to standard therapies (Kyritsis 1996). Adjuvant therapies are critical for patients with this subset of meningiomas. Radiation therapy and stereotactic radiosurgery are good adjuvant therapies but are limited by radiation neurotoxicity, tumor size constraints, and injury to adjacent vascular structures or cranial nerves (Goldsmith, Wara et al. 1994; Barnett, Suh et al. 2000; Goldsmith and Larson 2000). Standard chemotherapeutic treatments have been disappointing (Kyritsis 1996). Even drugs like temozolomide that have shown efficacy against malignant brain tumors have failed to inhibit the growth of refractory meningiomas in a phase II study (Chamberlain, Tsao-Wei et al. 2004).