Subependymal giant cell astrocytoma medical therapy

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Ifeoma Odukwe, M.D. [2], Sujit Routray, M.D. [3]

The mainstay therapy for subependymal giant cell astrocytoma is surgery, but medical therapy is preferred in some cases. Mammalian target of rapamycin (mTOR) inhibitors, everolimus and rapamycin, are the medications used. They are capable of reducing the size of the tumor and in some cases, the tumors grow back after upon cessation of use. The most common side effects associated with the use of mTOR inhibitors are stomatitis and upper respiratory tract infections.

• The mainstay treatment of subependymal giant cell astrocytoma is surgical resection but medical therapy may be used in certain cases such as:

• Bilaterally located subependymal giant cell astrocytomas
• Invasive lesions to the neighboring structures
• Growing residual tumors
• Lesions unlikely to be treated with gross total resection
• Multiple lesions

• The goal of medical therapy is to shrink or stabilize the tumor.^[1]
• Contraindications to treating subependymal giant cell astrocytoma with medical therapy include:^[1]

• The tumors that cause significant hydrocephalus with impending herniation
• Patients with severe acute infections

• Everolimus

• Everolimus may be associated with marked volume reduction of the tumor and a reduction in the frequency of seizures. The reduction in the primary tumor is more rapid during the first three months of treatment.^[2]
• It may be associated with an improvement in the quality of life and cognition score overtime.^[2]
• The chemical composition of everolimus is similar to rapamycin.^[1]
• Everolimus has a greater bioavailability and shorter half life in comparison to rapamycin.
• The dosing of everolimus depends on the body surface area of the patient:^[1]

                0.5 m2 to 1.2 m2: 2.5 mg once daily

                1.3 m2 to 2.1 m2: 5 mg once daily

                >2.2 m2: 7.5 mg once daily

• Rapamycin

• Rapamycin may be associated with a decrease in size of the tumor.^[3]
• The standard dosage is 1.5 mg/m2 per day. ^[1]
• In adults, this regimen could be used: Rapamycin PO 0.2 mg/kg/day.^[3]
• If the drug is stopped, the tumors may regrow.^[4]

• The dose of mTORi can be reduced after an initial response with the tumor volume reduction retained. ^[5]
• Stomatitis and upper respiratory infections are the most common adverse effects of mTOR inhibitors. This is due to suppression of the immune system by the medications. Other adverse effects include bronchitis, leukopenia, vomiting, thrombocytopenia, acneiform rash, hypercholesterolemia, and impaired wound healing.^[6][1]

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