Salvage therapy with temozolomide in patients with aggressive or metastatic pituitary adenomas: experience in six cases

Abstract

ObjectiveThe prognosis of either pituitary carcinoma or aggressive pituitary adenoma resistant to standard therapies is poor. We assessed the efficacy of treatment with temozolomide, an oral second-generation alkylating agent, in a consecutive series of six patients with aggressive pituitary adenomas.DesignThis was a 1-year prospective study of temozolomide therapy in six consecutive patients with pituitary carcinoma (one case) or atypical pituitary adenoma (five cases) resistant to standard therapies. There were three males and three females. Age at enrollment ranged between 52 and 64 years. Temozolomide was given orally at a dose of 150–200 mg/m2 per day for 5 days every 4 weeks for a maximum of 12 cycles.MethodsResponse assessment was based on measurable change in tumor size, as assessed on magnetic resonance imaging, and hormone levels. Response was defined as reduction of at least 50% of tumor size and hormone levels.ResultsFour patients completed the 12 cycles of temozolomide treatment, as planned. Two patients stopped the drug after 3 and 6 months respectively because of the progression of disease. Two patients responded to temozolomide, while the remaining two patients had stable disease. Immunohistochemistry for O6-methylguanine-DNA methyltransferase (MGMT) in tumor sample showed a partial association with treatment response.ConclusionsTemozolomide treatment has a wide range of efficacy in patients with pituitary carcinoma or locally aggressive pituitary adenoma. Positive staining for MGMT seems likely to predict a lower chance of response.