Temozolomide retreatment in a recurrent prolactin-secreting pituitary adenoma: Hormonal and radiographic response

Temozolomide is an oral alkylating agent with schedule-dependent antitumor activity against high-grade malignancies including high-grade glioma. Increasingly, reports have suggested that temozolomide may have activity as a salvage therapy for aggressive, recurrent pituitary adenomas or carcinomas that fail surgery, radiation and other pharmacotherapy. To our knowledge, temozolomide retreatment following initial responsiveness has not previously been demonstrated.

A woman was diagnosed with a prolactin-secreting pituitary adenoma in 1995 (age 44). Despite bromocriptine therapy, transphenoidal resection, radiotherapy, and cabergoline treatment she experienced continued clinico-radiographic progression, and temozolomide was initiated in 2011. She received three treatment cycles with rapid, dramatic clinico-radiographic response, and 99.3% reduction in serum prolactin. After three years of close observation, she developed recurrent radiographic progression and prolactin elevation. She was re-initiated on temozolomide, and after four cycles, clinical, radiographic and hormonal response was observed with a 92.2% reduction in serum prolactin.

Temozolomide is an increasingly described treatment option for refractory pituitary adenomas and carcinomas. In the current report, we document rapid biochemical response following retreatment with temozolomide in aggressive pituitary adenoma. When "off label" salvage therapy with temozolomide is offered for patients with recurrent prolactinomas, retreatment at the time of recurrence can be considered.