Despite promising early response rates to the oral chemotherapy drug temozolomide for aggressive pituitary tumors and carcinomas, long-term efficacy is less likely, according to study results published in The Journal of Clinical Endocrinology & Metabolism.

Retrospective survey data were available on temozolomide treatment in patients with aggressive pituitary tumors or pituitary carcinomas. The mean age at diagnosis was 45±15 years (range, 10-74 years), and 47% of the group members were female. Temozolomide therapy was initiated in 47 patients: 34 with aggressive pituitary tumors and 13 with pituitary carcinomas. The majority of patients started temozolomide therapy 8 years after initial diagnosis (mean age at initiation, 56±14 years; range, 24-78 years) and followed a standard regimen (median, 6 cycles).

Outcome data on radiologic response to temozolomide were available for 46 patients. At the end of the temozolomide treatment phase, tumor regression was seen in 15 patients, stable disease in 17, and tumor progression in 14. After a median follow-up period of 32 months, tumor progression increased to 29 patients, with tumor regression and disease stability decreasing to 9 and 8 patients, respectively. Tumor progression was documented after a median of 16 months after initiation of temozolomide. The median estimated progression-free survival was 23 months and did not differ between patients with aggressive pituitary tumors and those with carcinomas.

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Temozolomide was generally well tolerated compared with most other chemotherapies; 6 of 46 patients in this study were required to cease therapy because of severe adverse events, which was in line with previous data for the drug’s tolerance.

These study results may have been affected by differences in dosing regimens between the various medical centers caring for patients in the cohort; for example, administration in conjunction with radiation therapy vs monotherapy. The investigators also noted, “A trial of three monthly cycles might be too short to assess [temozolomide] efficacy. We would therefore suggest a prolonged trial of at least six cycles before deciding to withdraw [temozolomide] therapy, if safety concerns do not occur in the meantime.”

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Reference

Elbelt U, Schlaffer SM, Buchfelder M, et al. Efficacy of temozolomide therapy in patients with aggressive pituitary adenomas and carcinomas – a German survey [published online November 20, 2019]. J Clin Endocrinol Metab. doi:10.1210/clinem/dgz211