Temozolomide Therapy in Management of Refractory Pituitary Adenomas: A Case Series of 39 Patients.

Objective: The management of refractory pituitary adenomas (RPAs) presents significant challenges. This study aimed to evaluate the long-term treatment outcomes of patients with RPA managed with temozolomide (TMZ) and to identify potential biomarkers for predicting TMZ treatment response.

Methods: This retrospective case series included patients with RPA who underwent trans-sphenoidal surgery (TSS) or craniotomy at a comprehensive medical center in China between January 2014 and December 2021.

Results: 39 patients with RPA (median age 42 years; 23 males [59%]) were treated with TMZ for a median of 9 cycles. The median follow-up was 34.4 months. Complete response (CR) was observed in 2 patients, partial response (PR) in 11 patients, stable disease (SD) in 9, progressive disease (PD) in 11, and death in 6 patients. O6-methylguanine DNA methyltransferase levels were significantly lower in patients with CR, PR, or SD compared to those with PD or mortality, with mean values of 24.2% and 58.1, respectively. MutS homologs 6 levels were significantly higher in patients with CR, PR, or SD compared to those with PD or mortality, with mean values of 64.2% and 36.9%, respectively. Patients who received concomitant TMZ and external beam radiotherapy showed a significant tumor size reduction of 178,837 mm³ (P < .001) compared to those treated with TMZ alone.

Conclusions: TMZ demonstrates promising efficacy in eliciting tumor responses in patients with PRA. O6-methylguanine DNA methyltransferase and MutS homologs 6 have emerged as potential biomarkers for predicting treatment response. Furthermore, radiation with concurrent TMZ may significantly improve outcomes in patients with RPA.