Cabergoline in the Management of Residual Nonfunctioning Pituitary Adenoma: A Single-Center, Open-Label, 2-Year Randomized Clinical Trial.

Complete tumor removal by transsphenoidal surgery is usually difficult for large nonfunctioning pituitary adenomas (NFPAs). A validated medical treatment may be useful for their management. This study evaluates the clinical efficacy of the dopaminergic agonist cabergoline for residual NFPA. We conducted a randomized, parallel, open-label clinical trial that compared cabergoline with nonintervention in patients with residual NFPA after transsphenoidal surgery over 2 years. The primary outcome was clinical efficacy (tumor reduction). The secondary outcome was the relationship between tumor dopamine D2 receptor (D2R) expression and clinical responsiveness. Tumor measurements and clinical evaluations were performed every 6 months. In total, 59 and 57 individuals were randomly assigned to the study and control groups, respectively. At the end of the study, residual tumor shrinkage, stabilization, and enlargement were observed in 28.8%, 66.1%, and 5.1% of patients, respectively, in the medical-therapy group and in 10.5%, 73.7%, and 15.8% of patients, respectively, in the control group (P=0.01). The progression-free survival rate was 23.2 and 20.8 months for the study and control groups, respectively (P=0.01). D2R was not associated with cabergoline responsiveness. No major side effects were related to cabergoline use. Cabergoline was an effective drug for treating residual NFPA, and its use was associated with a high rate of tumor shrinkage (ClinicalTrials.gov NCT03271918).