Clinical characteristics and therapeutic responses in patients with germ-line AIP mutations and pituitary adenomas: an international collaborative study.

Context: AIP mutations (AIPmut) give rise to a pituitary adenoma predisposition that occurs in familial isolated pituitary adenomas and less often in sporadic cases. The clinical and therapeutic features of AIPmut-associated pituitary adenomas have not been studied comprehensively. Objective: The objective of the study was to assess clinical/therapeutic characteristics of AIPmut pituitary adenomas. Design: This study was an international, multicenter, retrospective case collection/database analysis. Setting: The study was conducted at 36 tertiary referral endocrine and clinical genetics departments. Patients: Patients included 96 patients with germline AIPmut and pituitary adenomas and 232 matched AIPmut-negative acromegaly controls. Results: The AIPmut population was predominantly young and male (63.5%); first symptoms occurred as children/adolescents in 50%. At diagnosis, most tumors were macroadenomas (93.3%); extension and invasion was common. Somatotropinomas comprised 78.1% of the cohort; there were also prolactinomas (n 13), nonsecreting adenomas (n 7), and a TSH-secreting adenoma. AIPmut somatotropinomas were larger (P 0.00026), with higher GH levels (P 0.00068), more frequent extension (P 0.018) and prolactin cosecretion (P 0.00023), and occurred 2 decades before controls (P0.000001). Gigantism was more common in the AIPmut group (P0.000001). AIPmut somatotropinoma patients underwent more surgical interventions (P 0.00069) and had lower decreases in GH (P 0.00037) and IGF-I (P 0.028) and less tumor shrinkage with somatostatin analogs (P 0.00001) vs. controls. AIPmut prolactinomas occurred generally in young males and frequently required surgery or radiotherapy. Conclusions: AIPmut pituitary adenomas have clinical features that may negatively impact treatment efficacy. Predisposition for aggressive disease in young patients, often in a familial setting, suggests that earlier diagnosis of AIPmut pituitary adenomas may have clinical utility.