Abiraterone acetate for treatment of ectopic Cushing syndrome caused by ACTH-producing neuroendocrine tumor: a case report.

Background: Ectopic Cushing syndrome (EAS) secondary to an adrenocorticotropin hormone (ACTH)-releasing neuroendocrine tumor (NET) is a rare diagnosis that can be resistant to standard treatments. Abiraterone acetate (AA) is a selective and irreversible inhibitor of 17α-hydroxylase/17,20-lyase that blocks adrenal steroidogenesis, including cortisol synthesis. In this case, we present the novel use of AA in treating malignant EAS by blocking cortisol synthesis. Case Description: We present a case in which a middle-aged female diagnosed with EAS secondary to metastatic ACTH-releasing NET who presented with progressively worsening weakness, diagnosed with glucocorticoid-induced myopathy associated with autonomic dysregulation. Due to her tenuous clinical status, the patient was not a candidate for any invasive procedures. She was treated with AA which led to a rapid quantitative reduction in the serum cortisol levels and hemodynamic improvement. This temporizing measure allowed for clinical stability, the patient underwent adrenal artery embolization and abiraterone was discontinued. The patient did not experience any further decline in her strength, her symptoms related to myopathy slowly improved, she was discharged to a rehabilitation facility. Conclusions: This case illustrates how the inhibition of cortisol caused by AA can be effectively used in the management of EAS. The potent and rapid effects of AA in blocking endogenous cortisol production may be considered as a temporizing measure in the treatment of malignant EAS.