Paradoxical responses to pasireotide in a patient with silent corticotroph adenoma that transformed to ACTH-secreting adenoma - case report

Anna Brona^*Aleksandra Zdrojowy-WełnaMarek Bolanowski

• Department and Clinic of Endocrinology and Internal Medicine, Wroclaw Medical University, Wroclaw, Poland

Introduction: There are only few reported cases of paradoxical response to pasireotide treatment of ACTH secreting tumors, mostly aggressive macroadenomas, that led to therapy discontinuation. We present a case of a patient with Cushing's disease and paradoxical responses to pasireotide LAR in whom despite the initial increase of hypercortisolemia the treatment was successful in terms of tumor shrinkage. Due to the rarity of paradoxical responses to pasireotide LAR, our case adds an interesting insight into this potentially dangerous and poorly understood clinical situation. Case description: The patient was diagnosed in 2008 with non-secreting pituitary macroadenoma, causing only neurological symptoms. The initial therapy included two transsphenoidal surgeries and stereotactic radiotherapy. In pathological report, ACTH expression was observed, but it was clinically silent. After 7 years the patients was reoperated due to sudden deterioration of neurological condition and regrowth of the tumor. In 2019, hypercortisolemia appeared and the treatment with pasireotide LAR was introduced. Pharmacotherapy continued for four years, four of eight pasireotide LAR injections were followed with paradoxical responses, managed with steroidogenesis inhibitors. During this therapy, there was a significant reduction of the tumor size. Conclusions: Pasireotide LAR was successful in reducing the tumor mass despite paradoxical responses. Transient increase of hypercortisolemia after pasireotide LAR was difficult to predict, but was managed with steroidogenesis inhibitors.