8594 Pasireotide and Pasireotide Combined Treatment in Aggressive, Giant Pituitary Neuroendocrine Tumours

Abstract Disclosure: K. Ciszek: None. A. Bogusławska: None. M. Komisarz-Calik: None. J. Kunicki: None. A. Hubalewska-Dydejczyk: None. A. Gilis-Januszewska: None. Pasireotide is a second-generation somatostatin analogue that gained recognition as a treatment option for acromegaly and Cushing disease. Recently, there are single reports of pasireotide treatment in other subtype of pituitary neuroendocrine tumours (PitNETs).We present a case series of aggressive, giant PitNETs which were treated with pasireotide alone or as combined multimodal treatment. Case 1: A 59-year-old male presented in our Unit due to severe headaches and visual field deficits. The patient underwent transsphenoidal surgery (TSS) ten years ago. Histopathology results showed partially acidophilic adenoma (FSH- LH- GH- ACTH- PRL-). Control MRI showed tumour regrowth - 56x56x89mm and invasion of local structures. The patient was qualified for radiotherapy, to which he did not consent. Due to the progression of symptoms, temozolomide and pasireotide were introduced. After 5 months, significant improvement in headaches and vision was observed. In MRI stable pituitary mass was noted. Case 2: A 17-year-old male presented in our clinic due to daily severe headaches and peripheral vision loss who underwent two non-radical surgeries for dopamine-resistant giant prolactinoma. In control MRIs progressing mass 38x34x33mm invading local structures was observed. Due to resistance to dopamine agonists and worsening of the symptoms, pasireotide was introduced resulting in a decrease of headaches and improvement in vision. The tumour size remained stationary. Case 3: A 59-year-old male presented with severe headaches and life threatening tumour mass effect.In MRI a 48x48x33mm mass was observed. The patient underwent two non-radical TSS, 4 cycles of pasireotide, and cyberknife treatment. Histopathology showed gonadotroph PitNET. MRI showed tumour shrinkage to 45x46x29mm, with persistent severe headaches. The patient was re-qualified for pasireotide treatment. Case 4: A 33-year-old male reported to the Clinic due to severe headaches and vomiting. In MRI pituitary mass 33x39x55mm and a cerebral oedema were revealed. TSS with external ventricular drainage was performed -histopathology results showed densely granulated silent corticotroph adenoma subtype 1, Ki67<1%. After 3 months, MRI showed tumour progression to 39x40x30mm. Two emergency TSS followed by stereotactic radiotherapy were performed. Combined therapy with pasireotide, cabergoline and temozolomide was introduced. After 18 months, stabilization of the disease was observed with the complete disappearance of headaches. Conclusions: Our study demonstrates the clinical potential of pasireotide treatment in aggressive, giant PitNETs. The therapy alone, or in combination has a potential role in reducing the tumour size, and allows the stabilization of the disease. The analgesic and anti-inflammatory effect of pasireotide could potentially alleviate headaches in this subset of patients. Presentation: 6/2/2024