Endocrine Abstracts

JOINT1488

Introduction: Acromegaly is a neuroendocrine disorder caused by chronic hypersecretion of growth hormone (GH). The primary treatment goals include achieving biochemical remission, reducing or stabilizing pituitary adenoma size, and alleviating clinical manifestations. While remission is not achieved in approximately 50% of patients, aggressive adenoma growth occurs in only 1-5% of cases.

Clinical Case Description: A 36-year-old patient was diagnosed with acromegaly after presenting with facial features enlargement and an elevated insulin-like growth factor 1 (IGF-1) level of 1000 ng/ml (reference range: 82.0–283.0 ng/ml). Brain MRI revealed a pituitary macroadenoma measuring 24×37×28 mm. Ophthalmological evaluation showed partial atrophy of the right optic nerve and strabismus. The patient underwent transnasal adenomectomy. However, five months post-surgery, the tumor measured 16×22×17 mm, with an IGF-1 level of 1549.5 ng/ml, indicating persistent disease activity. Medical therapy was initiated with 30 mg of long-acting octreotide every 28 days, later replaced with 120 mg of lanreotide every 28 days, followed by the addition of 20 mg of pegvisomant daily. One year later, MRI revealed continued tumor growth (28×29×20 mm), prompting a second adenomectomy. Despite this, the tumor further enlarged within six months (30×35×30 mm), with an IGF-1 level of 1277.6 ng/ml, necessitating radiosurgery. Two years after radiosurgery, MRI showed negative dynamics (tumor size: 32×32×24 mm) with optic chiasm compression. Given the challenging adenoma location and lack of response to conventional therapies, an oncologist was consulted. The patient underwent four courses of chemotherapy with temozolomide, and the pegvisomant dose was increased to 30 mg. However, one month after chemotherapy, tumor progression continued (32×32×38.7 mm), accompanied by worsening vision and right-sided ptosis. To assess the tumor’s sensitivity to checkpoint inhibitors, an immunohistochemical study was performed. PDL-1 and VEGF expression was detected in 70–80% of tumor cells, with a Ki-67 index of 17%. Weak expression of somatostatin receptor subtype 5 (IRS-1) was also noted. Based on a multidisciplinary consensus, considering resistance to standard acromegaly treatments and positive PDL-1 and VEGF expression, a combined regimen of nivolumab and bevacizumab was initiated.

Conclusion: This case highlights the importance of extended immunohistochemical analysis and interdisciplinary collaboration between endocrinologists and oncologists in the management of aggressive somatotropinomas. Personalized treatment strategies, including immunotherapy, may be crucial for patients unresponsive to conventional therapeutic approaches.