O-06 Efficacy of Lutetium-Peptide Receptor Radionuclide Therapy and osilodrostat treatment at achiving eucortisolism and tumour stabilization in a patient with metastatic ectopic ACTH-syndrome

Abstract

Abstract Introduction Ectopic ACTH syndrome (EAS) is a rare cause of endogenous hypercortisolism. We present a case of a patient diagnosed with severe EAS, achieving eucortisolism and a favorable outcome of ACTH-producing metastatic pancreatic neuroendocrine tumor (NET) after 177Lu-DOTATATE and osilodrostat treatment. Clinical Case A female patient was admitted to our clinic at the age of 55 complaining of severe fatigue, facial and leg edema. Laboratory tests revealed a significant degree of ACTH-dependent hypercortisolemia (late-night serum cortisol 1856 nmol/L (64–327), late-night salivary cortisol (LNSC) 387.7 nmol/L (0.5–9.65), 24hUFC 8561 nmol/L (100–379), ACTH 332.8 pg/mL (7.2–63.3)), hypokalemia (1.88 mmol/L), increased liver enzymes (alanine aminotransferase (ALT) 303.2 U/L (0–55), aspartate aminotransferase (AST) 94.3 U/L (5–34)). MRI of the brain was negative for pituitary abnormalities. CT and somatostatin receptor scintigraphy with 99mTc-Tektrotyd revealed NET of the pancreas and multiple liver metastases. Subsequent biopsy confirmed NET grade 2, Ki67 – 7%. Treatment with lanreotide 120 mg every four weeks was initiated. In order to control hypercortisolism the patient received osilodrostat at a dose of 10 mg daily, which improved the patient's general condition in the first days of therapy. After 1 month of treatment, her hypercortisolism symptoms improved, LNSC dropped to 0.54 nmol/L and morning cortisol dropped from 1451 nmol/L (101–535) to 60.7 nmol/L, which could suggest adrenal insufficiency. She also had normalization of potassium and liver enzymes (ALT 18.4 U/L, AST 23 U/L). The dose of osilodrostat was firstly reduced and then discontinued. 177Lu-DOTATATE treatment was offered with four doses (7.4 GBq (200 mCi) every 8 weeks). The first dose was administered in January 2023. The SPECT-CT performed after the second dose demonstrated disease stabilization. At the time of writing, the patient remains in eucortisolism (LNSC 5,36 nmol/L, morning cortisol 140 nmol/L, ACTH 36.4 pg/ml) with tumor stabilisation after 4 doses of 177Lu-DOTATATE. However, the most recent routine blood test revealed thrombocytopenia (platelets 44×109/μl (150–400)), decreased white blood cell count (3.24×109/μl (4.5–11)), lymphocytes (0.71×109/μl (1.18–1.34)) and hemoglobin 98 g/L (117–160). Nevertheless, her general condition remains stable and significantly improved versus the initial investigation. Conclusion This observation highlights the feasibility and efficacy of a combined approach using osilodrostat and 177Lu-DOTATATE in the management of patients with metastatic ACTH-producing NET. This approach resulted in a substantially improved patient quality of life. Funding Russian Scientific Foundation 19-15-00398