Pasireotide-LAR and pegvisomant combination in resistant acromegaly: a case series of predominantly mammosomatotroph adenomas.

PURPOSE: Long-term real-world data on concurrent pasireotide-LAR (PAS) and pegvisomant (PEGV) use in treatment-resistant acromegaly remain limited, especially for mammosomatotroph adenomas in younger adults. We report outcomes of six patients treated with this combination at a single tertiary pituitary center. METHODS: IRB-approved retrospective case series. Baseline and follow-up biochemical, radiological, histopathological, treatment and safety outcomes were captured. RESULTS: Six patients (5 females, 1 male; age 15 to 44 years) with somatotroph (n = 2) or mammosomatotroph (n = 4) adenomas, all macroadenomas, received PAS (20 to 60 mg every 28 days) plus PEGV (60 to 280 mg/week) over a median of 3.3 years (range 0.5 to 5.9) after lack of disease control post-surgery despite multiple lines of medical therapy. All six maintained tumor stability and achieved normal IGF-1. One had biochemical escape after 9 months of biochemical control requiring a 2nd surgery and radiosurgery. One patient discontinued PEGV after 3 years due to injection site pain, 3 patients developed hyperglycemia in the pre-diabetes range; no hepatotoxicity, acute symptomatic biliary disease, or arrhythmias occurred. CONCLUSIONS: In this series of predominantly mammosomatotroph adenomas in younger adults, combination PAS plus PEGV offers potential durable biochemical control, tumor stability and PEGV dose reduction in treatment-resistant acromegaly. Glucose monitoring during treatment is essential as concomitant use of PEGV does not appear to mitigate PAS-induced glycemic deterioration. Larger prospective studies are needed to better define predictors of response.