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.