Adenoma Receptors and Histologic Characteristics Determining Management Outcomes

Patient responses to medical therapy for acromegaly are variable. Adenoma features, including histologic characteristics and receptor density, are closely associated with distinct clinical behavior and therapeutic outcomes. Densely granulated pure somatotropinomas respond more favorably to somatostatin receptor subtype 2 (SST2)–selective ligands (octreotide and lanreotide) compared with sparsely granulated adenomas. In contrast, sparsely granulated adenomas may respond more favorably to pasireotide, which has higher affinity for somatostatin receptor subtype 5 (SST5). Expression levels of SST2 receptors are also associated with responsiveness to octreotide and lanreotide, whereas response to pasireotide is linked to higher SST5 expression. Recent prospective studies have highlighted that treatment strategies guided by biomarkers determining therapeutic response are more effective than standard, non–biomarker-based approaches. Current evidence supports the incorporation of biomarkers into decision-making for medical management of acromegaly, while these approaches are being further validated.