Effect of everolimus treatment for renal angiomyolipoma associated with tuberous sclerosis complex: an evaluation based on tumor density.

BACKGROUND: The aim of this study was to evaluate the influence of components of angiomyolipoma (AML) on the efficacy of everolimus.

METHODS: We investigated a total of 40 patients with tuberous sclerosis complex (TSC) who had AML ≥4 cm in diameter. The components of the AML were determined using abdominal computed tomography (CT) images. The AML density was measured as the mean Hounsfield unit (HU) values of the whole area of the AML on axial CT images. We classified them into two groups, i.e., a lipid group with a predominant lipid component (HU ≤ -50) and a solid group with predominant vascular and muscle components (HU ≥30). For each patient, we measured the AML reduction rate and transition of the mean HU value.

RESULTS: The mean reduction rate of AML in the lipid group was 24%, whereas it was 68% in the solid group (P < 0.001). The mean tumor density after 6 months was decreased in both groups. In particular, the density significantly decreased compared to the baseline in the solid group (P < 0.001). The tumor density did not change after 6 months in either group.

CONCLUSION: The effect of everolimus on TSC-AML is mainly a reduction of the solid components consisting of angioma and leiomyoma. The tumor density at the start of treatment might be a predictive marker for the response to everolimus in TSC-AML.