The effect of sirolimus on angiomyolipoma is determined by decrease of fat-poor compartments and includes striking
Elieser Hitoshi Watanabe1, Fernando Morbeck Almeida Coelho2, Hilton Leão Filho2
1Division of Nephrology, Department of Medicine, University of São Paulo School of Medicine, Avenida Dr. Arnaldo, 455 - Sala 4304, São Paulo, 01246-903, Brazil.
Scientific Reports
|April 20, 2021
Summary
Sirolimus effectively shrinks renal angiomyolipomas by reducing fat-poor and vascular components. This treatment significantly decreases aneurysms, lowering bleeding risk in patients with tuberous sclerosis complex.
Area of Science:
- Oncology
- Vascular Biology
- Medical Imaging
Background:
- Renal angiomyolipomas (AMLs) pose a risk of hemorrhage, influenced by tumor size and vascularity.
- Tuberous sclerosis complex (TSC) and other conditions are associated with AMLs.
Purpose of the Study:
- To analyze the effects of sirolimus on the distinct components of renal angiomyolipomas.
- To evaluate sirolimus's impact on vascular structures and overall tumor size.
Main Methods:
- Retrospective evaluation of 30 angiomyolipomas from 14 patients treated with sirolimus.
- Classification of tumors and compartments based on Hounsfield units (fat-rich, fat-poor, intermediate-fat, highly vascularized).
- Measurement of diameter changes in aneurysmatic/ectatic vascular formations.
Main Results:
- Sirolimus induced greater volume reduction in fat-poor AMLs compared to fat-rich ones.
- Tumor shrinkage was primarily due to decreased fat-poor and highly vascularized compartments; fat-rich areas increased.
- A median 100% reduction in the diameter of aneurysmatic/ectatic vessels was observed.
Conclusions:
- Sirolimus reduces AML size by targeting highly vascularized and fat-poor components.
- This mechanism significantly reduces tumoral aneurysms, likely explaining the decreased bleeding risk associated with mTOR inhibitors.
- Findings highlight mTOR's role in the vascular development of angiomyolipomas.
