Low-dose rapamycin reduces kidney volume angiomyolipomas and prevents the loss of renal function in a patient with tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is caused by constitutively activated mammalian target of rapamycin (mTOR) resulting in non-malignant tumours of several organs including renal angiomyolipomas (AMLs). AMLs may originate renal failure, hypertension and spontaneous lifethreatening bleeding. Recent reports suggest a possible beneficial role of the mTOR inhibitor rapamycin for TSC. However, safety and efficiency of rapamycin in TSC patients as an anti-proliferative agent are still undefined. A 40-year-old man with sporadic TSC and a history of spontaneous bleeding from his left kidney AMLs received low-dose rapamycin for 12 months, and this was associated with a reduction in bilateral kidney AML volume, stabilization and even improvement of renal function. There was also a reduction of facial angiofibromas, improvement of blood pressure control and absence of AML bleeding over this time period. Brain lesion images remained stable, and no significant rapamycin-associated side effects were noted. To the best of our knowledge, this is the first report of a case of reduction in renal AML volume together with preservation of renal function in a patient with TSC receiving low-dose rapamycin. These data suggest that it could be the result of the anti-angiogenic, anti-fibrotic and antiproliferative effects of rapamycin.