Intravitreal Injection of Sirolimus in the Treatment of Aggressive Retinal Astrocytic Hamartoma

Retinal astrocytic hamartomas (RAH) are benign tumors of glial cells arising from astrocytes in the nerve-fiber layer of the retina. They are often associated with tuberous sclerosis complex (TSC) and, more rarely, neurofibromatosis type 1 (NF1). RAH may be caused by dysregulated tumor suppressors genes TSC1 or TSC2, which play a role in cell cycle regulation in retinal astrocytes via the PDGF-signalling pathway. Downregulation of TSC1 or TSC2 can result in hyperactivation of mTOR. Sirolimus is an inhibitor of mTOR, therefore inhibiting cell growth and proliferation of astrocytes. Systemic mTOR inhibitors (sirolimus and everolimus) have shown impressive reduction in the size of RAH in animal models and many human case series.

This single patient study is investigating the use of concurrent oral and intravitreal Sirolimus to treat a patient with multiple retinal astrocytic hamartomas (RAH) of both eyes to improve intraocular response and reduce duration of treatment. The patient has no other clinical features suggestive of neurofibromatosis and a presumed diagnosis of tuberous sclerosis is being considered, with only two hypopigmented skin lesions noted.