Intravitreal erythropoietin encouraging for geographic atrophy

Boston-Results of a retrospective study have indicated that off-label intravitreal injection of erythropoietin ([EPO] Procrit, Amgen) is well tolerated and may slow progression of geographic atrophy (GA) and vision loss in eyes with age-related macular degeneration (AMD), Carolyn Majcher, OD, reported at the annual meeting of the American Academy of Optometry.

"Currently, there is no effective treatment for GA, which is responsible for about 20% of cases of visual acuity of 20/200 or worse among patients with advanced AMD. Our study results are encouraging and suggest that further study of EPO is warranted," said Dr. Majcher, of Pennsylvania College of Optometry, Salus University, Elkins Park, PA.

EPO is a glycoprotein hormone initially used in medicine as a hematopoietic growth factor. Interest in its use for GA relates to more recent research showing its neuroprotective and neuroregenerative activities within the central nervous system.

Both EPO and its receptors are also expressed in the human retina, with Müller cells as the main endogenous source. Recently, increased concentrations of EPO have been found within the vitreous of eyes with diabetic retinopathy. The increase in EPO in these eyes is thought to occur through pathways induced by hypoxic stress, and preclinical evidence has supported its use as an ocular neuroprotective agent, Dr. Majcher said.

"In a series of independent studies, intravitreal EPO was shown to prevent retinal ganglion cell loss in a mouse model of ocular hypertension, reduce retinal ganglion cell apoptosis in rats after optic nerve severance, and prevent retinal neuronal apoptosis and blood-retinal barrier breakdown in diabetic rats," she explained.

"In prior studies in humans, intravitreal injections of EPO demonstrated an excellent safety profile with essentially no systemic side effects. Consistent with that information, no ocular or systemic side effects were encountered during our study," Dr. Majcher added.

Salus study methodology

The Salus University study included eight patients with AMD-related GA in at least one eye that had threatened or recently involved the fovea but absent any evidence of choroidal neovascularization (CNV). In patients with bilateral disease, only one eye received treatment. Pretreatment data from a mean follow-up duration of 1.3 years was available for seven of the treated eyes. Five patients had atrophic GA without CNV in the nonstudy eye, while the fellow eyes in the other three patients had active or regressed CNV.

Initial mean GA area at the time of EPO initiation in treated eyes was 10.8 mm² . Patients received EPO 5 U/50 µl injections into the vitreous at intervals of approximately 6 weeks. They received an average of 9.6 injections during an average follow-up of 1.7 years.

The study endpoints were change in GA enlargement rate and central visual field acuity perimetry from pretreatment measurements. The study also compared GA enlargement rates compared with the fellow eyes in patients with bilateral disease.