Results of RPE cell transplantation encouraging in dry AMD
Subretinal transplantation of retinal pigment epithelial cells derived from human embryonic stem cells appears to be well tolerated in patients with dry age-related macular degeneration and geographic atrophy, according to the interim results of a phase 1/2 clinical trial.
Improved visual acuity was achieved in a subgroup of patients with better baseline vision, some of whom underwent cell injection with a new subretinal delivery system (SDS) without vitrectomy or retinotomy.
Christopher D. Riemann, MD, who presented the results at the virtual Association for Research in Vision and Ophthalmology meeting, said that the OpRegen transplant therapy (Lineage Cell Therapeutics) shows encouraging structural and clinical changes, such as improvements in drusen, slower growth of geographic atrophy (GA) and possible restoration of the photoreceptors and retinal pigment epithelial (RPE) layer within the area of the transplant in some patients.
“Subretinal pigmentation and hyperreflective areas suggest the presence and durability of the transplanted RPE cells,” he said.
Of the four cohorts of the study, the first three included patients with very large GA and very poor vision, currently on long-term follow-up. The fourth is still undergoing progressive enrollment and treatment of patients with better vision and smaller GA. In some of the patients in the last cohort, cell transplantation is performed with the new Orbit SDS (Gyroscope Therapeutics) under local anesthesia.
“A sclerotomy is created, and a special cannula is placed tangentially in the suprachoroidal space and advanced posteriorly toward the target area in the macula adjacent to the GA. Once the target area is reached, a screwdriver drives a needle through the choroid and into the subretinal space. We inject [balanced salt solution], and when we confirm the subretinal bleb we turn a valve, switch from [balanced salt solution] to cells and deliver the OpRegen into the subretinal space. The subretinal injection is accomplished without vitrectomy and retinotomy,” Riemann said.
Although only two patients have been operated with the Orbit SDS, he said it is important to note that neither of them developed pucker, lamellar hole, retinoschisis or retinal detachment. Both developed small asymptomatic subretinal hemorrhages that resolved spontaneously.
Cohort 1 to 3 had poor vision to begin with and ended up with poor vision but no further loss, he said. Cohort 4, however, had improved visual acuity between 10 and 22 letters and improved reading speed up to the year 1 time point of the last visit. – by Michela Cimberle
Reference:
Riemann CD, et al. Phase I/IIa clinical trial of human embryonic stem cell (hESC)-derived retinal pigmented epithelium (RPE, OpRegen) transplantation in advanced dry form age-related macular degeneration (AMD): interim results. Presented at: Association for Research in Vision and Ophthalmology meeting; May 6, 2020 (virtual meeting).
Disclosure: Riemann reports he is a consultant and investigator for Gyroscope Therapeutics and Lineage Cell Therapeutics.