Take-home message: Results of a 6-month phase I/II clinical trial of suprachoroidal injection of triamcinolone for noninfectious uveitis showed the treatment was safe and well tolerated.
Chicago—Patients with noninfectious uveitis who were treated with a single suprachoroidal injection of triamcinolone acetonide in a 6-month phase I/II clinical trial exhibited improvements in best-corrected visual acuity (BCVA), said investigator Debra A. Goldstein, MD.
In addition, the injection was generally safe and well tolerated, said Dr. Goldstein, professor of ophthalmology and director, Uveitis Service, Northwestern University Feinberg School of Medicine, Chicago.
Dr. Goldstein helped design the trial, in which eight patients at three U.S. centers received an injection of a commercially available formulation of triamcinolone acetonide using a proprietary microinjector (Clearside Biomedical Inc.)
No serious adverse events related to the drug or the injection were observed over the course of the trial. No patients developed or had progression of cataract and none had an elevation in IOP.
However, all eight patients experienced an adverse event of some sort, most commonly pain or redness at the injection site.
“In terms of safety, with only 6 months’ data on eight patients, the safety looks excellent,” Dr. Goldstein said.
Although the trial was not designed to evaluate efficacy, the limited data showed good results. Four patients showed improvements of ≥2 lines of BCVA as early as week 4.
“This persisted for all 26 weeks of the study, suggesting that the injection does last a long time,” Dr. Goldstein said.
The average was close to 3 lines of improvement at week 26.
Seven of the eight patients had macular edema and four also had vitreous haze. One of the study endpoints was a 20% reduction in macular edema, which is generally considered a valid endpoint. By week 1, 40% of patients had met this target; 71% reached the endpoint by week 4, and 67% of eyes retained the reduction in macular edema by the end of the study. Some patients also had complete resolution of macular edema, which persisted for the 6 months of the study.
Novel aspects of study
Triamcinolone has been used in intraocular injections for some time. The novel aspects of this trial were the injection site and the injector system, Dr. Goldstein said.
“The idea is to get the drug into a location that has not yet been used therapeutically,” she said.
Animal data on suprachoroidal injections suggest that a better effect can be achieved with a lower dose of triamcinolone than is typically used for intravitreal injection, which potentially could reduce the risk of side effects, Dr. Goldstein said.
Also, because the drug does not enter the vitreous cavity, patients are unlikely to experience the floaters commonly seen after intravitreal steroid injection. The suprachoroidal injection also may last longer than intravitreal injections, which typically last only 3 to 4 months.
Animal data also suggest that the drug can partition well when injected by the suprachoroidal method, with almost no drug seen in the anterior segment, thereby reducing the risk of cataract and glaucoma, and concentrating primarily in the outer retina and choroid, the areas needed to improve visual acuity.
With the microinjector system, the injection is performed 4 mm posterior to the limbus with a 30-gauge needle, which is customary for intraocular injections. However, the needles are much shorter than usual, Dr. Goldstein said.
Investigators in this study had a choice of needles of 850, 900, 950, or 1,100 µm in length. For each eye, the appropriate needle was selected by measuring scleral thickness at the injection site with ultrasound. The drug was then injected between the sclera and the choroid.
According to Dr. Goldstein, enrollment has begun for a phase II study of the suprachoroidal injection, with a larger, multicenter phase III trial beginning shortly.