Role of Port Delivery System in Retinal Diseases - Episode 1
Expert insight on the history of the port delivery system in neovascular AMD and how it has impacted patient experience and outcomes.
Chirag Jhaveri, MD: The port delivery system is an ocular delivery system that is surgically inserted via the pars plana area in the superotemporal quadrant of the eye. It provides continuous delivery of ranibizumab to the posterior segment. It has a reservoir chamber where a higher concentration of ranibizumab is held, and there is slow release into the vitreous cavity. It has been approved for use in patients with neovascular AMD [age-related macular degeneration], although other indications, including diabetic macular edema, are also being investigated.
With the approval of Lucentis [ranibizumab] for the indications of neovascular AMD, the treatments for neovascular AMD were revolutionized. However, there still is a significant treatment burden for many of our patients who require frequent, often monthly, injections. The treatment burden for both the patients and the family can be quite high. In addition, although we’re delivering a nice bolus of anti-VEGF treatment, there is a waning of the amount of medication in the vitreous cavity. Therefore, a more sustained, endurable treatment modality was needed. Like most devices, the port delivery system was started in the preclinical stages, where it was developed and then tested in nonhuman subjects. Once its safety was verified, it went on to trials to verify safety in human patients, and then to look at the efficacy.
In the phase 2 LADDER study, the technique that was done in human patients initially showed an increased risk for vitreous hemorrhages. The technique for implantation was modified to include laser cautery of the corneal bed]. After this, the incidence of vitreous hemorrhages dropped precipitously. Prior to the amendment, there were 6 out of 10 cases of vitreous hemorrhage. After the amendment, there were no cases of vitreous hemorrhage out of 48 patients within the first month, which is generally considered the postoperative period. At 2 months, there was 1 patient who did have a vitreous hemorrhage.
Although the procedure is generally well tolerated, since it is surgical procedure, there are some potential complications that surgeons and patients should be aware of. Initially, in the LADDER study, there was a higher rate of vitreous hemorrhages. A modification of the procedure has since reduced those rates tremendously. Any surgery has a risk of infection, and with respect to the implant itself, if the conjunctiva is not closed properly or not covering the implant adequately, there is a possibility of the implant being exposed. Also, if the conjunctiva is very thin, there is a possibility of erosion. Therefore, presurgical evaluation and meticulous care to close the conjunctiva are very important.
When evaluating a patient preoperatively, you want to take note of a few things. Particularly, you want to take note of the conjunctiva to see if it’s very thin, and if there’s good mobility of the conjunctiva, so that you can adequately access the subconjunctival and sub-Tenon space. In addition, you also want to note any areas of potential scleral thinning, so that when you’re making your wound you’re aware, and so you don’t start making your wound too deep. In addition, you may also want to avoid those areas, so that there isn’t a risk of dehiscence or any other potential issues with the wound.
Transcript edited for clarity.