PDS: A new era in the treatment of wet AMD

The Port Delivery System (PDS) with ranibizumab (Susvimo, Genentech) has ushered in a new treatment era for patients with wet age-related macular degeneration (AMD). In addition to the efficacy of this device, the treatment burden for patients needing monthly anti-vascular endothelial growth factor (VEGF) injections is reduced dramatically.

The LADDER Study evaluated the overall good safety and efficacy results of the PDS for treating neovascular AMD with 10-, 40- and 100-mg concentrations. The results showed that with the highest concentration, about 80% of patients went 6 months or longer before needing a refill (median time to refill was nearly 16 months). The refill was carried out in the clinic.

The 2-year, Phase 3 ARCHWAY Study compared the PDS containing 100 mg of ranibizumab to monthly ranibizumab injections in patients with recently diagnosed wet AMD. The results showed that 98% of patients did not need additional treatment in the PDS group and the drug was well tolerated. The Portal study, an open-label extension study, will evaluate the outcomes for patients after more than 2 years.

Considerations in this new treatment era

Dr Chirag Jhaveri, from Retina Consultants of Austin, and an investigator at the Austin Research Center for Retina, Texas, United States, emphasised: “As we embark on this new era for the treatment of wet macular degeneration, it is important that we use all resources available … as well as company representatives to help maximise our patient outcomes.”

The PDS is approved to treat neovascular AMD. The device is surgically inserted via the pars plana area, in the superotemporal quadrant of the eye, to deliver continuous slow release of the anti-VEGF drug to the posterior segment.

Picking the surgical candidates is an important step. While the procedure to insert the PDS is generally well tolerated, a preoperative evaluation is important. Dr Jhaveri reported that the Phase 2 LADDER Study found a high rate of vitreous haemorrhages, which was addressed and lowered substantially by adding laser cautery of the corneal bed.

Surgeons should also be aware of the infection risk and possible exposure of the device if it is not covered adequately or if the conjunctiva is not closed properly. Because the conjunctiva is thin, erosion may occur. “Preoperative evaluation and meticulous care to close the conjunctiva is very important,” Dr Jhaveri stated.

In addition to the conjunctival status, the tissue should have good mobility in order to facilitate adequate access to the subconjunctival and sub-Tenon spaces. Surgeons should look for areas of potential scleral thinning that can affect creation of the wound, and avoid those areas to prevent wound dehiscence or other potential issues.

Dr Jhaveri explained that his patients who are stable on monthly or 2-monthly injections without the presence of intraretinal fluid may be good candidates for implantation of the PDS. Surgical education and training are important for surgeons implanting the PDS.

Dr Jhaveri noted that as the device comes into more common use, it is important to review videos before the PDS is implanted, and that surgical simulators are available to provide hands-on experience. In addition, the company representatives will be helpful to guide surgeons through their first surgeries.

He also mentioned that detailed descriptions of the implantation and refilling procedures are in the process of being approved. Those descriptions and any videos can be obtained by contacting Genentech representatives.

Positive impact of the PDS

In addition to decreasing the treatment burden, the continuous exposure of the retinal tissue to ranibizumab might even modify the disease process. As Dr Jhaveri pointed out, the fact that 98% of people in the ARCHWAY Study did not need additional treatment before the first refill may imply that the disease is modified to the point of potential quiescence for some patients.

Another plus is the high patient satisfaction postoperatively; the implantation process is painless, and patients may report only slight itchiness or mild irritation 1–2 days postoperatively.

“They notice the disease stability after implantation of the PDS. The refill process is also easy for the patients. It is actually more tolerable because there is no transscleral penetration of a needle,” Dr Jhaveri explained.

The future of the PDS is bright. “The PDS has a lot of potential for wet AMD,” he said; however, he cautioned: “I highly encourage surgeons to use all of the information available, and the company representatives, to maximise the surgical outcomes.”

Studies are also underway to evaluate use of the PDS to treat diabetic macular oedema and diabetic retinopathy. “As better compounds are developed that may be more efficacious, such as by specific molecules, marrying the PDS platform with these new molecules may yield even better results for our patients,” Dr Jhaveri concluded.

Produced in partnership with Roche.