Treating MacTel: First identify patient candidates and appropriate eye selection

Ashkan M. Abbey, MD, FASRS, FAAO, of Texas Retina Associates in Dallas, moderated a recent Modern Retina Case-Based Roundtable on diagnosing and treating patients with macular telangiectasia type 2 (MacTel) and shared highlights of the discussion.

Neurotech Pharmaceuticals’ Encelto implantable device (revakinagene taroretcel-lwey), an encapsulated cell technology and the first treatment for MacTel, is known to the ophthalmic community in varying degrees. Abbey believes it is important for retina specialists to have a good understanding of the implant and the data behind it.

“Physicians are excited because the implant can preserve retinal tissue. Studies showed a significant reduction in the photoreceptor layer loss over time in implanted patients compared with sham. Hopefully, this will preserve vision for as long as possible,” he commented.

Recognizing MacTel

Because of the lack of familiarity with MacTel, a rare and progressive eye disease, patients may be referred later when they have visible cavitations on imaging that capture the attention of physicians. Abbey suggested that physicians evaluate the outer retinal layers on optical coherence tomography (OCT) images for disruptions, another early disease sign. Fluorescein angiography (FA) can be helpful in the diagnosis. OCT angiography can clearly identify a choroidal neovascularization membrane in the deeper retinal layers to distinguish nonneovascular from neovascular MacTel, which can be difficult for OCT and FA to do, he explained.

Most participants agreed that treating patients with anti-VEGF medications did not address nonneovascular MacTel.

“However, anti-VEGF medication helps neovascular MacTel, but some fibrosis and scarring remain, with some atrophy in the area of the neovascular membrane. Vision improves slightly, not fully,” Abbey said.

Candidate patients

This discussion centered around identifying candidate patients and selecting the better- or worse-seeing eye to be treated.

Case 1.

A 50-year-old woman had large cavitations bilaterally but 20/30 vision. Due to the resultant central scotomas, her vision was not equivalent to 20/30 in a normal retina. Damage was present in the outer retina and retinal pigment epithelium on OCT.

Most participants agreed with implantation. Abbey advised treating the better-seeing eye to maintain the better vision for as long as possible.

The risks of the surgery include meiosis and light-dark adaptation, the latter of which is delayed in approximately 20% of study patients. This can range from 30 seconds to 2 minutes. However, no study patient wanted to explant the device because of the delay.

Case 2.

A 72-year-old woman had 20/100 vision in the right eye and 20/40 in the left eye. Most of the subfoveal ellipsoid zone was destroyed, with almost no photoreceptors under the fovea in the right eye. The photoreceptor layer was relatively intact in the left eye, although slightly disrupted. A large cavitation was present at the fovea.

The discussion first centered around the need to even operate on the right eye, considering the damage. Some participants suggested implanting both eyes; others wanted to implant the left eye first to preserve more vision.

Case 3.

A 72-year-old woman was 20/20 bilaterally. The right eye had some disruption of the photoreceptor layer under and adjacent to the fovea. The left eye had an intact photoreceptor layer with some cavitations.

The consensus for treatment centered around the presence of a disrupted photoreceptor layer. This patient was symptomatic and wanted treatment in the right eye and, ultimately, in the left eye after hearing the prospects of worsening vision.

Abbey suggested studying patients who are less symptomatic and without disruption to determine whether implantation is even more impactful for those patients. “The clinical study showed that patients who did the best were the ones treated early and had the most mild findings,” he reported.

Case 4.

A 68-year-old woman had 20/30 vision in the right eye and 20/80 in the left eye with a full-thickness macular hole. The right eye was starting to develop significant cavitation at the fovea. She was motivated to treat the right eye. The highly compromised left eye was not considered for treatment.

Treatment challenges

The high cost of the implant (~ $250,000) and the potential for no reimbursement are the primary challenges to the surgical center’s acceptance of the device.

Abbey related that Neurotech has involved a specialty pharmacy that will purchase the implant and then provide it to the hospitals so that there will be no financial liability for the surgery center or hospital.

An option, he explained, is buy and bill. “If the hospital accepts this option, they could recoup a bit of a margin on the device, so there may be a financial incentive to actually buy and bill, but a risk exists regarding appropriate reimbursement or not by the insurance company,” he said.

Another challenge is learning the surgical technique. It requires creating an incision at the pars plana, suturing in the device, and closing the conjunctiva. However, Abbey described the surgery as not too complicated. Education about the treatment should be provided to referring physicians to ensure that patients are treated in a timely fashion, he concluded.