Most people have never heard of retinitis pigmentosa, a rare hereditary disease that affects fewer than 200,000 people in the United States. But for families who are affected by this condition, the prognosis is devastating: RP steals sight and there’s no treatment or cure.
Not yet, anyway. Sandeep Grover, M.D., an assistant professor of ophthalmology in the UF College of Medicine-Jacksonville on the Shands Jacksonville campus, is one of three state researchers testing an implant packed with a type of growth factor they hope will keep cells in the eye from deteriorating during RP. UF is one of only 12 centers participating in the national clinical trial, which Neurotech USA is sponsoring.
Grover describes RP’s complex course in simple terms.
"In the eye, the retina is like film in a camera, and the two types of cells in the retina that help us to see are the rods and cones," he said. "The rods help us see at night, and the cones help us see in daylight and identify colors.
"The rods and cones are like antennas on old TV sets, and if these antennas are broken, you don’t get a good picture on the TV," he explained. "So if enough rods and cones degenerate, then vision quality and center vision goes down."
"For those who inherit RP, cell death is pre-programmed (process called apoptosis) and starts the day they’re born. How fast it progresses differs in different people, but slowly these rods and cones degenerate," Grover added. "These patients start having problems with night vision first, then their peripheral vision, and finally their center vision. A majority of them are legally blind by age 40."
Researchers are looking at different ways to save these photoreceptor cells, Grover said.
One way to save the cells is to replenish the eye with naturally occurring proteins called growth factors, which scientists think may help rods and cones to survive — or maybe, even improve, Grover said.
"That is something we don’t know yet, but for at least two decades we have known about a certain kind of growth factor called CNTF — or ciliary neurotrophic factor — that is probably one of the best growth factors for the rods and the cones," he said. "But the problem was how to get it into the eye.
"Injecting it into the blood doesn’t work because the blood-retina barrier prevents anything from getting into the retina; and, directly injecting it in the eye may be toxic to the rods and cones, and then you’ve lost the game," Grover explained. "So you’ve got to give a sustained release of a known concentration of CNTF somehow, and that’s what took all this time."
Neurotech USA, a biotechnology company based in Lincoln, R.I., developed a sustained delivery method called encapsulated cell technology.
The ECT implant is a very small hollow tube — just six millimeters long, like the tip of a pencil — with pores in it and live cells inside the tube. These cells secrete CNTF at a constant rate that diffuses through these pores into the eye.
As part of the phase 2 study, Grover is studying the implant for its efficacy in patients. The implant will be in place for one year and then removed, but patients will be followed for an additional six months to ensure problems don’t occur.
Grover credits the success of this study locally to his team that includes K.V. Chalam, M.D., professor and chair of ophthalmology, who is the surgeon; clinical coordinator William Phillips; and Dr. Jason Sifrit and Nicole Perez, who assist in testing of the patients.
Tom Harcz is one of the patients Grover is following. Every month, his wife, Deborah, drives him more than 400 miles from their home in Holly Springs, N.C., to Jacksonville so Tom can participate in the study.
"I found out about the study on RPlist, an Internet listserv for people with RP and their families," he said. "I sort of knew I had RP when I was eight years old, but I really noticed it in eighth grade when my peripheral vision started to go and it got hard to play basketball and baseball," Harcz said. "Then it (RP) took my night vision and soon I couldn’t drive. I still have some central vision but very little peripheral vision.
"It gives us hope and it gives hope to our family members who could develop the disease, too," he said. "I feel like I’m losing my vision quickly at this point, but with this study maybe I’m not and that’s exciting."
Grover is hopeful, too. "We are hoping for the best because this is the first treatment trial ever for this almost blinding disease," he said. "It makes sense to do it, and with this new ECT technology we are all cautiously optimistic about it."