Drug Therapy for RP to Enter Human Studies
(Foundation Fighting Blindness, July, 2003)

According to the Foundation Fighting Blindness (FFB), the U.S. Food and Drug Administration approved an application from the biotechnology company Neurotech, to begin a phase I human clinical trial to test the safety of a delivery device containing a drug to treat patients with end-stage RP. Clinical testing will begin this Fall.

One of the major challenges to treatment of retinal disease has been the ability to deliver therapeutic drugs directly to the retina. Neurotech, based in France and Rhode Island, developed Encapsulated Cell Technology (ECT) which enables controlled, continuous, long term delivery of a drug called Ciliary Neurotrophic Factor (CNTF) in patients with end-stage RP.

Dr. Gerald Chader, Chief Scientific Officer of FFB said, "CNTF and several other drug therapies have shown promise in a wide variety of animal models with RP, but none of these drugs can pass through the blood/retina barrier, making traditional drug delivery with systemic injections or pills ineffective. The implantable ECT device may have at last broken through this barrier."

The ECT device was originally developed for use in treating Lou Gehrig's disease and cancer. It was during these studies that FFB realized that the ECT might be adaptable to treat diseases of the retina. They encouraged Neurotech to test the device with CNTF in RP animal models.

ECT consists of a very small capsule containing retinal pigment epithelial cells (RPE) that have been genetically modified to produce CNTF. The capsule has very small pores that allow oxygen and nutrients to diffuse in to sustain the RPE cells and also allow CNTF to diffuse out. The tiny pores prevent the modified RPE cells from escaping and protect the cells from the body's immune system. CNTF was chosen for its potent ability to delay the death of retinal photoreceptor cells in animal studies.

Because CNTF has not been tested in patients before, the first phase of this clinical trial will test the drug and ECT device in 10 pre-selected patients with end-stage RP. In this way, the safety of the treatment can be evaluated without risk to existing vision. If all goes well in this phase I safety study, a phase II trial would then test the ability of the treatment to preserve vision in sighted RP patients. The timing of future trials is not yet known, and at this time patients are not being selected for future trials.

ECT and other emerging drug delivery devices could open the door for several survival factors that, like CNTF, have shown promise is treating the entire spectrum of retinal degenerative diseases.

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