A Phase 2 interventional study of NT-501 and NT-501 in Retinitis Pigmentosa, sponsored by Neurotech Pharmaceuticals. Completed at 12 sites in United States. Open to participants aged 18 Years to 64 Years. Per ClinicalTrials.gov, last updated 2025-05-01.
Sponsored by Neurotech Pharmaceuticals · Phase 2, Interventional, and Treatment
The purpose of this study is to look at the safety and effectiveness of CNTF implants on vision in persons with retinitis pigmentosa, Usher type II \& III, and Choroideremia. This research is being done because there are no effective therapies for people with these retinal degenerations. They are genetic disorders that affect one's ability to see at night, and later cause tunnel vision and loss of central vision. Retinal degenerations affect the retina, a light sensitive layer of cells in the back of the eye. Slowly over time, these cells die and cause permanent loss of vision.
The implant is a small capsule that contains human retinal pigment epithelium cells. These cells have been given the ability to make CNTF and release it through the capsule membrane into the surrounding fluid. In this study, two different CNTF dose levels will be used: a high dose and a low dose in one eye, as well as a sham (or placebo) surgery in the other eye.
This study will involve about 18 visits over 2½ years for specific tests of the participant's vision and health. These visits may include visual exams, blood draw for laboratory testing, brief medical history and exam, and occasionally a questionnaire (survey), in addition to the visit for the surgical procedures. The primary effectiveness outcome for this study will be a visual field score one year after the implant surgery. There will be about 12 centers participating in this study, and up to 60 people enrolled, across the US. Each participant joining the study who has completed initial screening will then be scheduled to have a brief surgical procedure performed on each eye, one of which will include a very small cell-filled implant. Follow-up visits for repeat assessments will be required regularly to determine if the implant being tested is safe and effective for use to treat retinitis pigmentosa (RP).
278 studies on the registry are indexed under Retinitis Pigmentosa; 72 are open to participants now.
This study's enrollment of 73 is above the median of 27 across 179 interventional studies indexed under Retinitis Pigmentosa.
Browse Retinitis Pigmentosa studies →Neurotech Pharmaceuticals is the lead sponsor of 13 studies on the registry; 2 are open to participants now.
Of its 8 completed or terminated interventional studies of FDA-regulated products, 7 (88%) have results posted.
Counted across the registry records on this site, refreshed daily.
Study inclusion / exclusion criteria:
Criteria for patients to qualify for the study include, but are not limited to:
The following criteria will exclude patients from the study:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
NT-501 Low Dose Implant: encapsulated cell therapy that delivers ciliary neurotrophic factor to the retina Sham Implant in Fellow Eye
Drug: NT-501
NT-501 High Dose Implant: encapsulated cell therapy that delivers ciliary neurotrophic factor to the retina Sham Implant in Fellow Eye
Drug: NT-501
Change in Humphrey Visual Fields - Total Sensitivity
The primary efficacy endpoint was the change in Humphrey VFS from baseline to month 12 (Visit 10) as determined by the HVF 30-2 test, comprised of 76 points. The measure was the sum of actual thresholds for all 76 locations.
Time frame: 12 months
Change in Mean Humphrey Visual Fields Sensitivity
Time frame: Baseline compared to 6, 12, 18, 24 and 30 months
Mean Humphrey Visual Fields Sensitivity
Change in Humphrey Visual Field Sensitivity over time
Time frame: Baseline compared to 6, 12, 18, 24 and 30 months
| Milestone | Participants That Received Low Dose NT-501 Implant Surgery and Sham Surgery in Fellow Eye | Sham Treatment in Fellow Eye for Low Dose Arm | Participants That Received High Dose NT-501 Implant Surgery and Sham Surgery in Fellow Eye | Sham Treatment in Fellow Eye for High Dose Implant Arm |
|---|---|---|---|---|
| Started | 23 | 23 | 50 | 50 |
| Nt-501 surgery completed | 20 | 20 | 48 | 48 |
| Completed | 18 | 18 | 44 | 44 |
| Not completed | 5 | 5 | 6 | 6 |
| Withdrew: Withdrawal by subject | 1 | 1 | 4 | 4 |
| Withdrew: Lost to follow-up | 1 | 1 | 0 | 0 |
| Withdrew: Did not proceed with surgery | 3 | 3 | 2 | 2 |
The primary efficacy endpoint was the change in Humphrey VFS from baseline to month 12 (Visit 10) as determined by the HVF 30-2 test, comprised of 76 points. The measure was the sum of actual thresholds for all 76 locations.
| dB | Low Dose - Implant | Low Dose - Sham | High Dose - Implant | High Dose - Sham |
|---|---|---|---|---|
| Change in Humphrey Visual Fields - Total Sensitivity | 1.4 ± 174.58 | 16.8 ± 165.41 | -164.8 ± 115.02 | -66.7 ± 103.23 |
| dB | Low Dose - Implant | Low Dose - Sham | High Dose - Implant | High Dose - Sham |
|---|---|---|---|---|
| 6 Months - Change from BL | -1.21 ± 140.09 | 25.80 ± 128.34 | -135.23 ± 107.86 | -42.99 ± 82.85 |
| 12 Months - Change from BL | 1.35 ± 174.58 | 16.75 ± 165.41 | -164.79 ± 115.02 | -66.65 ± 103.23 |
| 18 Months - Change from BL | -62.65 ± 208.64 | -37.33 ± 173.46 | -202.31 ± 137.13 | -98.73 ± 127.09 |
| 24 Months - Change from BL | -104.15 ± 194.50 | -72.15 ± 162.72 | -227.89 ± 149.73 | -136.96 ± 126.73 |
| 30 Months (retained implant) - Change from BL | -46.977 ± 345.78 | -58.64 ± 275.09 | -321.72 ± 196.81 | -211.82 ± 145.25 |
| 30 Months (6 Months Post-Explant) - Change from BL | -82.67 ± 185.60 | -58.50 ± 148.57 | -188.64 ± 122.33 | -144.60 ± 134.31 |
Change in Humphrey Visual Field Sensitivity over time
| dB | Low Dose - Implant | Low Dose - Sham | High Dose - Implant | High Dose - Sham |
|---|---|---|---|---|
| Baseline | 1142.43 ± 446.33 | 1135.94 ± 423.50 | 969.83 ± 391.74 | 961.70 ± 435.68 |
| 6 Months | 1141.21 ± 438.07 | 1161.74 ± 399.67 | 834.60 ± 354.98 | 918.72 ± 422.60 |
| 12 Months | 1143.78 ± 409.76 | 1152.69 ± 388.30 | 805.03 ± 357.86 | 895.05 ± 427.12 |
| 18 Months | 1079.78 ± 440.81 | 1098.61 ± 427.23 | 757.80 ± 363.86 | 850.92 ± 404.91 |
| 24 Months | 1038.28 ± 430.12 | 1063.79 ± 398.68 | 745.62 ± 344.58 | 825.06 ± 396.47 |
| 30 Months with retained implant | 1176.22 ± 384.29 | 1173.32 ± 340.09 | 695.97 ± 251.57 | 787.30 ± 322.72 |
| 30 Months (6 Months Post-Explant) | 1090.92 ± 382.10 | 1056.08 ± 406.65 | 752.78 ± 345.78 | 782.60 ± 382.68 |
Collected over Time of consent through Month 30 (study exit). Non-serious events are listed at a 4% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Low Dose | 0/20 (0%) | 1/20 (5%) | 20/20 (100%) |
| High Dose | 0/48 (0%) | 4/48 (8.3%) | 48/48 (100%) |
| Event | Low Dose | High Dose |
|---|---|---|
| Cubital tunnel syndromeNervous system disorders | 1/20 | 0/48 |
| Acute appendicitisGastrointestinal disorders | 0/20 | 1/48 |
| Ovarian CystReproductive system and breast disorders | 0/20 | 1/48 |
| Hypertrophic medial synovial plica with synovitisMusculoskeletal and connective tissue disorders | 0/20 | 1/48 |
| Non-ischemic cardiomyopathyCardiac disorders | 0/20 | 1/48 |
| Event | Low Dose | High Dose |
|---|---|---|
| Conjunctival HaemorrhageEye disorders | 17/20 | 38/48 |
| Conjunctival HyperaemiaEye disorders | 12/20 | 17/48 |
| Anterior Chamber CellEye disorders | 7/20 | 9/48 |
| MiosisEye disorders | 0/20 | 15/48 |
| Eye PainEye disorders | 6/20 | 12/48 |
| Suture Related ComplicationInjury, poisoning and procedural complications | 5/20 | 14/48 |
| Anterior Chamber FlareEye disorders | 5/20 | 9/48 |
| Eye IrritationEye disorders | 5/20 | 4/48 |
| Vitreous DisorderEye disorders | 5/20 | 7/48 |
| HeadacheNervous system disorders | 5/20 | 3/48 |
The baseline analysis population includes all 73 participants who were randomized to a treatment arm including the 3 participants from low dose arm and the 2 participants from the high dose arm who discontinued prior to surgery, and study start.
| Age, Continuous(Years) | Low Dose - Implant | Low Dose - Sham | High Dose - Implant | High Dose - Sham | Total |
|---|---|---|---|---|---|
| Mean | 34.9 ± 12.0 | 34.9 ± 12.0 | 40.2 ± 11.8 | 40.2 ± 11.8 | 37.6 ± 11.9 |
| Sex: Female, Male(Participants) | Low Dose - Implant | Low Dose - Sham | High Dose - Implant | High Dose - Sham | Total |
|---|---|---|---|---|---|
| Female | 11 | 11 | 26 | 26 | 74 |
| Male | 12 | 12 | 24 | 24 | 72 |
| Ethnicity (NIH/OMB)(Participants) | Low Dose - Implant | Low Dose - Sham | High Dose - Implant | High Dose - Sham | Total |
|---|---|---|---|---|---|
| Hispanic or Latino | 1 | 1 | 4 | 4 | 10 |
| Not Hispanic or Latino | 22 | 22 | 46 | 46 | 136 |
| Unknown or Not Reported | 0 | 0 | 0 | 0 | 0 |
| Race (NIH/OMB)(Participants) | Low Dose - Implant | Low Dose - Sham | High Dose - Implant | High Dose - Sham | Total |
|---|---|---|---|---|---|
| American Indian or Alaska Native | 1 | 1 | 0 | 0 | 2 |
| Asian | 1 | 1 | 1 | 1 | 4 |
| Native Hawaiian or Other Pacific Islander | 0 | 0 | 0 | 0 | 0 |
| Black or African American | 0 | 0 | 0 | 0 | 0 |
| White | 21 | 21 | 49 | 49 | 140 |
| More than one race | 0 | 0 | 0 | 0 | 0 |
| Unknown or Not Reported | 0 | 0 | 0 | 0 | 0 |
| Ocular History - Years Since RP Diagnosis(years) | Low Dose - Implant | Low Dose - Sham | High Dose - Implant | High Dose - Sham | Total |
|---|---|---|---|---|---|
| Mean | 8.85 ± 8.39 | 8.85 ± 8.39 | 10.49 ± 9.86 | 10.49 ± 9.86 | 10.00 ± 9.41 |
| Type of Ocular History(Eyes) | Low Dose - Implant | Low Dose - Sham | High Dose - Implant | High Dose - Sham | Total |
|---|---|---|---|---|---|
| Ocular disease | 23 | 23 | 50 | 50 | 146 |
| Ocular surgery | 3 | 3 | 10 | 11 | 27 |
| Ocular treatment | 0 | 0 | 2 | 4 | 6 |
| Humphrey Visual Fields - Total Sensitivity (MITT Population)(dB) | Low Dose - Implant | Low Dose - Sham | High Dose - Implant | High Dose - Sham | Total |
|---|---|---|---|---|---|
| Mean | 1142.4 ± 446.33 | 1135.9 ± 423.50 | 969.8 ± 391.74 | 961.7 ± 435.68 | 1052.5 ± 424.31 |
Plan to share: No
Ran from Jan 2007 to primary completion in Apr 2010, 38 months.
Results were first posted in May 2025, 15 years after primary completion. A results delay was requested in Nov 2016.
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Studies of the drug tested here: Ciliary Neurotrophic Factor
Neurotech Pharmaceuticals