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NCT Number: NCT06971939

Phase 4 Study: Long-term Safety and Efficacy of NT-501 in MacTel Type 2, Including Sham Procedure Participants

The purpose of this global, multicenter, open-label, Phase 4 clinical extension study is to evaluate the long-term safety and efficacy of revakinagene taroretcel-lwey (Encelto™; hereinafter referred to as NT-501), in participants with macular telangiectasia type 2 (MacTel) who previously received the intraocular implant in a Phase 1, Phase 2, or Phase 3 clinical study. In addition, this study will evaluate the safety and efficacy of NT501 in participants who previously underwent the sham procedure in a Phase 3 MacTel clinical study and elect to have NT-501 implanted intraocularly in this Phase 4 study.

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Key information

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

Primary location

Cerulea, East Melbourne, Australia

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About this study

This extension study consists of 3 arms:

  • Arm 1 (Phase 3 Treated Participants' Long-term Follow-up): Arm 1 is to assess the long-term safety and efficacy of NT-501 in participants who received NT-501 in a previous MacTel Phase 3 clinical study (NTMT-03-A or NTMT-03-B) and have retained at least 1 NT-501at study entry.
  • Arm 2 (Phase 1 and Phase 2 Long-term Follow-up): Similar to Arm 1, Arm 2 is to assess the long-term safety of NT-501 in participants who received NT-501 in a previous MacTel Phase 1 or Phase 2 clinical study (NTMT-01, NTMT-02, or NTMT-01/02E) and have retained at least 1 NT-501 at study entry.
  • Arm 3 (Phase 3 Sham to Implant Crossover): Arm 3 will evaluate the safety and efficacy of NT-501 in participants who previously underwent the sham procedure in a Phase 3 MacTel clinical study (NTMT-03-A or NTMT-03-B) and elect to have NT-501 implanted intraocularly in this extension study.

Arms 1 and 2 are noninterventional and observational studies. For participants who previously received a single NT-501 implant, the implanted eye is designated the study eye. For participants who received an NT-501 in both eyes (ie, the first implant received in NTMT-01, NTMT-02, NTMT-01/02E, NTMT-03A, or NTMT-03B, and the second implant received in NTMT-02B), both eyes will be designated as study eyes.

Only participants in Arm 3 will receive active intervention during this Phase 4 study. A participant can receive NT-501 in either eye that meets eligibility criteria according to investigator assessment, and in accordance with participant choice. However, if only 1 eye is eligible for implantation based on all inclusion/exclusion criteria, then that eye will be selected for NT-501 implantation. The eye selected for NT-501 implantation will be designated as the study eye.

Regardless of study eye designation, both eyes of each participant in all 3 study arms will be evaluated during the study.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

To be eligible to participate in this study, an individual participant must meet all the following criteria:

  • Male or female adult participants who previously completed an NT-501 MacTel clinical study and:
  • Arm 1: received NT-501 intraocular implant in either Phase 3 study (NTMT-03-A or NTMT-03-B) and have retained at least 1 NT-501 at study entry.
  • Arm 2: received NT-501 intraocular implant in the Phase 1 study (NTMT-01), Phase 2 study (NTMT-02), or in the substudy of the Phase 1 and Phase 2 extension study (NTMT-01/02E) and have retained at least 1 NT-501 at study entry.

Note: participants who received NT-501 in both eyes (ie, participated in study NTMT-02B) will be enrolled in either Arm 1 or Arm 2 based on the study in which the first NT 501 was implanted (ie, participants who received the first implant in a Phase 3 study will be enrolled in Arm 1 and those who received the first implant in the Phase 1 study or Phase 2 study will be enrolled in Arm 2).

  • Arm 3: underwent the sham procedure in either Phase 3 study (NTMT-03-A or NTMT-03-B)
  • Participant or their legally authorized representative must be able to provide written informed consent to participate in the study, in accordance with the International Conference on Harmonisation (ICH) Good Clinical Practice (GCP) guidelines, and local regulations, before initiating any clinical study related procedures.
  • Arm 3: female participants of childbearing potential must agree to use highly effective contraception. Highly effective forms of contraception (generally a first-year typical use pregnancy risk of 1% or less) include the following: contraceptive implants; an intrauterine device; permanent contraceptive procedures (vasectomy, bilateral salpingectomy, bilateral tubal occlusion, or partial salpingectomy); abstinence. A combination of male condom with either cap, diaphragm, or sponge with spermicide (ie, double barrier methods) is also considered an acceptable, but not highly effective, method of birth control.

Exclusion criteria

To participate in this study, the potential participant must not meet any of the following criteria. (Note that the ocular exclusion criteria are relevant to the study eye[s], unless indicated for both eyes):

Exclusion criteria

Applicable to Arms 1, 2, and 3:

  • Participant is medically unable to comply with clinical study procedures or visits.
  • Participant has, in the opinion of the investigator, any physical or mental condition that would increase the risk of participation in the study or may interfere with the study procedures, evaluations, and outcome assessments.
  • Participant has undergone explantation of NT-501 prior to screening. Note: A participant who received bilateral implants and underwent explantation in only 1 eye prior to screening may be enrolled in the study.
  • Participant received Encelto commercial implant in the fellow eye, if applicable, less than 3 months prior to study screening.

Exclusion criteria

Applicable to Arm 3 Only:

  • Participant has significant corneal or media opacities in the study eye to be implanted.
  • Participant has evidence of pathologic myopia in the study eye to be implanted.
  • Participant has any of the following lens opacities in the study eye to be implanted: cortical opacity > standard 3, posterior subcapsular opacity > standard 2, or a nuclear opacity > standard 3 as measured on the Age- Related Eye Disease Study (AREDS) clinical lens grading system. Note: the participant can be reconsidered for enrollment 90 days after undergoing cataract surgery.
  • Participant has undergone lens removal in the study eye to be implanted in the previous 3 months or YAG laser within 4 weeks of the screening/baseline visit.
  • Participant has evidence of ocular disease in the study eye to be implanted other than MacTel that, in the judgment of the examining physician, may confound the diagnosis, procedures, or outcome of the study (eg. glaucoma, severe nonproliferative or proliferative diabetic retinopathy, uveitis).
  • Received intravitreal steroid therapy in the study eye to be implanted within 6 months prior to screening.
  • Evidence of active exudative intraretinal neovascularization or subretinal neovascularization in the study eye to be implanted, as evidenced by hemorrhage, hard exudate, subretinal fluid, or intraretinal fluid.
  • Evidence of central serous chorioretinopathy in the study eye to be implanted within 3 months prior to screening.
  • A history of ocular herpes virus in the study eye to be implanted.
  • Participant is on chemotherapy.
  • Participant is pregnant or breastfeeding.
  • Participation in any other clinical study of an intervention (drug or device) within 6 months prior to the screening/baseline visit.
  • A history of malignancy that would compromise survival during the clinical study.

Treatment and study plan

NT-501/revakinagene taroretcel-lwey

Combination Product

NT-501 is surgically implanted into the vitreous cavity to continuously release recombinant human ciliary neurotrophic factor (CNTF).

Other names: ENCELTO

Primary outcomes

  1. Incidence of ocular and nonocular adverse events (AEs) and serious adverse events (SAEs)

    Time frame: Baseline and annually for up to 5 yrs for Arms 1 and 2 and baseline, perioperative, and annually for up to 5 yrs for Arm 3 participants

    Incidence of ocular and nonocular adverse events (AEs) and serious adverse events (SAEs)

  2. Percentage of participants with a loss of 15 letters or more in best corrected visual acuity (BCVA) compared to presurgery baseline BCVA

    Time frame: Baseline and annually for up to 5 yrs for Arms 1 and 2 and baseline, perioperative, and annually for up to 5 yrs for Arm 3 participants

    Percentage of participants with a loss of 15 letters or more in best corrected visual acuity (BCVA) compared to presurgery baseline BCVA using the Early Treatment Diabetic Retinopathy Study (ETDRS) distance chart

Secondary outcomes

  1. Change from presurgery baseline in ellipsoid zone (EZ) area loss

    Time frame: Baseline and annually for up to 5 yrs for Arms 1 and 2 and baseline, perioperative, and annually for up to 5 yrs for Arm 3 participants

    Change from presurgery baseline in ellipsoid zone (EZ) area loss as measured by en face spectral domain optical coherence tomography (SD-OCT) for both eyes

  2. Change from presurgery baseline in BCVA

    Time frame: Baseline and annually for up to 5 yrs for Arms 1 and 2 and baseline, perioperative, and annually for up to 5 yrs for Arm 3 participants

    Change from presurgery baseline in BCVA using the ETDRS distance chart for both eyes

  3. Change from presurgery baseline in aggregate retinal sensitivity

    Time frame: Baseline and annually for up to 5 yrs for Arms 1 and 2 and baseline, perioperative, and annually for up to 5 yrs for Arm 3 participants

    Change from presurgery baseline in aggregate retinal sensitivity as measured by microperimetry within the EZ line break area for both eyes

  4. Change from presurgery baseline in monocular reading speed

    Time frame: Baseline and annually for up to 5 yrs for Arms 1 and 2 and baseline, perioperative, and annually for up to 5 yrs for Arm 3 participants

    Change from presurgery baseline in monocular reading speed for both eyes

  5. Change from presurgery baseline in the National Eye Institute Visual Function Questionnaire-25 (NEI-VFQ-25)

    Time frame: Baseline and annually for up to 5 yrs for Arms 1 and 2 and baseline, perioperative, and annually for up to 5 yrs for Arm 3 participants

    Change from presurgery baseline in NEI-VFQ-25 near activities subscale score. All items are scored so that a high score represents better functioning. Each item is then converted to a 0 to 100 scale so that the lowest and highest possible scores are set at 0 and 100 points, respectively.

Study contacts

Contact information is provided by the study sponsor or research team.

Patricia Davis

CONTACT

[email protected]

401-333-3880

Sponsors and collaborators

Lead sponsor

Neurotech Pharmaceuticals

Industry

Registry information

Official study title

A Phase 4, Multicenter, Open-label Study to Evaluate Long-term Safety and Efficacy of Revakinagene Taroretcel-Lwey (NT-501) Previously Implanted During a Phase 1, Phase 2, or Phase 3 Clinical Study and to Evaluate NT-501 Implanted in Participants Who Underwent the Sham Procedure in a Phase 3 Clinical Study of Macular Telangiectasia Type 2 (MacTel)

Important dates

Study start
2025
Primary completion
2032
Study completion
2032
First posted
May 14, 2025
Registry last updated
Jul 28, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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