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FIGHT-RP 1 Extension Study

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
ClinicalTrials.gov Identifier: NCT03999021
Recruitment Status : Active, not recruiting
First Posted : June 26, 2019
Last Update Posted : September 16, 2022
Information provided by (Responsible Party):
Johns Hopkins University

Brief Summary:

Retinitis Pigmentosa (RP) is a devastating eye disease and at present there are no known treatment options that can alter the rate of vision loss and eventual blindness. In a series of studies in animal models, the effects of exposing cones in the periphery of the retina to a large excess of oxygen results in progressive oxidative damage to cone photoreceptors and cone cell death. Cone cell death gradually spreads from the periphery of the retina toward its center, narrowing the visual field and eventually resulting in tunnel vision. Compared to control patients, those with RP showed significant reduction in the reduced to oxidized glutathione ratio (GSH/GSSG) in aqueous humor and a significant increase in protein carbonyl content. This demonstration of oxidative stress and oxidative damage in the eyes of patients with RP, suggests that oxidative damage-induced cone cell death in animal models of RP may translate to humans with RP and support the hypotheses that (1) potent antioxidants will promote cone survival and function in patients with RP and (2) aqueous GSH/GSSG ratio and carbonyl content on proteins provide useful biomarkers of disease activity in this patient population. Orally administered N-acetylcysteine (NAC) has been found to be a particularly effective antioxidant that promotes prolonged cone survival and maintenance of cone function in a mouse model of RP. Since oral and/or topical administration of NAC is feasible for long-term treatment in humans, and NAC has a good safety profile, there is good rationale to test the effect of NAC in patients with RP.

Oxidative damage has been implicated in several diseases including cystic fibrosis, chronic obstructive pulmonary disease (COPD), and Idiopathic Pulmonary Fibrosis. The effect of oral NAC has been tested in these indications in several clinical trials providing extensive safety data. In COPD, NAC 600mg bid improves airway function and reduces the frequency of acute exacerbations. Doses of up to 1800mg/day have been well-tolerated in the treatment of Idiopathic Pulmonary Fibrosis. Paracetamol (acetaminophen) toxicity is treated with a loading dose of 140 mg/kg NAC followed by 70 mg/kg every 4 hours for 17 doses. Normal volunteers tolerated a dose of 11.2 grams NAC/day for three months without any serious undesirable effects and in another study a dose of 500mg/kg/day was tolerated. The most frequent adverse events associated with the oral administration of NAC are gastrointestinal in nature and include vomiting, diarrhea, stomatitis, abdominal pain and nausea (incidence rate >1/1000 to <1/100). Hypersensitivity reactions including anaphylactic shock and anaphylactic/anaphylactoid reaction (incidence rate <1/10,000), dyspnea, bronchospasm (incidence rate >1/10,000 to <1/1000), angioedema, tachycardia, urticaria, rash and pruritus (incidence rate >1/1000 to <1/100) have been reported less frequently. Finally, reports of headache, tinnitus, pyrexia, blood pressure decreased (incidence rate >1/1000 to <1/100), face edema and hemorrhage have also been collected with oral NAC.

In the FIGHT-RP 1 Study, the investigators used escalating doses of NAC effervescent tablets (from 600 mg in Cohort 1 to 1800 mg in Cohort 3). The maximum tolerated dose was 1800 mg twice a day which will be continued in this study.

Condition or disease Intervention/treatment Phase
Retinitis Pigmentosa Drug: NAC effervescent tablets Phase 1

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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 30 participants
Allocation: N/A
Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: A Phase 1 Open-Label Extension Study to Assess the Long-Term Safety and Tolerability of N-Acetylcysteine (NAC) in Patients With Retinitis Pigmentosa
Actual Study Start Date : June 24, 2019
Estimated Primary Completion Date : February 2025
Estimated Study Completion Date : December 2025

Resource links provided by the National Library of Medicine

Arm Intervention/treatment
Experimental: Experimental Arm
All participants to receive study intervention.
Drug: NAC effervescent tablets
After completing the pretreatment visits, all patients will enter into the treatment phase where patients will receive 1800 mg of NAC effervescent tablets twice a day. The patients will be followed up every 3 months for 2 years. Therefore, there will be a total of 9 treatment visits (baseline, months 3, 6, 9, 12, 15, 18, 21 and 24).

Primary Outcome Measures :
  1. Blood Pressure (mmHg) [ Time Frame: Up to 2 years ]
    Blood pressure in mmHg will be used in assessing tolerability of N-Acetylcysteine.

  2. Tolerability of N-Acetylcysteine as assessed by drug-related symptoms [ Time Frame: Up to 2 years ]
    Participants will be assessed for the occurrence of any drug-related symptoms which includes nausea, stomach upset, diarrhea, heartburn, constipation, and vomiting. Based on the number and severity of the symptoms, the physician would conclude whether the patient is tolerating the medication or not.

  3. Tolerability of N-Acetylcysteine as assessed by time at which medication is taken [ Time Frame: Up to 2 years ]
    Medication diary provided to participants will be reviewed to see if participants are taking the medication within the designated time frame.

  4. Tolerability of N-Acetylcysteine as assessed by number of times medication is taken per day [ Time Frame: Up to 2 years ]
    Medication diary provided to participants will be reviewed to see if participants are taking the medication twice a day

Secondary Outcome Measures :
  1. Change in best corrected visual acuity (BCVA) [ Time Frame: Baseline, every three months up to 2 years ]
    Scoring is determined by the number of letters gained or lost per month using Early Treatment Diabetic Retinopathy Study (ETDRS) Letter Score and visual acuity score together with an overall score range of 0 to 20/20 where 0 is the worst vision and 20/20 is the best.

  2. Change in central retinal sensitivity as assessed by microperimetry [ Time Frame: Baseline, every three months up to 2 years ]
    Microperimetry (MAIA) is used to test whether there is an increase or decrease in sensitivity (dB) in the retina after initiation of N-Acetylcysteine

  3. Change in ellipsoid zone (EZ) width (µm) [ Time Frame: Baseline, every three months up to 2 years ]
    This will be assessed by spectral domain optical coherence tomography (SD-OCT) after initiation of N-Acetylcysteine.

  4. Change in aqueous reduced to oxidized glutathione ratio (GSH/GSSG) [ Time Frame: Baseline, every three months up to 2 years ]
    This will be calculated from the proportions of reduced glutathione and oxidized glutathione in the aqueous.

  5. Change in serum carbonyl content (nmol/mg) [ Time Frame: Baseline, every three months up to 2 years ]
  6. Change in aqueous levels of N-Acetylcysteine (mg) [ Time Frame: Baseline, every 6 months up to 2 years ]
  7. Change in plasma levels of N-Acetylcysteine (µg/ml) [ Time Frame: Baseline, every 3 months up to 2 years ]

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Age 18 years
  • Patients diagnosed with RP
  • Informed consent
  • Authorization of use and disclosure of protected health information

Exclusion Criteria:

  • Patients with a concomitant ocular pathology that limits central macular function, including but not limited to: age-related macular degeneration, diabetic retinopathy, and retinal vein occlusion
  • Patients with an active ocular infection
  • Patients with uncontrolled hypertension (defined as diastolic blood pressure > 95 mm Hg or systolic blood pressure > 160 mm Hg despite medical therapy)

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03999021

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United States, Maryland
Wilmer Eye Institute at Johns Hopkins University
Baltimore, Maryland, United States, 21287
Sponsors and Collaborators
Johns Hopkins University
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Principal Investigator: Peter Campochiaro Johns Hopkins University
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Responsible Party: Johns Hopkins University
ClinicalTrials.gov Identifier: NCT03999021    
Other Study ID Numbers: IRB00204017
First Posted: June 26, 2019    Key Record Dates
Last Update Posted: September 16, 2022
Last Verified: September 2022
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No

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Studies a U.S. FDA-regulated Drug Product: Yes
Studies a U.S. FDA-regulated Device Product: No
Additional relevant MeSH terms:
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Retinitis Pigmentosa
Retinal Diseases
Eye Diseases
Eye Diseases, Hereditary
Retinal Dystrophies
Retinal Degeneration
Genetic Diseases, Inborn