FIGHT-RP 1 Extension Study

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.

Conditions

• Retinitis Pigmentosa

Interventions

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).

Sponsors & Collaborators

• Zambon SpA

  collaborator INDUSTRY

• Johns Hopkins University

  lead OTHER

Principal Investigators

• Peter Campochiaro · Johns Hopkins University

Study Design

Allocation

NA

Purpose

TREATMENT

Masking

NONE

Model

SINGLE_GROUP

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2019-06-24

Primary Completion

2026-08-31

Completion

2027-06-30

FDA Drug

Yes

Countries

• United States

Study Locations