Carbidopa-levodopa in Neovascular AMD

NCT ID: NCT03022318

Last Updated: 2025-09-12

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: PHASE2
• Total Enrollment: 20 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2017-05-02
• Study Completion Date: 2020-05-04

Brief Summary

From 3 large patient databases, patients diagnosed with AMD who have never taken levodopa(L-DOPA) containing medications have a mean age of diagnosis at 71 years. Patients who have been treated with L-DOPA containing medications have a mean age of diagnosis of AMD at 79 years.

L-DOPA binds to GPR143 in the retinal pigment epithelium, and releases PEDF, which protects the retina and downregulates VEGF, which is the cause of neovascularization.

The Investigators will evaluate the safety and tolerability of carbidopa-levodopa in patients with Neovascular AMD, and measure the effects on visual acuity and retinal abnormalities due to "wet" (neovascular) AMD.

Detailed Description

Age-related macular degeneration (AMD) is the most common cause of blindness, in individuals over the age of 50, in the developed world. AMD becomes more common as people age and is more common in lightly pigmented individuals. AMD appears more common in patients with Parkinson's Disease than in those without. The AREDS nutritional supplements are effective in slowing the progress of intermediate AMD(5). Most AMD is "dry AMD", which progresses relatively slowly and may impair vision, but usually does not lead to legal blindness. There are two forms of AMD, "wet AMD" and geographic atrophy (GA), that can cause more profound vision loss. In aggregate, they occur in about 25% of patients with AMD. Wet AMD is due to new growth of abnormal blood vessels under the retina. The new blood vessels are believed to be due to an excessive release of vascular endothelial growth factor (VEGF) by the retinal pigment epithelium(RPE) cells. Wet AMD is now effectively treated with intraocular injections of VEGF inhibitors. Geographic Atrophy, the other form of advanced AMD, represents focal death of the RPE cells and overlying neurosensory retina. There is no current treatment for GA. It is suspected that GA is due in part to a localized inflammatory response, damage to RPE cells, and loss of RPE cell function. It may also be speculated that stimulation of RPE cells to release a potent neurotrophic factor, pigment epithelium derived factor (PEDF) may slow the progression of GA.

In 2008, Dr. Brian McKay identified a receptor, G protein coupled receptor #143(GPR143), on the surface of RPE cells and discovered that L-DOPA was the natural ligand or stimulator of GPR143. Dr McKay showed that treatment of RPE cells with exogenous L-DOPA resulted in the release of additional PEDF. In subsequent work, Dr. McKay's group also showed that L-DOPA stimulation of PEDF in RPE cells was also associated with a decrease in VEGF. Thus, Dr McKay hypothesized that exogenous L-DOPA may prevent the onset of AMD or progression to wet AMD.

In 2015, Dr McKay and his associates published a paper that showed that patients, who had been treated with L-DOPA, had a delay in the onset of AMD by 8 years, compared to patients who had not been treated with L-DOPA. In addition, those who had AMD and went on to develop wet AMD did so 5 years later than those with no history of L-DOPA treatment. L-DOPA is an intermediate in the pigmentation pathway. Dr McKay and his associates suggested that the reason darkly pigmented races do not get AMD nearly as frequently as lighter pigmented races is that they produce more pigment, and thus more L-DOPA to stimulate GPR143 on RPE cells. According to this hypothesis, the stimulated RPE cells release PEDF and decrease VEGF, which together are responsible for the protective effect.

Since there are no established animal models for AMD, and L-DOPA has a good safety profile in healthy volunteers and patients with Parkinson's disease, the Investigators propose a prospective experiment to determine the safety and tolerability of L-DOPA, in a population of patients with AMD. The participants will be made aware of potential side effects of L-DOPA, which are listed in the Informed Consent, during the consent process. Adverse events will be elicited by questioning the participants at each visit. The participants will also be advised to call the site if they have any medical problems between visits.

The Investigators will also use this study to examine whether L-DOPA has a positive effect on visual acuity and pathologic retinal changes of "wet" AMD. The parameters to be evaluated are best corrected ETDRS visual acuity, macular thickness by spectral domain optical coherence tomography (SD OCT), new blood (hemorrhage) by direct retinal examination, or subjective decrease in vision.

Pharmacology of L-DOPA and carbidopa:

L-DOPA is formed by 3-hydroxylation of tyrosine by tyrosine-3-monooxygenase (tyrosinase).(18) The primary metabolic pathway of L-DOPA is decarboxylation by amino acid decarboxylase to dopamine, which is responsible for most, but not all, of its pharmacologic effects and toxicity. When carbidopa is administered with L-DOPA, systemic levels of L-DOPA double and central nervous system (CNS) L-DOPA increases from about 1% of the administered dose to about 4%. Levodopa freely passes from the systemic circulation into the retina and brain, but dopamine and carbidopa do not. Adverse events are markedly decreased when carbidopa is administered with L-DOPA, because systemic levels of the toxic metabolite of L-DOPA, dopamine, are markedly reduced. In most patients, 25 mg of carbidopa is sufficient to control side effects of 100 mg of L-DOPA, primarily nausea, by 90%.

L-DOPA is the natural ligand for GPR143 in the RPE cells. The Investigators' intent is to increase the L-DOPA available to RPE surface receptors (GPR 143) while minimizing peripheral toxicity. This concept is unique, because all other uses of L-DOPA rely on CNS conversion of L-DOPA to dopamine, in order to produce the desired effect.

Excess VEGF is the mediator of the retinal neovascularization and other retinal pathological changes in "wet" AMD. Intraocular injections of anti-VEGF antibodies is the standard of care in "Wet" AMD. Several publications, including Lim et al, show that with careful monitoring of the visual acuity and retinas of patients with wet AMD, if there is no progression, there are no long-term adverse consequences of delaying initiation of anti-VEGF therapy for up to 4 weeks. The patients will be monitored at weekly intervals, for up to 4 weeks, for indications for initiation of anti-VEGF injections.

Criteria for anti-VEGF injections

This will be based on: weekly evaluation of ETDRS visual acuity (decrease of 5 letters from previous visit); increased macular thickness (compared to normal and previous visit as measured by OCT; new blood (hemorrhage) on direct retinal examination; or subjective decrease in vision. If any of these criteria are met, or if, in the opinion of the Ophthalmologist, the patient requires anti-VEGF therapy, the patient will have an anti-VEGF intraocular injection. If none of these criteria are met at visits 2, 3, or 4, with the patient agreement, anti-VEGF injection will not be done, and the patient will be reevaluated in 1 week. The patients will receive an anti-VEGF injection at the end of the 4th week if they have not received one earlier. Whenever a patient receives the first anti-VEGF injection, participation in this protocol will end. At that point, the patient will be able to enroll in Study 0002, Proof of Concept and Dose Ranging Study of carbidopa-levodopa in Neovascular AMD.

Treatments:

Randomized assignment to carbidopa-levodopa 25-100 mg tablets dosed hs or carbidopa-levodopa 25-100 mg tablets dosed 3 times daily, in the morning, with supper and hs. The second dosing regimen is the equivalent of a moderate dose of carbidopa-levodopa in patients with Parkinson's disease (maximum daily dose of levodopa 200-800 mg).

Number of participants: Up to 52 completed, randomized using a table of random numbers.

Informed Consent will be completed at the first visit. Duration: up to 32 days of treatment. Visits will occur at 5-8 day intervals. Overall trial duration for enrollment and treatment, screening 5 patients per week, will be approximately 10 months.

Primary Endpoint: A statistically significant improvement (5 letters) by carbidopa-levodopa treatment in ETDRS visual acuity.

Measurements:

Demographics at Visit 1; Medical History and Physical Examination at Visit 1; Electrocardiogram(ECG), complete blood count(CBC), Chem 20 and HbA1C at Visit 1; Vital signs at Visits 1,2,3,4 and 5; Non-directed assessment of adverse events at Visits 1,2,3,4 and 5. SD OCT at Visits 1,2,3,4,5; Pill count at Visits 2,3,4 and 5;

Statistics: Analysis of Variance with Independent Variables for each arm and comparing arms:

ETDRS visual acuity, central retinal (macular) thickness, presence of hemorrhage and duration of treatment prior to initiation of anti-VEGF (Vascular endothelial growth factor) intraocular injections.

Conditions

Age-related Macular Degeneration

Study Design

• Allocation Method: NON_RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: NONE

Study Groups

once daily

carbidopa-levodopa 25-100 mg tablets once daily hs for up to 32 days

Group Type: EXPERIMENTAL

carbidopa-levodopa 25-100 mg tablets

Intervention Type: DRUG

See arm/group descriptions

3 times daily

carbidopa-levodopa 25-100 mg tablets 3 times daily,in the morning, with supper and hs for up to 32 days

Group Type: EXPERIMENTAL

carbidopa-levodopa 25-100 mg tablets

Intervention Type: DRUG

See arm/group descriptions

Interventions

carbidopa-levodopa 25-100 mg tablets

See arm/group descriptions

Intervention Type: DRUG

Other Intervention Names

Sinemet

Eligibility Criteria

Inclusion Criteria

1. A diagnosis of AMD with choroidal neovascularization (CNV) in one eye;

2. Not previously treated with anti-VEGF injections;

3. Normal or dry AMD of any grade in the second eye;

4. Age 50-85 years;

5. Willingness to maintain AREDS vitamin supplements throughout the study, or remain off these supplements for the duration of the study, if not taking them prior to the study;

6. Signed Informed Consent.

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Exclusion Criteria

1. Any current use of L-DOPA containing medication or dopamine agonist medication, or any planned use of any of these agents, except for study medication, during the study;

2. Concurrent use of monoamine oxidase (MAO) inhibitors;

3. Any eye condition, disease, or history of trauma in either eye, which can impair vision, except cataract or cataract surgery;

4. Best Corrected Visual Acuity (BCVA )worse than 20/160 in the better eye;

5. Wet AMD in the second eye;

6. Neurologic conditions which can impair vision;

7. Parkinson's Disease;

8. Significant orthostatic hypotension, defined as a drop in systolic blood pressure, immediately upon changing from the supine to standing position, of >19 mmHg, or a symptomatic drop in systolic blood pressure, immediately upon changing from the supine to standing position;

9. Significant ECG abnormalities, as judged by the Investigator;

10. Estimated glomerular filtration rate (eGFR) <20 ml/min;

11. Liver enzymes >3 X the upper limit of normal;

12. HbA1C >9.0;

13. Any other significant lab abnormalities, as judged by the Investigator;

14. Women of childbearing potential;

15. Known retinal hemorrhage;

16. Subjects who are not fluent in English.

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• Minimum Eligible Age: 50 Years
• Maximum Eligible Age: 85 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Snyder, Robert W., M.D., Ph.D., P.C.

INDIV

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Robert W Snyder, MD, PhD

Role: PRINCIPAL_INVESTIGATOR

Robert W Snyder, MD, PhD, PC

Timothy C Fagan, MD

Role: STUDY_DIRECTOR

Robert W Snyder, MD, PhD, PC

Locations

Robert W Snyder, MD, PhD, PC

Tucson, Arizona, United States

Countries

United States

References

Resnikoff S, Pascolini D, Etya'ale D, Kocur I, Pararajasegaram R, Pokharel GP, Mariotti SP. Global data on visual impairment in the year 2002. Bull World Health Organ. 2004 Nov;82(11):844-51. Epub 2004 Dec 14.

Reference Type: BACKGROUND

PMID: 15640920 (View on PubMed)

Jager RD, Mieler WF, Miller JW. Age-related macular degeneration. N Engl J Med. 2008 Jun 12;358(24):2606-17. doi: 10.1056/NEJMra0801537. No abstract available.

Reference Type: BACKGROUND

PMID: 18550876 (View on PubMed)

Bressler SB, Munoz B, Solomon SD, West SK; Salisbury Eye Evaluation (SEE) Study Team. Racial differences in the prevalence of age-related macular degeneration: the Salisbury Eye Evaluation (SEE) Project. Arch Ophthalmol. 2008 Feb;126(2):241-5. doi: 10.1001/archophthalmol.2007.53.

Reference Type: BACKGROUND

PMID: 18268216 (View on PubMed)

Ferrara N. Vascular endothelial growth factor and age-related macular degeneration: from basic science to therapy. Nat Med. 2010 Oct;16(10):1107-11. doi: 10.1038/nm1010-1107. No abstract available.

Reference Type: BACKGROUND

PMID: 20930754 (View on PubMed)

Lopez VM, Decatur CL, Stamer WD, Lynch RM, McKay BS. L-DOPA is an endogenous ligand for OA1. PLoS Biol. 2008 Sep 30;6(9):e236. doi: 10.1371/journal.pbio.0060236.

Reference Type: BACKGROUND

PMID: 18828673 (View on PubMed)

Falk T, Congrove NR, Zhang S, McCourt AD, Sherman SJ, McKay BS. PEDF and VEGF-A output from human retinal pigment epithelial cells grown on novel microcarriers. J Biomed Biotechnol. 2012;2012:278932. doi: 10.1155/2012/278932. Epub 2012 Apr 2.

Reference Type: BACKGROUND

PMID: 22547925 (View on PubMed)

Brilliant MH, Vaziri K, Connor TB Jr, Schwartz SG, Carroll JJ, McCarty CA, Schrodi SJ, Hebbring SJ, Kishor KS, Flynn HW Jr, Moshfeghi AA, Moshfeghi DM, Fini ME, McKay BS. Mining Retrospective Data for Virtual Prospective Drug Repurposing: L-DOPA and Age-related Macular Degeneration. Am J Med. 2016 Mar;129(3):292-8. doi: 10.1016/j.amjmed.2015.10.015. Epub 2015 Oct 30.

Reference Type: BACKGROUND

PMID: 26524704 (View on PubMed)

Westfall TC, Westfall DP. Neurotransmission: The Autonomic and Somatic Motor nervous Systems. Pharmacological Basis of Therapeutics, 12th Edition, 171-218, McGraw-HILL, 2011.

Reference Type: BACKGROUND

Standaert DG, Roberson ED. Treatment of Central Nervous System Degenerative Disorders. Pharmacological Basis of Therapeutics, 12th Edition, 609-628, McGraw-HILL, 2011.

Reference Type: BACKGROUND

Lim JH, Wickremasinghe SS, Xie J, Chauhan DS, Baird PN, Robman LD, Hageman G, Guymer RH. Delay to treatment and visual outcomes in patients treated with anti-vascular endothelial growth factor for age-related macular degeneration. Am J Ophthalmol. 2012 Apr;153(4):678-86, 686.e1-2. doi: 10.1016/j.ajo.2011.09.013. Epub 2012 Jan 14.

Reference Type: BACKGROUND

PMID: 22245460 (View on PubMed)

Provided Documents

Document Type: Study Protocol

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Other Identifiers

0001

Identifier Type: -

Identifier Source: org_study_id