Oral Hydroxychloroquine (HCQ) for Retinitis Pigmentosa Caused by P23H- Rhodopsin (RHO)

Inclusion Criteria:

• Stated willingness to comply with all study procedures and availability for theduration of the study

• Signed and dated informed consent form

• Early Treatment Diabetic Retinopathy Study Best Corrected Visual Acuity (ETDRS BCVA)of 20 letters (approximately 20/400 Snellen) or better in at least one eye

• Clinical diagnosis of autosomal dominant retinitis pigmentosa

• Confirmed to have one copy of the P23H-RHO pathogenic variant by genetic testing ata Clinical Laboratory Improvement Amendments (CLIA)-certified laboratory

• Clarity of ocular media and adequate pupillary dilation to allow for adequateclinical ocular examination and retinal imaging

• Ability to perform testing required by the study as determined by the investigator

• Ability to take oral medication (medication tablets must be swallowed whole) and bewilling to adhere to the daily medication regimen

• For females of reproductive potential: use of highly effective contraceptionbeginning no later than 1 week after the first screening visit, and agreement to usesuch a method during study participation and through the end of the washout period (6 months after the end of HCQ administration)

• Agreement to adhere to Lifestyle Considerations throughout study duration (take thestudy drug with meals, avoid taking over-the-counter antacids or kaolin-containingproducts 4 hours before or after taking the study drug)

Exclusion Criteria:

• Use of any other drugs which are known to prolong the QT interval

• Concurrent use of any of the following drugs, if the drug cannot be discontinued orsubstituted: digoxin, antiepileptic medications, cimetidine, methotrexate,cyclosporine, praziquantel, ampicillin

• Current or previous use of tamoxifen

• Pregnancy or lactation

• Known allergy or hypersensitivity to hydroxychloroquine or any other 4-aminoquinoline drugs (chloroquine, amodiaquine, mefloquine, quinacrine, etc.), orknown history of glucose-6-phosphate dehydrogenase deficiency

• Treatment with another investigational medical intervention for retinitis pigmentosawithin 3 months, or any ever previous treatment with an investigational surgicalintervention

• Any pre-existing cardiac, renal, hepatic, or hematologic disease, any prior historyof psoriasis or porphyria, or any alcoholism

• Abnormal screening laboratory values including aspartate transaminase (AST) oralanine transaminase (ALT) > 2.0 x upper limit of normal, subnormal glomerularfiltration rate (< 90 mL/min/1.73m2) or abnormal complete blood count attributableto underlying hematologic disease such as malignancy, aplastic anemia,agranulocytosis, leukopenia, or thrombocytopenia.