The objective of this study is to evaluate the safety and efficacy of APX3330 to treat diabetic retinopathy (DR) and diabetic macular edema (DME).

The objective of this study is to evaluate the efficacy of APX3330 to improve Early Treatment Diabetic Retinopathy Study (ETDRS) Diabetic Retinopathy Severity Score (DRSS) in one hundred (100) subjects with moderately severe to severe NPDR or mild PDR.

Subjects with moderately severe to severe NPDR and mild PDR will be selected for study participation and be screened for study eligibility.

The eligible eye with the highest DRSS, as assessed by the central reading center, will be designated as the study eye for the primary efficacy analysis.

If the subject meets all eligibility criteria, then the subject will be randomized into the study and receive study medication. Blood will be drawn for biomarker analysis.

The total length of subject participation is approximately 26 weeks, with 5 clinic visits, 4 telephone safety calls, and one telephone call follow-up visit.

The execution of the entire study (first subject screen through last randomized subject completed) is expected to be approximately 12 to 15 months.

Inclusion Criteria:

1. Males or non-pregnant females ≥ 18 years of age
2. At least one eye with DR graded at least moderately severe to severe NPDR or mild PDR (corresponding to DRSS 47, 53, or 61)
3. BCVA assessed by ETDRS protocol letters score of ≥ 60 letters (Snellen equivalent ≥ 20/63)
4. Body mass index (BMI) between 18 and 40 kg/m2, inclusive

Exclusion Criteria:

Ophthalmic:

1. Any prior treatment in the study eye with:

   1. Focal or grid laser photocoagulation within the past year or PRP at any time
   2. Systemic or intravitreal anti-VEGF agents within the last 6 months
   3. Intraocular steroids including triamcinolone and dexamethasone implant within the last 6 months
   4. Fluocinolone implant within the last 3 years

2. Active uveitis, vitritis, or infection in either eye including infectious conjunctivitis, keratitis, scleritis, or endophthalmitis.

3. Ocular incisional surgery including cataract surgery in the study eye within 3 months.

4. Clinically significant ocular disease in either eye.

5. Presence of macular or retinal vascular disease including diabetic macular edema, retinopathy from causes other than diabetes, age-related macular degeneration, pattern dystrophy, choroidal neovascularization of any cause, retinal vein occlusion, retinal artery occlusion in the study eye.

6. History of retinal detachment, full-thickness macular hole in the study eye, or idiopathic or autoimmune uveitis in either eye.

Systemic:

1. Known hypersensitivity or contraindication to study drug.
2. Any disease or medical condition that in the opinion of the Investigator would interfere with the study, prevent the subject from successfully participating in the study, or which might confound the study results.
3. Participation in any investigational study within 30 days prior to screening or planning to participate in any other investigational drug or device clinical trials within 30 days of study completion.
4. Resting HR outside the specified range (50-110 beats per minute).
5. Known to be immunocompromised or receiving immunosuppressive therapy.
6. Hypertension with resting diastolic blood pressure (BP) > 105 mmHg or systolic BP > 200 mmHg.
7. History of chronic liver disease or presence of elevated alanine aminotransferase (ALT) and aspartate aminotransferase (AST) consistent with such diagnosis.
8. Women of childbearing potential who are pregnant, nursing, planning a pregnancy, or not using a medically acceptable form of birth control.

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