Nesvategrast (OTT166) in Diabetic Retinopathy (DR)

Inclusion Criteria: 1. Men or women ≥ 18 years of age with type 1 or 2 diabetes mellitus who have moderately severe to severe NPDR \[DRSS levels 47 or 53\], or mild PDR \[DRSS level 61\] NVE \< 0.5 DA in 1 + quadrants\], in whom PRP and/or anti-VEGF IVT can be safely deferred for at least 6 months per the Investigator 2. BCVA ETDRS letter score in the study eye of ≥ 69 letters (approximate Snellen equivalent of 20/40 or better) 3. Normal foveal contour 4. Treatment naïve (ie, no previous anti-VEGF or steroid treatment or PRP or laser) 5. Willing and able to return for all study visits and comply with study-related procedures 6. Able to adhere to the study dosing requirements 7. Understands and signs the written Informed Consent Form Exclusion Criteria: 1. CST of \> 325 μm a. Fluid in the central subfield is allowed so long as CST is ≤325 μm and there is a normal foveal contour as determined by the Central Reading Center 2. Any prior focal or grid laser photocoagulation or any prior PRP in the study eye as it pertains to treatment of DME or DR (peripheral retinal hole treated with laser is allowed) 3. Eyes with DRSS score 61 with fibrous proliferations at disc or fibrous proliferations elsewhere a. DRSS score 61B with NVE only is allowed. Any sign of fibrosis proliferation is exclusionary 4. Any prior systemic anti-VEGF treatment or IVT anti-VEGF treatment in the study eye 5. Any prior intraocular steroid injection in the study eye, inclusive of Iluvien® and Retisert® a. History of Ozurdex® and triamcinolone use prior to 12 months before study enrollment is allowed 6. Current ASNV, vitreous hemorrhage, or tractional retinal detachment visible at the screening assessments in the study eye 7. Uncontrolled glaucoma or ocular hypertension in the study eye defined as an IOP \> 25 mmHg regardless of concomitant treatment with IOP-lowering medications 8. Hypertension defined as systolic \> 180 mmHg or \> 160 mmHg on 2 consecutive measurements (during the same visit) or diastolic \> 100 mmHg 9. Screening HbA1c blood test \> 12.0% 10. Renal failure (stage 4 or end-stage), dialysis, or history of renal transplant 11. History of other disease, metabolic dysfunction, physical examination finding, or clinical laboratory finding giving reasonable suspicion of a disease or condition that contraindicates the use of an investigational drug or that might affect interpretation of the results of the study or render the participant at high risk for treatment complications 12. Initiation of intensive insulin treatment (a pump or multiple daily injections) within 4 months prior to randomization or plans to do so in the next 4 months 13. Epiretinal membrane, posterior hyaloidal traction, and/or vitreomacular traction in the study eye as determined to be significant by the Investigator 14. Previous pars plana vitrectomy in the study eye 15. Any intraocular surgery in the study eye within 90 days (3 months) prior to study enrollment 16. YAG laser treatment in the study eye within 90 days prior to study enrollment 17. Concomitant use of any topical ophthalmic medications in the study eye, including dry eye or glaucoma medications, unless on a stable dose for at least 90 days prior to study enrollment and expected to stay on stable dose throughout study participation. Topical eyedrops are allowed but not within ±10 minutes of study drop application 18. Contact lens use from time of screening throughout the study 19. Central corneal changes from dry eye that are visually significant and/or Sjogren's syndrome 20. Visually significant Fuchs endothelial dystrophy or other diagnosed conditions of corneal compromise including Anterior Basement Membrane Dystrophy, or any corneal dystrophy affecting central vision (peripheral processes are not exclusionary) 21. Chronic or recurrent uveitis in the study eye 22. Ongoing ocular infection or inflammation in either eye 23. A history of cataract surgery complicated by vitreous loss in the study eye 24. Congenital eye malformations in the study eye 25. A history of penetrating ocular trauma in the study eye 26. Cognitive impairment that, in the opinion of the investigator, could compromise compliance with the requirements of the study 27. Females of childbearing potential (ie, who are not postmenopausal for at least 1 year or surgically sterile for at least 6 weeks prior to Visit 1 - Screening/Randomization) who are lactating, or who are pregnant as determined by a positive serum pregnancy test at Visit 1 -Screening/Randomization. Women of childbearing potential must agree to use acceptable methods of birth control throughout the study a. Women who are breastfeeding or who have a positive serum hCG/urine pregnancy test at the screening or BL Visit 28. Females and males of childbearing potential unwilling or unable to utilize the following acceptable methods of birth control: tubal ligation, transdermal patch, intrauterine devices/systems, oral/implantable/injectable or contraceptives, diaphragm or cervical cap with spermicide, or vasectomized partner for females; condoms with spermicidal agent and vasectomy for males; or sexual abstinence for males and females 29. Participation in any other investigational device or drug clinical research study within 12 weeks of Visit 1 - Screening/Randomization and during the duration of enrollment 30. Contraindication to the study medications or fluorescein dye 31. Other ocular pathologies that, in the investigator's opinion, would interfere with the participant's vision in the study eye 32. Ocular media of insufficient quality to obtain fundus photographs, fluorescein angiography, and OCT images in the study eye 33. Concomitant use of Semaglutide (Wegovy®, Ozempic®, Rybelsus®), Thiazolidinediones (Actos®, Avandia®), Liraglutides (Victoza®, Saxenda®), Dulaglutide (Trulicity®), or Tirzepatide (Mounjaro®) within 12 months prior to Visit 1 (allowed if a stable dose has been established for at least 1 year of use) a. Plans to start concomitant use of Semaglutide or Thiazolidinediones during the study duration is exclusionary