This study is intended to assess the exposure, safety, biological activity, and durability of UBX1325, a phosphate pro-drug, and its active parent molecule (UBX0601) following a single intravitreal (IVT) injection of UBX1325 in patients with diabetic macular edema (DME).

This is a Phase 2a Proof-of-Concept (POC) study. The study will enroll approximately 62 patients randomized 1:1 into either the UBX1325 or sham study arms, in order to assess safety and tolerability as well as impact on visual function and retinal anatomy. Patients will be followed for 24 weeks for the primary outcome measure and for an additional 24 weeks (48 weeks total) for the secondary outcome measures.

Inclusion Criteria:

• Patients aged ≥ 18 years.
• Diabetic retinopathy patients (nonproliferative (NPDR) and proliferative (PDR)) with DME (ETDRS-DRSS Score at 65C [or DR severity level of 8]or less severe as determined by a Central Reading Center), who had at least 2 anti-VEGF intravitreal (IVT) injections (one or more of the following agents: aflibercept, bevacizumab or ranibizumab) in the preceding 6 months prior to Day 1, with the last anti-VEGF given between 3 and 6 weeks prior to Day 1.
• Center-involved DME with central subfield thickness (CST) ≥300 µm on SD-OCT at Screening
• BCVA in the study eye (most affected) of 73 to 20 ETDRS letters (equivalent to 20/40 to 20/400 on the Snellen chart) at Screening and at Day 1.

Exclusion Criteria:

• Concurrent disease in the study eye or structural damage, other than DME, that could compromise BCVA, prevent BCVA improvement, require medical or surgical intervention during the study period, confound interpretation of the results, or interfere with assessment of toxicity or color fundus photography (CFP) in the study eye.
• Any ocular/intraocular/periocular infection or inflammation in either eye in the past 4 weeks prior to screening
• History of vitreous hemorrhage in the study eye within 2 months prior to Screening
• Any condition, including laboratory findings and findings in the medical history or in the pre-study assessments, that, in the opinion of the Investigator, constitutes a risk or contraindication for participation in the study or that could interfere with the study objectives, conduct, or evaluation or prevent the patient from fully participating in all aspects of the study
• Significant media opacities, including cataract, which might interfere with VA, assessment of toxicity, or fundus imaging

This study will be double masked, so patients and Investigators are masked to the treatment assigned, while certain roles at the site and at the Sponsor are unmasked. Sites will have a qualified injector who is unmasked to perform the study treatment injection or sham procedure, as well as certain post-injection assessments on Day 1 only.