Study to Assess the Efficacy & Safety of KHK4951 in Patients With Diabetic Macular Edema

Inclusion Criteria: * Voluntary written informed consent to participate in the study * In Korea, participants must be 19 years or older to be enrolled * BCVA ETDRS letter score of 78 letters to 35 letters as measured by the ETDRS visual acuity chart in the study eye at screening * 500 μm ≥ CST ≥ 325 μm in the study eye at screening * HbA1c ≤ 11% at screening Exclusion Criteria: * Any signs of proliferative diabetic retinopathy in the study eye * History of rubeosis in the study eye * Uncontrolled glaucoma in the study eye * Aphakia or pseudophakia with AC-IOL in the study eye * Active intraocular inflammation in the study eye * Any current ocular condition for which visual acuity loss would not improve from resolution of macular edema in the study eye * History of rhegmatogenous retinal detachment in the study eye * Any current or history of ocular disease other than DME that may confound assessment of the macula or affect central vision in the study eye * History of the following therapies in the study eye * History of vitrectomy surgery, submacular surgery, or other surgical intervention for DME * Periocular or intraocular (sub-Tenon or IVT) corticosteroids within 12 weeks prior to Day 1 corticosteroids * Previous intraocular device implantation except PC-IOL * Laser (any type) to the macular area within 12 weeks prior to Day 1 * Peripheral retinal photocoagulation therapy within 12 weeks prior to Day 1 * Previous treatment with IVT anti-VEGF drugs other than ranibizumab, bevacizumab, aflibercept 2 mg, and their biosimilars * Treatment with ranibizumab, bevacizumab, aflibercept 2 mg, or their biosimilars within 12 weeks prior to Day 1. Previously treated patients who received these medications more than 12 weeks prior to Day 1 can be enrolled, but the patients should be diagnosed with DME within 3 years prior to Day 1 * Previous use of Ozurdex® or Iluvien® implant * Any current or history of endophthalmitis in either eye * History of idiopathic or autoimmune-associated uveitis in either eye * Active infectious conjunctivitis, keratitis, scleritis, or endophthalmitis in either eye