A Study to Evaluate THR-149 Treatment for Diabetic Macular Oedema

Key Inclusion Criteria: * Written informed consent obtained from the subject prior to screening procedures * Male or female aged 18 years or older at the time of signing the informed consent * Type 1 or type 2 diabetes * BCVA ETDRS letter score ≤ 73 and ≥ 39 in the study eye (for subjects in Part A); BCVA ETDRS letter score ≤ 73 and ≥ 24 in the study eye (for subjects in Part B) * Central involved DME (CI-DME) with CST of ≥ 320µm in men or ≥ 305µm in women, on spectral domain optical coherence tomography (SD-OCT), in the study eye * Received ≥ 5 anti-vascular endothelial growth factor (anti-VEGF) injections for the treatment of CI-DME * BCVA ETDRS letter score ≥ 34 in the fellow eye Key Exclusion Criteria: * Macular edema due to causes other than DME in the study eye * Concurrent disease in the study eye, other than central-involved DME, that could require medical or surgical intervention during the study period or could confound interpretation of the results * Any condition that could confound the ability to detect the efficacy of the investigational medicinal product * Previous confounding medications / interventions, or their planned administration * Presence of neovascularisation at the disc in the study eye * Presence of iris neovascularisation in the study eye * Uncontrolled glaucoma in the study eye * Any active or suspected ocular or periocular infection, or active intraocular inflammation, in either eye * Untreated Diabetes Mellitus * Glycated haemoglobin A (HbA1c) \> 12% * Uncontrolled hypertension