Activation of GPR40 (G-protein coupled receptor 40) in pancreatic β-cells may improve glycaemic control in type 2 diabetes (T2D) patients through enhancement of glucose-stimulated insulin secretion (GSIS). Here we present phase I an open label, dose-escalation study with single oral administration of GPR40 agonist - CPL207280 in healthy subjects in fasting conditions. The study was performed in conventional 3+3 design, where MTD (maximum tolerated dose) is to be determined. Caucasian male and female subjects (24 volunteers) were enrolled in 8 cohorts (n=3 per). Subjects received CPL207280 in doses ranging from 5 to 480 mg. Safety assessment included adverse events (AE) reporting, clinical laboratory tests, glucose, insulin, proinsulin, c-peptide and glucagon level monitoring, vital signs, physical examination, electrocardiography (ECG). Blood samples for pharmacokinetic (PK) analysis were collected up to 48 hours after administration. CPL207280 concentrations in human plasma were evaluated by HPLC/MS/MS. Pharmacokinetic parameters were calculated using a non-compartmental modelling approach. Administration of CPL207280 was safe and well tolerated with no serious AE. All adverse events were classified as not related to the study product. Despite administration up to 480 mg of CPL207280, no dose limiting toxicity (DLT) was observed, therefore no MTD was determined. The CPL207280 exposure increased in a dose-dependent manner. The CPL207280 mean maximum plasma concentration (Cmax) values ranged from 19 to 516 ng/mL for cohort 1 and 8, respectively, and were observed at 1-3 hours after administration. The area under the curve of plasma concentration vs. time (AUC0-24h) ranged from 516 to 4603 ng/mL*h, for cohort 1 and 8, respectively. CPL207280 administration in all doses was safe and well tolerated. No adverse events were related to the study product. Pharmacokinetics of CPL207280 supports once daily dosing regimen. The results justify further clinical development. Disclosure K. Bazydlo-guzenda: Employee; Self; Celon Pharma SA. A. Gierczak-pachulska: Employee; Self; Celon Pharma SA. K. Jarus-dziedzic: Other Relationship; Self; Celon Pharma SA. P. Rudzki: Employee; Self; Celon Pharma SA. M. Wieczorek: Other Relationship; Self; Celon Pharma SA. Funding National Centre for Research and Development (POIR.01.01.01-00-0334/17)