Abstract Disclosure: J. Choi: Employee; Self; Hanmi Pharm. Co., Ltd. C. Park: Employee; Self; Hanmi Pharm. Co., Ltd. E. Park: Employee; Self; Hanmi Pharm. Co., Ltd. H. Kwon: Employee; Self; Hanmi Pharm. Co., Ltd. S. Bae: Employee; Self; Hanmi Pharm. Co., Ltd. D. Kim: Employee; Self; Hanmi Pharm. Co., Ltd. S. Lee: Employee; Self; Hanmi Pharm. Co., Ltd. I. Choi: Employee; Self; Hanmi Pharm. Co., Ltd. Short bowel syndrome (SBS) with intestinal failure requires partial or total parenteral nutrition (PN) to maintain health and growth. However, long-term use of PN may lead to life-threatening complications. Although teduglutide was firstly approved, the widespread use of it is still limited due to insufficient efficacy and leading to a significant burden for patients by daily administration. Hence, there is a medical unmet needs for more effective and longer lasting GLP-2 analog drugs. Here, we investigated the potential therapeutic effect of HM15912, which is currently under clinical development for once a month use, in small bowel resected rat model of SBS. To evaluate in vitro activity of HM15912, cAMP accumulation in CHO cells overexpressed human GLP-2 receptor (GLP-2R) was measured, and HM15912 was potently activated GLP-2R with a full agonistic activity as native human GLP-2 (EC50= 0.327 vs 0.173 nM, relative activity= 52.5%). Next, to demonstrate that GLP-2R stimulation by HM15912 results in the production and release of insulin-like growth factor-1 (IGF-1) as a known mechanism of GLP-2, HM15912 was treated to mice primary intestinal subepithelial myofibroblasts. mRNA transcription and protein secretion levels of IGF-1 was dose-dependently increased by treatment of HM15912 (p < 0.05 and p < 0.001, respectively). Longer-lasting property was evaluated in rats after single administration, and HM15912 exhibited 70-fold extended elimination half-life (42.4 h) compared to teduglutide (0.6 h). Based on this prolonged mode of action with the potent in vitro activity, intestinotrophic effect of HM15912 was investigated in 80% of small intestine (SI) resected jejuno-ileal anastomosis model rats. The SBS rats given HM15912 every week for 2 weeks significantly increased wet weight of jejunum compared to resection vehicle or b.i.d treatment of teduglutide. This result was well-correlated with histological analysis such as villus height, crypt depth, and mucosal area. In addition, HM15912 treated group was associated with a significant increase in absorption capacity of SI such as plasma D-xylose concentrations. Furthermore, the mice given HM15912 with various administration intervals for 2 weeks significantly increased SI weight compared to b.i.d treatment of teduglutide (35% over vehicle). In Q2D, Q4D and Q1W dosing intervals of HM15912, SI weights were dose-dependently increased 66∼112% (p < 0.001), 91∼103% (p < 0.001) and 55∼74% over vehicle (p < 0.05∼0.001), respectively. The results supported that small bowel hypertrophic effect of HM15912 are well-correlated with functional improvement of SI in short bowel condition, and superior efficacy to teduglutide was still observed even after once weekly administration in mice. Therefore, HM15912 could be a novel therapeutic option for SBS by providing remarkable small bowel tropic effect with extended administration interval. Presentation: Saturday, June 17, 2023