CDD-2789 is a highly selective small molecule inhibitor that targets Activin receptor type 1 (ALK2, also known as ACVR1). It effectively blocks the BMP and activin A-induced downstream phosphorylation reactions by inhibiting the ALK2/ALK1-mediated SMAD1/5 signaling pathway. In the NanoBRET cell model, CDD-2789 demonstrates an inhibitory activity with an IC50 value of 0.54 µM for ALK2. This compound holds potential for research in ALK2-related diseases, including brainstem glioma (DIPG), ependymoma, endometrial cancer, melanoma, non-small cell lung cancer, colorectal cancer, and pancreatic cancer.