B-I09

B-I09 is a **small molecule inhibitor** of the *inositol-requiring enzyme 1* (IRE-1) RNase activity, specifically blocking the splicing and function of the transcription factor *X-box binding protein 1* (XBP1)[3][4][5][6]. By inhibiting the **IRE-1/XBP1 pathway**, B-I09 phenocopies genetic XBP1 deficiency and impairs cellular processes critical for the survival and proliferation of malignant B cells, notably in models of **chronic lymphocytic leukemia (CLL)**, **multiple myeloma (MM)**, and **mantle cell lymphoma (MCL)**[1][7]. B-I09 also demonstrates immunomodulatory effects, attenuating dendritic cell (DC) responses to inflammatory signals, thus showing efficacy in models of **graft-versus-host disease (GVHD)** and protecting against solid organ rejection[2]. In preclinical models, B-I09 suppresses leukemic growth, reduces GVHD, and displays synergistic cytotoxicity with BTK inhibitors such as ibrutinib. The compound acts as a prodrug, with favorable pharmacokinetics and low apparent systemic toxicity in mice[1][3].

Other names

B-I09B-I-09B-I 09