LG-362B targets PML-RARα and blocks ATRA resistance of acute promyelocytic leukemia.

Acute promyelocytic leukemia (APL) is a M3 subtype of acute myeloid leukemia (AML). Promyelocytic leukemia (PML)-retinoic acid receptor α (RARα) translocation generally occurs in APL patients and makes APL unique both for diagnosis and treatment. However, some conventional drugs like all-transretinoic acid (ATRA) and arsenic trioxide (ATO), as the preferred ones for APL therapy, induce irreversible resistance and responsible for clinical failure of complete remission. Herein, we screened a library of novel chemical compounds with structural diversity and discovered a novel synthetic small compound, named LG-362B, specifically inhibited the proliferation of APL and induced apoptosis. Notably, the differentiation arrest was also relieved by LG-362B in cultured APL cells and APL mouse models. Moreover, LG-362B overcame the ATRA resistance on cellular differentiation and transplantable APL mice. These positive effects were driven by caspases-mediated degradation of PML-RARα when treated with LG-362B, making it specific to APL and reasonable for ATRA resistance relief. We propose that LG-362B would be a potential candidate agent for the treatment of the relapsed APL with ATRA resistance in the future.