Bcl-2 inhibition combined with PPARα activation synergistically targets leukemic stem cell-like cells in acute myeloid leukemia

Persistence of leukemic stem cells (LSCs) is one of the determining factors to acute myeloid leukemia (AML) treatment failure and responsible for the poor prognosis of the disease. Hence, novel therapeutic strategies that target LSCs are crucial for treatment success. We investigated if targeting Bcl-2 and peroxisome proliferator activated receptor alpha (PPAR alpha), two distinct cell survival regulating mechanisms could eliminate LSCs. This study demonstrate that the Bcl-2 inhibitor venetoclax combined with the PPAR alpha agonist chiglitazar resulted in synergistic killing of LSC-like cell lines and CD34(+) primary AML cells while sparing their normal counterparts. Furthermore, the combination regimen significantly suppressed AML progression in patient-derived xenograft (PDX) mouse models. Mechanistically, chiglitazar-mediated PPAR alpha activation inhibited the transcriptional activity of the PIK3AP1 gene promoter and down-regulated the PI3K/Akt signaling pathway and anti-apoptotic Bcl-2 proteins, leading to cell proliferation inhibition and apoptosis induction, which was synergized with venetoclax. These findings suggest that combinatorial Bcl-2 inhibition and PPAR alpha activation selectively eliminates AML cells in vivo and vitro, representing an effective therapy for patients with relapsed and refractory AML.