AOH1996 targets mitochondrial dynamics and metabolism in leukemic stem cells via mitochondrial PCNA inhibition.

Cytoplasmic proliferating cell nuclear antigen (PCNA) is highly expressed in acute myeloid leukemia (AML) cells, supporting oxidative metabolism and leukemia stem cell (LSC) growth. We report on AOH1996 (AOH), an oral compound targeting cancer-associated PCNA, which shows significant antileukemic activity. AOH inhibited growth in AML cell lines and primary CD34 + CD38 - blasts (LSC-enriched) in vitro while sparing normal hematopoietic stem cells (HSCs). In vivo, AOH-treated mice demonstrated prolonged survival compared to controls (50 vs. 35 days; p < 0.0001) with reduced LSC burden, as shown in secondary transplants (42 vs. 30 days, p < 0.0001). Mechanistically, AOH disrupted mitochondrial PCNA's binding to the OPA1 protein, enhancing OPA1's interaction with its E3 ligase, MARCH5, which led to OPA1 degradation. This process reduced mitochondrial length, fatty acid oxidation (FAO), and oxidative phosphorylation (OXPHOS), thereby inhibiting LSC expansion. The addition of venetoclax (VEN), an FDA-approved Bcl-2 inhibitor, further enhanced AOH's effects, reducing mitochondrial length, FAO, and OXPHOS while improving survival in AML models. While VEN is approved for AML, AOH is under clinical investigation for solid tumors, and our findings support its broader therapeutic potential.