Catechol-O-methyltransferase bioactivation of the imiqualine EAPB02303 generates EAPB04303, a broadly active anti-leukemic agent in acute myeloid leukemia

Imiqualines, analogs of the immunomodulatory drug Imiquimod, display potent anticancer properties. The first-generation EAPB0503 demonstrated high efficacy and selectivity against acute myeloid leukemia (AML) expressing mutant nucleophosmin-1 (NPM1c). The second-generation EAPB02303 was more potent and exhibited broader activity against AML with various mutations in vitro. However, the in vivo survival advantage was limited only to NPM1c AML xenograft mice. The enzyme catechol-O-methyltransferase (COMT) was implicated in the bioactivation of EAPB02303 in pancreatic cancer. In this study, we demonstrated that COMT is highly expressed in AML cells, and converts EAPB02303 into an active metabolite, EAPB04303. This metabolite had lower IC50s than its parent compound, and a similar mechanism of action through inhibition of PI3K/AKT/mTOR signaling pathway. Furthermore, EAPB04303 significantly increased mitochondrial stress in NPM1c AML cells, presumably explaining their higher sensitivity to this metabolite. In vivo, EAPB04303 attenuated leukemic burden and significantly extended survival in all tested AML cell-derived and patient-derived xenograft mouse models. These findings poise EAPB04303 as a promising candidate for AML therapy.