Targeting Menin in T-Lineage Acute Lymphoblastic Leukemia [menin_treatments]

The efficacy of menin inhibition was evaluated in 14 primary T-ALL samples with diverse genetic backgrounds using ziftomenib. Sensitivity was not correlated with HOXA expression or KMT2A rearrangements, and in vivo treatment significantly reduced tumor burden in xenograft models without notable toxicity. Transcriptomic and proteomic analyses confirmed on-target activity, including downregulation of menin targets and activation of differentiation pathways. Phosphoproteomic profiling identified phospho-MEF2C (S222) as a key marker of sensitivity, regulated by CDK and MAPK signaling. Combination treatment with ziftomenib and CDK1/2 or ERK1/2 inhibitors showed synergistic effects, suggesting a mechanistic link between menin inhibition and p-MEF2C–driven T-ALL vulnerability. Overall design: Primary human T-ALL blasts were collected from the peripheral blood or bone marrow of patients under informed consent, in accordance with protocols approved by the University of Chicago Institutional Review Board. Mononuclear cells were isolated using Ficoll-Paque PLUS density gradient centrifugation and cryopreserved in fetal bovine serum (FBS) containing 10% dimethyl sulfoxide (DMSO). For in vitro assays, cells were thawed and cultured in RPMI-1640 medium supplemented with 10% FBS, 2 mM L-glutamine, and an insulin–transferrin–selenium supplement at 37°C and 5% CO2 in the gas phase. Cells were treated with 2.5 mM ziftomenib, and total RNA was extracted on days 4 and 7 using TRIzol reagent (Thermo Fisher Scientific), following the manufacturer's instructions. Untreated baseline samples (day 0) were also collected, and all conditions were processed in technical replicates.