Pharmacological Characterization of JNJ-75276617, a Menin-KMT2A Inhibitor, As Targeted Treatment for KMT2A-Altered and NPM1-Mutant Acute Leukemia

Background: AML is characterized by a differentiation block leading to the accumulation of immature cells. Therefore therapies capable of inducing differentiation of these immature cells, particularly if also associated with antiproliferative activity, are considered an attractive therapeutic approach in acute leukemias. Histone-lysine N-methyltransferase-2A (KMT2A; also known as Mixed lineage leukemia 1 (MLL1))-fusion proteins require direct interaction with the nuclear scaffolding protein menin, a key component of the menin-KMT2A complex, for transcription of multiple leukemogenic target genes. Genetic or pharmacologic disruption of the interaction between menin-KMT2A has been shown to induce differentiation and block progression of KMT2A-rearranged (KMT2A-r) AML and B-cell ALL in vivo. Similarly, disruption of the crucial menin-KMT2A interaction inhibits leukemias driven by mutations in nucleophosmin 1 (NPM1) which constitute ~30% of AML and rely on the expression of menin-KMT2A target genes, e.g. MEIS1. Blocking the menin-KMT2A interaction by small-molecule inhibitors is being explored clinically as a treatment for KMT2A-altered and NPM1-mutant AML which represent areas of high unmet medical need.

Results and Conclusions: JNJ-75276617 is a novel, orally bioavailable, potent, and selective protein-protein interaction inhibitor of the binding between KMT2A (wild-type [WT] and fusion) and menin. JNJ-75276617 binds with high affinity to the KMT2A binding pocket on human, mouse, and dog menin. JNJ-75276617 has a high biochemical potency across species evaluated by a homogenous time-resolved fluorescence (HTRF) assay. In KMT2A-r and cytoplasmic NPM1 (NPM1c)-mutant AML cells, JNJ-75276617 inhibited the association of the menin-KMT2A complex with the chromatin of KMT2A-target gene promoters, resulting in reduced expression of menin-KMT2A target genes such as MEIS1 and FLT3. Moreover, JNJ-75276617 increased expression of differentiation genes such as ITGAM and MNDA. JNJ-75276617 displayed potent antiproliferative activity across a range of AML cell lines and patient samples harboring KMT2A alterations or NPM1c mutations in vitro, with >95.5-fold selectivity over WT KMT2A/NPM1 AML and normal peripheral blood mononuclear cells (PBMCs). JNJ-75276617 treatment of KMT2A-r and NPM1c AML cell lines induced differentiation marker expression, followed by induction of apoptotic cell death. Additionally, JNJ-75276617 induced neutrophil-like morphological differentiation in KMT2A-AF9 fusion gene-transduced mouse bone marrow cells. Using in vivo preclinical AML models, JNJ-75276617 resulted in reduction of leukemic burden and provided a significant dose-dependent survival benefit with accompanying decreases in expression of menin-KMT2A target genes. JNJ-75276617 showed good oral bioavailability and favorable pharmacokinetics in preclinical animal species. Our data demonstrate JNJ-75276617 to be a highly selective and potent menin-KMT2A that disrupts the crucial menin-KMT2A protein complex and mediates significant preclinical activity against AML/ALL cell lines and primary AML cells. JNJ-75276617 also demonstrates pharmacodynamic markers to assess target engagement. Collectively, these data support the recently initiated first-in-human trial evaluating JNJ-75276617 as monotherapy for relapsed/ refractory acute leukemia patients harboring either KMT2A or NPM1 alterations (NCT04811560).

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