MI-503

MI-503 is a highly potent and orally bioavailable small molecule inhibitor of the menin-mLL interaction.

Signaling Pathways >> Epigenetics >> Histone Methyltransferase

Research Areas >> Cancer

MI-503 occupies the F9 and P13 pockets on menin, forming a hydrogen bond with Tyr276, and also extends beyond the P13 pocket to form hydrogen bonds with Trp341 and Glu366. Treatment of murine bone marrow cells (BMC) transformed with the mLL-AF9 oncogene with MI-503 results in substantial growth inhibition, with GI50 of 0.22 μM. The cell growth inhibitory effect of MI-503 is time-dependent, with a pronounced effect achieved after 7–10 days of treatment[1].

MI-503 achieves high level in peripheral blood following a single intravenous or oral dose, while also showing high oral bioavailability (75%). MI-503 induces strong inhibition of tumor growth with once daily intraperitoneal (i.p.) administration. Treatment with MI-503 results in an over 80% reduction in MV4;11 tumor volume and complete tumor regression in two mice. Ten consecutive days of treatment with MI-503 results in a marked delay in progression of mLL leukemia in mice and significantly reduces leukemia tumor burden. Treatment with MI-503 and MI-463 leads to markedly reduced expression of Hoxa9 and Meis1, downstream targets of mLL fusion proteins substantially upregulated in mLL leukemias[1].

Leukemia cells are treated with MI-503 or 0.25% DMSO and cultured at 37 °C for 7 days. Media is changed at day 4, viable cell numbers are restored to the original concentration and MI-503 are re-supplied. MTT cell proliferation assay kit is then employed, and plates are read for absorbance at 570 nm using a microplate reader[1].

Mice: For efficacy studies in MV4;11 subcutaneous xenograft mice model, 5×106 cells are injected into the 4-6 week old female BALB/c nude mice. Treatment is started when the tumor size reached ~100 mm3. Vehicle (25% DMSO, 25% PEG400, 50% PBS) or compounds (MI-463 or MI-503) are administrated once daily at designated doses using i.p. injections[1].

[1]. Borkin D, et al. Pharmacologic inhibition of the Menin-MLL interaction blocks progression of MLL leukemia in vivo. Cancer Cell. 2015 Apr 13;27(4):589-602.

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