Crescent Biopharma, Inc.

Fms-like tyrosine kinase 3 inhibitor(s) (FLT3i), including sorafenib, quizartinib, and FDA-approved midostaurin and gilteritinib, are commonly used to treat adult acute myelogenous leukemia (AML) with FLT3 internal tandem duplication (ITD) mutations.We hypothesized that concomitantly targeting CXCR4 and E-selectin could enhance the anti-leukemia efficacy and alleviate the bone marrow niche-mediated resistance to FLT3-targeted therapy.If this hypothesis is validated, this concept could serve as a backbone for developing combinatorial strategies with FLT3i as a frontline therapy for FLT3-mutant AML.To this end, we first investigated whether the baseline levels of CXCR4/E-selectin-L were associated with FLT3i resistance.Results showed that leukemia blasts from relapsed/refractory FLT3- mutated AML patients exhibited higher levels of CXCR4 and CD44 compared to those of newly diagnosed or complete remission patients.In summary, CXCR4/CXCL12 and E-selectin/E-selectin-L axes play critical roles in leukemia cell homing to the BMM niche and are closely associated with resistance to FLT3-targeted therapy in FLT3-mutant AML patients.We here report for the first time that CXCR4/E-selectin-L are transcriptionally upregulated by FLT3 inhibition, which was associated with suppression of MAPK signaling, and nuclear translocation of phospho-ERK may be involved in CXCR4 transcriptional regulation.Concomitant blockade of CXCR4/E-selectin with the dual inhibitor GMI-1359 disrupts leukemia cell homing/migration to BM niches.Combination treatment with GMI-1359 and quizartinib significantly reduces the leukemia burden and extends mouse survival in a PDX AML model, and the combination of GMI-1359 with sorafenib benefits the recoveryof normal hematopoiesis. These findings provide pre-clin. rationale for combined CXCR4/E-selectin/FLT3 targeting in FLT3-mutant AML.

Determination of a glycolipid ligand can quickly reveal the carbohydrate epitope recognized by carbohydrate-binding proteins (CBP) which may include antibodies, lectins, toxins, and virulence factors. Thin layer chromatography (TLC) is a simple, well-known, and heavily used method to separate glycolipids based on their migration through a thin layer of chromatography media, usually silica gel, coated on the surface of a rigid plate. Reacting carbohydrate-binding proteins directly on a TLC plate of separated glycolipids is a powerful technique to quickly determine functional carbohydrate epitopes present in an entire glycolipid extract of a target cell type or tissue.

Breast cancer cells traffic to and from the peripheral blood within specific vascular niches, and this migration can be therapeutically targeted.