TO THE EDITOR:

Chronic myelomonocytic leukemia (CMML), an aggressive hematological neoplasm characterized by sustained peripheral blood monocytosis (≥1 × 109/L, ≥10% of white cell count), is associated with a median overall survival of 28 to 32 months, with no current therapies that improve its natural history.1,2  Although hypomethylating agents (HMAs) have been approved for the management of CMML, the overall response and complete response rates are 40% to 50% and <20% respectively, with no impact on mutational allele burdens, even in responding patients.3,4  We have previously demonstrated that primary CMML samples exhibit granulocyte-macrophage colony-stimulating factor (GM-CSF)–dependent hypersensitivity by hematopoietic progenitor colony-formation assays and by phospho-STAT5 (pSTAT5) flow cytometry and that the GM-CSF axis is a viable therapeutic target in CMML. Lenzilumab (KB003) is a novel engineered human immunoglobulin G1κ monoclonal antibody, with high affinity for human...

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