LFM-A13（IC50=2.5 μM）, a specific Bruton's tyrosine kinase (BTK), is more than 100-fold specificity than other protein kinases, such as JAK1, JAK2, HCK, EGFR, and IRK.

BTK:2.5 μM

In BTK+ B-lineage leukemic cells, LFM-A13 enhances their sensitivity to ceramide- or vincristine-induced apoptosis. [1] In BCL-1 cells, NALM-6 cells, or normal BALB/c splenocytes, LFM-13 inhibits the enzymatic activity of BTK in BCL-1 cells without affecting the BTK protein expression levels [2] In human neutrophils, LFM-A13 decreases the tyrosine phosphorylation induced by fMet-Leu-Phe and inhibits the production of superoxide anions and the stimulation of adhesion, chemotaxis, and phospholipase D activity. [3]

In BALB/c mice bearing BCL-1 leukemia, combination of LFM-A13 (50 mg/kg/day i.p.) and the standard triple-drug VPL prolongs the median survival time. [2] In primary myeloma-bearing SCID-rab mice, LFM-A13 inhibits osteoclast activity, prevents myeloma-induced bone resorption and suppresss myeloma growth. [4]