OTX008 (PTX008) is a selective galectin-1 inhibitor.

OTX008 inhibits Gal1 expression and ERK1/2 and AKT-dependent survival pathways in SQ20B and A2780-1A9 cells and induces G2/M cell cycle arrest through CDK1. OTX008 increases the anti-proliferative effects of Semaphorin-3A (Sema3A) in SQ20B cells and reverses invasion induced by exogenous Gal1. Growth inhibitory concentrations (GI50) of OTX008 range from 3 to 500 μM in a large panel of human solid tumor cell lines. A significant correlation between OTX008 GI50 values and Gal1 mRNA (LGALS1) and protein expression levels in the panel of cancer cells is observed. OTX008 affects endothelial cell proliferation, motility, invasiveness, and cord formation. Tumor cell proliferation is also inhibited, with differences in sensitivity among cell lines (IC50 from 1 to 190 μM)[1][2].

OTX008 treatment is associated with the down-regulation of Gal1 and Ki67 in treated tumors, as well as decreased microvessel density and VEGFR2 expression. OTX008 inhibits the growth of A2780-1A9 xenografts. Combination studies display OTX008 synergy with several cytotoxic and targeted therapies, principally when OTX008 is administered first[1].