The approval of histone deacetylase inhibitors for treatment of lymphoma 
subtypes has positioned histone modifications as potential targets for the 
development of new classes of anticancer drugs. Histones also undergo 
phosphorylation events, and Haspin is a protein kinase the only known target of 
which is phosphorylation of histone H3 at Thr3 residue (H3T3ph), which is 
necessary for mitosis progression. Mitotic kinases can be blocked by small drugs 
and several clinical trials are underway with these agents. As occurs with 
Aurora kinase inhibitors, Haspin might be an optimal candidate for the 
pharmacological development of these compounds. A high-throughput screening for 
Haspin inhibitors identified the CHR-6494 compound as being one promising such 
agent. We demonstrate that CHR-6494 reduces H3T3ph levels in a dose-dependent 
manner and causes a mitotic catastrophe characterized by metaphase misalignment, 
spindle abnormalities and centrosome amplification. From the cellular 
standpoint, the identified small-molecule Haspin inhibitor causes arrest in G2/M 
and subsequently apoptosis. Importantly, ex vivo assays also demonstrate its 
anti-angiogenetic features; in vivo, it shows antitumor potential in xenografted 
nude mice without any observed toxicity. Thus, CHR-6494 is a first-in-class 
Haspin inhibitor with a wide spectrum of anticancer effects that merits further 
preclinical research as a new member of the family of mitotic kinase inhibitors.