NS-187, a potent and selective dual Bcr-Abl/Lyn tyrosine kinase inhibitor, is a novel agent for imatinib-resistant leukemia.

Although the Abelson (Abl) tyrosine kinase inhibitor imatinib mesylate has improved the treatment of breakpoint cluster region-Abl (Bcr-Abl)-positive leukemia, resistance is often reported in patients with advanced-stage disease. Although several Src inhibitors are more effective than imatinib and simultaneously inhibit Lyn, whose overexpression is associated with imatinib resistance, these inhibitors are less specific than imatinib. We have identified a specific dual Abl-Lyn inhibitor, NS-187 (elsewhere described as CNS-9), which is 25 to 55 times more potent than imatinib in vitro. NS-187 is also at least 10 times as effective as imatinib in suppressing the growth of Bcr-Abl-bearing tumors and markedly extends the survival of mice bearing such tumors. The inhibitory effect of NS-187 extends to 12 of 13 Bcr-Abl proteins with mutations in their kinase domain but not to T315I. NS-187 also inhibits Lyn without affecting the phosphorylation of Src, Blk, or Yes. These results suggest that NS-187 may be a potentially valuable novel agent to combat imatinib-resistant Philadelphia-positive (Ph+) leukemia.

Complete cDNA coding sequence of the HLA-DRB1*1405 allele.

Cloning report of complete coding region of HLA-DRB1*1405 has never appeared in the literature. We have isolated and sequenced it from a B cell line with a DRB1*1405/1502 genotype. The sequence information of this gene and previously published DRB1 genes for the other DR serotypes facilitated us to find that the cytoplasmic domain sequences of DRB1 genes fall into three groups. It is known that antigen presenting cells are differentially activated when products of different MHC class II genes are triggered. Functional analyses would discern if these allelic differences in the cytoplasmic domain are of functional significance.