A tubulin binding molecule drives differentiation of acute myeloid leukemia cells.

Despite much progress in developing better drugs, many patients with acute myeloid leukemia (AML) still die within a year of diagnosis. This is partly because it is difficult to identify therapeutic targets that are effective across multiple AML subtypes. One common factor across AML subtypes is the presence of a block in differentiation. Overcoming this block should allow for the identification of therapies that are not dependent on a specific mutation for their efficacy. Here, we used a phenotypic screen to identify compounds that stimulate differentiation in genetically diverse AML cell lines. Lead compounds were shown to decrease tumor burden and to increase survival in vivo. Using multiple complementary target deconvolution approaches, these compounds were revealed to be anti-mitotic tubulin disruptors that cause differentiation by inducing a G2-M mitotic arrest. Together, these results reveal a function for tubulin disruptors in causing differentiation of AML cells.

Thiazolidine derivatives as potent and selective inhibitors of the PIM kinase family.

The PIM family of serine/threonine kinases have become an attractive target for anti-cancer drug development, particularly for certain hematological malignancies. Here, we describe the discovery of a series of inhibitors of the PIM kinase family using a high throughput screening strategy. Through a combination of molecular modeling and optimization studies, the intrinsic potencies and molecular properties of this series of compounds was significantly improved. An excellent pan-PIM isoform inhibition profile was observed across the series, while optimized examples show good selectivity over other kinases. Two PIM-expressing leukemic cancer cell lines, MV4-11 and K562, were employed to evaluate the in vitro anti-proliferative effects of selected inhibitors. Encouraging activities were observed for many examples, with the best example (44) giving an IC50 of 0.75µM against the K562 cell line. These data provide a promising starting point for further development of this series as a new cancer therapy through PIM kinase inhibition.

Stemistry: the control of stem cells in situ using chemistry.

A new paradigm for drug research has emerged, namely the deliberate search for molecules able to selectively affect the proliferation, differentiation, and migration of adult stem cells within the tissues in which they exist. Recently, there has been significant interest in medicinal chemistry toward the discovery and design of low molecular weight molecules that affect stem cells and thus have novel therapeutic activity. We believe that a successful agent from such a discover program would have profound effects on the treatment of many long-term degenerative disorders. Among these conditions are examples such as cardiovascular decay, neurological disorders including Alzheimer's disease, and macular degeneration, all of which have significant unmet medical needs. This perspective will review evidence from the literature that indicates that discovery of such agents is achievable and represents a worthwhile pursuit for the skills of the medicinal chemist.

Design, synthesis and biological evaluation of 6-pyridylmethylaminopurines as CDK inhibitors.

The cyclin-dependent kinase (CDK) inhibitor seliciclib (1, CYC202) is in phase II clinical development for the treatment of cancer. Here we describe the synthesis of novel purines with greater solubility, lower metabolic clearance, and enhanced potency versus CDKs. These compounds exhibit novel selectivity profiles versus CDK isoforms. Compound αSßR-21 inhibits CDK2/cyclin E with IC(50)=30 nM, CDK7-cyclin H with IC(50)=1.3 µM, and CDK9-cyclinT with IC(50)=0.11 µM; it (CCT68127) inhibits growth of HCT116 colon cancer cells in vitro with GI(50)=0.7 µM; and shows antitumour activity when dosed p.o. at 50mg/kg to mice bearing HCT116 solid human tumour xenografts.

Phase I clinical and pharmacokinetic study of oral sapacitabine in patients with acute leukemia and myelodysplastic syndrome.

PURPOSE: Sapacitabine is an oral deoxycytidine nucleoside analog with a unique mechanism of action that is different from cytarabine. PATIENTS AND METHODS: To define the dose-limiting toxicities (DLT) and maximum-tolerated dose (MTD) of sapacitabine given orally twice daily for 7 days every 3 to 4 weeks, or twice daily for 3 days for 2 weeks (days 1 through 3 and days 8 through 10) every 3 to 4 weeks, in refractory-relapse acute leukemia and myelodysplastic syndrome (MDS). A total of 47 patients were treated in the phase I study that used a classical 3 + 3 design. Sapacitabine was escalated from 75 to 375 mg twice daily for 7 days (n = 35) and from 375 to 475 mg twice daily for 3 days on days 1 through 3 and days 8 through 10. RESULTS: The DLTs with both schedules were gastrointestinal. The MTDs were 375 mg twice daily for 7 days and 425 mg twice daily for 3 days on days 1 through 3 and days 8 through 10. The recommended phase II single-agent dose schedules were 325 mg twice daily for 7 days and 425 mg twice daily for 3 days on days 1 through 3 and days 8 through 10. Responses were observed in 13 patients (28%); four were complete responses, and nine were marrow complete responses. CONCLUSION: Sapacitabine is a new, safely administered, oral deoxycytidine analog that has encouraging activity in leukemia and MDS. Phase II studies are ongoing.