Cancer Stem Cell (CSC) Inhibitors in Oncology-A Promise for a Better Therapeutic Outcome: State of the Art and Future Perspectives.

Cancer stem cells (CSCs), a subpopulation of cancer cells endowed with self-renewal, tumorigenicity, pluripotency, chemoresistance, differentiation, invasive ability, and plasticity, reside in specialized tumor niches and are responsible for tumor maintenance, metastasis, therapy resistance, and tumor relapse. The new-age "hierarchical or CSC" model of tumor heterogeneity is based on the concept of eradicating CSCs to prevent tumor relapse and therapy resistance. Small-molecular entities and biologics acting on various stemness signaling pathways, surface markers, efflux transporters, or components of complex tumor microenvironment are under intense investigation as potential anti-CSC agents. In addition, smart nanotherapeutic tools have proved their utility in achieving CSC targeting. Several CSC inhibitors in clinical development have shown promise, either as mono- or combination therapy, in refractory and difficult-to-treat cancers. Clinical investigations with CSC marker follow-up as a measure of clinical efficacy are needed to turn the "hype" into the "hope" these new-age oncology therapeutics have to offer.

Conjugation of Dasatinib with MHI-148 Has a Significant Advantageous Effect in Viability Assays for Glioblastoma Cells.

We hypothesized that conjugation of the near-infrared dye MHI-148 with the anti-leukemia drug dasatinib might produce a potential theranostic for glioblastoma. In fact, the conjugate was found to bind the kinases Src and Lyn, and to inhibit the viability of a glioblastoma cell line with significantly greater potency than dasatinib alone, MHI-148 alone, or a mixture of dasatinib and MHI-148 at the same concentration. It was also used to successfully image a subcutaneous glioblastoma tumor in vivo.

Design and synthesis of novel dasatinib derivatives as inhibitors of leukemia stem cells.

We used the concept of bioisosteres to design and synthesize a novel series of dasatinib derivatives for the treatment of leukemia. Unfortunately, most of the dasatinib derivatives did not show appreciable inhibition against leukemia cell lines K562 and HL60. However, acrylamide compound 2c had comparable inhibitory activity with dasatinib against K562 cells (IC50 = 0.039 nM vs. 0.069 nM). And amide compound 2a and acrylamide compound 2c also had comparable inhibitory activity with dasatinib against the leukemia cell line HL60 (IC50 = 0.25 nM and 0.26 nM vs. 0.11 nM). Against the leukemia progenitor cell line KG1a, triazole compounds 15a and 15d-15f and oxadiazole compounds 24a-24d were more potent than dasatinib. In particular, the hydroxyl compounds 15a and 24a were about 64 and 180 fold more potent than dasatinib against KG1a cells (IC50 = 0.14 µM and 0.05 µM vs. 8.98 µM). Compounds 15a and 24a also inhibited colony formation in MCF-7 cells and inhibited cell migration in the cell wound scratch assay in B16BL6 cells. Moreover, hydroxyl compounds 15a and 24a had low toxicity in vivo.

2-Aminoxazole and 2-Aminothiazole Dasatinib Derivatives as Potent Inhibitors of Chronic Myeloid Leukemia K562 Cells.

Dasatinib is an important drug against chronic myeloid leukemia (CML). In this paper, we describe the preparation and anti-CML activity of 2-aminoxazole and 2-aminothiazole dasatinib derivatives. Biological activity was measured by the inhibition of proliferation of human CML K562 cells. The 2-aminoxazole derivatives had similar activities as the 2-aminothiazole derivatives. All newly synthesized compounds demonstrated more potent antiproliferative activity than imatinib. A few compounds (8b, 8c, 9b) showed nanomolar inhibitory activity, similar to that of dasatinib.