Wei-Gang Tong

PURPOSE: SNS-032 is a highly selective and potent inhibitor of cyclin-dependent kinases (Cdks) 2, 7, and 9, with in vitro growth inhibitory effects and ability to induce apoptosis in malignant B cells. A phase I dose-escalation study of SNS-032 was conducted to evaluate safety, pharmacokinetics, biomarkers of mechanism-based pharmacodynamic (PD) activity, and clinical efficacy. PATIENTS AND METHODS: Parallel cohorts of previously treated patients with chronic lymphocytic leukemia (CLL) and multiple myeloma (MM) received SNS-032 as a loading dose followed by 6-hour infusion weekly for 3 weeks of each 4-week course. RESULTS: There were 19 patients with CLL and 18 with MM treated. Tumor lysis syndrome was the dose-limiting toxicity (DLT) for CLL, the maximum-tolerated dose (MTD) was 75 mg/m(2), and the most frequent grade 3 to 4 toxicity was myelosuppression. One patient with CLL had more than 50% reduction in measurable disease without improvement in hematologic parameters. Another patient with low tumor burden had stable disease for four courses. For patients with MM, no DLT was observed and MTD was not identified at up to 75 mg/m(2), owing to early study closure. Two patients with MM had stable disease and one had normalization of spleen size with treatment. Biomarker analyses demonstrated mechanism-based PD activity with inhibition of Cdk7 and Cdk9, decreases in Mcl-1 and XIAP expression level, and associated CLL cell apoptosis. CONCLUSION: SNS-032 demonstrated mechanism-based target modulation and limited clinical activity in heavily pretreated patients with CLL and MM. Further single-agent, PD-based, dose and schedule modification is warranted to maximize clinical efficacy.

We performed a genome-wide analysis of aberrant DNA methylation in chronic lymphocytic leukemia (CLL) using methylated CpG island amplification (MCA) coupled with a promoter microarray. We identified 280 potential targets of aberrant DNA methylation in CLL. These genes were located more frequently in chromosomes 19 (16%, p=0.001), 16 (11%, p=0.001), 17 (10%, p=0.02) and 11 (9%, p=0.02) and could be grouped in several functional networks. Methylation status was confirmed for 22 of these genes (SOX11, DLX1, FAM62C, SOX14, RSPO1, ADCY5, HAND2,SPOCK, MLL, ING1, PRIMA1, BCL11B, LTBP2, BNC1, NR2F2, SALL1, GALGT2, LHX1, DLX4, KLK10, TFAP2 and APP) in 78 CLL patients by pyrosequencing. As a proof of principle, we analyzed the expression of 2 genes, PRIMA1 and APP, in primary cells and of GALGT2, TFAP2C and PRIMA1 in leukemia cells. There was an inverse association between methylation and gene expression. This could be reversed by treatment with 5-aza-2'-deoxycytidine in cell lines. Treatment in a clinical trial with 5-azacitidine resulted in decreased methylation of LINE, DLX4 and SALL1 in the peripheral blood B-cells of patients with CLL. IgVH mutational status or ZAP-70 expression were not associated with specific methylation profiles. By multivariate analysis, methylation of LINE and APP was associated with shorter overall survival (p = 0.045 and 0.0035, respectively). This study demonstrates that aberrant DNA methylation is common and has potential prognostic and therapeutic value in CLL.