Detection of chromosome translocations by bead-based flow cytometry.

Chromosome translocations resulting in fusion genes have been implicated in leukemogenesis. The paradigm involves the fusion of the genes encoding BCR and ABL, leading to a constitutively active tyrosine kinase. The detection of BCR-ABL has been limited to fluorescence in situ hybridization analysis, reverse transcription-polymerase chain reaction, of mRNA, and Western blot of analysis downstream effectors in the BCR-ABL activated pathway.

Measuring humanized antibodies in plasma of patients treated with antibody-based therapy using bead-based flow cytometry: the story of alemtuzumab.

Alemtuzumab (Campath), the humanized rat monoclonal antibody that targets the CD52 surface antigen, is currently used for treatment of patients with resistant chronic lymphocytic leukemia. Monitoring levels of the antibody in plasma/serum could provide insight into the optimal dosing and scheduling of therapy. Current methods of detecting alemtuzumab in serum or plasma are complicated and difficult to adapt to high-throughput testing.

Cell-free bead-based detection of total and phosphorylated proteins in plasma and cell lysates: detection of FLT3.

Frequently direct measurement of proteins or their phosphorylation in intact cells is not possible, for instance, when cells are too few, frozen, or subject to degradation. We have demonstrated that tumor cells pour their DNA, RNA, and protein content into circulation because of turnover and breakdown of cell structures. Proteins in solution most likely circulate as complexes, which protects them from degradation.

Monitoring cell signaling pathways by quantitative flow cytometry.

As the signaling pathways involved in leukemogenesis are being elucidated, several proteins have emerged as potential targets for therapy. Downstream from those targets are numerous intracellular factors that are constantly modulated. Monitoring those factors could provide insight into the potential efficacy of therapies by predicting which patients will respond to them and by determining the optimal dosage that will inhibit the target protein.

Quantification of surface antigens and quantitative flow cytometry.

Measuring expression levels of cell surface antigens is important for the diagnosis of diseases such as B-cell chronic lymphocytic leukemia and the monitoring of targeted therapy, particularly antibody-based therapy. In some cases, the number of antigens that the therapeutic antibodies bind on the cell surface may reflect the efficacy of therapy. Thus, quantitating the number of molecules on the surface of cells before, during, and after therapy would provide important information for monitoring antibody-based therapy and potentially can be used to adjust dosing.