Use of a moving optical gradient to determine ex vivo chemosensitivity of B- cell chronic lymphocytic leukemias (B-CLL)

Abstract

2097 Background: Induction of apoptosis is a foundation of anti-neoplastic therapies. Existing ex vivo techniques to analyze apoptotic responses are limited to a particular biological aspect of the multi-factorial apoptotic cellular machinery. We have developed a cell-based analysis that detects broad cellular changes, based on physical characteristics of the cell, such as morphology, size, refractive index, density and surface properties. This method quantifies cell motion induced by exposure to a moving optical gradient. Cells are analyzed in their native state with no labels required for quantitation of functional responses; nevertheless fluorescent tags may be used to identify cell subpopulations. Only small numbers of cells are needed, from 500 to 2000 per measurement. Methods: Isolated peripheral lymphocytes from B-CLL patients were incubated for 60 hours. Tested drugs included fludarabine, chlorambucil, vincristine, doxorubicin, and others. Dose response curves were generated for each drug. Results: The initial study included 30 patients. Resistance/sensitivity determinations were based on analysis of the distribution of EC50 values. Clinical outcomes were available for 9 of the patients. For eight of these patients, where historical outcomes were available, ex vivo drug sensitivity correlated with clinical response. For the ninth patient, a prospective outcome was established and the ex vivo cell sensitivity was in good correlation. In some cases fluorescent labels were added to quantitate drug-mediated effects in cell subpopulations of interest (CD19 positive cells). We are monitoring outcomes for the rest of the patients, and expanding tested population. Data indicate inter- and intra-individual variability in response to different drugs. For example the median EC50 was 0.7μM and 3.9μM for fludarabine and chlorambucil respectively. Conclusions: A novel ex vivo analysis based on cell behavior within moving optical gradients quantifies pharmacological responses to chemotherapeutic drugs and provides an advantage over other approaches by integrating fluorescent detection of specific cell subpopulations. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Genoptix Genoptix Genoptix Genoptix