New diagnostic technology for the isolation and analysis of live myeloma cells from the blood of multiple myeloma patients.

e14543 Background: Multiple myeloma (MM) is a plasma cell malignancy in which plasma cells proliferate in bone marrow (BM), so BM examination is essential for diagnosis. Since it is a disease with a high recurrence rate, especially after complete recovery, regular checkups at short intervals are necessary. However, BM examination cannot be performed frequently due to the patient's condition. Therefore, the development of new diagnostic methods is necessary for the patients’ diagnostic convenience. The aim of this study was to investigate the feasibility of isolating myeloma cells from the peripheral blood (PB) of MM patients and conduct a cross-analysis with clinical data to explore the possibility of diagnostic use. Methods: Spiking test using the MM cell line (RPMI8226, 200 cells) mixed into human blood samples (5mL, healthy donor) was conducted to check the recovery rate of CytoGen’s Smart Biopsy platform. For the clinical evaluation, 10 newly diagnosed MM patients (ISS I: 3, ISS II: 4, ISS III: 3) and 3 patients with MGUS were selected at Samsung Medical Center (Seoul, Korea). Circulating myeloma cells in PB (7.5 mL) were isolated by Smart Biopsy Cell Isolator, subsequently quantification of isolated myeloma cells was accessed by counting using immunofluorescence (IF) staining with MM specific marker, CD138 and/or CD38. Automated IF sample analysis and quantification was proceeded with Smart Biopsy Cell Image analyzer. Results: Recovery rate of the isolation of MM cells was optimized with spiking test and CytoGen’s Smart Biopsy platform showed a high level of recovery rate (over 80%). Clinical evaluation of CytoGen’s platform for the isolation and analysis of MM cells in blood was performed with samples of patients with MM and precursor state of MM, MGUS. The median value of MM cells in blood was as follows: MGUS: 52 cells, ISS I: 162 cells, ISS II: 1,448 cells, and ISS III: 2,094 cells. Even with a small number of patient samples, an increase in the number of cells by ISS stage was observed. This clinical evaluation clearly demonstrated the possibility of isolation and quantification of MM cells in the PB of MM patients. Conclusions: MM is a blood cancer that has a very high recurrence rate even after treatment, so a new diagnostic system replacing BM biopsy is an unmet medical need for patient’s convenience. Although various methods have been attempted to identify MM cells in the PB, they could not isolate live MM cells retaining intact MM markers for accurate analysis. CytoGen’s Smart Biopsy platform, a size-based separation technology, can isolate live cancer cells including MM, and we verified through clinical evaluation that live MM cells in PB can be isolated and analyzed in this study. Furthermore, we found an increasing tendency of MM cells number in PB by the stage of MM patients. Expanded clinical study will be performed for clinical validation.