Ex vivo treatment of myeloma cells by 4‐HC, VP‐16, LAK cells and antibodies

Abstract

To assess the usefulness of 4‐hydroperoxycyclophosphamide (4‐HC) and Etoposide (VP‐16) as a purging agent for myeloma cells in bone marrow ex‐vivo, myeloma cell lines (SK‐RCS‐1, RPMI‐8226), lymphoma cell line (SK‐DHL‐2) and normal bone marrow (BM) cells were treated at different concentrations of 4‐HC, VP‐16. In separate experiments, LAK cells or antibodies were also used to treat the above cell lines. Clonogenic tumor cells from all three cell lines could be reduced by more than 4 logs, when treated alone or as a mixture with irradiated normal bone marrow cells at a 4‐HC concentration of 60 μmol/l. Under similar conditions, approximately 1% of normal BM myeloid progenitor granulocyte‐macrophage colony forming cells (CFU‐GM) survived. The results with LAK cells and antibodies were also encouraging. These observations support the use of various purging methods for myeloma cells for autologous bone marrow transplantation.