Ex vivo treatment of myeloma cells by 4-hydroperoxycyclophosphamide and VP-16-213

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

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 mumol/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.

Prolonged survival after intensive therapy and purged ABMT in patients with multiple myeloma

Despite numerous strategies, the cure of multiple myeloma remains a difficult challenge. Recent approaches have involved dose-intensive therapy followed by stem cell transplantation, most often with autologous stem cells (ASCT). Although ASCT is of benefit, it is not considered curative. Between 1988 and 1995, we utilized an aggressive three-drug conditioning regimen followed by ABMT using marrow purged with either 4-hydroperoxycyclophosphamide (4-HC) or mafosphamide (MAF). Twenty-nine of 42 patients who had first received VAD (14 patients) or VAD followed by cyclophosphamide (7 g/m2 i.v.) + dexamethasone (40 mg/day p.o. x4) + GM-CSF (15 patients) met the eligibility criteria needed to undergo bone marrow harvest and ABMT, ie < or =10% marrow plasma cells and > or =50% decrease in paraprotein level. Alpha-interferon maintenance therapy was given post ABMT. Median follow-up is 7.5 years (range 5.0-11.25). Six early and two late non-relapse deaths occurred; 15 patients have relapsed. Seven patients remain in continuous CR (five) or PR (two), including three with stage IIIB disease at diagnosis. One patient developed a soft tissue sarcoma 8 years post ASCT. Although this protocol produced excessive toxicity compared with current approaches, the results demonstrate that dose-intensive therapy and ASCT can produce durable remission in this disease. Further development of dose-intensive strategies is warranted.

Autologous bone marrow transplantation

Autologous bone marrow transplantation has become a very popular and successful treatment for many patients with lymphomas and other malignancies. The current indications, pretreatment regimes, and laboratory manipulations are discussed as well as the application of gene transfer to eliminate selected genetic diseases and detect disease relapse.