HLA allogene expression in multiple myeloma cells : possible use as anti-tumor vaccine

Multiple myeloma (MM) is a plasma cell malignancy with a high mortality rate. The current treatment options may prolong survival but none of them are curative. Allogeneic gene therapy is a novel vaccine strategy that can augment anti-tumor immune responses and cause remission in some non-hematologic cancers. Immunogene transfer has been successfully performed in human and murine myeloma cells using viral vectors. We used immuno-magnetic negative selection to purify myeloma cells from bone marrow (BM) specimens. We investigated the possibility of in vitro culture of bone marrow mononuclear cells (BMMC) and myeloma cell enrichments. We used liposomal and adenoviral vectors to transduce myeloma cell lines. We cloned the allogene HLA-B7 into a recombinant adenoviral transfer plasmid and, subsequently, produced a recombinant, HLA-B7-positive, adenoviral vector. We evaluated allogene expression by the adenoviral vector in myeloma cell lines. In three of four BM samples tested, 95--99% purification of primary myeloma cells was achieved. Poor expansion and considerable variability (6--22 days) in the duration of culture of BMMC (two samples) and purified myeloma cells (four samples) was observed. Adenoviral vectors expressing green fluorescent protein (GFP) were highly efficient (70--94%) for transduction of myeloma cell lines. Using the HLA-B7-adenoviral vector, a small population (13%) of HLA-B7-positive myeloma cells (RPMI-8226 cell line) was identified. These observations support the feasibility of creating a myeloma vaccine by transduction of primary human myeloma cells with an allogene