ALLOGENEIC TRANSPLANTATION OF UNMANIPULATED PERIPHERAL-BLOOD STEM-CELLS IN PATIENTS WITH MULTIPLE-MYELOMA

In multiple myeloma (MM), allogeneic bone marrow transplantation may p roduce complete and durable responses, but is accompanied by significa nt transplant-related mortality (TRM). To assess feasibility and possi ble advantages offered by the use of allogeneic, growth factor-primed PBSC instead of marrow, we analyzed the data of 10 patients with MM (I gG = 6, IgA = 1, BJ = 2, non-secreting = 1; stage II = 1, stage III = 8, plasma-cell leukemia = 1) who received an allogeneic transplant wit h PBSC. Their age ranged between 35 and 53 years (median 45). All were HLA-identical to their sibling donors. Prior to allograft, six patien ts received standard-dose chemotherapy (DAV or CY-Dexa) and four a seq uential intensified scheme with autologous PBSC support. At the time o f transplantation, three patients were in CR, three in PR, three had r efractory disease, one progressive disease. Patients were conditioned with busulfan-melphalan (n = 9) or busulfan-cyclophosphamide (rt = 1), and were allografted with unmanipulated PBSC obtained by apheresis af ter treatment with G-CSF alone (n = 6) or GM-CSF followed by G-CSF (n = 4). All patients engrafted, with 0.5 x 10(9)/l PMN and 50 x 10(9)/l platelets on (median) day 13. Four patients had greater than or equal to grade II acute GVHD (grade II in 3, grade III in 1). Following allo graft, CR was achieved in 71% patients. Eight are currently alive, wit h six in CR at a median of 18.5 months (range 7-28) from the transplan t. Two patients died, 1 and 4 months from the allograft, respectively, and one is alive with progression. A PCR analysis of IgH rearrangemen t showed that residual disease was no more molecularly detectable in f our out of seven evaluated patients following allograft. The results s uggest that PBSC may improve the therapeutic efficacy of allogeneic tr ansplant in MM, not only by a reduction of TRM but also by an improvem ent of rate and quality of response.