Discrepancy between serological complete remission and concomitant new bone lytic lesions after infusion of escalating low doses of donor lymphocytes in multiple myeloma: a case report.

A graft-versus-myeloma effect has been previously induced by infusing high numbers of donor lymphocytes after allogeneic stem cell transplantation in relapsed/refractory multiple myeloma (MM) patients. A 43-year-old patient with MM refractory to standard chemotherapy and autologous transplantation received an allogeneic HLA-matched T cell-depleted marrow transplant from his sister after conditioning with single dose total-body irradiation, melphalan and cyclophosphamide. Twenty-four months after transplant neither a significant reduction of serum M protein nor evidence of acute or chronic graft-versus-host disease (GVHD) were observed. The patient was then treated with four escalating low doses of donor lymphocyte infusions (DLI) (0.1, 1.0, 5.0 and 5.0 x 106 CD3+ T cells/kg, respectively) over a 13 month period. Following the second infusion a mild liver acute GVHD and a partial, but transient, response occurred. After the last DLI the patient achieved a complete remission and developed extensive chronic GVHD. However, concomitant with the disappearance of clonal plasma cells from the marrow and of serum M protein, two new bone lytic lesions appeared requiring treatment with radiotherapy. In conclusion, escalating low doses of DLI may be effective in MM and may prevent severe acute but not chronic GVHD. However, the efficacy of DLI in extramedullary MM lesions is still unclear.