Background: Chromosomal deletion of q13 (del q13) and plasma cell leukemia predict both a worse prognosis in myeloma. Experiences with bortezomib in plasma cell leukemia prior to allogeneic stem cell transplantation (SCT) have not yet been reported.
Case report: A 66- year-old male patient was admitted for IgA myeloma(IIIA) with del q13. The myeloma progressed to plasma cell leukemia. Bortezomib was given, free light chain (FLC) excretion decreased, and myeloma cells disappeared from blood and decreased in marrow. An unrelated, mismatched allogeneic SCT was performed. The patient was discharged after engraftment with full chimerism without signs of GvHD. FLC excretion increased, and immunosuppression was discontinued. From day +84 on, bortezomib was infused again and FLC excretion decreased rapidly. Relapse was confirmed in marrow, and bortezomib was continued. Donor lymphocyte infusions (DLI) had no effect, and a further cycle of bortezomib and thalidomide had only minor effects. On day +209, the patient died from myeloma.
Conclusion: This case gives evidence for an excellent initial response of plasma cell leukemia to bortezomib, however, early relapse after SCT clearly indicates limitations of both bortezomib therapy and allogeneic SCT in high-risk myeloma. Future developments are mandatory and could include combination of bortezomib with other cytostatics and early DLI in the absence of GvHD. In addition, there is need to clarify if graft-versus-myeloma effect is diminished by bortezomib therapy after allogeneic SCT.