Plasma Cell Leukemia in China: Retrospective Analysis of Clinical Characteristics and Prognosis

Background: Plasma cell leukemia (PCL) is an aggressive malignancy characterized by the presence of ≥ 20% plasma cells in the peripheral blood or an absolute plasma cell count >2× 10⁹/L. PCL exists in two forms: primary PCL (PPCL) presents de novo, whereas secondary PCL (SPCL) defined as a leukemic transformation from a previously diagnosed MM.

Materials and methods: We conducted a retrospective analysis in 46 cases with PCL patients enrolled in Blood Diseases Hospital, Chinese Academy of Medical Sciences from June 1997 to June 2016. Survival analysis and treatment response according to the response criteria of IMWG were analyzed to assess the efficacy of Bortezomib or Thalidomide based therapy combined with standard chemotherapy.

Results: Median age of 46 cases was 54.5 years (29-72 years), 28 males and 18 females; primary PCL 20 cases, secondary PCL 26 cases. Among those, 20 cases with kappa type, while 22 λ cases, 4 cases no secretion. Renal dysfunction occurs 51.4% of patients, 69.6% with osteolytic changes. D-S stage: I 1 case, 2 cases of stage II, stage III 43 cases. Complex karyotypes accounted for 45.2%, high frequency of cytogenetic abnormalities occur in IgH / CCND1 rearrangement with 8 cases, 1q21 amplification in 8 cases, RB-1 abnormalities in 6 cases, 4 cases of 17p deletion and 1 IgH / MAF rearrangement . 36 patients were evaluated in treatment responses, the overall reaction (≥MR) was 97.2%; 7 cases acquired complete remission (CR), 14 near complete remission (nCR), 6 very good partial response (VGPR), 8 cases of partial remission (PR), 1 case loss response. 16 cases of Bortezomib based therapy combined with chemotherapy; while 18 patients were treated with thalidomide combined with chemotherapy, 2 cases were conducted with allogeneic stem cell transplantation, 2 patients with chemotherapy underwent autologous stem cell transplantation after standard chemotherapy. Mean Overall survival (OS) was 19 months; primary and secondary PCL median OS was 15 months and 22 months separately (P = 0.098); Thalidomide based regimens and bortezomib-based regimen acquired a median OS 15 months and 30 months (P = 0.083). Median time to progression (TTP) of thalidomide and bortezomib based therapy was 6 months and 25 months (P = 0.03). The overall median TTP was 9 months.

Conclusions: Higher incidence in cytogenetic aberrations was observed in plasma cell leukemia. Combined chemotherapy with bortezomib can improve progression-free survival of patients, but cannot improve overall survival.