Autologous peripheral-blood progenitor-cell support following high-dosechemotherapy or chemoradiotherapy in patients with high-risk multiple myeloma.

Purpose: The aims of the current study were to evaluate in patients with high-risk multiple myeloma (MM) the feasibility and usefulness of high-dose chemotherapy or chemoradiotherapy followed by hematopoietic stem-cell support with autologous peripheral-blood progenitor cells (PBPC) harvested after high-dose cyclophosphamide (HDCYC).
Patients and Methods: Seventy-three patients with high-risk MM were entered onto the study. Before the procedure, all patients had received HDCYC to collect PBPC by leukapheresis. One patient died of infection after HDCYC. All other patients subsequently received high-dose melphalan (HDM) (140 mg/m2) either alone (n = 1) or associated with either busulfan (16 mg/kg; n = 4) or total-body irradiation (TBI) (8 to 15 Gy; n= 67). In addition, three of the latter patients received cyclophosphamide (120 mg/kg). Thereafter, PBPC were reinfused either alone in 61 patients or together with back-up bone marrow cells in 11 patients in whom the granulocyte-macrophage colony-forming unit (CFU-GM) cell content of the leukapheresis was low.
Results: One patient died of acute cardiac failure after reinfusion of PBPC; three patients did not respond after autologous blood progenitor cell transplantation (ABPCT), while the other 68 patients achieved either a complete response (CR; n = 32) or partial response (PR; n = 36). Thirty-six patients relapsed or progressed after a median response duration of 14.5 months (range, 3 to 43) and 19 of these subsequently died. Four other patients died while still responsive of lung cancer (n = 1) or infection (n = 3). The remaining 28 patients are currently alive and still responding with a median follow-up duration of 27 months (range, 6 to 66). The 3-year probability of survival was 66% +/- 12% (95% confidence interval [CI] after ABPCT and 77% +/- 51% (95% CI) from diagnosis.
Conclusion: High-dose chemotherapy or chemoradiotherapy followed by autologous PBPC support in MM is feasible and efficient. Further studies are needed to confirm these encouraging, although preliminary, results and to compare this technique with other therapeutic strategies.