Collection of peripheral blood stem cells in newly diagnosed myeloma patients without any prior cytoreductive therapy: the first step towards an 'operational cure'?

We have shown that primary therapy with non-myeloablative (140 mg/m(2)) high-dose melphalan (HDM) without hematopoietic support results in high response rates in untreated myeloma and very long-term survival of some patients. This study was designed to see if sufficient CD34 (+) cells can be harvested at presentation in newly diagnosed patients to administer myeloablative HDM (200 mg/m(2); HDM200) with autograft as primary therapy. This may improve outcome by rapid achievement of complete remission (CR) and possible avoidance of late myelodysplasia as a consequence of non-transplant induction chemotherapy. Thirty untreated patients received 1 g/m(2) methylprednisolone daily (days 1-6) and 12-16 micro g/kg G-CSF daily (days 3-6), and underwent leukapheresis on days 6 and 7. The median CD34(+) cell yield was 1.31 x10(6)/kg (range, 0.23-5.63), and was > or =1 x10(6)/kg in 73%. Cell yields were significantly lower than in 82 historical controls apheresed after completion of induction chemotherapy (median 2.16 x 10(6)/kg), and improved in patients who were apheresed again after induction chemotherapy. Three patients received primary therapy with HDM200 and autograft using these cells and attained CR. We conclude that it is possible to harvest stem cells in three-quarters of untreated myeloma patients. Increasing the number of apheresis procedures is needed to improve the number of CD34(+) cells collected.