Background: Allogeneic stem-cell transplantation (SCT) can eradicate myelofibrosis (MF), but is limited by donor availability and toxicity. We previously reported normalization of counts and resolution of MF after ablative, syngeneic SCT in spent phase polycythemia vera (PV). Hence, GvL is not required to eradicate MF. Autologous SCT may advance treatment for spent phase PV by restoring effective hematopoiesis. The influence of organomegaly, myelosuppression and MF on PBSC collection has not been studied in the setting of PV.
Methods: Sixteen patients with PV underwent PBSC collection. Mobilization was with filgrastim alone, with a target cell content of 2.5 x 10(6) CD34(+)/kg. All myelosuppression was discontinued 2 weeks prior to collection.
Results: Median ages at diagnosis and collection were 47 and 57 years, respectively. Organomegaly, MF and use of myelosuppressive therapies were present in 10 (63%), 4 (25%) and 7 (44%) patients. Median total nucleated cells (TNC) and CD34(+) counts were 8.3 x 10(8)/kg and 4.98 x 10(8)/kg. MF had an adverse effect on TNC (p=0.05) but not on the CD34(+) content. Time from diagnosis and the use of myelosuppresion had no influence on TNC and CD34(+) contents. Four patients had CD34(+) contents <2.5 x 10(6)/kg. Complete blood count (CBC) parameters were not predictive of CD34(+) content.
Discussion: Autologous PBSC collection is feasible in PV several years after diagnosis. Organomegaly and MF are not absolute contraindications for collection. Discontinuing myelosuppresion for 2 weeks before mobilization appears sufficient to collect adequate numbers of CD34(+) progenitors.