Long-term follow up of patients proceeding to transplant using plerixafor mobilized stem cells and incidence of secondary myelodysplastic syndrome/AML.

We report the long-term follow up of 49 patients (pts) enrolled on plerixafor compassionate use protocol. Thirty-seven pts (76%) had failed one previous mobilization attempt, while 12 (24%) had failed two or more previous attempts. Using the combination of plerixafor and granulocyte colony-stimulating factor, we collected2.5 × 10(6) CD34+cells/kg in 33 pts (67%). Forty-three of the 49 pts proceeded to an auto-SCT (ASCT). The median days to WBC and platelet engraftment were 11 (range, 9-13 days) and 16 (range, 11-77 days) days post ASCT, respectively. The median WBC count, Hb and platelet counts 1 year after ASCT were 4.7 × 10(9)/L, 12.2 g/dL and 109 × 10(9)/L, respectively. With median follow up of 42 months (range <1-54 months), 21 pts had evidence of disease progression. Five pts developed myelodysplastic syndrome (MDS)/AML at median of 29 months post ASCT. The cumulative incidence of MDS/AML at 42 months was 17% (95% confidence interval, 6 to 32%). Development of secondary MDS/AML in pts proceeding to ASCT after plerixafor mobilization needs to be studied further in a larger cohort.