Mobilization of Ph-Negative Peripheral Blood Stem Cells (PBSCs) with rHu-G-CSF in Chronic Myeloid Leukemia (CML) Patients Achieving Complete Cytogenetic Response with Imatinib Mesilate (Glivec).

Imatinib Mesilate (Glivec) is able to induce a high rate of Complete Cytogenetic Response (CCyR) with low treatment-related toxicity. The long-term duration of this Ph-negative status is, however, still undefined. Therefore, some groups (

We discontinued Imatinib four days (range 3–5) before starting rHu-G-CSF as single agent (5–10 μg/Kg/day), which was maintained until WBC < 50x10⁹/L. Failure of mobilization was defined as CD34+ circulating cells < 10/m L. The collection started after a median of 6 days (range 4 –10), when CD34+ cells were > 10/μ L. Eleven of 12 pts (92%) reached the threshold of 10/μ L and started harvesting. The single patient failing collection had been pretreated with IFN and was PCR negative at the time of mobilization. The remaining 11 reached the target of 2.5 x10⁶ CD34+ cells/Kg with a median of two apheresis (range 1–3). The median harvest was 3.14 CD34+ x 10⁶/Kg (range 2.56–4.55). Conventional cytogenetic analysis, RT-PCR and coltural tests were performed in all apheretic samples. All the 11 mobilized patients obtained a Ph-negative harvest, which was also PCR negative in 4/11 (36%).

In our experience adequate yields of PBSCs were collected with rHu-G-CSF alone in 11/12 patients achieving CCyR with Glivec, as well as in the majority of those previously treated with α-IFN (7/8).

Results of harvesting after rHu-G-CSF alone in 11 CML patients achieving CCyR after Imatinib Mesilate