Factors affecting autologous peripheral blood hematopoietic stem cell collections by large-volume leukapheresis: a single center experience

The Effect of Iron Overload on the Mobilization of Peripheral Blood Hematopoietic Stem Cells in Pediatric Patients with Thalassemia Major

INTRODUCTION

The purpose of this study was to examine the effect of iron overload on the mobilization of peripheral blood stem cells (PBSCs) in pediatric patients with β-thalassemia major (TM).

METHODS

We retrospectively reviewed the records of 226 patients with TM from whom PBSCs were collected. Iron overload was based on serum ferritin level, and liver and cardiac iron overload was measured by magnetic resonance imaging (MRI) T2*.

RESULTS

The mean age of the TM patients was 7.35 ± 3.41 years. Of the patients, only 171 received MRI. Of the 171 patients, 35 had normal liver iron levels, 39 mild liver iron overload, 90 intermediate liver iron overload, and 7 severe liver iron overload. The intermediate + severe group was associated with significantly higher age and BMI and lower leukapheresis product white blood cell count and CD34+ cell levels (all, p < 0.05).

CONCLUSION

Leukapheresis indices were similar between patients with different degrees of iron overload according to the ferritin level and cardiac iron overload, in which the later might be due to the small number of patients with cardiac overload. In patients with TM, the intermediate and severe liver iron overload was associated with poorer mobilization of PBSCs.

Impact of gemtuzumab ozogamicin consolidation on hematopoietic stem cells (HSCs) mobilization in AML: analysis of 20 patients

Gemtuzumab ozogamicin (GO), is an anti-CD33 monoclonal antibody, approved for AML CD33 + , those patients with low and intermediate-risk who obtain a complete response may also be candidated for consolidation with autologous stem cell transplantation (ASCT). However, there are scant data on the mobilization of hemopoietic stem cells (HSC) after fractionated GO. We retrospectively studied data from five Italian centers and identified 20 patients (median age 54 years, range 29-69, 15 female, 15 NPM1^mutated) that attempted HSC mobilization after fractionated doses of GO + "7 + 3" regimen and 1-2 cycles of consolidation (GO + HDAC + daunorubicin). After chemotherapy and standard G-CSF, 11/20 patients (55%) reached the threshold of 20 CD34 + /µL, and HSC were successfully harvested, while 9 patients (45%) failed. The median day of apheresis was Day + 26 from the start of chemotherapy (range 22-39 days). In good mobilizer patients, the median circulating CD34 + cells were 35.9 cells/µL and the median CD34 + harvested were 4.65 × 10⁶/kg of patients' body weight. With a median follow-up of 12.7 months, at 24 months from the first diagnosis, 93.3% of all 20 patients were alive and the median overall survival was 25 months. The 2-year RFS rate from the timepoint of the first CR was 72.6%, while the median RFS was not reached. However, only five patients underwent ASCT and achieved full engraftment.In conclusion, in our cohort of patients, the addition of GO reduced HSC mobilization and harvesting, which was reached in about 55% of patients. Nevertheless, further studies are warranted to evaluate the effects of fractionated doses of GO on HSC mobilization and ASCT outcomes.

[Absolute numbers of peripheral blood CD34+ hematopoietic stem cells prior to a leukapheresis procedure as a parameter predicting the efficiency of stem cell collection]

AIM

To identify a parameter predicting a collection of at least 2·106 CD34+ hematopoietic stem cells (HSC)/kg body weight per leukapheresis (LA) procedure.

SUBJECTS AND METHODS

The investigation included 189 patients with hematological malignancies and 3 HSC donors, who underwent mobilization of stem cells with their subsequent collection by LA. Absolute numbers of peripheral blood leukocytes and CD34+ cells before a LA procedure, as well as a number of CD34+ cells/kg body weight (BW) in the LA product stored on the same day were determined in each patient (donor).

RESULTS

There was no correlation between the number of leukocytes and that of stored CD34+ cells/kg BW. There was a close correlation between the count of peripheral blood CD34+ cells prior to LA and that of collected CD34+ cells calculated with reference to kg BW.

CONCLUSION

The optimal absolute blood CD34+ cell count was estimated to 20 per µl, at which a LA procedure makes it possible to collect 2·106 or more CD34+ cells/kg BW.