Prospective Qualitative Study Concerning the Efficiency of PBSC Collections after a Change of Apheresis Device

Background

Efficiency measurement is an important indicator to improve quality of PBSC harvests. We have recently changed our apheresis device for PBSC collections: from the Cobe Spectra (Terumo BCT) to the Optia Spectra (Terumo BCT). We have further to this change decided to follow prospectively the harvests to estimate the efficiency of the new apheresis device.

Material and Method

Between November 2013 and April 2014, 21 consecutive harvests were conducted on Optia Spectra for ten consecutive patients/healthy donors. Six patients (3 multiple myeloma and 3 NHL) gave autologous PBSC. They were all mobilized with filgrastim (Neupogen, Amgen) which was associated with plerixafor (Mozobil, Genzyme) for two patients and pegfilgrastim (Neulasta, Amgen) for one patient. Four healthy donors gave PBSC for allogeneic HSCT; three were mobilized with filgrastim (Neupogen, Amgen) and one was mobilized with lenograstim (Granocyte, Chugai).

Results

The data of our 21 consecutive harvests showed a median PB CD34+ count of 20/mL [range, 7-132] and a median collection of 1.94 CD34 +/kg [range, 0.48-8.33]. The correlation between the PB CD34+ count and the number of CD34+ collected was strong (R²=0.83) (fig.1). A median of 3 and 2 collections were necessary in order to obtain a suitable graft for autologous and allogeneic HSCT respectively.

In this study, the efficiency of leukapheresis was only calculated for harvests with a PB CD34+ count > or = 20/µL (n=11), yielding a median efficiency of 30% (range, 13-52). These results were compared with those of our historic cohort of harvests achieved with the Cobe Spectra apheresis machine which yielded a median efficiency of 50% [range, 20-70]. In May 2014, in view of our lower efficiency results with the new device after 6 months of prospective study, we asked the Terumo BCT Company for an analysis of the harvests' data recorded in the Optia Spectra apheresis machine.

This analysis revealed a systematic accumulation of the buffy coat layer during the procedures, which led to the low efficiency of our harvests. Awareness of the fast accumulation of the buffy coat layer in the collection chamber, especially when the donor's white blood cell count is > 30 G/L, is of utmost importance. The correction has to be made quickly by reducing the depth of collection from 60 to 40 (or 40 to 30) and by decreasing the speed of the pump to 3mL/min if the initial speed is > 3 mL/min. Theoretically, these two operations should allow the elimination of the buffy coat layer and improve the efficiency of the harvests. The outcomes of our patients are described in Table 1.

Conclusion

After 6 months of prospective study, the median efficiency of our PBSC harvests with the new device was 30%, that is below our expected value. Repeated procedures were necessary to collect enough CD34+ cells for grafting. For this reason, we requested that Terumo BCT make a retrospective analysis of the collection data recorded in the Optia Spectra system. Their audit showed a systematic accumulation of the buffy coat layer in the collection chamber. Now corrective measures have been implemented and we are going to continue this study over the next 6 months (June 2014 - November 2014) to estimate our new PBSC collections' efficiency.

Figure 1

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Correlation between CD34+ cells collected and CD34+ peripheral blood stem cell (PB)

Count (R²= 0.83)

Figure 1

View largeDownload slide

Correlation between CD34+ cells collected and CD34+ peripheral blood stem cell (PB)

Count (R²= 0.83)

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