Significantly Lower Cryopreservation Volumes for PBSC Collections Using Spectra Optia® Version 5 Software Compared with the MNC Setting on COBE® Spectra, Particularly When Using Plerixafor for Mobilisation

Abstract 825

Plerixafor (Mozobil®, Genzyme), an antagonist of the alpha chemokine receptor CXCR4, is highly effective as a novel PBSC mobilisation agent for patients failing to mobilise PBSC by conventional means, and is now licensed for this indication in Europe and the USA. However, significantly larger cryopreservation volumes have been reported as a disadvantage when plerixafor is used as part of PBSC mobilisation regimes (Tanhehco et al., Journal of Clinical Apheresis 2010, advance online publication). Although not an insurmountable problem in our own experience, this does increase liquid nitrogen freezer space requirements and also increases DMSO exposure for the patient at the time of re-infusion. In the course of a pre-marketing audit of the Version 5 PBSC collection software for the new Spectra Optia® apheresis platform (CaridianBCT), we observed significantly lower cryopreservation volumes for plerixafor collections when using Spectra Optia® than when using the widely-used mononuclear cell (MNC) setting (“Version 4.1”) on the conventional COBE® Spectra (Caridian BCT) apheresis platform. Formal audit was carried out of a series of 21 consecutive aphereses for PBSC procurement from 16 patients where plerixafor had been used as part of the conditioning regime, with Spectra Optia® being used for 10 procedures and COBE® Spectra for 11. Cryopreservation volume was strikingly and significantly lower for the Spectra Optia® procedures (median 351 mls; range 170 – 716 mls) than for COBE® Spectra procedures (median 756 mls; range 524 – 2400 mls; p<0.001). Extension of this audit to a comparator group of 26 procedures on a temporally matched series of 18 consecutive patients where plerixafor was not used as part of the conditioning regime, of which Spectra Optia® was used for 7 procedures and COBE® Spectra for the remainder, did show lower cryopreservation volume for non-plerixafor collections compared with the 22 plerixafor collections though this did not reach statistical significance (p=0.11). The total white cell count was noted to be significantly higher on the day of PBSC collection for the plerixafor group (median WCC 29.8 × 10^⋀9/l) compared to the non-plerixafor group (median WCC 15.1 × 10^⋀9/l; p<0.001). Slightly lower cryopreservation volumes were seen in the non-plerixafor group when comparing the Spectra Optia® procedures to the COBE® Spectra procedures, but this was not statistically significant (median for Optia 354 mls, range 99–668 mls compared with median for Spectra 488 mls; range 298–954 mls; p>0.05). However, comparison of Spectra Optia® collections with COBE® Spectra collections for all 47 procedures (plerixafor plus non-plerixafor collections) showed significantly lower cryopreservation volumes for Spectra Optia® (p<0.01). Initial results with Spectra Optia® have shown that it yields a purer product than COBE® Spectra MNC, with lower granulocyte contamination, while maintaining the high PBSC collection efficiency of COBE® Spectra MNC (CaridianBCT, personal communication). In our experience, this translates into a greater than 50% reduction in median cryopreservation volume in the context of collection procedures where plerixafor is used as part of the conditioning regime, probably because of the higher total peripheral WCC seen in plerixafor-mobilised patients which leads to significant granulocyte contamination of the product with older cell separator platforms. Spectra Optia® therefore shows great promise as a solution to the problem of higher cryopreservation volumes when using plerixafor.