Similar dynamics of intraapheresis autologous CD34+ recruitment and collection efficiency in patients undergoing mobilization with or without plerixafor

Crude collection efficiency of CD34+ hematopoietic stem cell apheresis

Understanding the apheresis principles for harvesting hematopoietic stem cells (HSCs) is critical for performing efficient procedures. However, despite significant advances in estimating the collection efficiency (CE) of aphereses, many confounding factors still need to be addressed in the classical calculations. The CE values are unrestricted, and many procedures exhibit CEs of a given cell population greater than 100%. This report introduces a simple equation that estimates the "crude" CE, which ranges from 0% to 100% and intrinsically considers the contribution of donor-related variables such as the pre-procedure mobilization and intra-apheresis recruitment of CD34+ cells (as a convenient marker for HSCs), as well as the performance of the apheresis system itself.

Collection efficiency in apheresis

Significant advances in procedural information displayed by current apheresis machines have been made, but analyses of cell collection efficiency (CE) still rely on calculations done by apheresis professionals. Accordingly, understanding CE equations can support the optimization of apheresis techniques and identification of incidents that could impact the procedure's effectiveness. This report summarizes classical and novel CE analyses applied to apheresis exemplified by an actual case of hematopoietic progenitor cell collection. In addition to the apheresis yield and most common CE1 and CE2 formulas, we present the instantaneous and corrected CE, fold enrichment, collection throughput, collection rate and its variants, average inlet rate, classical and adjusted captured cells, recruitment pool, recruitment factor, recruitment coefficient, blood component loss, predictive apheresis yield, and performance ratio calculations. Moreover, the mathematical relationship between these CE equations is also shown, which can be helpful in many apheresis procedures.

Impact of Plerixafor Use at Different Peripheral Blood CD34+ Thresholds on Autologous Stem Cell Collection in Patients with Multiple Myeloma

Patients with multiple myeloma (MM) scheduled for autologous stem cell transplantation must undergo autologous stem cell mobilization; unfortunately, however, many do not obtain an adequate collection yield. Despite the availability of plerixafor, its widespread and uniform use is limited by its cost, and consequently, many institutions have adopted various risk-adapted algorithms. We report our mobilization experience as we have modified our plerixafor algorithm to a more liberal one, with the expectation of greater collection efficiency and mobilization success with higher plerixafor use. A total of 344 mobilization attempts were analyzed over 3 time periods and using 3 different peripheral blood CD34⁺ cell counts to guide plerixafor use: <15/µL (n = 66), <20/µL (n = 130), and <40/µL (n = 148). The primary endpoints were evaluation of changes in mean plerixafor utilization and apheresis days and assessment of the impact on overall mobilization costs. Secondary endpoints were a description of the impact of lenalidomide use on mobilization and evaluation of the rate of mobilization failure. We found that mean plerixafor use increased from 1.32 to 1.65 to 1.74 doses per mobilization (P = .026) and the mean days of apheresis decreased from 2.15 to 2.17 to 1.89 days per mobilization for the <15/µL, <20/µL, and <40/µL cohorts, respectively (P = .011). The combined cost of plerixafor and apheresis procedures at a threshold of 40/µL is close to that at a threshold of 15/µL, while saving 26 apheresis days per 100 patients. In general, there were low rates of mobilization failure across all thresholds. Patients who received more than 6 cycles of lenalidomide demonstrated impaired mobilization and required more apheresis sessions (P < .013) and greater plerixafor use (P < .001) to achieve target stem cell yields. Overall, using plerixafor in patients with MM, with a day 4 pCD34 count of <40/µL is a reasonable and cost-effective strategy to optimize apheresis utilization.

Autologous Stem Cell Mobilization and Collection

Peripheral blood stem cell collection is an effective approach to obtain a hematopoietic graft for stem cell transplantation. Developing hematopoietic stem/progenitor cell (HSPC) mobilization methods and collection algorithms have improved efficiency, clinical outcomes, and cost effectiveness. Differences in mobilization mechanisms may change the HSPC content harvested and result in different engraftment kinetics and complications. Patient-specific factors can affect mobilization. Incorporating these factors in collection algorithms and improving assays for evaluating mobilization further extend the ability to obtain sufficient HSPCs for hematopoietic repopulation. Technological advance and innovations in leukapheresis have improved collection efficiency and reduced adverse effects.