Efficiency of autologous stem cell collection: Comparison of three different cell separators

Simple method to predict lymphocyte collection for chimeric antigen receptor T-cell engineering

INTRODUCTION

T lymphocyte collection is essential for CAR T-cell engineering in refractory hematologic malignancies but needs to be optimised. No guidelines have been established for predicting the amount of T lymphocytes to be collected. The quantity of lymphocytes and especially T cells collected depends on the pre-cytapheresis lymphocyte blood level (pcLBL) and the number of blood volumes (BVs) processed. Our aim was to define and standardise a simple method for predicting the number of T lymphocytes collected, taking into account the number of BVs processed and the pcLBL regardless of the procedures defined by different companies.

METHODS

We used data from our large retrospective series, which included 407 collection sessions using the same cytapheresis method in 400 patients mainly being followed up for non-Hodgkin's lymphoma (NHL) or multiple myeloma (MM). We initially analysed the performance of lymphocyte collections using collection efficiencies (CE1 and CE2), which are indices that determine the ability to collect as many cells as possible, and also assessed the percentage of neutrophils collected. Finally, we evaluated whether the number of T cells collected could be easily predicted by multiplying the pcLBL and number of BVs by an average factor.

RESULTS

In our series, CE1 and CE2 for total lymphocytes and T cells were between 76 ± 15% and 69 ± 15%, thus confirming adequate cell collection. A low percentage of neutrophils was collected (9 ± 12%). Confirmation of adequate cell collection led us to consider the relationship between pcLBL and T-cell collection. We then demonstrated that the amount of T cells collected correlated with pcLBL, and could be predicted by multiplying pcLBL by 2.5 for each BV processed.

CONCLUSION

Easy prediction of T-cell collection is an important tool that can help apheresis and haematology teams monitor collection sessions, regardless of the companies involved and CAR T-cell technology.

Combined peripheral blood monocyte count and white blood cell count as a guide for successful one-day autologous peripheral blood stem cell collection

INTRODUCTION

Peripheral blood stem cells (PBSCs) are the most common source of stem cell transplantation, which depends on an adequate number of CD34+ cells. Although pre-apheresis CD34+ cell count is a standard guide for the collection, it is not always available. This study aimed to evaluate complete blood count parameters for predicting successful one-day autologous PBSC collection.

METHODS

Data from the patients who underwent autologous PBSC collection at a tertiary care hospital were retrospectively reviewed.

RESULTS

There were 123 patients (185 leukapheresis procedures). Successful PBSC collection (CD34+ cells ≥4.0 × 106 cells/kg) was obtained in 85 patients (69.1%), of which 55 (44.7%) were successfully obtained on the first day. The median CD34+ collection efficiency was 44.1%. The mean platelet loss during apheresis was 39.9%. The adverse event rate was 18.9%. Patients in whom PBSCs were collected within one day were less likely to experience adverse effects related to leukapheresis. Pre-apheresis CD34+ cells ≥10 cells/μLand combined white blood cell (WBC) counts ≥5 × 109/L and/or monocyte ≥10% were independently associated with the successful one-day PBSC collection (adjusted odds ratio 24.06, 95% confidence interval [CI] 5.30-109.10, p < 0.001; and 6.94, 95% CI 1.35-35.79, p = 0.021, respectively). Only pre-apheresis CD34+ cells had a strong correlation with the total stem cell yield.

CONCLUSIONS

To reduce the complication of leukapheresis, the combined pre-apheresis WBC ≥5 × 109/L and/or monocyte ≥10% is a practical parameter to initiate a successfully one-day PBSC collection with or without pre-apheresis CD34+ cell results.

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.

Comparison of hematopoietic progenitor cell collection using different inlet flow rates with the Fenwal Amicus

PURPOSE

We have used a hematopoietic progenitor cell (HPC) algorithm (standard [STD]) that restricted the inlet flow rate to 65 mL/min for peripheral white blood cell count (PWBC) >35 × 109 /L (STD). In this study, we evaluated a technique that allows 85 mL/min, regardless of the PWBC count (high). For patients with PWBC >35 × 109 /L, a prospective, randomized comparison of the high flow rate vs the STD PWBC-based flow rate (65 mL/min) was performed, comparing CD34+ and lymphocyte yields, collection efficiencies (CE1), mononuclear cells (MNC), and granulocytes, red blood cell (RBC), and platelet content.

METHODS

The Fenwal Amicus version 4.5 with a heparinized ACD-A anticoagulant (AC) delivered at a 26:1 AC ratio was used. Paired comparisons between high and STD techniques were assessed with Wilcoxon signed rank tests, with P < .05 considered significant. Data are summarized as medians.

RESULTS

Forty patient pairs (autologous) were compared. Diagnoses included primarily multiple myeloma (60%) and lymphoma (37.5%). High had significantly higher median average inlet rates (69 vs 55 mL/min), whole blood processed (20 vs 16 L), and cycles (15 vs 14) than STD. There were no significant differences in pre-procedure counts. Collection contents were (high/STD): 306/328 × 106 CD34+ cells, 48/59% CD34+ CE1 (significant), 0.2/0.2 × 109 /kg lymphocytes, 45/57% lymphocyte CE1, 63/59 × 109 WBC, 15/16 × 109 granulocytes, and 1.9/1.7 × 1011 platelets.

CONCLUSIONS

The simpler, standardized high flow technique did not significantly increase or decrease CD34+ cells or lymphocyte yields, but did significantly decrease CD34+ CE1. The effects on cross-cellular content were minimal and not clinically significant.

A new protocol for improving efficiency of autologous peripheral blood stem cell collection in patients with high white blood cell counts

BACKGROUND

Collection efficiency (CE) of peripheral blood stem cell (PBSC) collections is negatively affected by increasing white blood cell (WBC) counts of the patient. This study compared a new optimized mononuclear cell (MNC) collection protocol (OPP) to the standard MNC collection protocol recommended by the manufacturer (STP) for PBSC collection in patients with WBC counts >35 000/μL.

STUDY DESIGN AND METHODS

Single-center, retrospective, and observational study of 81 autologous PBSC collections on Fenwal Amicus cell separators in 70 adult patients.

RESULTS

Median peripheral WBC count (×10³ /μL; 44.2 in OPP group vs 46.5 in STP group) and median CD34⁺ count (105/μL in OPP group vs 40/μL in STP group) at the beginning of PBSC collection did not differ significantly. Median CE2 (45% vs 31%; P < .001) as well as CD34⁺ yield of the apheresis product both with regards to median absolute CD34⁺ content (×10⁶ ; 793 vs 188; P = .001) as well as median CD34⁺ content (×10⁶ )/kg body weight (8.93 vs 2.51; P = .002) were significantly higher for the OPP. Overall, 18/21 (86%) patients with the OPP obtained their target CD34⁺ amount with a single apheresis session, compared to 25/50 (50%) with the STP (P = .005). PBSC collections using OPP lasted significantly longer (median 377 minutes vs 260 minutes; P < .001) than with the STP.

CONCLUSIONS

The OPP significantly improves CE2 for PBSC collections on Fenwal Amicus cell separators in patients with pre-apheresis WBC counts >35 000/μL and significantly reduces the necessity for multiple apheresis sessions. The OPP is therefore suited to reduce both patient burden and cost in autologous PBSC collection.

Trends in peripheral stem/progenitor cell manipulation and clinical application

Transplants using peripheral blood hemopoietic stem/progenitor (PBHS) cells are widely performed for the treatment of patients with hematologic disorders in routine practice and clinical trials. Although the process from mobilization to infusion of PBHS cells has been mostly established, optimal conditions for each process remain undetermined. Adverse reactions caused by PBHS cell infusions have not been systematically recorded. In transplants using PBHS cells, a number of problems still exist. In this section, the current status of and future perspectives regarding PBHS cells are described.

Change of apheresis device decreased the incidence of severe acute graft-versus-host disease among patients after allogeneic stem cell transplantation with sibling donors

BACKGROUND

The composition of the graft used for allogeneic hematopoietic stem cell transplantation (HSCT) is important for the treatment outcome. Different apheresis devices may yield significant differences in peripheral blood stem cell graft cellular composition. We compared stem cell grafts produced by Cobe Spectra (Cobe) and Spectra Optia (Optia) with use of the mononuclear cell (MNC) protocol, and evaluated clinical outcome parameters such as graft-versus-host disease (GvHD), transplant-related mortality (TRM), relapse, and overall survival.

STUDY DESIGN AND METHODS

During 5 years, 31 Cobe Spectra and 40 Spectra Optia grafts were analyzed for CD34, CD3, CD4, CD8, CD19, and CD56 cell content. Clinical outcome parameters were correlated and compared between the two patient groups using different apheresis devices.

RESULTS

Optia grafts contained fewer lymphocytes compared to Cobe (p < 0.001). Optia grafts had a significantly lower incidence of acute GvHD Grades II through IV (Cobe 45% vs. Optia 23%; p = 0.039) and TRM (16% vs. 2.5%; p < 0.05) but higher chronic GvHD (32% vs. 67%; p = 0.005) compared to Cobe grafts. Finally, the multivariate analysis showed a significant correlation among the different apheresis devices and both acute GvHD II through IV and severe chronic GvHD. The multivariate analysis also showed a significant correlation between the CD3+ cell dose and the incidence of severe acute GvHD.

CONCLUSION

Optia-obtained grafts yielded a lower acute GvHD Grades II-IV and TRM risk, but had no impact on relapse or overall survival in this study. Understanding and further improvement of peripheral blood stem cell (PBSC) apheresis techniques may be used in the future to personalize HSCT by, for example, fine-tuning the GvHD incidence.

Hurdles Associated with the Translational Use of Genetically Modified Cells

Purpose of Review

Recent advancements in the use of genetically modified hematopoietic stem cells (HSCs) and the emergent use of chimeric antigen receptor (CAR) T-cell immunotherapy has highlighted issues associated with the use of genetically engineered cellular products. This review explores some of the challenges linked with translating the use of genetically modified cells.

Recent Findings

The use of genetically modified HSCs for ADA-SCID now has European approval and the U.S. Food and Drug Administration recently approved the use of CAR-T cells for relapsed/refractory B-cell acute lymphoblastic leukemia. Current good manufacturing processes have now been developed for the collection, expansion, storage, modification, and administration of genetically modified cells.

Summary

Genetically engineered cells can be used for several therapeutic purposes. However, significant challenges remain in making these cellular therapeutics readily available. A better understanding of this technology along with improvements in the manufacturing process is allowing the translation process to become more standardized.