Successful mobilization, intra-apheresis recruitment, and harvest of hematopoietic progenitor cells by addition of plerixafor and subsequent large-volume leukapheresis

Optimizing leukapheresis product yield and purity for blood cell-based gene and immune effector cell therapy

PURPOSE OF REVIEW

A critical common step for blood-based ex-vivo gene and immune effector cell (IEC) therapies is the collection of target cells for further processing and manufacturing, often accomplished through a leukapheresis procedure to collect mononuclear cells (MNCs). The purpose of this review is to describe strategies to optimize the apheresis product cell yield and purity for gene and IEC therapies. Relevant data from the conventional bone marrow transplant literature is described where applicable.

RECENT FINDINGS

Product yield is affected by three main factors: the peripheral blood concentration of the target cell, optimized by mobilizing agents, donor interventions or donor selection; the volume of peripheral blood processed, tailored to the desired product yield using prediction algorithms; and target cell collection efficiency, optimized by a variety of device and donor-specific considerations. Factors affecting product purity include characteristics of the donor, mobilizing agent, device, and device settings.

SUMMARY

Strategies to optimize product yield and purity for gene and IEC therapies are important to consider because of loss of target cell numbers or function with downstream steps and detrimental effects of nontarget cells on further manufacturing and patient outcome.

Mobilization kinetics of CD34+ hematopoietic stem cells stimulated by G-CSF and cyclophosphamide in patients with multiple sclerosis who receive an autotransplant

BACKGROUND AIMS

Autologous hematopoietic stem cell transplantation (AHSCT) is an alternative for multiple sclerosis (MS) patients who do not respond to conventional treatment. Mobilization kinetics of CD34+ cells in MS patients has not been studied.

METHODS

Patients with MS mobilized with granulocyte colony-stimulating factor (G-CSF) and cyclophosphamide (Cy) were prospectively studied. Three counts of CD34+ cells were done in peripheral blood: at baseline before mobilization, at the start, and immediately at the end of apheresis. Complete blood counts were performed at the times of CD34+ cell counting. Standard statistical descriptive analysis of MS patients' salient features was performed, and after log 10 transformation of the data, Pearson test was performed to assess correlation between variables and CD34+ cell count. In addition, multiple linear regression of relevant data was carried out for multivariate analysis.

RESULTS

Data of 51 consecutive MS patients with median age of 48 (31-64) years were analyzed. The CD34+ cell count increased 26-fold after mobilization. During large volume leukapheresis (LVL), the number of CD34+ cells in peripheral blood increased from 51.29 CD34+/μL at the start to 62.3 CD34+/μL at the end. A negative correlation between CD34+ cell count after leukapheresis and age (r = -0.32, P = 0.02) was observed. Neither the CD34+ baseline count nor sex correlated with the CD34+ count in peripheral blood immediately at the end of apheresis.

CONCLUSIONS

Mobilization with G-CSF and Cy in MS patients resulted in effective CD34+ hematoprogenitors release from the bone marrow and in intra-apheresis recruitment.

Comparison and cost analysis of three protocols for mobilization and apheresis of haematopoietic progenitor cells

INTRODUCTION

Autologous bone marrow transplantation is a component of the malignant hemopathy therapy. The preferred mobilization and collection method is apheresis. The aim of this study is to compare three protocols analyzing the effect of plerixafor, higher dose of G-CSF and large volume leukapheresis (LVL).

MATERIALS AND METHODS

A retrospective cohort study including 119 patients referred for mobilization. Three protocols were compared: (a) G-CSF 10 μg/kg/day subcutaneous (sc) × 4 days mobilizing 1 to 1.5 blood volumes. (b) G-CSF 10 μg/kg/day sc × 4 days + plerixafor 0.24 mg/kg/day sc preventively or as a rescue agent mobilizing 1 to 1.5 blood volumes. (c) G-CSF 20 μg/kg/day sc × 4 days ± plerixafor 0.24 mg/kg/day sc preventively or as a rescue agent mobilizing 3 to 4 blood volumes.

RESULTS

The average number of days of apheresis was reduced to 1.37 with protocol 3. The average cost per patient was reduced by 67% compared with protocol 2 and increased by only 5% compared with protocol 1, reducing the failure rate to 0%.

CONCLUSION

Adding preemptive or rescue plerixafor (protocol 2) to G-CSF 10 μg/kg/day alone (protocol 1) did not improve the days of apheresis nor the number of CD34+ cells collected but had higher cost and failure rate. Using LVL, plerixafor and G-CSF 20 μg/kg/day (protocol 3) decreased the number of sessions to 1.37, reduced the failure rate to 0% and led to a significant increase in the number of CD34+ cells collected without toxicity and with a similar cost to protocol 1.

The prognostic impact of peripheral blood progenitor cell dose following high-dose therapy and autologous stem cell transplant for hematologic malignancies

High-dose chemotherapy (HDT) followed by autologous peripheral blood progenitor cell transplant (PBPCT) has become a standard intervention in certain clinical settings of hematologic malignancies, particularly multiple myeloma and relapsed/refractory lymphoma. While the minimal required PBPCs infused, as defined by number of CD34 + cells, has been relatively well delineated for adequate hematopoietic recovery post-HDT, optimal PBPC dose has not been clearly defined. This is particularly relevant in the context of retrospective data suggesting improved survival outcomes with increased PBPC doses. The potential confounding of these data as they relate to disease risk is discussed within this review. Additionally, other retrospective data have suggested that enhanced quantitative lymphocyte subset reconstitution post-HDT-PBPCT may confer progression-free and overall survival advantage. These reported series herein reviewed may inform discussion of future, prospective clinical trials with the intent of defining optimal autologous PBPC dose following HDT, especially as it may relate to metrics beyond hematopoietic recovery.