Use of various offset settings in the Fenwal Amicus during hematopoietic progenitor cell collection to increase lymphocyte yield and reduce cross-cellular contamination

Stem Cells Collection and Mobilization in Adult Autologous/Allogeneic Transplantation: Critical Points and Future Challenges

Achieving successful hematopoietic stem cell transplantation (HSCT) relies on two fundamental pillars: effective mobilization and efficient collection through apheresis to attain the optimal graft dose. These cornerstones pave the way for enhanced patient outcomes. The primary challenges encountered by the clinical unit and collection facility within a transplant program encompass augmenting mobilization efficiency to optimize the harvest of target cell populations, implementing robust monitoring and predictive strategies for mobilization, streamlining the apheresis procedure to minimize collection duration while ensuring adequate yield, prioritizing patient comfort by reducing the overall collection time, guaranteeing the quality and purity of stem cell products to optimize graft function and transplant success, and facilitating seamless coordination between diverse entities involved in the HSCT process. In this review, we aim to address key questions and provide insights into the critical aspects of mobilizing and collecting hematopoietic stem cells for transplantation purposes.

Natural Killer Cells Are Key Host Immune Effector Cells Affecting Survival in Autologous Peripheral Blood Hematopoietic Stem Cell Transplantation

The infusion of autograft immune effector cells directly impacts the clinical outcomes of patients treated with autologous peripheral blood hematopoietic stem cell transplantation, suggesting the possibility of an autologous graft-versus tumor cells. Furthermore, the early recovery of immune effector cells also affects survival post-autologous peripheral blood hematopoietic stem cell transplantation. Natural killer cells are among the immune effector cells reported to be collected, infused, and recovered early post-autologous peripheral blood hematopoietic stem cell transplantation. In this review, I attempt to give an update on the role of natural killer cells regarding improving survival outcomes on patients treated with autologous peripheral blood hematopoietic stem cell transplantation.

The Impact of Infused Autograft Absolute Numbers of Immune Effector Cells on Survival Post-Autologous Stem Cell Transplantation

Autologous stem cell transplantation treatment has been viewed as a therapeutic modality to enable the infusion of higher doses of chemotherapy to eradicate tumor cells. Nevertheless, recent reports have shown that, in addition to stem cells, infusion of autograft immune effector cells produces an autologous graft-versus-tumor effect, similar to the graft-versus-tumor effect observed in allogeneic-stem cell transplantation, but without the clinical complications of graft-versus-host disease. In this review, I assess the impact on clinical outcomes following infusions of autograft-antigen presenting cells, autograft innate and adaptive immune effector cells, and autograft immunosuppressive cells during autologous stem cell transplantation. This article is intended to provide a platform to change the current paradigmatic view of autologous stem cell transplantation, from a high-dose chemotherapy-based treatment to an adoptive immunotherapeutic intervention.

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.

Higher Donor Apheresis Blood Volumes Are Associated with Reduced Relapse Risk and Improved Survival in Reduced-Intensity Allogeneic Transplantations with Unrelated Donors

Allogeneic hematopoietic stem cell transplantation (HSCT) with reduced-intensity conditioning (RIC) offers a curative option for patients with hematologic malignancies who are unable to undergo myeloablative conditioning, but its success is limited by high rates of relapse. Several studies have suggested a role for T cell doses in peripheral blood stem cell grafts in RIC HSCT. Because T cell dose is typically not known until after the collection, and apheresis blood volume is easily modifiable, we hypothesized that higher donor apheresis blood volumes would improve transplantation outcomes through an effect on graft composition. Thus, we analyzed the relationships between apheresis volume, graft composition, and transplantation outcomes in 142 consecutive patients undergoing unrelated donor allogeneic RIC HSCT. We found that apheresis volume ≥15 L was associated with a significantly decreased risk of relapse (adjusted hazard ratio [aHR], .48; 95% confidence interval [CI], .28 to .84]; P = .01) and improved relapse-free survival (aHR, .56; 95% CI, .35 to .89; P = .02) and overall survival (aHR, .55; 95% CI, .34 to .91; P = .02). A high apheresis volume was not associated with increased rates of acute or chronic graft-versus-host disease. These results demonstrate that an apheresis volume of at least 15 L is independently predictive of improved transplantation outcomes after RIC allogeneic HSCT.

Autograft immune effector cells and survival in autologous peripheral blood hematopoietic stem cell transplantation

In addition to stem cells, T-cells, natural killer cells, dendritic cells, and monocytes are also collected and infused from the autograft in patients undergoing autologous peripheral blood hematopoietic stem cell transplantation. Recent reports have shown that these autograft immune effector cells can affect the clinical outcome postautologous peripheral blood hematopoietic stem cell transplantation. In this article, I will review the clinical impact on the survival of these autograft immune effector cells conferring the concept of autologous graft versus tumor effect.

A novel hematopoietic progenitor cell mobilization and collection algorithm based on preemptive CD34 enumeration

BACKGROUND

The collection of autologous peripheral blood (PB) stem cells can be challenging in the subgroup of patients deemed "poor mobilizers" with granulocyte-colony-stimulating factor. Plerixafor, a CXCR-4 antagonist, is an alternative mobilizing agent, but is costly, and the optimal mobilization algorithm has yet to be determined.

STUDY DESIGN AND METHODS

To address the question we developed a protocol measuring PB CD34 on Day 4 of mobilization. We examined 26 patients before initiating the protocol versus 24 patients after initiation.

RESULTS

Significant differences (p ≤ 0.05) included fewer days of collection (1.25 days vs. 2.42 days), lower total blood volume processed (25.9 L vs. 57.2 L), lower total product volume (324 mL vs. 691 mL), lower RBC content (9 mL vs. 18 mL), and lower granulocyte percentage per collection (35% vs. 11%). There were no significant differences between the two groups in demographics, baseline platelet count, total CD34, or CD34/kg harvested.

CONCLUSION

Use of a protocol to assess PB CD34 1 day before collection allows for preemptive administration of plerixafor to augment mobilization. Subsequently, days of collection and processed blood volume are reduced while there is less RBC and granulocyte contamination in the collected stem cell product.

Manual color monitoring to optimize hematopoietic progenitor cell collection on the Fenwal Amicus

A technique was developed to improve consistency of MNC transfers from the centrifuge to the collection bag in the Fenwal Amicus. The operator assures that RBCs completely fill the cassette by the end of the transfer by adjusting the RBC offset in succeeding cycles. We compared yields and crosscellular content before and after implementation of the monitoring technique. Retrospective data from 400 consecutive HPC collection procedures (200 for each technique) were compared. In 40 monitored collections, the RBC offset was adjusted to 6-9 mL to ensure that RBCs completely filled the cassette. Collections requiring these adjustments were not associated with a specific diagnosis. Median values were compared between the 40 collections requiring offset adjustment and those performed before implementation of monitoring. Baseline peripheral CD34+ cell (17 vs. 14 cells μL(-1)), lymphocytes (2 vs. 1.3 × 10(9) /L), WBCs, HCT, and PLTs were significantly higher in the group requiring offset changes. The group requiring offset changes had significantly more CD34+ cells per collection (190.8 × 10(6) or 2.04 × 10(6) /kg vs. 84.3 × 10(6) or 0.89 × 10(6) /kg) and more lymphocytes per collection (16.9 × 10(9) vs. 11.6 × 10(9)). Crosscellular content of the group requiring offset changes was significantly higher for WBCs (41.8 vs. 33.1 × 10(9)), granulocytes (9.6 vs. 7.2 × 10(9)), RBCs (23 vs. 17 mL), and PLTs (2.1 vs. 1.2 × 10(11)). Manual monitoring is a simple, inexpensive method to optimize each HPC collection to maximize CD34+ cell and lymphocyte yields.

Predicting PBSC harvest failure using circulating CD34 levels: developing target-based cutoff points for early intervention

PBSCs are usually mobilized using G-CSF with or without chemotherapy. With the emergence of newer mobilizing agents, predicting poor mobilization may allow early intervention and prevent the costs and complications associated with remobilization. We retrospectively evaluated a cohort of 1556 patients seen between January 2000 and September 2008 with multiple myeloma (565; 36%), non-Hodgkin's lymphoma (NHL) (562; 36%), amyloidosis (345; 22%) or Hodgkin's disease (94; 6%), who were initially mobilized with single agent G-CSF. Sensitivity and specificity analysis was used to identify ideal peripheral blood CD34 count (PB-CD34) cutoff points that predicted successful collection. In patients with plasma cell disorders, a PB-CD34 count of 11, 17, 21 and 28/μL by day 4 or 5 was required to collect a target of 2, 4, 8 or 12 million cells/kg, respectively. A CD34 yield of <0.8 million cells/kg on first apheresis also predicted for <2 million CD34 cells/kg. For patients with NHL or Hodgkin's disease, a PB-CD34 count of <6 and <15/μL on day 4 or 5 predicted failure to achieve a target collection of 2 and 4 million cells/kg, respectively. This study suggests that PB-CD34 thresholds should be based on collection target to allow for early intervention and to prevent collection failures.