Continuous Mononuclear Cell Collection (cMNC) protocol impact on hematopoietic stem cell collections in donors with negative collection predictors

Evaluating the efficiency and safety of large-volume leukapheresis using the Spectra Optia continuous mononuclear cell collection protocol for peripheral blood stem cell collection from healthy donors: A retrospective study

BACKGROUND

Large-volume leukapheresis (LVL) refers to processing of more than three volumes of blood in a single session for peripheral blood stem cell collection. Recently, continuous mononuclear cell collection (cMNC) protocol has been developed using the Spectra Optia system, which is a widely used apheresis device. LVL using the novel protocol has been investigated in patients. However, the efficiency and safety of LVL in healthy donors using this protocol has not been characterized. Therefore, this study aimed to evaluate the efficiency and tolerability of CD34+ collection of LVL with the cMNC protocol in healthy donors.

STUDY DESIGN AND METHODS

We retrospectively collected data on LVL (>3 total blood volume) and normal-volume leukapheresis (NVL) performed in healthy donors between October 2019 and December 2021. All procedures were performed using the cMNC protocol.

RESULTS

Although pre-apheresis CD34+ cell count was lesser in LVL (23.5 vs. 58.0/μL, p < .001), CD34+ collection efficiency was comparable between LVL and NVL (61.2% vs. 61.4%, p = .966). Platelet loss was significantly higher in LVL compared to NVL (38.0% vs. 29.4%, p < .001), with no correlation between attrition of platelet and processing blood volume. Moreover, the incidence of citrate toxicity during procedures was comparable between the two groups (31.6% vs. 21.4%, p = .322). All LVL procedures could be completed without any adverse events.

CONCLUSION

Allogeneic LVL procedure using Spectra Optia cMNC protocol was well tolerated by the donors and resulted in efficient collection of CD34+ cells, which was comparable to that of NVL.

Impact of Mobilization Strategies on Peripheral Blood Stem Cell Collection Efficiency and Product Quality: A Retrospective Single-Center Study

Autologous stem cell transplantation is routinely used in the management of several hematological diseases, solid tumors, and immune disorders. Peripheral blood stem cell (PBSC) collection performed by apheresis is the preferred source of stem cells. In this study, the potential impact of mobilization regimens on the performance of the Spectra Optia^® continuous mononuclear cell collection system was evaluated. We performed a retrospective data analysis for patients undergoing autologous PBSC collection at the Medical University Vienna, Vienna General Hospital between September 2016 and June 2018. Collections were divided into two main groups according to the mobilization regimen received: without (210 collections) or with (99 collections) plerixafor. Assessed variables included product characteristics and collection efficiency (CE). Overall, product characteristics were similar between the groups. Median CD34+ CE2 was 50.1% versus 53.0%, and CE1 was 66.9% versus 69.9% following mobilization without and with plerixafor, respectively; the difference was not statistically significant. Simple linear regression showed a very weak positive correlation between the mobilization method and CE1 or CE2 (mobilization with plerixafor increased CE2 by 4.106%). In conclusion, the Spectra Optia^® apheresis system led to high CE and a good quality of PBSC products when mobilization regimens with or without plerixafor were used.

Low hematocrit reduces the efficiency of CD34+ cell collection when using the Spectra Optia continuous mononuclear cell collection procedure

BACKGROUND

CD34⁺ cell collection efficiency (CE) is the determining factor when calculating processed blood volume (PBV) for leukapheresis (LP). However, the factors affecting CE in the continuous mononuclear cell collection (cMNC) protocol performed by the Spectra Optia apheresis system are not well established.

STUDY DESIGN AND METHODS

We retrospectively collected the data from 147 consecutive apheresis procedures across 106 healthy donors and 27 patients completed between July 2016 and December 2020 at the Okayama University Hospital. All procedures were performed using the Optia cMNC protocol.

RESULTS

The median CD34⁺ CE2 was significantly higher in the donor samples (64.3%) than in the patient samples (46.8%) (p < .0001). WBC counts, hematocrit, and platelet counts were all significantly higher in the donors than in the patients, and there was a moderate positive correlation between CD34⁺ CE2 and hematocrit (r = .47, p < .0001), with the equation of the line being y = 1.23x + 12.23. In contrast, there was only a very weak correlation between CD34⁺ CE2 and WBC or platelet count. In addition, low hematocrit correlated with an increased time to interface formation.

CONCLUSION

These data revealed the negative impact of low hematocrit on the efficiency of CD34⁺ cell collection when using the Optia cMNC protocol and suggest that hematocrit values should also be considered when determining PBV.

Use of plerixafor to mobilize haematopoietic progenitor cells in healthy donors

Increased transplant activity calls for improved stem cell collection, especially when peripheral blood is the preferred source of haematopoietic progenitor cells (HPCs). Plerixafor is a bicyclam molecule that mobilizes CD34+ cells by reversibly disrupting CXCR4-CXCL12-supported HPC retention. Plerixafor is given with granulocyte colony-stimulating factor (G-CSF) to help harvest autologous CD34+ cells for transplantation when mobilization with G-CSF fails. Mobilization protocols with the same doses of plerixafor and G-CSF have been used off-label in healthy allogeneic donors, with equal success and scarce side effects, both in adult and paediatric patients. Plerixafor has also been used as a sole mobilization agent. Plerixafor alone or coupled with G-CSF might lead to harvesting distinct cellular populations conferring improved engraftment properties and increased survival. Those characteristics might make plerixafor an especially attractive mobilization agent, particularly for non-related donations. However, available data are limited, and long-term follow-up is needed to clarify the best scenario for using plerixafor with or without G-CSF in healthy donors. In this review, we will summarize the evidence supporting this practice, highlighting the practical aspects and providing clues for an expanded use of plerixafor.

Seasonal variation of human physiology does not influence the harvest of peripheral blood CD34+ cells from unrelated hematopoietic stem cell donors

There are many reports on factors predicting the outcome of PBSC (peripheral blood stem cell) mobilization, such as the donor's gender, age, weight, white blood cell count, platelets pre apheresis, LDH and iron status. Although there are reports of seasonal variation in the physiology of the human immune system and hematopoiesis there are no data that such differences play a role in the response to G-CSF in healthy hematopoietic stem cell donors. The response to G-CSF could also impact the collection results during different seasons. To assess the possible impact of seasonal variation we performed a retrospective, single-center analysis of mobilization and harvest of PBSC in 330 healthy unrelated donors. We found no significant differences in the number of CD34+ cells in peripheral blood after G-CSF mobilization and in collection results when all donors were analyzed. In the subgroup of male donors the number of CD34+ stem cells after G-CSF mobilization was higher than average in summer and autumn (p = 0.036), however, it did not translate into clinically relevant differences in stem cell harvest. We conclude that although there is possible seasonal variation in the response to G-CSF in male donors there is no impact on PBSC harvest in healthy unrelated donors.

Unstimulated apheresis for chimeric antigen receptor manufacturing in pediatric/adolescent acute lymphoblastic leukemia patients

Autologous unstimulated leukapheresis product serves as starting material for a variety of innovative cell therapy products, including chimeric antigen receptor (CAR)-modified T-cells. Although it may be reasonable to assume feasibility and efficiency of apheresis for CAR-T cell manufacture, several idiosyncrasies of these patients warrant their separate analysis: target cells (mononuclear cells [MNC] and T-cells) are relatively few which may instruct the selection of apheresis technology, low body weight, and, hence, low total blood volume (TBV) can restrict process and product volume, and patients may be in compromised health. We here report outcome data from 46 consecutive leukaphereses in 33 unique pediatric patients performed for the purpose of CD19-CAR-T-cell manufacturing. Apheresis targets of 2×10⁹ MNC/1×10⁹ T-cells were defined by marketing authorization holder specification. Patient weight was 8 to 84 kg; TBV was 0.6 to 5.1 L. Spectra Optia apheresis technology was used. For 23 patients, a single apheresis sufficed to generate enough cells and manufacture CAR-T-cells, the remainder required two aphereses to meet target dose and/or two apheresis series because of production failure. Aphereses were technically feasible and clinically tolerable without serious adverse effects. The median collection efficiencies for MNC and T-cells were 53% and 56%, respectively. In summary, CAR apheresis in pediatric patients, including the very young, is feasible, safe and efficient, but the specified cell dose targets can be challenging in smaller children. Continuous monitoring of apheresis outcomes is advocated in order to maintain quality.

An alternative test for determining autologous stem cell transplantation cell harvesting outcome: Comparison between predictive values of two tests

Daily CD34+ cells enumeration as a success indicator of stem cell pheresis procedure using flow cytometry is costly, lengthy, and labor-intensive. Thus, finding a simpler method to achieve the optimum time for harvesting the minimum required stem cells for transplantation could be helpful. The aim of this study was to evaluate the predictive value of reticulocytes fractions and their sensesivity and specificity in guiding CD34+ cell harvesting by G-CSF mobilization strategy. In this study, 49 candidates for autologous peripheral blood stem cell transplantation were enrolled. Before leukapheresis, the immature reticulocytes fraction (IRF) and CD34+ cell count were measured. Moreover, patients were evaluated for leukapheresis outcomes in two MNC and cMNC groups. Here we demonstrated that IRF, LFR, and MFR with the associated criterion of >17.3, ≤82.5, and >15.9, respectively, earned 100 % specificity and 47.2 %, 47.22 %, and 41.46 % sensitivity to predict the minimum required CD34+ cell count. Furthermore, IRF-V (Value) and MFR-V with the associated criterion of >0.77 and >0.55, respectively, earned 58.33 %, 66.67 % sensitivity and 84.62 %, 69.23 % of specificity, separately. As only MFR-V was able to predict the platelet engraftment (P-value = 0.014), none of the other above mentioned factors were not able to predict the neutrophil engraftment. Likewise, it was shown that patients who underwent MNC leukapheresis had a statistically significantly higher total WBC, harvested CD34⁺ cells, MNCs/ kg, and lower apheresis durations (P-values<0.05). Taken together, using IRF and its maturity stages seems to be a compelling predictor of minimal required CD34+ cells in autologous peripheral blood stem cell transplantation.

Validation of simple prediction algorithms to consistently achieve CD3+ and postselection CD34+ targets with leukapheresis

BACKGROUND

Cellular therapies using engineered T cells, haploidentical transplants, and autologous gene therapy are increasing. Specified CD3+ or high CD34+ doses are typically required for subsequent manufacturing, manipulation, or CD34+ selection. Simple, practical, and reliable lymphocyte and hematopoietic progenitor cell (HPC) collection algorithms accounting for subsequent CD34+ selection have not been published.

STUDY DESIGN AND METHODS

In this analysis of 15 haploidentical donors undergoing tandem lymphocyte and HPC collections, we validated one-step, practical prediction algorithms (Appendix S1, available as supporting information in the online version of this paper) that use conservative facility-specific collection efficiencies, CD34+ selection efficiency, and donor-specific peripheral counts to reliably achieve the target CD3+ and CD34+ product doses. These algorithms expand on our previously published work regarding predictive HPC collection algorithms.

RESULTS

Ninety-three percent of lymphocyte and 93% of CD34+ collections achieved the final target CD3+ and CD34+ product dose when our algorithm-calculated process volumes were used. Linear regression analysis of our algorithms for CD3+, preselection CD34+, and postselection CD34+ showed statistically significant models with R² of 0.80 (root mean square error [RMSE], 31.3), 0.72 (RMSE, 385.7), and 0.56 (RMSE, 326.0), respectively, all with p values less than 0.001.

CONCLUSION

Because achievement of CD3+ or CD34+ dose targets may be critical for safety and efficacy of cell therapies, these simple, practical, and reliable prediction algorithms for lymphocyte and HPC collections should be very useful for collection facilities.

Prior blood donations do not affect efficacy of G-CSF mobilization nor outcomes of haematopoietic stem cell collection in healthy donors

BACKGROUND AND OBJECTIVES

Many consider volunteer blood donors as ideal candidates for unrelated haematopoietic progenitor cell (HPC) donation. However, frequent blood donations could influence the results of HPC mobilization. To our best knowledge, there are no data on the possible impact of repeated blood donation on efficiency of subsequent HPC mobilization by granulocyte colony-stimulating factor (G-CSF).

MATERIALS AND METHODS

We compared outcomes of HPC mobilization in unrelated donors with and without a history of blood donation. We conducted a prospective study on 287 consecutive donors admitted to the Department of Hematology since January 2016. The final analysis included 153 donors who agreed to take part in the study and had undergone stem cell mobilization with G-CSF.

RESULTS

History of blood donations prior to haematopoietic stem cell mobilization with G-CSF does not have a significant impact on the number of collected CD34+ cells in the first leucocytapheresis (516.2 x 10⁶ (170-1148) in blood donors vs 490.5 x 10⁶ (101-1154) in non-donors) (P = 0.32). In all donors, in this study mobilization of HPC was successful: 87.5% of blood donors and 85.6% of non-donors collected the required cell number in a single apheresis. In blood donors, a higher number of blood donations within 2 and 5 years prior to HPC mobilization correlated significantly with successful donation within one leucocytapheresis (P = 0.014 and P = 0.024, respectively).

CONCLUSION

Multiple blood donations do not significantly influence the outcome of HPC collection in unrelated donors. Blood donors and non-donors have similar results of HPC collection, so there is no reason to favour either group.