Mononuclear cell variability and recruitment in non-cytokine-stimulated donors after serial 10-liter leukapheresis procedures

A novel predictive algorithm to personalize autologous T-cell harvest for chimeric antigen receptor T-cell manufacture

BACKGROUND AIMS

The most widely accepted starting materials for chimeric antigen receptor T-cell manufacture are autologous CD3+ T cells obtained via the process of leukapheresis, also known as T-cell harvest. As this treatment modality gains momentum and apheresis units struggle to meet demand for harvest slots, strategies to streamline this critical step are warranted.

METHODS

This retrospective review of 262 T-cell harvests, with a control cohort of healthy donors, analyzed the parameters impacting CD3+ T-cell yield in adults with B-cell malignancies. The overall aim was to design a novel predictive algorithm to guide the required processed blood volume (PBV) (L) on the apheresis machine to achieve a specific CD3+ target yield.

RESULTS

Factors associated with CD3+ T-cell yield on multivariate analysis included peripheral blood CD3+ count (natural log, ×109/L), hematocrit (HCT) and PBV with coefficients of 0.86 (95% confidence interval [CI], 0.80-0.92, P < 0.001), 1.30 (95% CI, 0.51-2.08, P = 0.001) and 0.09 (95% CI, 0.07-0.11, P < 0.001), respectively. The authors' model, incorporating CD3+ cell count, HCT and PBV (L), with an adjusted R2 of 0.87 and root-mean-square error of 0.26 in the training dataset, was highly predictive of CD3+ cell yield in the testing dataset. An online application to estimate PBV using this algorithm can be accessed at https://cd3yield.shinyapps.io/cd3yield/.

CONCLUSIONS

The authors propose a transferrable model that incorporates clinical and laboratory variables accessible pre-harvest for use across the field of T-cell therapy. Pending further validation, such a model may be used to generate an individual leukapheresis plan and streamline the process of cell harvest, a well-recognized bottleneck in the industry.

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.

Increased collection efficiency of CD34+ cells after mobilization with preemptive use of plerixafor followed by leukocytapheresis on the same day

BACKGROUND

Plerixafor should be administered 6 to 11 hours before starting leukocytapheresis. However, we have been using plerixafor followed by leukocytapheresis according to different time schedules since 2007. Our objective was to compare the CD34+ cell collection efficiency (CE1) of the first leukocytapheresis performed after using plerixafor at different time intervals.

STUDY DESIGN AND METHODS

Same-day schedule refers to the administration of plerixafor at 10:00 AM and starting the leukocytapheresis on the same day at 4:00 PM (6 hours interval). Next-day schedule refers to the administration of plerixafor at 8:00 PM and starting the leukocytapheresis on the next day (10:00 AM or 4:00 PM; either a 14- or 20-hr interval). Variables that might influence the CE1 of CD34+ cells were analyzed by longitudinal linear regression with a random effects model derived by generalized estimating equations.

RESULTS

The median CE1 of CD34+ cells was higher in the group of 30 patients who underwent leukocytapheresis on the same day when compared with the group of 62 patients who underwent leukocytapheresis on the next day (65.8% vs. 56.7%; p < 0.01). In the longitudinal linear regression analysis, only the time from plerixafor administration to leukocytapheresis start was associated with a statistically significant decrease in the CE1 of CD34+ cells (CE1 change -0.034%; p < 0.01).

CONCLUSION

Higher CE1 of CD34+ cells was observed when patients underwent leukocytapheresis on the same day after receiving plerixafor in comparison with administering plerixafor and underwent leukocytapheresis on the next day. Larger studies are necessary to confirm present results.

Efficacy and safety of one-day offline extracorporeal photopheresis schedule processing one total blood volume for treating patients with graft-versus-host disease

BACKGROUND

Extracorporeal photopheresis (ECP) has been increasingly used as a second-line therapy for graft-versus-host disease (GVHD) but there is no consensus regarding the best therapeutic schedule.

STUDY DESIGN AND METHODS

Our offline ECP schedule for treating patients with GVHD was retrospectively reviewed. Patients with acute GVHD were treated on 2 days per week for the first 2 weeks, followed by 1 day per week for 2 more weeks. After the first month of treatment, patients received treatment 1 day every 2 weeks for a minimum of 16 ECP procedures. Patients with chronic GVHD were treated on 1 day per week for 4 weeks followed by 1 day every 2 weeks for a minimum of 14 ECP procedures.

RESULTS

Our series comprises 21 (45%) patients with acute GVHD and 26 (55%) patients with chronic GVHD who received 667 ECP procedures. A median (interquartile range [IQR]) of 1.0 (1.0-1.12) total blood volume was processed. Patients with acute and chronic GVHD received ECP procedures during a median of 49 (IQR, 14-103) and 180 (IQR, 111-274) days, respectively. Mild citrate-induced symptoms were present in 98 (46%) and 232 (51%) procedures in patients with acute and chronic GVHD, respectively. Overall response rate (ORR) and overall survival (OS) were 57 and 38% (95% confidence interval [CI], 17%-59%), respectively, for patients with acute GVHD. For patients with chronic GVHD, ORR and OS were 77 and 61% (95% CI, 18%-87%), respectively.

CONCLUSION

Our new offline ECP schedule for treating patients with acute and chronic GVHD was efficacious and safe.

Low-Volume Leukapheresis in Non-Cytokine-Stimulated Donors for the Collection of Mononuclear Cells

Background

There is an increasing demand for products containing mononuclear cells (MNCs) for cellular immune therapy. Hence, leukapheresis is increasingly performed in healthy volunteer donors.

Methods

We evaluated 147 low-volume leukapheresis procedures from 77 healthy non-cytokine-stimulated donors. Complete blood counts (CBCs) of the donors were measured before and directly after the procedures as well as from the MNC products. Follow-up CBCs were collected from donors within 21 days.

Results

The product hematocrit within a range from 1.2 to 6.0% did not correlate with the collection efficiency of any cell population or the granulocyte and platelet yield. There was a strong correlation between the CBC values before leukapheresis and the cell yield of lymphocytes and monocytes as well as a perfect negative correlation between cell recruitment and cell loss in all cell populations. Furthermore, we observed a significant decrease in the CBC values in all cell populations directly after leukapheresis, which recovered within a mean of 16.1 days (SD ± 2.1 days) and even showed a significant increase in granulocytes and platelets.

Conclusion

Low-volume leukapheresis is feasible for the collection of MNCs in which the product hematocrit is negligible for the collection efficiency, cell yield, or contamination of residual cells under operational settings recommended by the manufacturer. Our data suggests that cell recruitment is regulated by the number of cells removed, which may also be the stimulus to induce granulo- and thrombopoiesis within the first days after leukapheresis.

Evolution of MNC and lymphocyte collection settings employing different Spectra Optia® Leukapheresis systems

BACKGROUND AND OBJECTIVES

The Spectra Optia^® continuous mononuclear cell (CMNC apheresis) system has emerged as the preferred device in peripheral blood stem cell collections over the original two-step Spectra Optia^® mononuclear cell (MNC apheresis) system. Until now, no comparative data were available for non-stimulated MNC collections that are required for immunotherapy.

MATERIALS AND METHODS

We compared collection parameters and product composition for Spectra Optia MNC- as well as CMNC-apheresis systems in non-stimulated MNC collections from 35 registry donors intended for donor lymphocyte infusions. In a subsequent analysis, different centrifugation forces (determined as packing factor or PF) were investigated regarding target cell yield and contamination in 61 collections using the CMNC device only.

RESULTS

Comparable collection efficiencies as well as target cell yields could be achieved with the Spectra Optia MNC- versus CMNC program. Similar numbers of MNC, T, B and NK cells could be collected with both devices. This led to a more than twofold lymphocyte recruitment from lymphatic tissue into the blood during apheresis. However, significantly more blood had to be processed with longer procedure time using the MNC program resulting in larger product volumes compared to the CMNC setting. Red blood cell and platelet (PLT) contamination were similar. Lowering the centrifugation force from PF4·5 to PF4·0 significantly reduced PLT contamination without affecting target cell yield in the product.

CONCLUSION

The Spectra Optia^® CMNC device using lower centrifugal force (PF4·0) showed similar target cell yield and composition as well as collection efficiencies with superior performance parameters and lower PLT contamination compared to the MNC setting.

Perspectives on sipuleucel-T: Its role in the prostate cancer treatment paradigm

Sipuleucel-T is an autologous cellular immunotherapy approved in the US for patients with asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer (mCRPC). This significant advance for mCRPC treatment provides healthcare professionals with another effective therapy to extend survival. As an immunotherapy, sipuleucel-T possesses specific characteristics differentiating it from traditional therapies. At a roundtable meeting of experts, sipuleucel-T data were discussed, focusing on interpretation and clinical implications. Important differences between immunotherapies and traditional therapies were explored, e.g., mode of action, outcomes, data consistency and robustness, timing of sipuleucel-T treatment, and future perspectives in areas such as short-term markers of long-term benefit.

A transient increase in eosinophils is associated with prolonged survival in men with metastatic castration-resistant prostate cancer who receive sipuleucel-T

Sipuleucel-T is an autologous cellular immunotherapy used to treat asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer (mCRPC). Traditional short-term indicators of clinical response commonly used with chemotherapy have not correlated with survival in patients treated with sipuleucel-T. This retrospective study aimed to evaluate laboratory parameters as possible early biomarkers associated with clinical benefit following sipuleucel-T treatment. Patients treated with sipuleucel-T from three randomized, controlled, phase III clinical trials in mCRPC were considered: IMPACT (NCT00065442; n = 512), D9901 (NCT00005947; n = 127), and D9902A (NCT01133704; n = 98). Patients from these trials were included in this study if their samples were analyzed by the central laboratory and if data were available from baseline and ≥ 1 posttreatment time point (n = 377). We found that sipuleucel-T treatment was associated with a transient increase in serum eosinophil count at week 6 that resolved by week 14 in 28% of patients (105 of 377). This eosinophil increase correlated with induced immune response, longer prostate cancer-specific survival [HR, 0.713; 95% confidence interval (CI), 0.525-0.970; P = 0.031], and a trend in overall survival (HR, 0.753; 95% CI, 0.563-1.008; P = 0.057). Median serum globulin protein levels also increased transiently, which was associated with antigen-specific antibody responses; however, this finding did not correlate with longer survival. We conclude that transient increases in eosinophils at week 6 may be a useful, objective, short-term indicator of global immune activation and survival benefit with sipuleucel-T in patients with mCRPC. This observation warrants prospective evaluation in future clinical trials.

Unstimulated leukapheresis in patients and donors: comparison of two apheresis systems

BACKGROUND

Unstimulated mononuclear cell (MNC) apheresis plays a role in the generation of donor lymphocytes (DLIs; healthy donors) and in extracorporeal photopheresis (ECP; patients). The new apheresis system Spectra Optia MNC has been shown in small studies to be capable of performing the desired cell collections, but larger data sets from real-life clinical apheresis procedures are lacking.

STUDY DESIGN AND METHODS

Presented are comparative data from DLI collections randomly performed with either the new technology or a clinical standard technology, COBE Spectra MNC, as well as data from patients with chronic graft-versus-host disease undergoing MNC collections alternating between the two apheresis systems to generate products for ECP. Target cell yield and collection efficiency, product volume, nontarget cell contamination, platelet (PLT) attrition, and some process variables such as process volume and time were analyzed.

RESULTS

For most relevant apheresis outcomes, differences between the devices were at best marginal. Spectra Optia MNC collections in patients, but not in donors, took 10% longer to achieve the target process volume. Not unexpectedly, given previous observations for granulocyte-colony-stimulating factor-stimulated leukapheresis, the novel device collected smaller products with less red blood cell contamination. PLT attrition with Spectra Optia MNC was markedly lower in donors. ECP apheresis outcome variability was, to a significant degree, donor dependent, irrespective of the device used.

CONCLUSION

Based on more than 200 unstimulated apheresis procedures, we conclude that both apheresis systems are safe, robust, and equally suitable for unstimulated MNC collections. Both can be successfully run with manufacturer-recommended settings and algorithms.

An analysis of leukapheresis and central venous catheter use in the randomized, placebo controlled, phase 3 IMPACT trial of Sipuleucel-T for metastatic castrate resistant prostate cancer

PURPOSE

Sipuleucel-T is an autologous cellular immunotherapy. We review the safety of the leukapheresis procedure required for sipuleucel-T preparation and complications related to venous catheter use in the randomized, placebo controlled phase 3 IMPACT (IMmunotherapy for ProstAte Cancer Trial) study (NCT 00065442).

MATERIALS AND METHODS

A total of 512 patients with asymptomatic or minimally symptomatic metastatic castrate resistant prostate cancer were enrolled in the study. All patients were scheduled to undergo 3 standard 1.5 to 2.0 blood volume leukapheresis procedures at 2-week intervals. Leukapheresis related adverse events and those related to venous catheter use were reviewed. Immune cell counts were examined throughout the treatment course.

RESULTS

Of 512 enrolled patients 506 underwent 1 or more leukapheresis procedures and were included in this analysis. Adverse events were comparable between the sipuleucel-T and control arms. Leukapheresis related adverse events were primarily associated with transient hypocalcemia (39.3%). Most leukapheresis related adverse events (97%) were of mild/moderate intensity. Median white blood cell count and absolute monocyte and lymphocyte counts were stable and within normal ranges throughout the treatment course. Of all patients 23.3% had a central venous catheter placed primarily for leukapheresis. Patients with vs without a central venous catheter had a higher risk of infection potentially related to catheter use (11.9% vs 1.3%, p <0.0001) and a trend toward a higher incidence of venous vascular events potentially related to catheter use, excluding the central nervous system (5.9% vs 2.1%, p = 0.06).

CONCLUSIONS

Adverse events related to leukapheresis are manageable and quickly reversible. The majority of patients can undergo leukapheresis without a central venous catheter. Central venous catheters are associated with an increased risk of infections and venous vascular events. Peripheral intravenous access should be used when feasible.

Leukapheresis in non-cytokine-stimulated donors with a new apheresis system: first-time collection results and evaluation of subsequent cryopreservation

BACKGROUND

Adoptive cell therapy based on mononuclear cells (MNCs) became an important modality of cancer immunotherapy. Data about collection results and donor response of leukapheresis with the Spectra Optia v.5.0 (Terumo BCT) in nonmobilized donors are required.

STUDY DESIGN AND METHODS

Twelve MNC collections were performed using the Spectra Optia v.5.0 in non-cytokine-stimulated donors. Leukapheresis products and peripheral blood samples from donors were assayed for CD45+, CD34+, CD3+, and CD14+ cells by flow cytometry. Prefreeze and postthaw cell counts, cell viability, and numbers of colony-forming units were assessed in cryobags and compared to data from cryovials.

RESULTS

Leukapheresis yielded a mean of 5.26×10(9) ±2.2×10(9) CD45+ cells, 1.5×10(9) ±0.77×10(9) CD14+ monocytes, and 2.28×10(9) ±1.2×10(9) CD3+ Tcells by processing 6690±930mL of whole blood. A significant positive correlation between yield of CD3+ Tcells and residual platelets (PLTs) and red blood cells (RBCs) was observed. This did not apply for CD34+ and CD14+ white blood cell subsets. Mean collection efficiencies for CD14+ monocytes and CD3+ Tcells were 61.8±17 and 37.2±18%, respectively. Recovery of CD14+ cells after cryopreservation was 75.2±8.2%, which was significantly lower than recovery of CD45+ cells (81.4±5.5%; p=0.01).

CONCLUSION

This study of a small cohort demonstrates that the Spectra Optia v.5.0 is capable of collecting low product volumes with satisfactory MNC yields and low residual RBCs and PLTs in non-cytokine-mobilized apheresis. Our data suggest that cryovials can serve as a representative surrogate for the primary product cryobag.

Optimization of leukocyte collection and monocyte isolation for dendritic cell culture

Leukapheresis is the method of choice to collect monocytes for dendritic cell (DC) culture. Improvement of cell separators and cell collection software have enabled the collection of 10(9) monocytes for the generation of monocyte-derived DCs, which is sufficient to prepare a DC vaccine series. However, leukapheresis works with the technique of differential centrifugation which is not applicable to selectively collect mononuclear cells of similar density. After leukapheresis, thus, additional preparation steps are required to isolate and enrich the desired monocyte population. The cell isolation and cultivation techniques depend on the quality of the original leukocyte harvest due to the monocyte yield and the content of residual erythrocytes and platelets. Monocyte elutriation from the leukapheresis product shows a high monocyte recovery of 80%. However, only 30% of the isolated monocytes can be developed into mature DCs. The factors responsible for DC maturation and the development of different DC subsets are the subject of current research.

Automated CD14+ monocyte collection with the autoMNC program of the COM.TEC cell separator

BACKGROUND

The standard mononuclear cell (MNC) program of the COM.TEC device (Fresenius HemoCare GmbH) showed excellent collection efficiency of CD14+ monocytes. A major disadvantage was high content of residual cells in MNC harvests, which could influence dendritic cell (DC) culture.

STUDY DESIGN AND METHODS

The autoMNC program (COM.TEC) was compared with the standard MNC program (n = 12). Additionally, two cycle volumes (300 mL vs. 450 mL, n = 19) were compared (standard MNC program). Samples were assayed for white blood cells (WBCs), red blood cells (RBCs), granulocytes (PMNs), hematocrit, and platelets (PLTs) on an automated blood cell counter (Sysmex K 4500, TAO Medical). CD14+ cells were analyzed by flow cytometry (FACSCalibur, BD).

RESULTS

The autoMNC program produced 1.33 x 10(9) +/- 0.36 x 10(9) CD14+ cells, 5.60 x 10(11) +/- 0.97 x 10(11) PLTs, and 1.43 x 10(11) +/- 0.37 x 10(11) RBCs. Compared to the standard MNC program, significantly higher PLT yields but lower RBC yields and product volume were harvested. Increasing the CV from 300 to 450 mL dropped the product volume, residual PLTs, and RBCs significantly, whereas WBC and monocyte yields did not change. The WBC predonation counts of donors correlated significantly with monocyte yields.

CONCLUSIONS

The autoMNC program reduced the buffy coat (BC) volume and RBC yields in products compared to the standard MNC program. Increasing the CV (standard MNC program) reduced residual PLTs, RBCs, and the BC volume of MNC harvests. The donor WBC predonation count was a good predictor for the monocyte yield of products.

Evaluation of a new apheresis system for the collection of leukoreduced single-donor platelets

BACKGROUND

The Fresenius COM.TEC cell separator is a new device for producing white cell concentrates (WBCs) and leukoreduced single-donor platelet concentrates (SDPs) and performing therapeutic cytapheresis and plasmapheresis that might replace the Fresenius systems AS104 and AS.TEC 204. This novel system's performance was evaluated for producing leukoreduced SDPs.

STUDY DESIGN AND METHODS

In an investigational phase, each of 200 donors underwent plateletpheresis with the AS.TEC 204 and the COM.TEC systems. The collection efficiency (CE) and WBC contamination of the different techniques were compared. After some hard- and software modifications, the system was evaluated in an additional 800 procedures in the confirmatory phase.

RESULTS

In the investigational phase, the CE of the COM.TEC device was increased significantly in comparison to the AS.TEC 204 device's CE (by 45 +/- 32% when collecting 1 unit of platelets [PLTs] and 1 unit of fresh-frozen plasma and by 43 +/- 42% when collecting only 1 unit of PLTs). Although all AS.TEC products proved to be leukoreduced, 2 percent of the COM.TEC procedures led to PLT concentrates containing more than 1 x 10(6) WBCs. In the confirmatory phase, all 1300 products from 800 COM.TEC procedures proved to be leukoreduced. Furthermore, the CE increased significantly from 53.5 +/- 4.6 percent in the investigational phase to 55.5 +/- 4.9 percent (p < 0.001) in the confirmatory phase.

CONCLUSIONS

These data suggest that the new COM.TEC system offers a significantly and importantly improved CE in plateletpheresis procedures in comparison to the AS.TEC system. In the final version, the PLT products collected with this system fulfill the most stringent criteria for leukoreduced PLTs. This aim was achieved without additional filtration steps and thus without filtration-related PLT loss.

CD14+ cell collection in non-cytokine-stimulated donors with the COM.TEC cell separator

BACKGROUND

The COM.TEC cell separator (Fresenius Hemocare), equipped with the MNC program (single-stage chamber) and the PBSC-LYM program (dual-stage chamber), was evaluated for CD 14+ cell collection regarding cell yields, collection efficiencies (CEs), and the content of residual cells in harvests.

STUDY DESIGN AND METHODS

Twenty-four non-cytokine-stimulated donors underwent 5-L mononuclear cell (MNC) collections on the COM.TEC device to compare both programs. Two software versions (v02.03.05 vs. v 03.00.04) were investigated for optimization of the CD 14+ cell collection process. Blood counts of donors and products were analyzed for CD 14+ cells by flow cytometry and for platelets (PLTs), white blood cells, and red blood cells (RBCs) by a blood cell counter.

RESULTS

In 5-L collections, the MNC program resulted in high CEs (83+/- 23%) and yields (1.2 x 10(9)+/- 0.6 x 10(9) per unit) of CD 14+ cells, but the products showed high residual PLTs. The use of a dual-stage chamber in the PBSC-LYM program produced a low content of residual PLTs (0.7 x 10(11) +/- 0.3 x 10(11) per unit) and RBCs but failed to reach a target of 1 x 10(9) CD 14+ cells. Modulated light to stabilize the buffy-coat detection by the interface monitor significantly improved CD 14+ cell enrichment. By use of the PBSC-LYM program, higher centrifuge velocity (1700 rpm [382 x g] vs. 1500 rpm [297 x g]) improved significantly CD 14+ cell yields (0.7 x 10(9) vs. 0.5 x 10(9) cells).

CONCLUSION

A pure CD 14+ cell product with low numbers of residual cells was obtained by the PBSC-LYM program, which could be useful for good manufacturing practice-conformed production within closed systems. The MNC program offers the collection of high CD 14+ cell yields with excellent CEs but also high residual PLT counts.