Tumor cell depletion of peripheral blood progenitor cells using positive and positive/negative selection in metastatic breast cancer

BACKGROUND

The clinical relevance of tumor cell purging of hematopoietic progenitor cell grafts has yet to be conclusively determined. Therefore, in addition to the demonstration that a method for graft purification is capable of removing an adequate number of tumor cells, it is critical that the procedure has as benign an impact upon the hematopoietic repopulating potential of the graft as possible. We evaluated tumor cell depletion, recovery of CD34(+) cells and post transplant engraftment kinetics as accepted measures of the effectiveness of an immunomagnetic bead (positive and positive/negative) purging methodology.

METHODS

The patients received either positive selection (CD34 selection alone) or a combination of positive and negative (CD34 selection followed by breast cancer cell depletion) using the Isolex 300 (automated and semiautomated) devices. Immunocytochemistry was used to determine the degree of breast cancer cell contamination before and after the selection procedures to determine the efficacy of the procedure. CD34 enumeration was employed to evaluate the recovery and purity of the CD34-selected cellular products and engraftment indices (days to absolute neutrophil count (ANC) recovery and platelet count (Plt) recovery and transfusion requirements) were evaluated to determine the safety of the procedure.

RESULTS

A total of 130 aphereses was performed on 101 patients. Ten pairs of collections were pooled before selection to increase the likelihood of achieving CD34 dose goals after selection. In all, 100 positive selections and 20 positive/negative selections were performed. Of the 10 (10.4%) ICC-positive preselection samples, 2 products showed persistent contamination after processing. The majority of patients (85.4%) required one selection procedure to achieve an adequate CD34(+) selected cell dose. Median CD34(+) cell recovery was > 50% for positive selection procedures and > 60% for the positive/negative procedures. The dose of CD34(+) cells infused ranged from 0.76 x 10(6) CD34(+) cells/kg to 27.7 x 106 CD34(+) cells/kg. There were no significant delays in neutrophil or platelet recovery or infections between any of the treatment groups.

DISCUSSION

CD34 selection alone or in combination with negative selection can result in a significant reduction of contaminating tumor cells in the peripheral blood progenitor cell autograft. Although there was one engraftment failure with the CD34-positive selected cells, transplantation of the selected products after high-dose chemotherapy for metastatic breast cancer did not result in a clinically significant delay in the hematopoietic reconstitutive capacity of the autografts.

Challenges associated with the development, manufacturing, and delivery of cellular medicines

As the potential of these exciting therapeutics approaches reality, the challenges associated with their discovery, approval, and widespread distribution are just now being realized. The current health care infrastructure is unable to accommodate the complexity of cellular therapy, which exceeds the capability of existing treatment facilities to provide ready access for patients to receive standardized collections for consistent quality of apheresis product and the most consistently acceptable and potent therapeutic agent. The goal is to develop a system for seamless international access to cellular therapies and will involve the unification of the systems for the collection of patient-specific cellular materials, the development of an international network of FDA (and other regulatory agencies) registered facilities, the preservation of patient-specific product control from acquisition to re-infusion, the integration of a sophisticated transportation network to meet the time and environment-critical nature of the raw materials and the finished product, and the development of a comprehensive informatics system to coordinate all of the elements.

Treatment of leukemic relapse following unrelated umbilical cord blood transplantation with interleukin-2: potential for augmenting graft-versus-leukemia and graft-versus-host effects with cytokines

In comparison to bone marrow, umbilical cord blood has decreased intrinsic immune responsiveness allowing transplantation across HLA barriers with lower rates of graft-versus-host disease. However, laboratory models have also suggested that cord blood may be extremely sensitive to stimulation by cytokines. We report an adult recipient of an ex vivo expanded, HLA-mismatched, unrelated cord blood transplant who experienced a late extramedullary relapse while still in hematologic remission. Despite demonstrating immune tolerance on minimal immunosuppressive agents, a brief course of intravenous interleukin-2 resulted in rapid, aggressive graft-versus-host and graft-versus-leukemia reactions. This case highlights the potential of cytokine immunomodulation following cord blood transplantation, but also suggests caution in stimulating these cells.

Prompt and durable engraftment in two older adult patients with high risk chronic myelogenous leukemia (CML) using ex vivo expanded and unmanipulated unrelated umbilical cord blood

Delayed engraftment, graft failure, and adverse transplant-related events have been observed in unrelated umbilical cord blood (UCB) recipients, particularly in those receiving a low leukocyte cell dose and in CML patients. We report the outcomes of two older adult patients with high risk CML who received a low leukocyte cell dose of unmanipulated UCB cells supplemented with ex vivo expanded (AastromReplicell System) UCB cells. Each engrafted promptly and neither patient experienced GVHD or life-threatening infection. Both remain engrafted with cells exclusively of donor origin and are in cytogenetic remission at 19 and 8 months follow-up. Ex vivo expanded UCB cells appear to facilitate hematopoietic recovery and therefore may increase the number of CML patients eligible for unrelated UCB transplant.

Process validation

Process validation is a required element in the clinical good manufacturing practice equation that helps to ensure that systems are performing in the intended manner and that the product we manufacture has the required potency, purity and safety. The parameters defined during the validation process help to define the elements of process control and provide a mechanism for on-going quality assurance, quality control, training, competency review and continuous improvement.

CD34+CD33- cells influence days to engraftment and transfusion requirements in autologous blood stem-cell recipients

PURPOSE

To evaluate the reliability of CD34/CD33 subset enumeration as a predictor of hematopoietic repopulating potential in autologous blood stem-cell transplantation and to determine which patient and treatment-related factors affect the timing, quantity, and type of blood stem cells mobilized.

PATIENTS AND METHODS

We analyzed blood stem-cell collections from 410 consecutive cancer patients who received mobilization therapy and evaluated factors, including CD34+ subset quantities, that might influence engraftment kinetics and transfusion requirements in autologous blood stem-cell recipients.

RESULTS

The majority of patients (97%) mobilized CD34+33- cells, which were usually collected in the greatest quantity on the first day of apheresis. Patients who received only growth factor mobilized the highest percentage of CD34+33- cells. Extensive prior chemotherapy limited the collection of CD34+33- cells. In addition to patient diagnosis (P < .006) and total CD34+ cell dose (P = .0001), CD34+33- cell dose (P < .005) and percentage of CD34+33- cells (P < .005) were identified as independent factors significantly predictive of engraftment kinetics. CD34+33- cell dose (R2 < or = .177; P < .0001) was a strong and the only significant predictor of RBC and platelet transfusion requirements. Furthermore, independent of the total CD34+ cell dose, as the CD34+33- cell dose increased, days to neutrophil recovery, days to platelet recovery, and transfusion requirements decreased.

CONCLUSION

These findings show that CD34+33- cells are readily collected in most cancer patients and significantly influence engraftment kinetics and transfusion requirements in autologous blood stem-cell recipients. CD34+33- cell quantity of the blood stem-cell graft appears to be a more reliable predictor of hematopoietic recovery rates than total CD34+ cell quantity in this setting.

Effect of interface/offset (I/O) adjustment on collection efficiency using the Fenwal CS3000 Plus Blood Cell Separator for peripheral blood progenitor cell collection

Peripheral blood progenitor cells (PBPC) reside within the mononuclear cell (MNC) component of the blood and can be collected using a number of apheresis devices, including the Fenwal CS3000 Plus Blood Cell Separator. Increased MNC collection efficiency, therefore, may reduce the number of apheresis required to achieve collection goals. In this study, patients were divided into groups by absolute MNC count to determine the effect of interface detector offset (I/O) adjustment on MNC collection efficiency. Apheresis products from 104 procedures collected using a standard I/O setting of 100 were compared with 121 collections for which the I/O setting was adjusted according to the preapheresis MNC count. Adjustment of the I/O setting in this manner had no statistically significant impact on the per kilogram dose of MNC collected. The data did show that MNC collection efficiency was reduced as both the MNC count and I/O setting increased, as the collection efficiency was greatest for patients with the lowest peripheral MNC counts and was inversely correlated with the preapheresis MNC count. Although contamination of the product with platelets was drastically reduced at higher I/O settings, there was a concomitant rise in RBC contamination. We conclude that a standard setting of 100 is preferable to adjustment of the I/O setting as a function of the preapheresis MNC count.

New York State guidelines for cord blood banking. Department of Health

In response to the profound interest in the transplantation of umbilical cord blood, the New York State (NYS) Department of Health embarked on a regulatory strategy designed to provide guidance to the practitioner while allowing for the flexibility required by the inherent developmental nature of the technology. The result was the development of the Guidelines for Collection, Processing, and Storage of Cord Blood Stem Cells, adherence to which is optional. It is anticipated that through the use of such guidelines as a supplement to the existing hematopoietic progenitor cell (HPC) regulations for tissue banks, practitioners may provide to potential patients the safest and most efficacious cord blood products currently available, and information gained through the use of these products will be of optimal value toward the goal of continuous improvement in the delivery of this new technology.

An intralaboratory quality control program for quantitation of CD34+ cells by flow cytometry

This study was undertaken to develop a quality control protocol to monitor instrument, operator, and CD34 assay performance. A dual level control system was established by cryopreserving aliquots of cells from peripheral blood progenitor cell (PBPC) collections exhibiting different percentages of CD34+ cells. Twenty-five samples from each control specimen were assayed to establish a control range (mean +/- 2 SD). Levey-Jennings graphs were prepared for each control specimen to plot multiple measurements of CD34%. No significant differences were observed between fresh or cryopreserved PBPC aliquots in terms of light scatter properties or CD34 antigen density within the gated cell population. Cryopreserved PBPC samples are ideal for serving as a positive methodology control for daily CD34 analysis. Furthermore, such a system can help identify problems with assay reagents, sample preparation technique, or incorrect data analysis.

Single and double autotransplants for relapsing/refractory Hodgkin's disease: results of two consecutive trials

To evaluate a strategy of one cycle of dose-intensive chemotherapy for patients with Hodgkin's disease in sensitive relapse and two cycles for those with refractory disease, 122 patients received dose-intensive chemotherapy followed by autotransplant in two consecutive studies. Patients with refractory disease were offered a second transplant with different conditioning in the absence of progression or excessive toxicity. CR was present after treatment in 46% while 16% died in the peritransplant period. Of 41 patients with primary refractory disease and 42 with refractory relapse, 24 and 21 respectively received a second cycle. Of these 45 refractory patients, 12 were in CR and 11 in PR after the first cycle and 10 of these 11 in PR achieved a durable CR with the second transplant. The CR rate is 37% in patients with refractory relapse and 19% in those with primary refractory disease. At a median follow-up of 4 years, median survival is 45 months. Progression-free survival of the refractory patients who could receive a second cycle was similar to that of patients with sensitive disease. A sequential transplant strategy is feasible. A subgroup of patients with refractory disease can achieve long-term survival after sequential BMT.

Optimization of CD34+ cell selection using immunomagnetic beads: implications for use in cryopreserved peripheral blood stem cell collections

Isolation of CD34+ cells from bone marrow, umbilical cord blood, and mobilized peripheral blood stem cell (PBSC) collections has many potential clinical benefits. The aim of this study was to evaluate the use of the ISOLEX 300 system to select hematopoietic precursors and determine the effectiveness at depleting contaminating tumor cells from cryopreserved/thawed PBSC. Median recovery of CD34+ cells and CFU-GM colonies was 71% and 51.5%, respectively, using a protocol optimized for our laboratory. A mean 2.9 log10 decrease in contaminating breast carcinoma cells was seen after the selection process. Selected CD34+ cells underwent a second round of cryopreservation/thawing while retaining 85.6% viability and 72.3% recovery of CFU-GM colonies.

The effect of UVB irradiation on proliferative activity and cell growth potential of cord blood

To determine the degree of graft versus host disease (GVHD) prophylaxis that might be necessary if cord blood (CB) transplantation is more widely applied, we compared human cord blood mononuclear cell (CBMC) and adult peripheral blood mononuclear cell (PBMC) proliferative responses and stimulatory capabilities; to examine the utility of UVB irradiation for GVHD prophylaxis, we compared proliferative responses, antigen-presenting cell (APC) stimulatory functions, and cytokine production by untreated and UVB-irradiated CBMCs. The two cell types, CBMC and PBMC, proliferated equally both in response to phytohemagglutinin (PHA) and alloantigen in mixed lymphocyte culture (MLC). Cord blood stimulatory function in MLC was significantly (P < 0.05) reduced to 60% of PBMC stimulatory capability. Ultraviolet-B irradiation at a dose of 100 J/m2 of CBMCs significantly (P < 0.01) inhibited PHA stimulation by 79.4%, reduced responder activity in MLC by 75.8%, and inhibited stimulatory activity in MLC by 55.6% as compared with the activity shown by untreated CBMCs. The same dose of UVB preserved 59.9% of CFU-GM and 65.9% of BFU-E colony growth as compared with untreated CBMCs. Production of lymphokines (IL-2, GM-CSF, LIF, and gamma-IFN) by PHA-stimulated CBMCs was decreased, but monokine (IL-1 beta and IL-6) production was unchanged. We conclude that UVB irradiation at a dose of 100 J/m2 inhibits CB lymphocyte activation and preserves the cellular growth potential of CB hematopoietic progenitor cells.

Clinical and laboratory comparison study of refrigerated and cryopreserved bone marrow for transplantation

Refrigerated storage for short-term preservation of bone marrow is an alternative to cryopreservation where chemotherapeutic regimens include drugs with short in vivo half-lives. We performed a clinical and laboratory comparison of bone marrow stored at 4 degrees C for up to 9 days to bone marrow cryopreserved at -90 degrees C for autotransplantation. After adjusting for the confounding effects of disease type or sex, no clinically meaningful variation in post-transplant course between refrigerated storage and cryopreserved was found. Therefore, the data presented in this study suggest that the clinical recovery indices following transplantation between the two storage groups are essentially equivalent. One potential advantage to refrigerated storage, however, is that it may provide an opportunity for extended exposure to growth factors and/or purging agents in vitro prior to transplantation. To prepare for an in vitro analysis of this hypothesis, we concentrated the stem cell population and compared the nucleated cell recovery, viability and colony forming potential following refrigerated storage of whole bone marrow and buffy coat to cryopreserved bone marrow stored for the same interval. While the nucleated cell recovery for cryopreserved marrow was significantly greater than for refrigerated storage, the viability and colony forming potential of the refrigerated storage was superior or equivalent, independent of prior processing.

The combined use of soybean agglutinin and immunomagnetic beads for T lymphocyte subset depletion of bone marrow allografts: a laboratory analysis

The prevention of graft-versus-host disease by T-lymphocyte depletion of allografts prior to bone marrow transplantation has resulted in an increase in graft failure/rejection and relapse of disease. Evidence for the selective roles of specific T-lymphocyte subsets in each of the engraftment, graft-versus-host disease, and disease relapse processes has been presented, but sufficient clinical verification to support any hypothesis in this regard is lacking. In this paper we describe a convenient and highly flexible clinical laboratory method for depletion of specific T-lymphocytes in controllable quantities by the use of select monoclonal antibodies. Almost 3 log10 removal of CD2+ and CD8+ cells without significant loss of hematopoietic progenitors (CFU-GM, BFU-E, and CD34+ cells) can be reproducibly achieved. This method, employing soybean agglutination and immunomagnetic beads, is potentially adaptable to depletion of any cell subset or any tumor cell for which unique cell-surface antigen characteristics have been defined. In addition, our protocol is equally suited to the positive selection of stem cells and hematopoietic progenitors bearing the CD34 surface antigen.

ISHAGE bone marrow processing survey: report on an international information gathering process. International Society for Hematotherapy Graft Engineering

Significant amounts of information are currently available within the database generated by the responses to the Bone Marrow Processing Survey. As additional Surveys are returned, the data will continue to be entered into a Lotus spreadsheet, until a more sophisticated database with a programmed interface becomes available. The readership is encouraged to enter or edit the databank by returning a completed or amended Survey to the Society. Copies of the form are available from the Society or can be found in the first issue of the Journal of Hematotherapy.

Hemopoietic stem cell processing: comparison of progenitor cell recovery using the Cobe 2991 cell washer and the Haemonetics V50 apheresis system

Using 24 bone marrow (BM) harvests intended for cryopreservation and transplantation, we compared the use of the Cobe 2991 cell washer (2991) and the Haemonetics V50 apheresis system (HV50) for automated BM processing. Our in vitro data indicate that while the mononuclear cell (MNC) concentration of the HV50 product was significantly greater than that of the 2991, the overall MNC recovery of the two products was equivalent. In addition, although the concentration of CFU-GM and BFU-E in the products was equivalent, recovery of these progenitors in the 2991 product was significantly greater than those of the HV50 product. There was no significant difference in either the final product concentration or the overall recovery of cells bearing the primitive myeloid antigens, CD33 or CD34, between the two methods. The HV50 product volume, the red cell and the granulocyte mass were significantly lower than those of the 2991. We conclude that the advantages gained through the use of each machine should be evaluated within the context of the specific intention for the graft. Future advances in the identification and understanding of the primitive stem cell will aid in attempts to evaluate the methods used to isolate these cells.

Temporal relation between a hepatic erythropoietic factor and the site of rat erythropoietin production

Serum borne hepatic erythropoietic factor (HEF), which can stimulate hepatic erythropoietin (Ep) production in the adult rat, is found at elevated levels in the serum of partially hepatectomized rats and of rats subjected to hepatotoxic injury. It is also detected in sera of patients with liver disease. The purpose of the present study was to determine whether or not HEF activity is increased in the serum of the normal neonatal rat at a time when the liver is the primary site of Ep production. Our results show significantly increased HEF activity in the serum of young rats during the second to fifth weeks of life. Negligible activity was detected in rats over five weeks of age. In the rat, the kidney is reported to begin producing Ep by the third week of life and by the eighth week the kidney is the major site of synthesis with liver production at this age significantly diminished. Thus, our findings show a temporal relation between HEF activity in the serum and the reported transition from liver to kidney production of Ep.

The effects of interferon on murine erythropoiesis

The effects of interferon (IF) on erythropoietin (Ep) action and production were studied in mice. In comparison to control animals, Ep action in exhypoxic, polycythemic mice was significantly decreased (p less than 0.05) following two low dose injections of IF (2.9-3.5 X 10(4) units). In addition, renal Ep production in normal intact mice was also significantly decreased (p less than 0.01) following a single injection of IF (5.4-6.3 X 10(4) units) and hypoxic exposure.

The effect of methylcellulose on extrarenal erythropoietin production

The macromolecular polymer, methyl cellulose (MC), is a known hepatosplenomegalic agent which promotes a state of experimental hypersplenism in rats. This is characterized by massive splenomegaly, pancytopenia of the blood elements, medullary hypoplasia, and marked gross and histologic alteration of the liver, kidney, adrenals, and lungs. Massive splenomegaly results from storage of this inert material by splenic macrophages. In the present study, chronic MC administration in rats augmented the hepatic Ep response to hypoxia but did not appreciably affect renal production of Ep. Splenectomy resulted in a decrease in the extrarenal Ep response to hypoxia indicating a possible role of the massively enlarged spleen of these MC-treated rats in extrarenal Ep production. The augmentation of extrarenal Ep elaboration may be attributed to a stimulatory effect of MC on the hepatic and splenic macrophages.

Hepatic and renal erythropoietin production during various intervals of short-term hypoxia

Hypoxia stimulates erythropoietin (Ep) production and subsequent stimulation of erythropoiesis. Chronically applied hypoxia results in a variety of physiological alterations including polycythemia, hemoglobinemia, and vascular and metabolic changes. As red cell mass increases to such an extent to allow for adequate tissue oxygenation, plasma Ep levels drop and the rate of erythropoiesis is lowered. In the present work, the precise contribution of the kidney and the liver to the Ep response to acutely administered hypoxia (6-24 hr/0.4 atm) was determined using an in situ tandem perfusion of the liver and kidneys. The results indicate that hepatic and renal Ep production during different intervals of acute hypoxia is not uniform. This alteration may be partially explained by the reported reduction in splanchnic blood flow and a possible redistribution of hepatic microcirculation, which may cause the liver to become more hypoxic than the kidney under the same ambient pO2. The role of the liver becomes more pronounced as the time of acute hypoxic exposure increases, whereas the Ep content of renal perfusates is not drastically altered. At certain intervals during hypoxia, the liver displays a greater potential to elaborate Ep.