Clinical-scale production of cGMP compliant CD3/CD19 cell-depleted NK cells in the evolution of NK cell immunotherapy at a single institution

BACKGROUND

Allogeneic natural killer (NK) cell adoptive immunotherapy is a growing therapeutic option for patients. Clinical-scale production of NK cells using immunomagnetic selection complies with current good manufacturing practices (cGMPs) and allows for closed-system, automated purification. We report our experience with CD3/CD19 cell-depleted (CD3/CD19_dep ) NK cell production and compare to previous methods of CD3 cell depletion and CD3 cell depletion/CD56 cell enrichment.

STUDY DESIGN AND METHODS

Nonmobilized mononuclear cells collected by apheresis were incubated with anti-CD3/anti-CD19 microbeads and depleted in an automated cell selection system (CliniMACS, Miltenyi). The NK cell-enriched products were incubated overnight in interleukin (IL)-2 or IL-15, washed, and resuspended prior to lot release testing and infusion.

RESULTS

Since 2010, 94 freshly infusible CD3/CD19_dep NK cell products were manufactured in support of eight clinical trials. Sixty-six products were incubated in IL-2 and 28 products in IL-15. Processing resulted in a mean NK cell recovery of 74% and viability of 95.8%; NK cells, T cells, B cells, and monocytes accounted for 47%, 0.2%, 0.08%, and 49% of the final products, respectively. Seven products required dose adjustments to meet lot release. The specification for purity changed throughout the evolution of manufacturing. IL-2 or IL-15 activation enhanced in vitro cytotoxicity compared to preactivated cells. There was no difference in final product composition or cytotoxicity between cytokine cohorts.

CONCLUSION

Clinical-scale/cGMP production of NK cells using CD3/CD19 cell-depletion effectively minimized T-cell and B-cell contamination in a single manipulation without compromise to NK-cell recovery. Cytokine activation increased in vitro cytotoxicity compared to column-depleted, preactivated NK cells.

Clinical mesenchymal stromal cell products undergo functional changes in response to freezing

BACKGROUND AIMS

Current methods of mesenchymal stromal cell (MSC) cryopreservation result in variable post-thaw recovery and phenotypic changes caused by freezing. The objective of this investigation was to determine the influence of ex vivo cell expansion on phenotype of MSCs and the response of resulting phenotypes to freezing and thawing.

METHODS

Human bone marrow aspirate was used. MSCs were isolated and cells were assessed for total count, viability, apoptosis and senescence over 6 passages (8-10 doublings/passage) in ex vivo culture. One half of cells harvested at each passage were re-plated for continued culture and the other half were frozen at 1°C/min in a controlled-rate freezer. Frozen samples were stored in liquid nitrogen, thawed and reassessed for total cell count, viability and senescence immediately and 48 h after thaw.

RESULTS

Viability did not differ significantly between samples before freeze or after thaw. Senescence increased over time in pre-freeze culture and was significantly higher in one sample that had growth arrest both before freeze and after thaw. Freezing resulted in similar initial post-thaw recovery in all samples, but 48-h post-thaw growth arrest was observed in the sample with high senescence only.

CONCLUSIONS

High pre-freeze senescence appears to correlate with poor post-thaw function in MSC samples, but additional studies are necessary to obtain a sample sizes large enough to quantify results.

Establishment of an unrelated umbilical cord blood bank qualification program: ensuring quality while meeting Food and Drug Administration vendor qualification requirements

BACKGROUND

Qualification of a cord blood bank (CBB) is a complex process that includes evaluation of multiple aspects of donor screening and testing, processing, accreditation and approval by professional cell therapy groups, and results of received cord blood units. The University of Minnesota Medical Center Cell Therapy Laboratory has established a CBB vendor qualification process to ensure the CBB meets established regulatory and quality requirements.

STUDY DESIGN AND METHODS

The deployed qualification of CBBs is based on retrospective and prospective review of the CBB.

RESULTS

Forty-one CBBs were evaluated retrospectively: seven CBBs were disqualified based on failed quality control (QC) results. Eight CBBs did not meet the criteria for retrospective qualification because fewer than 3 cord blood units were received and the CBB was not accredited. As of March 2012, three US and one non-US CBBs have been qualified prospectively. One CBB withdrew from the qualification process after successful completion of the comprehensive survey and subsequent failure of the provided QC unit to pass the minimum criteria. One CBB failed the prospective qualification process based on processing methods that were revealed during the paper portion of the evaluation.

CONCLUSIONS

A CBB qualification process is necessary for a transplant center to manage the qualification of the large number of CBBs needed to support a umbilical cord blood transplantation program. A transplant center that has utilized cord blood for a number of years before implementation of a qualification process should use a retrospective qualification process along with a prospective process.

Autologous stem cell transplant recipients tolerate haploidentical related-donor natural killer cell-enriched infusions

BACKGROUND

In the setting of allogeneic stem cell transplantation (SCT), infusing natural killer (NK) cells from a major histocompatibility complex (MHC)-mismatched donor can mediate an antileukemic effect. The graft-versus-tumor effect after autologous stem cell transplantation (ASCT) may result in less disease relapse.

STUDY DESIGN AND METHODS

We performed a Phase I clinical trial to assess the safety and feasibility of infusing distantly processed donor NK-enriched mononuclear cell (NK-MNC) infusions from a MHC haplotype-mismatched (haploidentical) donor to patients who recently underwent ASCT for a hematologic malignancy. On Day 1, peripheral blood MNCs were obtained by steady-state leukapheresis and sent from Boston to the Production Assistance for Cellular Therapies (PACT) facility at the University of Minnesota, where immunomagnetic depletion of CD3 cells was performed on Day 2. NK-MNC products were then returned to Boston on Day 2 for infusion on Day 3. Toxicity, cellular product characteristics, and logistic events were monitored.

RESULTS

At a median of 90 days (range, 49-191 days) after ASCT, 13 patients were treated with escalating doses of NK-MNCs per kilogram from 10(5) to 2 × 10(7) . Adverse effects included Grade 2 rigors and muscle aches, but no Grade 3 or 4 events and no graft-versus-host disease or marrow suppression. One air courier delay occurred. NK-MNC products were viable with cytotoxic activity after transport.

CONCLUSION

CD3-depleted, MHC-mismatched allogeneic NK-MNC infusions can be safely and feasibly administered to patients after ASCT after distant processing and transport, justifying further development of this approach.

Results of a phase 1, randomized, double-blind, placebo-controlled trial of bone marrow mononuclear stem cell administration in patients following ST-elevation myocardial infarction

BACKGROUND

Initial clinical trials from Europe have demonstrated that the administration of bone marrow-derived mononuclear cells (BMCs) may improve left ventricular (LV) function in patients following ST-elevation myocardial infarction (STEMI). However, results from trials performed in the United States have not yet been presented.

METHODS

We developed a phase 1, randomized, placebo-controlled, double-blind trial to investigate the effects of BMC administration in patients following STEMI on recovery of LV function using cardiac magnetic resonance imaging (cMRI). Forty patients with moderate to large anterior STEMIs were randomized to 100 million intracoronary BMCs versus placebo 3 to 10 days following successful primary angioplasty and stenting (percutaneous coronary intervention) of the left anterior descending coronary artery.

RESULTS

Administration of BMC was safely performed in a high-risk cohort with minimal major adverse clinical event rates, and all patients remain alive to date. Left ventricular ejection fraction increased from 49.0% +/- 9.5% at baseline to 55.2% +/- 9.8% at 6 months by cMRI in the BMC group (P < .05), which was not different from the increase in the placebo group (48.6% +/- 8.5% to 57.0% +/- 13.4%, P < .05). Left ventricular end-diastolic volume decreased by 4 mL/m(2) in the BMC group at 6 months but increased significantly in the placebo group (17 mL/m(2), P < .01).

CONCLUSIONS

This phase 1 study from the United States confirms the ongoing safety profile of BMC administration in patients following STEMI. The improvement in LV ejection fraction at 6 months by cMRI in the cell therapy group was not different than the placebo group. However, BMC administration had a favorable effect on LV remodeling at 6 months.

Shipping of therapeutic somatic cell products

BACKGROUND AIMS

Shipment of therapeutic somatic cells between a current good manufacturing practice (cGMP) facility and a clinic or between different cGMP facilities requires validated standard operating procedures (SOP). Under National Heart Lung & Blood Institute (NHLBI) sponsorship, the Production Assistance for Cellular Therapies (PACT) group conducted a validation study for the shipping SOP it has created, including shipments of cryopreserved somatic cells, fresh peripheral blood specimens and apheresis products.

METHODS

Comparisons of pre- and post-shipped cells and cell products at the three participating facilities included measurements of viability, phenotypic profiles and cellular functions. The data were analyzed at the University of Pittsburgh Biostatistics Facility.

RESULTS

No consistent shipping effects on cell viability, phenotype or functions were detected for cryopreserved and shipped peripheral blood mononuclear cells (PBMC), monocytes, immature dendritic cells (iDC), NK-92 or cytotoxic T cells (CTL). Cryopreserved mesenchymal stromal cells (MSC) had a significantly decreased viability after shipment, but this effect was in part because of inter-laboratory variability in the viable cell counts. Shipments of fresh peripheral blood and apheresis products for the generation of CTL and dendritic cells (DC), respectively, had no significant effects on cell product quality. MSC were successfully generated from fresh bone marrow samples shipped overnight.

CONCLUSIONS

This validation study provides a useful set of data for guiding shipments of therapeutic somatic cells in multi-institutional clinical trials.

CD34(+) cell selection using small-volume marrow aspirates: a platform for novel cell therapies and regenerative medicine

BACKGROUND AIMS

This study was initiated to determine whether CD34(+) cell selection of small-volume bone marrow (BM) samples could be performed effectively on the Isolex(R) 300i Magnetic Cell Selection System device and whether the results obtained from these samples were comparable with results from large standard-volume samples. The impact on CD34(+) recovery using a full versus half vial of Isolex(R) CD34 reagent and the effects of shipping a post-selection product were evaluated.

METHODS

A protocol to evaluate CD34(+) cell selection with two ranges of smaller volume BM samples (c. 50 mL and c. 100 mL) was developed and instituted at three Production Assistance for Cellular Therapies (PACT) facilities. The study was performed in two phases.

RESULTS

In phase I, the mean post-selection CD34(+) recoveries from the two sizes of samples were 104.1% and 103.3% (smallest and largest volumes, respectively), and mean CD34(+) recoveries were 115.6% and 88.7%, with full and half vials of reagent, respectively. Mean CD34(+) recoveries for post-shipment smaller volume samples were 106.8% and for larger volume samples 116.4%; mean CD34(+) recoveries were 99.9% and 127.4% for post-shipment samples processed with full and half vials of reagent, respectively. In phase II, mean CD34(+) recovery was 76.8% for post-selection samples and 74.0% for post-shipment samples.

CONCLUSIONS

The results suggest that smaller volume BM sample processing on the Isolex(R) system is as efficient or more efficient compared with standard-volume sample processing. Post-processing mean CD34(+) recovery results obtained using a full or half vial of CD34 reagent were not significantly different.

Mislabeled units of umbilical cord blood detected by a quality assurance program at the transplantation center

We instituted procedures to check the identity of cord blood unit provided for transplantation by carrying out ABO and human leukocyte antigen (HLA) typing of the thawed units before transplantation. ABO typing is done using standard techniques. Rapid HLA class I serology is with monoclonal antibody trays (One Lambda Inc) using standard incubations. One mislabeled umbilical cord blood (UCB) unit was detected on the day of intended transplantation by repeat ABO typing of the thawed unit at our transplantation center. Because ABO typing will not detect all labeling errors, the rapid serologic class I HLA typing procedure was done on thawed units just before transplantation for all units without an attached segment. This procedure identified a second mislabeled unit. In a 6-year period, 2 of 871 (0.2%) cord blood units sent to us for transplantation were mislabeled and potentially would have been transplanted incorrectly. This error rate of 1 per 249 (0.4%) patients could have potentially devastating consequences.

A multicenter comparison study between the Endosafe PTS rapid-release testing system and traditional methods for detecting endotoxin in cell-therapy products

BACKGROUND

Rapid-release testing reduces the waiting period for administration of time-sensitive cell-therapy products. Current assay systems are labor intensive and time consuming. The Endosafe portable test system (PTS) is a chromogenic Limulus amebocyte lysate (LAL) portable endotoxin detection system that provides quantitative results in approximately 15 min. To evaluate Endosafe performance with cell-therapy products, side-by-side testing of traditional LAL systems and the Endosafe system was conducted at the Production Assistance for Cellular Therapies (PACT) facilities and the National Institutes of Health's Department of Transfusion Medicine, USA.

METHODS

Charles River Laboratories provided each center with a PTS reader and two commercially prepared lyophilized reference standard endotoxin (RSE) vials. All samples tested with the Endosafe system used 0.05-5.0 endotoxin unit/mL (EU/mL) sensitivity cartridges provided by Charles River. Each vial was reconstituted with LAL water and tested in triplicate using the Endosafe and in-house LAL methods. Subsequently, each center tested the endotoxin content of standard dilutions of cell-therapy products, thus creating paired test results for each sample. Additionally, fabricated endotoxin-positive samples containing varying concentrations of endotoxin were prepared and shipped to all centers to perform blinded testing.

RESULTS

Valid paired results, based on each center's LAL method and the Endosafe system criteria, were analyzed. Endotoxin detection between paired results was equivalent in most cases.

DISCUSSION

The Endosafe system provided reliable results with products typically produced in cell-therapy manufacturing facilities, and would be an appropriate test on which to base the release of time-sensitive cell-therapy products.

Microbial Contamination of Hematopoietic Stem Cell Products: Incidence and Clinical Sequelae

Microbial contamination of hematopoietic stem cell products is a rare but potentially fatal complication of hematopoietic stem cell transplantation. We report the incidence of contaminated products and describe the clinical outcomes for 35 patients at the University of Minnesota who received contaminated products from January 1990 to December 2004. In total, 2935 products were infused for 2863 transplants during this time, 36 of which 36 (1.2%) were contaminated. Coagulase negative Staphylococcus was the predominant species isolated on culture of the hematopoietic stem cell products. Patients received prophylactic antibiotics before infusion of the contaminated product based on the organism identified from culture and antibiotic sensitivities, if known. After transplantation, blood cultures from 2 patients grew the same pathogen as in the infused contaminated product, including 1 patient who had blood cultures positive for Pseudomonas cepacia. All patients who received contaminated products had benign post-transplantation courses except for the patient with Pseudomonas bacteremia, who ultimately died from complications. These results suggest that, although rare, microbial contamination of stem cell products does occur and there must be ongoing efforts by physicians and laboratory personnel to minimize the risk for introduction of contaminants. Prophylactic antibiotics are useful for certain contaminants; however, caution must be exercised when gram-negative contaminated products are administered.

Cell loss and recovery in umbilical cord blood processing: a comparison of postthaw and postwash samples

BACKGROUND

Engraftment after umbilical cord blood (UCB) transplantation is highly dependent on nucleated cell (NC) and CD34+ cell content. Current standard postthaw (PT) processing includes a wash step to remove dimethyl sulfoxide (DMSO), lysed red cells, and stroma. The contribution of the wash step to cell loss and ultimately the dose of cells available for transplant have yet to be systematically reported. This study examines the effect of the wash step as well as that of PT storage on various quality control variables of UCB units.

STUDY DESIGN AND METHODS

Ten units were thawed and washed based on the New York Blood Center method. Samples were removed from each unit at six time points: prefreeze (PF), immediately PT, immediately postwash (PW), and 1, 2, and 5 hours PW. On each sample, total nucleated cell (TNC) count, CD34+ cell enumeration, colony-forming unit (CFU)-granulocyte-macrophage, and viability assays (fluorescence microscopy [acridine orange/propidium iodide, or AO/PI] and flow cytometry [7-aminoactinomycin]) were obtained.

RESULTS

TNC counts decreased PT and at subsequent time points; the PT TNC recovery was 89 percent compared to 82 percent PW (p < 0.01). TNC recovery decreased to 90 percent of PW (82% of PT) values (p < 0.01) and 83 percent of PW (76% of PT) values (p < 0.001), at 2 and 5 hours PW, respectively. CD34+ cell loss PT was not significant. Viability by AO/PI decreased PT and plateaued over time. In contrast, viability by flow cytometry remained higher and increased slightly over time. CFUs were significantly lower PT, recovering PW.

CONCLUSIONS

Our data indicate that the thawing and washing results in a substantial loss of cells, with TNC loss approaching 20 percent when compared with PF counts; the wash step was responsible for nearly half of the cell loss. The reduced PT viability was expected. Elapse of time PW resulted in further loss of NCs but no detectable significant changes in CD34+ cell content and viability and/or CFU.

Issues in the quality of umbilical cord blood stem cells for transplantation

BACKGROUND

Because the frequency of umbilical cord blood (UCB) stem cell transplantation has increased, the quality of UCB available in banks is an important part of the success of UCB stem cell transplants.

STUDY DESIGN AND METHODS

A quality assurance monitoring system was used to evaluate 268 UCB units provided to us for transplant by UCB banks in the United States and Europe.

RESULTS

Quality issues were found in 151 (56%) of 268 units, and there were a total of 246 specific issues in 151 units. The issues involved quality control (54%), medical history (40%), and labels and documentation (6%). Risks to patients from these issues were likely in 10 percent, potential in 35 percent, and unlikely in 55 percent.

CONCLUSION

Because standards have evolved over time, cord blood banks contain units that have different levels of quality. Some units have been placed in the usable inventory with incomplete test results and/or documentation or that may not meet the bank's own current criteria. Information about any quality or operating procedure deviation should be provided in sufficient detail and at the initiation of the search process so that transplant physicians can consider these quality issues against the unique value of a particular UCB unit.

Development and operation of a quality assurance system for deviations from standard operating procedures in a clinical cell therapy laboratory

BACKGROUND

Errors and accidents, or deviations from standard operating procedures, other policy, or regulations must be documented and reviewed, with corrective actions taken to assure quality performance in a cellular therapy laboratory. Though expectations and guidance for deviation management exist, a description of the framework for the development of such a program is lacking in the literature. Here we describe our deviation management program, which uses a Microsoft Access database and Microsoft Excel to analyze deviations and notable events, facilitating quality assurance (QA) functions and ongoing process improvement.

METHODS

Data is stored in a Microsoft Access database with an assignment to one of six deviation type categories. Deviation events are evaluated for potential impact on patient and product, and impact scores for each are determined using a 0- 4 grading scale. An immediate investigation occurs, and corrective actions are taken to prevent future similar events from taking place. Additionally, deviation data is collectively analyzed on a quarterly basis using Microsoft Excel, to identify recurring events or developing trends.

RESULTS

Between January 1, 2001 and December 31, 2001 over 2500 products were processed at our laboratory. During this time period, 335 deviations and notable events occurred, affecting 385 products and/or patients. Deviations within the 'technical error' category were most common (37%). Thirteen percent of deviations had a patient and/or a product impact score > or = 2, a score indicating, at a minimum, potentially affected patient outcome or moderate effect upon product quality.

DISCUSSION

Real-time analysis and quarterly review of deviations using our deviation management program allows for identification and correction of deviations. Monitoring of deviation trends allows for process improvement and overall successful functioning of the QA program in the cell therapy laboratory. Our deviation management program could serve as a model for other laboratories in need of such a program.

Improved progenitor assay standardization using peripheral blood progenitor cells from a donor treated with granulocyte-colony-stimulating factor

BACKGROUND

Progenitor assays are the principal method for evaluating hematopoietic cell function. The magnitude of assay variability and the assay steps contributing to variability were determined, and modifications intended to increase assay consistency were evaluated.

STUDY DESIGN AND METHODS

Assays were performed using a serum-free progenitor assay medium with cells plated at 5.0 x 10(4) and 1.0 x 10(5) cells per plate. A peripheral blood progenitor cell component collected from a normal donor after administration of granulocyte-colony-stimulating factor was divided into identical aliquots. Each experiment involved at least 5 technologists, each performing assays in duplicate on five aliquots, with each person scoring all assay plates. Three sample preparation methods were tested: 1) ficoll mononuclear cell enrichment and sample dilution, 2) sample dilution without ficoll separation, and 3) sample dilution without ficoll separation, with cell counts performed before and after each dilution step, dilution volumes calculated on the basis of each cell count, automated electronic pipettors used in dilution steps, and colony frequency calculated on the basis of cell counts from the final specimen.

RESULTS

Global variability for colony-forming units-granulocyte-macrophage, represented by the percentage of CV for all specimens and all technologists, was 89.6 percent at 5.0 x 10(4) cells per plate and 81.3 percent at 1.0 x 10(5), when ficoll separation was used. Subjective differences in scoring plates did not account for most of the variability observed, as results for any individual plate read by multiple technologists had a mean CV of 15.6 percent and 19.7 percent at the two plating concentrations. Method 3 resulted in the greatest improvement, reducing CV to 24.4 percent at 5.0 x 10(4) cells per plate and to 24.2 percent at 1.0 x 10(5) cells per plate. Similar results were obtained for erythroid-burst-forming units.

CONCLUSIONS

Baseline assay results were extremely inconsistent. Interindividual differences in colony interpretation did not contribute significantly to assay variability, although sample preparation and plating did. Improved control over cell concentration decreased assay variability by 70 to 73 percent.