Umbilical Cord Blood Hematopoietic Stem Cell Transplantation Research Articles

Outcomes with Mismatched Unrelated Donor Allogeneic Hematopoietic Stem Cell Transplantation: A Systematic Review and Meta-Analysis

BackgroundAllogeneic hematopoietic stem cell transplantation (HCT) is the optimal and potentially curative therapy in various high-risk hematologic malignancies. Although a human leukocyte antigen (HLA)-matched sibling or unrelated donor is a clinically preferred stem cell source, the use of haploidentical family donors and umbilical cord blood HCT now offers the option of HCT in patients lacking a matched donor. However, many patients lack an appropriate donor, in particular the ethnic minorities. Mismatched unrelated donors (MMUD) have historically been utilized as alternative donor source for these patients due to ease of donor availability but is associated with increased risk of graft versus host disease (GVHD) and non-relapse mortality (NRM). In this systematic review and meta-analysis, we aimed to assess the outcomes with MMUD HCT.Methods:Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, a comprehensive literature search was performed on three databases (PubMed, Cochrane Library, and ClinicalTrials.gov) from date of inception through February 2021 using the MeSH and entry terms for “hematopoietic stem cell transplantation”, OR “hematologic neoplasms”, AND unrelated donors“ AND ”treatment outcome“. A total of 2477 records were identified and primary and secondary screening was done. After excluding review, duplicate, and non-relevant articles, we included 13 studies (11 retrospective, 2 prospective) reporting outcomes following MMUD HCT. The Joanna Briggs Institute (JBI) critical appraisal checklist for studies reporting prevalence data and randomized control trial was used for quality assessment, and all studies were reported as good. Proportions along with a 95% confidence interval (CI) were extracted to compute pooled analysis using the ‘meta’ package by Schwarzer et al. in the R programming language (version 4.16-2). The variance between the studies was calculated using Der Simonian-Laird Estimator.Results:We identified 2588 patients from 13 included studies who had MMUD HCT. (Table 1) Median age was 51.7 (18-76) years and 52% (n=1347) were males. Source of primary graft was bone marrow (BM) in 19% (n=478/2508) and peripheral blood (PB) in 81% (n=2030/2508) HCT recipients. Median time to transplant was 10.45 (1.5-139.6) months and median follow up was 41.5 (0.4-136.5) months. Reduced intensity conditioning (RIC) conditioning was used for 73% (n=1884) of the patients while 27.2% (n= 704) patients received myeloablative conditioning (MAC). We estimated a pooled overall survival (OS) of 59% (95% CI 0.52-0.66, I 2 = 92%, n=2563) at one year and 44% (0.36-0.53, I 2=92%, n=1972) at three years. The pooled incidence of acute GVHD (grade II-IV), acute GVHD (grade III-IV), and chronic GVHD were 39% (95% CI 0.33-0.44, I 2=84%, n=2282), 19% (95% CI 0.15-0.23, I 2=65%, n=1417), and 38% (95% CI 0.32-0.47, I 2=93%, n=2477) respectively. Progression free survival (PFS) was 39.5% (95% CI 0.31-0.48, I 2=94% n=2505). The pooled incidence of relapse rate (RR) and NRM were 31% (95% CI 0.25-0.38, I 2=90%, n=2482) and 27% (95% CI 0.21-0.34, I 2 =90% n=2448) respectively.Conclusion:Mismatched unrelated donor HCT has shown favorable outcomes with acceptable toxicity profile. MMUD HCT represents a promising option for patients lacking an HLA-matched donor and has expanded access to HCT in patients with ethnic minorities who often lack a matched donor. [Display omitted] DisclosuresAbhyankar: Incyte/Therakos: Consultancy, Research Funding, Speakers Bureau. McGuirk: Juno Therapeutics: Consultancy, Honoraria, Research Funding; Fresenius Biotech: Research Funding; Novartis: Research Funding; Gamida Cell: Research Funding; Magenta Therapeutics: Consultancy, Honoraria, Research Funding; Pluristem Therapeutics: Research Funding; Allovir: Consultancy, Honoraria, Research Funding; EcoR1 Capital: Consultancy; Kite/ Gilead: Consultancy, Honoraria, Other: travel accommodations, expense, Kite a Gilead company, Research Funding, Speakers Bureau; Astelllas Pharma: Research Funding; Bellicum Pharmaceuticals: Research Funding; Novartis: Research Funding.

Umbilical Cord Blood Transplantation and Delay Engraftment Are Associated with Increased Risks of Diffuse Alveolar Hemorrhage

Diffuse alveolar hemorrhage (DAH) is a serious pulmonary complication of hematopoietic stem cell transplantation (HCT). The incidence of DAH in allograft recipients varies between 3%-7% with a reported mortality rate of 70% or higher. Although some risk factors are established, the effect of donor sources, especially umbilical cord blood (UCB), is unknown.Methods: We studied patients receiving allogeneic HCT between 2008-2015 at the University of Minnesota. DAH defined by strict clinical criteria include acute onset of hypoxia in the present of diffuse pulmonary infiltrates on chest X- ray or CT of the scan, along with broncho-alveolar lavage (BAL) findings of progressively bloody alveolar washings.Results: Of 1228 patients (658 bone marrow/peripheral blood stem cell (BM/PBSC) and 570 UCB) receiving allogeneic HCT, 59 patients (5%) were diagnosed with DAH. The median time to DAH from HCT was 30 days (range 3-168). Patients with DAH had the following characteristics: median age 32 years (range, 1-72), 66% were male, 42% had a smoking history, and 5% had history of prior lung disease. At the time of DAH, the median platelet count was 24 x 109/L (range, 1.0-114), 34% had renal dysfunction (creatinine >1.3 mg/dL), 34% had liver dysfunction (ALT>35), 10 % had INR> 1.5, 46% had fever, 27% had documented systemic infection, and 19% had infectious organism isolated from BAL; Majority (92%) received high dose steroids for treatment of DAH and 75% required mechanical ventilator support.In univariate analysis comparing DAH incidence, following factors were found associated with higher DAH incidence rate: patients with UCB transplants (7% vs. 3% in BM/PB, p=0.01), HCT for malignant disease (6% vs. 3% in nonmalignant disease, p<0.01),myeloablative conditioning regimens (6% vs 4% for NMA; p=0.04), total-body irradiation (TBI) in conditioning (6% vs. 3% for no TBI; p= 0.03) and patients with delayed engraftment (i.e., >21 days, 2% vs. 100%, p<0.01). There was no significant difference between these 2 groups regarding patient’s age, sex or CMV serostatus.When we compared UCB recipients with DAH (n=40) and without DAH (n=530), the DAH group received fewer total nucleated cells (TNC) x107/kg recipient weight (0.39 (0.21-2.04) vs. 0.46 (0.03-99.01), p<0.01), more often had TBI (90.0% vs.76%, p=0.05), and double UCB grafts (90% vs. 63% single p=<0.01), and more neutrophil-recovery (70% vs. 91%, p=<0.01) and platelet-recovery (30% vs. 79%, p=<0.01).In multivariate analysis, later neutrophil engraftment was the only risk factor associated with DAH for all patients and patients for the UCB cohort. Treatment-related mortality (TRM) at 6 months was 65% for the DAH group vs. only 14% for the no DAH group, p<0.01. Patients with DAH had significantly poorer 1 year overall survival (20% (95%CI 11-31%) vs. 70% (95% CI 68-73%) p <0.01). Poor survival in patients with DAH was not affected by donor type (13% (5-25%) in UCB vs. 37% (17-57%) in PB/BM p=0.14). Among UCB recipients, those with DAH had a higher 1 year mortality of 87% (95% CI 75% -95%) than those without DAH 31% (95% CI 27-35%), p < 0.01.Conclusions: DAH after allogeneic HCT remains serious and most often fatal. MAC, TBI, malignant disease were risk factors for DAH. UCB HCT is associated with higher rates of DAH; particularly associated with late engraftment and with a smaller TNC dose infused (rather than unit number). Interestingly, prior lung disease or history of smoking did not have any effect on the incidence of DAH. Current therapy of DAH with high dose steroids is inadequate, and mortality rates in patients with DAH remain very high. Therefore, studies to expedite engraftment after UCB HCT and to further understand the pathophysiology of DAH are essential. DisclosuresNo relevant conflicts of interest to declare.

Optimization of cGMP purification and expansion of umbilical cord blood–derived T-regulatory cells in support of first-in-human clinical trials

Background aimsThymic-derived regulatory T cells (tTreg) are critical regulators of the immune system. Adoptive tTreg transfer is a curative therapy for murine models of autoimmunity, graft rejection, and graft-versus-host disease (GVHD). We previously completed a “first-in-human” clinical trial using in vitro expanded umbilical cord blood (UCB)-derived tTreg to prevent GVHD in patients undergoing UCB hematopoietic stem cell transplantation (HSCT). tTreg were safe and demonstrated clinical efficacy, but low yield prevented further dose escalation. MethodsTo optimize yield, we investigated the use of KT64/86 artificial antigen presenting cells (aAPCs) to expand tTreg and incorporated a single re-stimulation after day 12 in expansion culture. ResultsaAPCs increased UCB tTreg expansion greater than eightfold over CD3/28 stimulation. Re-stimulation with aAPCs increased UCB tTreg expansion an additional 20- to 30-fold. Re-stimulated human UCB tTreg ameliorated GVHD disease in a xenogeneic model. Following current Good Manufacturing Practice (cGMP) validation, a trial was conducted with tTreg. tTreg doses up to >30-fold higher compared with that obtained with anti-CD3/28 mAb coated-bead expansion and Foxp3 expression was stable during in vitro expansion and following transfer to patients. Increased expansion did not result in a senescent phenotype and GVHD was significantly reduced. DiscussionExpansion culture with cGMP aAPCs and re-stimulation reproducibly generates sufficient numbers of UCB tTreg that exceeds the numbers of T effector cells in an UCB graft. The methodology supports future tTreg banking and is adaptable to tTreg expansion from HSC sources. Furthermore, because human leukocyte antigen matching is not required, allogeneic UCB tTreg may be a useful strategy for prevention of organ rejection and autoimmune disease.

Very Short Telomeres As a Novel Mechanism Of Donor-Cell Derived Leukemia After Cord Blood Transplantation

Donor-cell derived leukemia (DCL) is a rare but serious complication of hematopoietic stem cell transplantation (HSCT), reported in 5% of all relapses following allogeneic HSCT. Only 12 cases of DCL after umbilical cord blood (UCB) HSCT are reported in the literature. Multiple mechanisms have been proposed for DCL, including occult donor leukemia, impaired immunity, drug toxicity, or a bone marrow “leukemogenic milieu”.We propose a novel mechanism of leukemogenesis, mediated by very short telomeres of donor cells with subsequent severe telomere attrition in vivo, genomic instability, and progression to complex cytogenetics acute myeloid leukemia (AML), based on study of a patient who underwent UCB HSCT for myelodysplasia (MDS). The patient was a 44-year-old woman, subsequently shown to have a T354M mutation in GATA2, who presented at age 19 years with multiple infections and MDS. At age 41, due to progression of MDS to AML, she received induction chemotherapy and underwent a single 4/6 HLA-matched UCB HSCT. She had delayed engraftment. achieving an absolute neutrophil count of 500/ul more than 100 days post-transplant. Chimerism studies demonstrated 100% donor cell at all time-points post-transplant. Two years and eight months after HSCT she presented with pancytopenia, circulating myeloblasts, and 50% myeloblasts in bone marrow, indicating recurrence of with AML. However, cytogenetics revealed complex abnormalities, t(2p;3q) and an interstitial deletion of 5q, male cells, indicating donor origin of AML.Telomere length of the transplanted cord blood cells measured by Q-PCR showed a severe decrease in length to 7.7 kb compared with an average length of 13 kb in control UCB (n=12). Moreover the telomere length decreased precipitously to 6.6 kb 2 years after transplantation and 5.6 kb at the time of diagnosis of AML. Single telomere length assay (STELA) was used to assess chromosome-specific telomere length. Very short telomeres (<3.0 kb) were present in the UCB before transplant that increased in proportion post-transplant before progression to AML. In contrast, very short telomeres were not present in control UCB STELA. Sequencing of cord blood-derived myeloid cells showed no mutation in TERT or TERC. Comparative genomic hybridization confirmed the complex cytogenetics.Telomere attrition occurs in the first year after HSCT, presumably due to proliferative stress on the stem cell compartment. In comparison to bone marrow, UCB have longer telomeres, but HSC number may be lower than in a BM inoculum, especially for adult recipients. In our case, initial telomere length of UCB was extremely short, for unclear reasons but possibly related to low cord blood cell viability. The long time that was needed for engraftment generated additional telomere attrition with accumulation of very short telomere and genomic instability leading to development of leukemia. Screening UCB for telomere length prior to HSCT might prove useful in identifying situations at risk for graft failure or malignant transformation. Disclosures:No relevant conflicts of interest to declare.

Adoptive Immunotherapy Following Umbilical Cord Blood Transplantation Using The Sleeping Beauty System and Artificial Antigen Presenting Cells To Generate Donor-Derived T Cells Expressing a CD19-Specific Chimeric Antigen Receptor

▪ BackgroundThe ability to transplant across HLA disparities makes allogeneic umbilical cord blood (UCB) an attractive graft source for hematopoietic stem-cell transplantation (HSCT). Disease relapse remains a limitation, and adoptive transfer of tumor-specific T cells post UCB HSCT has not been feasible due to the functionally naïve CB T cells, and the small size as well as anonymity of the donor. We report a new approach to non-viral gene transfer using the Sleeping Beauty (SB) transposon/transposase system to stably express a 2nd generation CD19-specific chimeric antigen receptor (CAR, designated CD19RCD28) on UCB-derived T cells manufactured in compliance with current good manufacturing practice (cGMP). MethodsAfter thawed UCB units are washed for clinical infusion 5% to 10% of cells are used to generate CAR+ T cells. The mononuclear cells are electroporated using a Nucleofector device to synchronously introduce two DNA plasmids coding for SB transposon (CD19RCD28) and hyperactive SB transposase (SB11). T cells stably expressing the CAR are retrieved over 28 days of co-culture by recursive additions of g-irradiated artificial antigen presenting cells (aAPC) in presence of soluble recombinant interleukin (IL)-2 and IL-21. The aAPC (designated clone #4) were derived from K562 cells and genetically modified to co-express the CD19 as well as the co-stimulatory molecules CD86, CD137L, and a membrane-bound protein of IL-15. Enrolled patients on our phase I trial receive two UCB units, thus two genetically modified T-cell products are made for each patient. We infuse thawed donor-derived CD19-specific CAR+ T cells from the dominant CB unit based on peripheral blood chimerism on days 40-100 post transplant in the adjuvant setting after double UCB HSCT ResultsTo date we have successfully manufactured 8 products for 4 patients (ALL n=3, NHL=1) enrolled on trial. The median number of T cells in the starting CB aliquot was 8.6x106 (range, 2.5x106 to 54.8x106) with final modified T cell count at median 3x109 (range,1.7x108 to 4.1x1010) at time of cryopreservation days 28-32. In the final product, the median CD19-CAR+ cell purity by flow was 88% (range, 81.9% to 95.8%). The modified T cell product consisted of median 97.3% CD3+, 2.7 CD3-/CD56+ cells. All of the products exhibited CD19-specific killing by chromium assay as illustrated (Figure). Each clinical-grade T-cell product was subjected to a battery of in-process testing to complement release testing. One patient with ALL has been infused to date with a T cell dose of 106T cells/m2 and no toxicity has been observed. The patient remains alive and in continued molecular remission at 111 days post HSCT. ConclusionWe combined the SB system and aAPC-mediated propagation of T cells to successfully manufacture disease-specific T cells from small aliquots of UCB used to restore hematopoiesis. Importantly, this approach allows us to employ adoptive therapy to enhance the graft-versus-tumor effect in UCB HSCT as an approach to improve overall survival for these recipients. Accrual to the trial continues and updated results will be presented at the meeting. [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Higher Counts Of Plasmacytoid Dendritic Cells In The Allograft Are Associated Increased Risk Of Acute Gvhd After Stem Cell Transplantation

Background Recent studies suggest that higher circulating dendritic cell counts after hematopoietic stem cell transplantation (HSCT) may be associated with lower risk of graft versus host disease (GVHD) and mortality. Plasmacytoid dendritic cells (pDC) have tolerogenic properties and may explain such results. However, only a few studies with conflicting results analyzed pDC counts in the allograft, mainly in the related HSCT setting. Objectives To compare pDC counts among different cell sources [umbilical cord blood (UCB), bone marrow (BM), and peripheral blood (PBSC)] and to correlate the pDC content on the graft with main HSCT outcomes. Methods Plasmacytoid dendritic cells (pDC: lineage negative, HLA-DR+ and CD123+) were quantified by multiparametric flow cytometry in the graft just before its infusion. Overall, 77 patients (49 male; median age 21y, range 1-74y) receiving UCB (n=26), BM (n=34) or PBSC (n=17) HSCT from unrelated (n=67) or related donors (n=10) were studied. The most common diagnosis was acute leukemia (ALL, 30 cases; AML, 22). Most patients received myeloablative conditioning regimens (n=47, 61%). Antithymocyte globulin was used in 30 patients (39%) and total body irradiation in 41 (53%). Median follow up time was 15 months (4-33). Results Median time to neutrophil engraftment was 19 days (range: 11-49) and 35 days to platelet engraftment (range 2-176). The median percentage of pDC on the graft was 0.20% of non erythroid nucleated cells (range: 0.02-0.67) and no differences were noticed among sources. Cumulative incidence (CI) of grade II-IV acute GVHD at 100 days was higher on patients receiving grafts with higher percentages of pDC (22% for patients with less than 0.15%pDC graft content vs. 52% for patients receiving grafts with higher counts, p=0.026). There was no impact of graft pDC content on mortality, relapse, chronic GVHD or overall survival. In a multivariate analysis, graft pDC content remains an independent risk factor for acute GVHD [HR: 3.0, CI (95%): 1.15-7.8]. Conclusion Higher pDC graft percentages were associated with increased risk of acute GVHD, but had no impact on non-relapse mortality or survival. The precise role of pDC on immunity after HSCT deserves further investigation and might be related not only to pDC biology itself but to the chronology of the pDC interaction with host antigens. Disclosures: No relevant conflicts of interest to declare.

Primary Graft Failure After Umbilical Cord Blood Transplant Rescued by Parental Haplocompatible Stem Cell Transplantation

AB Graft failure and aplasia are known complications of umbilical cord blood (UCB) hematopoietic stem cell transplantation (HSCT). In the absence of a second HSCT, graft failure is generally a fatal complication due to overwhelming infection. We describe 2 children with primary graft failure and life-threatening infections after UCB HSCT who were rescued by the use of related haplocompatible T-cell-depleted peripheral blood stem cell transplants. The rapid availability of haplocompatible donors and the brisk neutrophil recovery after haplocompatible peripheral blood stem cell transplant with high numbers of CD34+ cells make this an attractive rescue strategy for patients with graft failure after UCB HSCT.

Incidence and Outcomes of Immune Thrombocytopenia (ITP) Following Hematopoietic Stem Cell Transplantation (HCT).

While thrombocytopenia is common following HCT, and has been associated with delayed engraftment, disease relapse, infections and drugs, autoantibody mediated ITP is rarely observed. In one series of non-Hodgkin's lymphoma patients, development of ITP following autologous HCT (autoHCT) was associated with long-term disease free survival (Hequet et al. Bone Marrow Transplant 2003; 32:89). Limited data is available on occurrence and prognosis of ITP following allogeneic HCT (alloHCT). Here we report the incidence and outcomes of ITP in 1700 adults who underwent autoHCT (n=749) and alloHCT (n=951) between January 1990 and December 2004. Of the alloHCT recipients, 531 patients received stem cells from a sibling donor (SD), 268 from an unrelated donor (URD), and in 147 patients umbilical cord blood (UCB) was used as the stem cell source. ITP was defined according to the American Society of Hematology guidelines for diagnosis of ITP (Ann Intern Med 1997; 126:319). In addition, a confirmatory bone marrow examination demonstrating adequate megakaryocyte numbers and morphology and absence of CMV viremia were required. Patients receiving interferon therapy around the time of ITP diagnosis were excluded. Recovery from ITP was defined as a sustained increase in platelet count to 140 x 109/liter (l). Ten patients (median age 37 years [range 25–51]), including 7 alloHCT and 3 autoHCT recipients developed ITP at a median 15 months (range 4–76) post transplant, with an overall cumulative incidence of 0.8% at 5 years (95% confidence interval [CI] 0.3–1.6%). Of the alloHCT recipients, four patients received one or two antigen mismatched UCB HCT, two received matched HCT from an URD and one a SD HCT. The overall cumulative incidence of ITP at 5 years was highest among UCB HCT recipients (3%; 95% CI 0–6%) as compared to SD (0.2%; 95%CI 0–0.5%) and URD (0.7%; 95% CI 0–1.7%) HCT recipients (p<0.01). Nine (7 alloHCT and 2 autoHCT) recipients were transplanted for hematologic malignancy and one autoHCT patient for metastatic breast cancer. Nine of ten patients received myeloablative conditioning regimen. Six of the seven alloHCT recipients received cyclosporin for graft versus host disease (GVHD) prophylaxis. ITP was severe, with a nadir platelet count of 10 x 109/l in all patients. Platelet antibodies were present in 50% (3 of 6) of patients tested. Nine of the ten patients were in complete remission from their underlying malignancy at the time of ITP diagnosis. ITP was steroid refractory in the majority of patients, and required multiple treatment modalities. All alloHCT recipients with ITP developed chronic GVHD and systemic viral infections. While nine patients recovered, one autoHCT recipient died of multi-organ hemorrhage at 76 months post HCT. At a median follow-up of 61 months, seven patients are still alive and disease free, while two additional patients died (one from relapsed acute myeloid leukemia 32 months and one from pulmonary Aspergillosis 154 months post HCT). In summary, we found ITP to be a rare complication of HCT, with the highest incidence in recipients of UCB HCT. While the majority of patients eventually recovered from ITP and achieved long-term overall survival, the illness was severe, associated with chronic GVHD and serious viral infections. Degree of antigenic disparity, immune dysregulation, development of autoimmunity and its contribution to maintenance of disease control after transplantation may be implicated in pathogenesis of ITP following HCT.

Hematopoietic Stem Cell Transplantation (HSCT) for Malignancies Using Plasma Depleted Umbilical Cord Blood (UCB) That Were Not Red Blood Cell Depleted.

Cell dosage is a limiting factor for UCB HSCT, especially for adult patients. Most UCB banks practice red cell depletion (RCD) techniques to save storage space, which incur significant nucleated cell loss after processing. One method to minimize cell loss and still reduce volume after processing is to deplete plasma (PD), but not the red blood cells. Not washing UCB (NW) after thawing also minimizes cell loss. A large racially diverse PD UCB inventory of over 25,000 units is now available on stem cell registries. There were 70 ALL, 54 AML, 19 CML, and 45 others transplanted for malignant indications. A retrospective audited analysis was performed on 170 patients with engraftment and/or survival information. Of the ALL/AML/CML cases with available information, there were 32 1CR/CP, 33 2CR, and 13 3CR/CP. The median age of patients was 13 years old (range 05–59); median weight 50 kg (range 5–137); male 45%. Transplant characteristics indicated a median # HLA ABDR matches of 4.0; median pre-freeze TNC dose 4.1 × 107/kg; median post-thaw TNC dose as reported by TC 3.7 × 107/kg; median pre-freeze CD34 dose 1.4 × 105/kg; transplants outside of U.S. 34%; double unit transplant 30%; non-myeloablative 16%. Sixty-one percent of the transplanted UCB were washed post-thaw (W), 39% were infused without post-thaw wash (NW), with 20% of the units without available post-thaw data. Kaplan-Meier estimates of 3-month ANC500 and 6-month platelet 20K and 50K engraftment are 89±3%, 81±5%, and 73±5% respectively. Median time to engraftment for ANC 500, platelet 20K, and 50K were 22 days (range 7–69 days), 52.5 days (range 12–181 days), and 64 days (range 25–374 days) respectively. Median time to engraftment for post-thaw washed units (W) versus PD CBU not washed and infused directly after thawing (NW) were 24 vs. 22 days for ANC500, and 57 vs. 48 days for platelet 20K respectively. The incidence of reported grade II-IV and III-IV acute GVHD were 32% and 14% respectively. Twelve percent developed limited chronic GVHD and 14% developed extensive chronic GVHD. With a median follow-up of 170 days (range 4–1402 days), the Kaplan-Meier estimates of 1-year TRM, OS and relapse-free survival were 31±4%, 51±4% and 47±4% respectively. These results demonstrate that HSCT using unrelated PD UCB can be performed safely and effectively in patients with malignancies, and post-thaw wash may not be necessary.