Peripheral Blood Stem Cell Grafts Research Articles

Long-Term Cryopreservation Does Not Affect Quality of Peripheral Blood Stem Cell Grafts: A Comparative Study of Native, Short-Term and Long-Term Cryopreserved Haematopoietic Stem Cells

Cryopreserved haematopoietic progenitor cells are used to restore autologous haematopoiesis after high dose chemotherapy. Although the cells are routinely stored for a long period, concerns remain about the maximum storage time and the possible negative effect of storage on their potency. We evaluated the effect of cryopreservation on the quality of peripheral stem cell grafts stored for a short (3 months) and a long (10 years) period and we compared it to native products.The viability of CD34+ cells remained unaffected during storage, the apoptotic cells were represented up to 10% and did not differ between groups. The clonogenic activity measured by ATP production has decreased with the length of storage (ATP/cell 1.28 nM in native vs. 0.63 in long term stored products, P < 0.05). Only borderline changes without statistical significance were detected when examining mitochondrial and aldehyde dehydrogenase metabolic activity and intracellular pH, showing their good preservation during cell storage. Our experience demonstrates that cryostorage has no major negative effect on stem cell quality and potency, and therefore autologous stem cells can be stored safely for an extended period of at least 10 years. On the other hand, long term storage for 10 years and longer may lead to mild reduction of clonogenic capacity. When a sufficient dose of stem cells is infused, these changes will not have a clinical impact. However, in products stored beyond 10 years, especially when a low number of CD34+ cells is available, the quality of stem cell graft should be verified before infusion using the appropriate potency assays.

Transplantation of allogeneic cryopreserved hematopoietic cell grafts during the Covid-19 pandemic: A National Marrow Donor Program perspective.

Transplantation of allogeneic cryopreserved hematopoietic cell grafts during the Covid-19 pandemic: A National Marrow Donor Program perspective.

Impact of Cryopreservation of Donor Grafts on Outcomes of Allogeneic Hematopoietic Cell Transplant (HCT)

Introduction: Cryopreservation of peripheral blood stem cell (PBSC) or bone marrow (BM) grafts is rarely performed, thus information about the effect of cryopreservation on graft characteristics and HCT outcomes is limited. Given the global pandemic leading to changing practices for donor graft collection and increasing utilization of cryopreservation, we evaluated the outcomes of HCT recipients who received either fresh or cryopreserved allogeneic BM or PBSC grafts. The primary endpoint was engraftment. Secondary endpoints were incidence of acute graft-vs.-host disease (aGVHD), relapse, transplant related mortality (TRM), disease free survival (DFS), and overall survival (OS). Methods: We included 7397 patients transplanted between 2013 and 2018. 1883 cryopreserved graft recipients were divided into three cohorts based on graft source and donor type: matched related (MRD) PBSC (n=1,051), matched unrelated (MUD) PBSC (n=678), and matched related or unrelated bone marrow donors (n=154). All patients received conventional calcineurin-based GVHD prophylaxis strategies. Patients who received cryopreserved grafts were matched with 5514 patients who received fresh adjusting for graft type (BM vs. PB), donor source (MRD vs. 8/8 MUD), Disease Risk Index (DRI, low risk vs. intermediate risk vs. high risk), recipient age (within 5-years) and propensity score (within 1 standard deviation from pooled sample). The propensity score was based on age, Karnofsky score, diagnosis, disease risk index, HCT-comorbidity index, and conditioning intensity. The level of statistical significance for the main analyses was p&amp;lt;0.01 due to multiple comparisons. The reason for cryopreservation was available on a subset of URD product recipients. Results: Baseline characteristics for all cohorts are shown in Table 1. CD34+ doses reflect enumeration at infusion. In univariate analyses, rates of graft failure and neutrophil recovery at day 28 were similar for cryopreserved and fresh grafts for BM or related PBSC recipients but differed in cryopreserved vs. fresh MUD PBSC (5% vs 2%, p&amp;lt;0.001 and 87 vs 94%, p&amp;lt;0.001, respectively). Rates of platelet recovery within 28 days were similar in marrow cohorts, but lower with cryopreserved related (92% vs 96%, p&amp;lt;0.001) and MUD PBSC (87 vs 94%, p&amp;lt;0.001) grafts. In matched pair multivariable analyses, there were no significant differences in any outcomes with cryopreserved vs fresh BM grafts, irrespective of donor type. With related donor PBSC, cryopreservation was associated with decreased platelet recovery (HR=0.73, CI=0.68-0.78, p&amp;lt;0.001) and an increased risk of both grade II-IV (HR=1.27, CI=1.09-1.48, p=0.002) and grade III-IV (HR=1.48, CI=1.19-1.84, p&amp;lt;0.001) aGVHD, but had no impact on other outcomes. In contrast, with MUD PBSC grafts, cryopreservation was associated with delayed engraftment of neutrophils (HR=0.77, CI=0.71-0.84, p&amp;lt;0.001) and platelets (HR=0.61, CI=0.56-0.66, p&amp;lt;0.001), an increased risk of TRM (HR=1.4, CI=1.18-1.66, p&amp;lt;0.001) and relapse (HR=1.32, CI=1.11-1.58, p=0.002), and decreased DFS (HR=1.36, CI=1.20-1.55, p&amp;lt;0.001) and OS (HR=1.38, CI=1.22-1.58, p&amp;lt;0.001) but did not affect the incidence of aGVHD. In a subset analysis of 299 URD recipients, the most common reason for cryopreservation was delays due to patient-related events, eg., additional chemotherapy, infection. These recipients had decreased OS compared to products cryopreserved for non-patient reasons (HR=0.65, CI=0.44-0.96, p=0.029). Conclusions: The retrospective nature of this analysis, and the fact that cryopreservation is likely to have been performed in recipients with a different (higher) risk profile compared to those receiving fresh products limits our ability to draw firm confusions. Despite these limitations, we conclude that cryopreservation in some patient populations may have a negative impact on engraftment and transplant outcomes. The decision to cryopreserve donor grafts, particularly PBSC grafts, should be carefully considered and highlights the need for further investigation of the effect of cryopreservation of allogeneic grafts where patient factors can be controlled for. Disclosures Farhadfar: CSL Behring: Research Funding; Incyte pharmaceutical: Other: Member of GVHD advisory forum. Frey:Kite Pharma: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Syntax: Consultancy, Honoraria. Devine:Magenta Therapeutics: Consultancy. Shaw:Orca Bio: Consultancy. Wingard:Shire: Other: Personal Fees - serve on data monitoring committee for clinical trial; Ansun: Other: Personal Fees - serve on data monitoring committee for clinical trial; Merck: Other: Personal Fees - serve on data monitoring committee for clinical trial; Cidara: Other: Personal Fees - serve on data monitoring committee for clinical trial; ReViral: Other: Personal Fees - serve on data monitoring committee for clinical trial.

Early Infection after Allogeneic Transplant Increases NRM without Influencing Relapse Rate

Intro: Relapse post allogeneic transplant is the leading cause of early mortality in patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Known risk factors of relapse include persistent disease at the time of transplant, use of anti-thymocyte globulin, reduced intensity conditioning, and absence of chronic graft versus host disease (GVHD). Early infection has been reported to increase non-relapse mortality (NRM) while protecting against hematologic disease relapse (Auletta et al., Blood 2016). We sought to determine the influence of patient features and post-transplant early infection (bacterial, fungal, and viral) on acute GVHD, relapse, and mortality. Methods: Adult patients (N=146) with myeloid disorders (AML, MDS, MPN/CMML) who received an initial allogeneic transplantation from 2013-2018 at Oregon Health &amp; Science University were retrospectively identified and followed until 6/30/20 for acquired infections, hematologic relapse, and survival outcomes. Time-to-event endpoints, starting from transplant date, were modeled with Cox regression for single events (overall survival [OS], cause-specific hazards for competing events) and Fine-Gray subdistribution regression for events with a competing risk (early infection vs. death, acute GVHD vs. death, relapse vs. NRM). Infection status (one or more confirmed infections) in the first 100 days post-transplant was considered as a time-dependent covariate. Results: Among 146 adult patients, 77% had AML, 54% were male, and the median age was 59 years (range 18 - 72). The Karnofsky score was 90-100 in 44% and 60-80 in 51% of patients. Using 2017 ELN risk guidelines for AML and IPSS-R for MDS and MDS/MPN, 11% of patients were classified as low risk, 33% as intermediate, and 50% as adverse. The median time from diagnosis to transplant was 5 months (range 2 - 203). At the time of transplant, 63% of patients had attained some degree of response (i.e., complete remission [CR] or hematologic improvement). However, 66% had minimal residual disease (defined as persistent cytogenetic abnormalities or leukemia-associated mutations detected by NGS). Fifty-one percent of patients had myeloablative conditioning and 90% received peripheral blood stem cell grafts with methotrexate and calcineurin-based GVHD prophylaxis. Donors were HLA-matched in 86% of patients, with haploidentical and umbilical cord blood grafts representing 10% and 3%, respectively. Forty-six percent of donors were positive for cytomegalovirus (CMV). Seventy-five percent (n=109) of patients had at least one infection in the first 100 days after transplant. Cumulative incidence rates of any infection are displayed in Table 1. The median time from transplant to first infection was 22 days, ranging from 0 to 73 days. Forty-three patients (29%) relapsed during study follow-up. The median time from transplant to relapse was 6.1 months (IQR 3.1 - 12.0). Over a median follow-up time of 18.7 months, 78 patients (53%) died, with median time to death of 4.1 months after transplant. Forty-six (59%) of the deaths were attributed to causes other than hematologic disease (i.e., infection, GVHD, other cancer). Low prognostic risk and total body irradiation during conditioning were associated with early infection (Table 2). In the multivariable setting, a higher rate of death was associated with male gender (HR=1.67; p=0.040), having at least a 6-month lag between diagnosis and transplant (HR=2.79; p&amp;lt;0.001), and contracting an infection of any type (HR=2.54; p=0.003; Table 3). There was no association between early infection and acute GVHD, which occurred in 85 patients (58.2%) with a median time to onset of 34 days. A greater incidence of acute GVHD was related to older recipient age (HR=1.88 for ≥50 years vs. &amp;lt;50; p=0.014), being male (HR=2.62; p&amp;lt;0.001), not having achieved a CR (HR=1.66; p=0.020), and undergoing transplant ≥ 6 months after diagnosis (HR=1.72; p=0.014). Infection did not correlate with the rate of relapse (HR=1.02, p=0.942) but significantly elevated the rate of NRM (HR=5.72, p&amp;lt;0.001). Time-independent variables associated with a higher probability of relapse were failure to attain a pre-transplant CR (HR=1.87; p=0.038) and having a CMV-positive donor (HR=2.11; p=0.016). Conclusion: Our retrospective study found that post-transplant early infection in AML and MDS/MPN patients did not impact relapse rate but drastically increased the rate of NRM. Disclosures Saultz: Kyn Theraputics: Research Funding. Maziarz:Novartis, Incyte, CRISPR Therapeutics, Artiva Biotherapeutics, and AlloVir: Consultancy; Novartis and Athersys: Other: DSMB participant; Novartis and Juno: Research Funding; Incyte, Kite, BMS/Celgene, PACT Pharma, Orca BioSystems, and Omeros: Honoraria; Athersys: Patents &amp; Royalties.

Chromosomal Aberrations in Pre-HCT Blood Samples and Outcomes after Transplantation in Patients with Myelofibrosis

Introduction: Allogeneic hematopoietic cell transplantation (HCT) is curative for myelofibrosis (MF). However, prognosis post HCT is variable. Identifying subsets of patients who can greatly benefit from HCT is important for clinical decision-making and patient counseling. The Dynamic International Prognostic Scoring System (DIPSS) score includes cytogenetic abnormalities provides important prognostic information. Here, we used high-resolution single nucleotide polymorphism (SNP) arrays to characterize chromosomal aberrations in pre-HCT blood samples from patients with MF and evaluated their added value in patient risk stratification for post HCT survival. Methods: We used the Illumina Global Screening Array to detect somatic copy number alterations (SCNAs) sized ≥2Mb (by calculating the log2 R ratio and B allele frequency and leveraging haplotype information) in pre-HCT blood samples (collected 2-4 weeks prior to HCT conditioning regimen administration) from 923 MF patients who underwent HCT between 2000-2016. Clinical data and blood samples were obtained from the Center for International Blood and Marrow Transplant Research. We used Kaplan-Meier survival analysis and multivariable Cox regression to evaluate the prognostic significance of observed SCNAs on survival after HCT. Results: Median age at HCT was 58 years (range=0.7-76). About 58% were males (N=536), 85% received unrelated donor HCT (N=787), 90% received peripheral blood stem cell grafts (N=826), 47% (N=429) received myeloablative conditioning (MAC), 34% (N=312) received HCT within 1 year from diagnosis, and 537 patients (58%) had known DIPSS score at HCT (47% of them were intermediate II or high). A high frequency of SCNAs were noted in MF (N=623; 67.5%), most commonly on chromosome (chr) 9p (N=224, 24%), chr13q (N=104, 11%), and chr20q (N=102, 11%) (Figure 1). Aberrations noted on chromosomal regions harboring the known MF genes (MPL, DNMT3A, TET2, EZH2, JAK2, SRSF2, CALR, ASXL1, U2AF1) accounted for 28% of all detected (40% of the patients), including JAK2 (9p24.1, N=253, 27%), MPL (1p34.2, N=30, 3.3%) and CALR (19p13.13, N=23, 2.5%). Multivariable models including all MF genes (adjusted for DIPSS score, KPS, year of HCT, hemoglobin count, splenectomy, age, sex, time from diagnosis to HCT, and stratified on CMV match, graft type and conditioning regimen) showed an association between SCNAs on TET2 or SRSF2 regions and poor survival (HR for TET2 =2.40, 95% CI=1.33-4.32, p=0.004; and HR for SRSF2= 2.22, 95% CI=1.26-3.89, p=0.006). TET2 region aberrations were associated with an increased risk of transplant-related mortality (TRM) (HR=2.97, 95% CI=1.53-5.78, p=0.001), worse disease-free survival (DFS; HR=2.22, 95% CI=1.33-3.69, p=0.002), but not the risk of relapse (p=0.12). SRSF2 region aberrations were associated with DFS (HR=1.94, 95% CI=1.11-3.37, p=0.02); no statistically significant association was noted with the risk of relapse (p=0.07) or TRM (p=0.44). These associations were predominant in patients receiving reduced intensity (RIC) or non-myeloablative regimens (Figure 2). Further univariate analyses focusing on all frequently affected chromosomes (affecting ≥10 patients) showed poor OS with SCNAs on chr17p (log-rank p&amp;lt;0.0001), 12p (p&amp;lt;0.0001), 5q (p&amp;lt;0.0001), 13q (&amp;lt;0.001), 8q (p=0.004), 18q (p=0.02) and 4q (p=0.03). In multivariable models stratified on conditioning regimens, chr17p aberrations showed a significant association with excess risk of relapse independent of regimen intensity (HR=5.31, p=0.01 in MAC, and HR=2.70, p=0.02 in RIC). The HR for OS was 2.55, p=0.09, and 2.86, p=0.002, respectively. Other chromosomal aberrations that showed significant associations with inferior OS in patients receiving RIC were SCNAs on chr8q (HR=5.55, p&amp;lt;0.001) (Figure 3), with excess risk of TRM (HR=5.09, p=0.002) but not relapse (p=0.34). In patients that received MAC, elevated risk of mortality was noted with chr5q SCNAs (HR=2.83, p=0.02) with a suggestive association with relapse (HR=2.72, p=0.08) but not with TRM (p=0.59). Conclusion: This study highlights the prognostic ability of pre-HCT detected SCNAs in patients with myelofibrosis, independent on DIPSS score. Relapse risk in patients with aberrations affecting TP53 region was not eliminated by MAC. Follow-up studies to confirm the poor prognosis of those chromosomal changes are warranted. Disclosures Lee: Incyte: Consultancy, Research Funding; Syndax: Research Funding; Kadmon: Research Funding; AstraZeneca: Research Funding; Pfizer: Consultancy, Research Funding; Amgen: Research Funding; Takeda: Research Funding; Novartis: Research Funding.

Early Reconstitution of CD6+ T Cells after Hematopoietic Cell Transplantation Identifies a Suitable Target for Acute Graft Versus Host Disease Treatment Using Anti-CD6 Monoclonal Antibody Itolizumab

Early Reconstitution of CD6+ T Cells after Hematopoietic Cell Transplantation Identifies a Suitable Target for Acute Graft Versus Host Disease Treatment Using Anti-CD6 Monoclonal Antibody Itolizumab

Hypomethylating Agents in Combination with Venetoclax As a Bridge to Allogeneic Transplant in Acute Myeloid Leukemia

Introduction Older adults with AML are often ineligible for high intensity chemotherapy and potentially curative allogeneic hematopoietic cell transplantation (HCT) due to poor performance status at presentation, comorbidities, and/or adverse genetic features associated with refractory disease and chemoresistance. Recently, the lower intensity combination of a hypomethylating agent and venetoclax (HMA/Ven) was shown to achieve durable responses in patients with AML. Despite this combination having been studied primarily in older, transplant-ineligible adults, a small subset of patients on the Phase 1b trial were successfully bridged to HCT (Pratz et al, 2019). We conducted a multi-center analysis assessing patient characteristics and clinical outcomes of patients treated with HMA/Ven who subsequently proceeded to HCT. Methods We retrospectively identified 51 adults who received HMA/Ven in either the front-line or relapsed/refractory (R/R) setting and underwent subsequent HCT between 2017 - 2019 at Stanford University, the University of California, San Francisco, and the University of California, Los Angeles. Patients received either azacitidine or decitabine in combination with venetoclax. Patients were evaluated for efficacy endpoints including: best response prior to HCT (complete remission [CR], CR with incomplete hematologic recovery [CRi], morphologic leukemia-free state [MLFS]), measurable residual disease (MRD) prior to HCT by flow cytometry (sensitivity threshold ≤1x10-4), and post-HCT relapse and survival. Results The median age at HCT was 65.5 years (24 - 76). Fifty-three percent of patients had a KPS of ≤ 80, and 29% had an HCT-CI of ³ 3. Fifty-seven percent had adverse-risk disease by 2017 European Leukemia Net criteria. The majority (63%) received decitabine; 23 (45%) received HMA/Ven as front-line induction and 28 (55%) for R/R disease. Compared to patients with R/R disease, patients who received front-line HMA/Ven were more likely to be older (67 vs 54 years, p = 0.003) and have a KPS ≤ 80 (65% vs 47%, p = 0.03). Patients with R/R disease had a median of 2 (1 - 4) lines of therapy prior to receiving HMA/Ven and 2 patients had undergone prior HCT. The number of HMA/Ven cycles prior to HCT varied considerably, with a median of 3 (1 - 11). The majority (78%) of patients achieved a complete remission prior to HCT. Of the patients who received front-line HMA/Ven, 83% achieved CR, 13% CRi, and 4% MLFS; 17 (74%) patients had a pre-HCT MRD assessment, of which 71% were MRD-negative. Of the patients who received HMA/Ven for R/R disease, 41% achieved CR, 22% CRi, 33% MLFS, and 4% had refractory disease; 24 (86%) of patients had a pre-HCT MRD assessment, of which 54% were MRD-negative. Across the full cohort, 49% of patients received non-myeloablative, 35% myeloablative, and 16% reduced intensity conditioning. The majority (94%) of patients received peripheral blood stem cell grafts; donor sources were 35% HLA-matched related, 43% HLA-matched unrelated, and 22% haploidentical. Following HCT, 100-day non-relapse mortality was 4%, 6-month overall survival (OS) was 85% and 6-month relapse-free survival (RFS) was 63%. Among patients who received front-line HMA/Ven, 6-month OS was 88% and 6-month RFS was 80%; among patients with R/R disease, 6-month OS was 81% and 6-month RFS was 51%. Patients who were MRD-negative had a 6-month OS of 87% and RFS of 75%; MRD-positive patients had 6-month OS of 73% and RFS of 46%. Among the 27 patients transplanted prior to July 1, 2019, 1-year OS and RFS were 78% and 59% for the entire cohort, 90% and 80% for the 10 patients receiving frontline HMA/Ven, and 71% and 47% for the 17 patients with R/R disease. Conclusion In patients with AML, an HMA in combination with venetoclax can achieve complete remissions-MRD-negative in many cases-thus providing a viable pathway to potentially curative HCT. This treatment pathway is especially important in older/unfit patients receiving front-line HMA/Ven due to ineligibility for high intensity induction chemotherapy, as well as those with relapsed/refractory and previously chemoresistant disease. Following HCT, patients treated in both settings had low NRM and favorable rates of disease response. Prospective studies are warranted to further explore the optimal use of HMA/Ven therapy as a bridge to successful transplant outcomes. Disclosures Muffly: Amgen: Consultancy; Adaptive: Research Funding; Servier: Research Funding. Logan:Abbvie: Consultancy; Amgen: Consultancy; Novartis: Consultancy; Amphivena: Research Funding; Autolus: Research Funding; Jazz: Research Funding; Kadmon: Research Funding; Kite: Research Funding; Pharmacyclics: Research Funding. Mannis:AbbVie, Agios, Bristol-Myers Squibb, Genentech: Consultancy; Glycomimetics, Forty Seven, Inc, Jazz Pharmaceuticals: Research Funding.

A Phase 1 Single Dose Escalation Study of Palifermin Administered Pre-Transplant Conditioning in Subjects Undergoing Matched Unrelated Donor Allogeneic Hematopoietic Stem Cell Transplantation

Background: Early initiation of graft-versus-host disease (GvHD) is driven by donor alloreactive T-lymphocytes directed against recipient's histocompatibility antigens often overexposed during damage to tissues during the conditioning chemotherapy. Palifermin is a truncated form of human recombinant keratinocyte growth factor (KGF, also known as FGF7) that binds to FGF receptor 2b expressed in many epithelia including the epithelium of the epidermis, oral and GI mucosa, urothelium, and thymus, in which it exerts cytoprotective and regenerative effects. Palifermin also has immunomodulatory effects manifested as improvements in thymic function and downregulation of pro-inflammatory cytokines. Palifermin was FDA approved in 2004 at a dose of 60 mcg/kg/day (x3 consecutive days) for prevention of severe oral mucositis in hematologic malignancy patients receiving autologous hematopoietic stem cell transplant (HSCT). A single dose of 180 mcg/kg/day appears to have similar effects. In animal models, palifermin showed efficacy in controlling acute and chronic GvHD. However, subsequent clinical studies did not confirm efficacy for prevention of GvHD or for stimulation of functional thymus recovery using a dose/schedule based on the one that had been approved for autologous HSCT. We conducted a phase 1 study (NCT02356159) to determine the maximal safe single dose level of palifermin administered prior to starting transplant conditioning. Methods: This was an open-label, dose escalation study with standard 3+3 design. Four different dose levels of palifermin (180, 360, 540 and 720 µg/kg) were administered as a single dose on day -7 pretransplant. The reduced-intensity conditioning regimen (cyclophosphamide 1200 mg/m2/day IV and fludarabine 30 mg/m2/day IV), was given on days -6 to -3. Sirolimus, tacrolimus and low-dose post-HSCT methotrexate were used for GvHD prophylaxis. On day 0 all subjects received a peripheral blood stem cell (PBSC) graft from an unrelated donor (MUD) matched at least at HLA-A, -B, -C, -DRB1. Prior to transplant, subjects received one or two cycles of disease-specific lymphodepleting induction chemotherapy (EPOCH-F/R or FLAG). Subjects must have been ≥18 years old with a high-risk hematologic malignancy, Karnofsky performance status ≥60%, and acceptable organ function. The primary objective was to assess safety of palifermin and to recommend the phase 2 study dose. DLT was defined as non-relapse mortality before day 30 post-HSCT regardless of attribution to palifermin and non-hematologic grade ≥4 adverse events (AEs) occurring within 14 days after administration. AEs were recorded according to CTCAEv4. Results: From Oct 2015 to Mar 2019, 18 subjects were enrolled (NHL=7, AML/MDS=5, ALL/LBL=2, CML=2, MPN=1 and MM=1). Kahl's relapse risk was high, standard, and low in 15, 2, and 1 subject, respectively. Median HCT-CI score was 1 (0-4) with median age 47 years (21-66); 14 (78%) were males. Six subjects received dose level 1 (subject #3 was diagnosed with achalasia and grade 4 elevated lipase without radiological signs of pancreatitis, still attributed as DLT possibly related to palifermin). No DLTs occurred afterwards. Three subjects were enrolled onto each of dose levels 2, 3 and 4, with expansion of dose level 4 to 3 more subjects for additional safety exploration. Skin rash and Increased serum amylase or lipase were the most frequent AEs (Table 1A). Grade 3 increased serum amylase and grade 3 possible pancreatitis in subject #3 were the only SAEs attributed to study drug. All subjects engrafted successfully. Day 14 median CD3 and myeloid chimerism was 97% (36-100) and 99% (82-100), respectively, with the median time to 100% CD3 chimerism of 44 days (14-181). Table 1B lists occurrence of GvHD prior to any malignancy relapse. Four subjects had relapsed malignancy, for which 3 received DLI. After a median follow up of 28 months (2-55), 5 subjects have died, 2 malignancy relapses and 3 non-relapse related causes. Conclusion: Palifermin administered at dose four-times higher than previously given in humans is safe to use in patients undergoing MUD peripheral blood HSCT. MTD was not reached. Recommended phase 2 dose for examining efficacy in prevention of GvHD is 720 µg/kg. Disclosures Rubin: NIH/NCI: Ended employment in the past 24 months, Patents &amp; Royalties; KGF/palifermin: Patents &amp; Royalties; Paradigm Shift Therapeutics: Membership on an entity's Board of Directors or advisory committees. OffLabel Disclosure: Palifermin was FDA approved at a dose of 60 mcg/kg/day (x3 consecutive days) for prevention of severe oral mucositis in hematologic malignancy patients receiving autologous hematopoietic stem cell transplant (HSCT).

Comparison of Bone Marrow Versus Peripheral Blood in Haploidentical Transplantation Using Post-Transplant Cyclophosphamide- a Retrospective Analysis

Comparison of Bone Marrow Versus Peripheral Blood in Haploidentical Transplantation Using Post-Transplant Cyclophosphamide- a Retrospective Analysis

Naive T-cell depletion in stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (HCT) is curative in many patients with advanced hematopoietic malignancies. Donor T cells not only facilitate engraftment and protect against opportunistic pathogens and residual disease, but can also cause graft-versus-host disease (GVHD), with significant morbidity and mortality. Complete T-cell depletion can not only substantially reduce GVHD rates but can also delay immune reconstitution and increase rates of opportunistic infections and relapse. Murine models have shown that naive T cells (TNs) consistently cause severe GVHD, whereas memory T cells cause milder or no GVHD and have critical graft-versus-tumor function. Informed by experiments performed in murine models of HCT, clinical trials are being conducted to evaluate TN-depleted peripheral blood stem cell (PBSC) grafts. These trials are showing very low rates of chronic GVHD and of serious acute GVHD in the HLA-matched HCT setting, with lower frequencies of opportunistic infections than after fully T-cell-depleted HCT and no apparent increase in relapse rates. Randomized clinical trials are ongoing, comparing standard unselected HCT with TN-depleted PBSCs and other promising GVHD-reduction strategies. Correlative laboratory studies will clarify how antitumor function is retained in TN-depleted HCT and inform strategies to further augment graft-versus-leukemia in patients at a high risk of relapse. TN depletion of donor lymphocyte infusions and of haploidentical stem cell grafts is also being investigated.

Cryostorage to What End? – Autologous Stem Cell Products in Burkitt Lymphoma, Acute Lymphoblastic Leukemia, Acute Myeloid Leukemia, and Myeloproliferative Neoplasm Patients

Introduction: Recently, we identified a huge discrepancy between the collection practice and the actual utilization of cryopreserved peripheral blood stem cells (PBSCs) for high-dose chemotherapy (HDCT) and autologous blood stem cell transplantation (ABSCT). Specifically, patients with Burkitt lymphoma, acute leukemia, and myeloproliferative neoplasms (MPN) were frequently not referred for ABSCT after successful PBSC collection. Objective: The aim of this study was to identify variables that are associated with the non-utilization of PBSC grafts. Methods: We retrospectively analyzed the collection, storage, and disposal of PBSC grafts in Burkitt lymphoma (n = 18), acute lymphoblastic leukemia (ALL, n = 22), MPN (n = 18), and acute myeloid leukemia (AML, n = 71) patients. Patients who underwent autologous PBSC collection at 2 collection and transplantation centers between 2001 and 2012 were included and followed up until 2016. Results: None of the Burkitt lymphoma patients were referred for ABSCT. Only in 1 (6%) patient, the graft was discarded after the patient’s death. In all other patients (n = 17, 94%), the grafts were stored independently of the patient’s status (death, n = 4, 22%; no follow-up, n = 6, 33%; no indication for ABSCT given, n = 7, 39%). In ALL patients, 4 (18%) patients underwent ABSCT after a median follow-up of 74 (1–182) months. In the remaining patients, PBSC grafts were either discarded (8 patients, 36%) or stored until the reference date (10 patients, 45%). Seven of 18 MPN patients (39%) underwent ABSCT. ABSCT was performed in 24 (34%) AML patients. In 20 (28%) patients who were not referred to ABSCT, an allogeneic transplantation (TPL) was performed. Fifteen (21%) patients received palliative care or deceased, and their grafts were discarded in all but 1 patient. Additional grafts were discarded in 21 (31%) patients and stored in 9 (13%) patients who underwent ABSCT or allogeneic TPL (n = 44). Conclusions: As the role and efficacy of autologous HDCT/ABSCT are not established in the analyzed entities, the indication for PBSC collection should be reanalyzed in regular intervals. Moreover, PBSC grafts from patients who have deceased, have insufficient grafts, or have already undergone an allogeneic TPL should be considered for disposal or (if applicable) for research use, to economize storage costs on a rational basis.

Impact of donor age and kinship on clinical outcomes after T-cell–replete haploidentical transplantation with PT-Cy

AbstractDonor selection contributes to improve clinical outcomes of T-cell–replete haploidentical stem cell transplantation (haplo-SCT) with posttransplant cyclophosphamide (PT-Cy). The impact of donor age and other non-HLA donor characteristics remains a matter of debate. We performed a multicenter retrospective analysis on 990 haplo-SCTs with PT-Cy. By multivariable analysis, after adjusting for donor/recipient kinship, increasing donor age and peripheral blood stem cell graft were associated with a higher risk of grade 2 to 4 acute graft-versus-host-disease (aGVHD), whereas 2-year cumulative incidence of moderate-to-severe chronic GVHD was higher for transplants from female donors into male recipients and after myeloablative conditioning. Increasing donor age was associated with a trend for higher nonrelapse mortality (NRM) (hazard ratio [HR], 1.05;P= .057) but with a significant reduced risk of disease relapse (HR, 0.92;P= .001) and improved progression-free survival (PFS) (HR, 0.97;P= .036). Increasing recipient age was a predictor of worse overall survival (OS). Risk of relapse was higher (HR, 1.39;P< .001) in patients aged ≤40 years receiving a transplant from a parent as compared with a sibling. Moreover, OS and PFS were lower when the donor was the mother rather than the father. Pretransplant active disease status was an invariably independent predictor of worse clinical outcomes, while recipient positive cytomegalovirus serostatus and hematopoietic cell transplant comorbidity index >3 were associated with worse OS and PFS. Our results suggest that younger donors may reduce the incidence of aGVHD and NRM, though at higher risk of relapse. A parent donor, particularly the mother, is not recommended in recipients ≤40 years.

Efficacy of folinic acid rescue following MTX GVHD prophylaxis: results of a double-blind, randomized, controlled study

AbstractThe use of methotrexate (MTX) for graft-versus-host disease (GVHD) prophylaxis is associated with increased rates of organ-specific toxicities. Despite limited data, the European Society for Blood and Marrow Transplantation-European LeukemiaNet working group recommend the use of folinic acid (FA) rescue to reduce MTX toxicity after allogeneic hematopoietic cell transplantation (allo-HCT). In a multicenter, double-blind, randomized, controlled trial, we explored whether FA rescue reduces MTX-induced toxicity. We enrolled patients undergoing allo-HCT with myeloablative conditioning with peripheral blood stem cell grafts, with GVHD prophylaxis consisting of cyclosporine and MTX. Patients were randomized to receive FA or placebo starting 24 hours after each MTX dose and continuing over 24 hours in 3 to 4 divided doses. The primary end point was the rate of grades 3 and 4 oral mucositis. After enrollment of 52 patients (FA, n = 28; placebo, n = 24), preplanned interim analysis revealed similar rates of grade 3 and 4 (46.6% vs 45.8%;P= .97) and grades 1 to 4 (83.3% vs 77.8%;P= .65) oral mucositis. With a median follow-up of 17 (range, 4.5-50) months, there was no difference in the rates of acute and chronic GVHD, disease relapse, nonrelapse mortality, and overall survival. These interim results did not support continuation of the study. We conclude that FA rescue after MTX GVHD prophylaxis does not decrease regimen-related toxicity or affect transplantation outcomes. This study was registered atclinicaltrials.govas #NCT02506231.

Improved Relapse-Free Survival in Patients With High Natural Killer Cell Doses in Grafts and During Early Immune Reconstitution After Allogeneic Stem Cell Transplantation.

Mature immunocompetent cells from the stem cell graft as well as early robust immune reconstitution are essential for the graft-vs. -tumor (GVT) effect to eliminate residual malignant cells after allogeneic hematopoietic stem cell transplantation (HSCT). In this prospective study we characterized graft composition of T- and NK cell subsets in 88 recipients of peripheral blood stem cell grafts with multicolor flowcytometry. Our primary aim was to analyze the impact of graft composition on immune reconstitution and clinical outcomes after transplantation. Patients transplanted with graft NK cell doses above the median value of 27 × 106/kg had significantly increased relapse-free-survival compared to patients transplanted with lower doses, HR 2.12 (95% CI 1.01–4.45, p = 0.04) Peripheral blood concentrations of NK cells obtained from donors before G-CSF mobilization were significantly correlated to graft NK cell doses (Spearman's ρ 0.53, p = 0.03). The dose of transplanted NK cells/kg correlated significantly with NK cell concentrations in patients early after transplantation (Spearman's ρ 0.26, p = 0.02, and ρ = 0.35, p = 0.001 for days 28 and 56, respectively). Early immune reconstitution above median values of NK cells was significantly associated with improved relapse-free survival (HR 2.84 [95% CI 1.29–6.28], p = 0.01, and HR 4.19 [95% CI 1.68–10.4], p = 0.002, for day 28 and 56, respectively). Early concentrations above the median value of the mature effector CD56dim NK cell subset were significantly associated with decreased relapse incidences at 1 year, 7% (95% CI 1.8–17) vs. 28% (95% CI 15–42), p = 0.04, and 7% (95% CI 1.8–18) vs. 26% (95% CI 14–40) %, p = 0.03, for days 28 and 56, respectively. The results suggest a protective effect of high doses of NK cells in grafts and during early immune reconstitution and support the perception of NK cells as innate effector cells with anti-tumor effects in the setting of allogeneic stem cell transplantation.

Storage, Utilization, and Disposal of Hematopoietic Stem Cell Products in Patients with Multiple Myeloma.

High-dose chemotherapy (HD-CHT) and autologous blood stem cell transplantation (ABSCT) represent the standard of care in multiple myeloma (MM) for transplantation-eligible patients. Up to 3 HD-CHT/ABSCT treatments may be administered during the course of disease, including during late-onset relapse. Transplantation centers routinely collect more than 1 peripheral blood stem cell (PBSC) graft; however, subsequent HD-CHT/ABSCT treatments are often not performed, for various reasons. Currently, little is known about the actual utilization rate of stored PBSCs. The collection, storage, and disposal of PBSC products was analyzed in a large cohort of patients with MM (n=1114) over a 12-year period with a minimum follow-up of 6 years. The final dataset analysis was performed in March 2019, which was set as the reference date. Based on institution-specific charges, the costs for PBSC collection, processing, and storage were estimated. The median number of sufficient PBSC transplantations per patient was 3 (range, 0 to 6), which were stored in a median of 3 (range, 1 to 11) cryopreserved bags (overall, n=3644). A total of 95% of all patients (n=1059) underwent at least 1 HD-CHT/ABSCT treatment. However, multiple ABSCTs were performed in 51% of the patients (n2/3 ABSCTs=538), and only 14% of the patients underwent ABSCT 3 times (n3 ABSCTs=149). Only a small proportion of collected PBSC bags (5%; n=109) were used after being stored for longer than 5 years. Overall, 23% of the products (n=830) were discarded, and 16% (n=566) were kept in storage until the reference date. From a retrospective standpoint, the collected and discarded (definitively not used) or stored (potentially not used) cryostored PBSCs were associated with considerable costs for long-term cryostorage of approximately €1,600,000. We identified considerable discrepancies between the collection/storage and utilization of PBSCs. This is associated with significant efforts and costs on the one hand; on the other hand, disposal may raise legal and ethical questions. Therefore, we implemented comprehensive guidelines for the systematic reevaluation of stored PBSC grafts at our institution.

Bone marrow versus mobilized peripheral blood stem cell graft in T-cell-replete haploidentical transplantation in acute lymphoblastic leukemia.

The ideal stem cell graft source remains unknown in haploidentical haematopietic cell transplantation (haplo-HCT) with posttransplantation cyclophosphamide (PTCy). This study compared outcomes of bone marrow (BM) versus peripheral blood (PB) stem cell graft for haplo-HCT in acute lymphoblastic leukemia (ALL). A total of 314 patients with ALL (BM-157; PB-157) were included in this study. The cumulative incidence of engraftment at day 30 was higher in the PB group compared with BM (93% vs. 88%, p < 0.01). The incidences of acute graft-versus-host disease (GVHD) and chronic GVHD were not significantly different between the study cohorts. In the multivariate analysis, there were tendencies toward a higher incidence of grade II-IV acute GVHD (hazard ratio (HR) = 1.52, p = 0.07), chronic GVHD (HR = 1.58, p = 0.05), and nonrelapse mortality (NRM) (HR = 1.66, p = 0.06) in patients receiving PB versus BM graft, respectively. The use of PB grafts was associated with lower leukemia-free survival (LFS) (HR = 1.43, p = 0.05), overall survival (OS) (HR = 1.59, p = 0.02), and GVHD-free, relapse-free survival (GRFS) (HR = 1.42, p = 0.03) compared with BM grafts. There was no difference in relapse incidence (HR = 1.23, p = 0.41) between the study groups. In conclusion, use of BM graft results in better survival after haplo-HCT with PTCy in patients with ALL, compared with PB stem cell graft.

Absence of influence of peripheral blood CD34+ and CD3+ graft cell counts on outcomes after reduced-intensity conditioning transplantation using post-transplant cyclophosphamide

The influence of peripheral blood stem cell (PBSC) graft cell contents after transplant with post-transplant cyclophosphamide (PTCY) remains unclear. Here, we retrospectively report on a cohort of 77 adults who received a Baltimore-based reduced-intensity conditioning regimen either with fludarabine (n = 40) or clofarabine (n = 37) and PTCY. With a median follow-up of 29.2months, [2-]year overall (OS), disease-free (DFS), and GVHD/relapse-free survival (GRFS) rates were 62.8%, 51%, and 36.7%, respectively. The incidence of grades [2-]4 acute GVHD was significantly higher in patients transplanted with a haplodonor (n = 56), at 57.1% vs 19% (p = 0.006). PBSC graft cell contents (CD45+, CD34+, and CD3+ cells) had no impact on any outcome. Considering immune reconstitution until 1year, only monocytes were above the normal range (as early as day + 30) during the first year post-transplant. In multivariate analysis, an older donor (> 45years) and a high/very high disease risk index were independently associated with lower OS. A higher monocyte count (> median) at day + 90 was also associated with better OS, DFS, and GRFS. Donor/recipient CMV status matching was independently associated with GRFS. In conclusion, our data support the fact that there is no need to manipulate the graft before infusion in the particular context of PBSC/PTCY Baltimore-based allotransplant.

Low-dose peripheral blood stem cell graft after high-dose chemotherapy - an evaluation of hematopoietic reconstitution

BackgroundHigh-dose (HD) chemotherapy followed by autologous blood stem-cell transplantation (ASCT) is the standard treatment for multiple myeloma (MM) patients. However, the collection of sufficient peripheral blood stem cell (PBSC) grafts can be challenging, and the question arises whether reinfusion of low-dose grafts will lead to a hematopoietic recovery.MethodsThe hematopoietic recovery of 148 MM patients who underwent HD melphalan chemotherapy and received PBSC transplants with varying CD34+ cells doses (3–4 × 106 [n = 86], 2–2.5 × 106 [n = 53], < 2 × 106 [n = 9] per kg body weight [bw]) was analyzed in this retrospective single-center study.ResultsAll patients reached hematopoietic reconstitution, even those who received < 2 × 106 CD34+ cells/kg bw. 62 (42%) patients received granulocyte-colony-stimulating factor (G-CSF). The median duration to leukocyte recovery ≥1.0 × 109/L was 12 days in every group. The median duration to platelet recovery ≥20 × 109/L was 11, 13 and 13 days, respectively. In the multivariate analysis, a low number of reinfused CD34+ cells was associated with prolonged time until leukocyte reconstitution (p = 0.010, HR 0.607) and platelet recovery (p < 0.001, HR 0.438). G-CSF support significantly accelerated leukocyte (p < 0.001, HR 16.742) but not platelet reconstitution.ConclusionIn conclusion, reinfusion of low- and even very-low-dose PBSC grafts leads to sufficient hematopoietic reconstitution. No severe adverse events were observed during or after HD chemotherapy and ASCT in the analyzed cohort. While the impact of CD34+ cell dose is marginal, G-CSF significantly accelerates the leukocyte recovery.

Securing the graft during pandemic: are we ready for cryopreservation for all?

Allogeneic hematopoietic cell transplantation (allo-HCT) from an unrelated donor involves complex interplay of multiple organizations working together for a successful delivery of a stem cell graft to the recipient. Historically, cryopreservation of stem cell graft has been done only for a small fraction of allo-HCT due to concerns around negative impact of freezing and thawing on the viability of hematopoietic stem cells and function of donor lymphocytes [1]. Previous retrospective studies comparing allo-HCT outcomes of cryopreserved versus freshly infused peripheral blood stem cell (PBSC) graft from matched donors have shown comparable survival outcomes but marginally delayed neutrophil and platelet engraftment with cryopreservation [1,2].

Graft Cryopreservation Does Not Impact Overall Survival after Allogeneic Hematopoietic Cell Transplantation Using Post-Transplantation Cyclophosphamide for Graft-versus-Host Disease Prophylaxis.

The COVID-19 pandemic has created significant barriers to timely donor evaluation, cell collection, and graft transport for allogeneic hematopoietic stem cell transplantation (allo-HCT). To ensure availability of donor cells on the scheduled date of infusion, many sites now collect cryopreserved grafts before the start of pretransplantation conditioning. Post-transplantation cyclophosphamide (ptCY) is an increasingly used approach for graft-versus-host disease (GVHD) prophylaxis, but the impact of graft cryopreservation on the outcomes of allo-HCT using ptCY is not known. Using the Center for International Blood and Marrow Transplant Research (CIBMTR) database, we compared the outcomes of HCT using cryopreserved versus fresh grafts in patients undergoing HCT for hematologic malignancy with ptCY. We analyzed 274 patients with hematologic malignancy undergoing allo-HCT between 2013 and 2018 with cryopreserved grafts and ptCY. Eighteen patients received bone marrow grafts and 256 received peripheral blood stem cell grafts. These patients were matched for age, graft type, disease risk index (DRI), and propensity score with 1080 patients who underwent allo-HCT with fresh grafts. The propensity score, which is an assessment of the likelihood of receiving a fresh graft versus a cryopreserved graft, was calculated using logistic regression to account for the following: disease histology, Karnofsky Performance Score (KPS), HCT Comorbidity Index, conditioning regimen intensity, donor type, and recipient race. The primary endpoint was overall survival (OS). Secondary endpoints included acute and chronic graft-versus-host disease (GVHD), non-relapse mortality (NRM), relapse/progression and disease-free survival (DFS). Because of multiple comparisons, only P values <.01 were considered statistically significant. The 2 cohorts (cryopreserved and fresh) were similar in terms of patient age, KPS, diagnosis, DRI, HCT-CI, donor/graft source, and conditioning intensity. One-year probabilities of OS were 71.1% (95% confidence interval [CI], 68.3% to 73.8%) with fresh grafts and 70.3% (95% CI, 64.6% to 75.7%) with cryopreserved grafts (P=.81). Corresponding probabilities of OS at 2 years were 60.6% (95% CI, 57.3% to 63.8%) and 58.7% (95% CI, 51.9% to 65.4%) (P=.62). In matched-pair regression analysis, graft cryopreservation was not associated with a significantly higher risk of mortality (hazard ratio [HR] for cryopreserved versus fresh, 1.05; 95% CI, .86 to 1.29; P=.60). Similarly, rates of neutrophil recovery (HR, .91; 95% CI, .80 to 1.02; P=.12), platelet recovery (HR, .88; 95% CI, .78 to 1.00; P=.05), grade III-IV acute GVHD (HR, .78; 95% CI, .50 to 1.22; P=.27), NRM (HR, 1.16; 95% CI, .86 to 1.55; P=.32) and relapse/progression (HR, 1.21; 95% CI, .97 to 1.50; P=.09) were similar with cryopreserved grafts versus fresh grafts. There were somewhat lower rates of chronic GVHD (HR, 78; 95% CI, .61 to .99; P=.04) and DFS (HR for treatment failure, 1.19; 95% CI, 1.01 to 1.29; P=.04) with graft cryopreservation that were of marginal statistical significance after adjusting for multiple comparisons. Overall, our data indicate that graft cryopreservation does not significantly delay hematopoietic recovery, increase the risk of acute GVHD or NRM, or decrease OS after allo-HCT using ptCY.