Allogeneic Peripheral Blood Stem Cell Research Articles

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<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<0.001 and 87 vs 94%, p<0.001, respectively). Rates of platelet recovery within 28 days were similar in marrow cohorts, but lower with cryopreserved related (92% vs 96%, p<0.001) and MUD PBSC (87 vs 94%, p<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<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<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<0.001) and platelets (HR=0.61, CI=0.56-0.66, p<0.001), an increased risk of TRM (HR=1.4, CI=1.18-1.66, p<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<0.001) and OS (HR=1.38, CI=1.22-1.58, p<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.

Salvage treatment with plerixafor in poor mobilizing allogeneic stem cell donors: results of a prospective phase II-trial

We conducted a prospective clinical trial to investigate the safety and efficacy of plerixafor (P) in allogeneic peripheral blood stem cells (PBSC) donors with poor mobilization response to standard-dose granulocyte colony-stimulating factor (G-CSF), defined by <2 × 106 CD34 + cells/kg recipient body-weight (CD34+/kg RBW) after 1st apheresis. A single dose of 240 µg/kg P was injected subcutaneously at 10 p.m. on the day of the 1st apheresis. Thirty-seven allogeneic PBSC donors underwent study treatment. The median CD34+ count in peripheral blood was 15/µl on Day 1 after G-CSF alone, versus 44/µl on Day 2 after G-CSF plus P (p < 0.001). The median yield of CD34+ cells was 1.1 × 108 on Day 1 and 2.8 × 108 on Day 2. In contrast to a median yield of only 1.31 × 106 CD CD34+/kg RBW on Day 1, triggering study inclusion, a median of 3.74 × 106 CD CD34+/kg RBW were collected with G-CSF plus P on Day 2. Of 37 donors, 21 reached the target cell count of >4.5 × 106 CD34+/kg RBW (57%, 95%CI 40–73%). No donor experienced a severe adverse event requiring treatment. In conclusion, P might be considered on a case-by-case basis for healthy allogeneic donors with very poor stem cell mobilization success after G-CSF.

905P Outcomes of fludarabine, melphalan and low dose total body irradiation as a reduced intensity regimen in allogeneic peripheral blood stem cell transplantation

905P Outcomes of fludarabine, melphalan and low dose total body irradiation as a reduced intensity regimen in allogeneic peripheral blood stem cell transplantation

Reduced Calcium Signaling Is Associated With Severe Graft-Versus-Host Disease: Results From Preclinical Models and From a Prospective EBMT Study.

Despite its involvement in various immune functions, including the allogeneic activation of T-lymphocytes, the relevance of calcium (Ca2+) for GVHD pathobiology is largely unknown. To elucidate a potential association between Ca2+and GVHD, we analyzed Ca2+-sensing G-protein coupled receptor 6a (GPRC6a) signaling in preclinical GVHD models and conducted a prospective EBMT study on Ca2+ serum levels prior alloSCT including 363 matched sibling allogeneic peripheral blood stem cell transplantations (alloSCTs). In experimental models, we found decreased Gprc6a expression during intestinal GVHD. GPRC6a deficient alloSCT recipients had higher clinical and histopathological GVHD scores leading to increased mortality. As possible underlying mechanism, we found increased antigen presentation potential in GPRC6a–/– alloSCT recipients demonstrated by higher proliferation rates of T-lymphocytes. In patients with low Ca2+ serum levels (≤median 2.2 mmol/l) before alloSCT, we found a higher incidence of acute GVHD grades II-IV (HR = 2.3 Cl = 1.45–3.85 p = 0.0006), severe acute GVHD grades III-IV (HR = 3.3 CI = 1.59–7.14, p = 0.002) and extensive chronic GVHD (HR = 2.0 Cl = 1.04–3.85 p = 0.04). In conclusion, experimental and clinical data suggest an association of reduced Ca2+ signaling with increased severity of GVHD. Future areas of interest include the in depth analysis of involved molecular pathways and the investigation of Ca2+ signaling as a therapeutic target during GVHD.

Influencing Factors and Prevation of Infection in Leukemia Patients after Allogeneic Peripheral Blood Stem Cell Transplantation

To explore the influencing factors and countermeasures of infection in leukemia patients after allogeneic peripheral blood hematopoietic stem cell transplantation. A total of 126 patients with leukemia admitted in our hospital from August 2016 to March 2018 were selected. The number of infected patients after transplantation was recorded, and the causes of infection were analyzed. Among the 126 patients, 43 were positive for infection, and the infection rate was 34.13%. A total of 89 pathogens were detected, of which bacteria accounted for 64.05%; virus accounted for 22.47%, and fungi accounted for 13.48%. The patient's age, donor type, pre-transplant infection, prophylactic use of antibiotics and aGVHD all were factors influencing the patient's infection (P＜0.05). The follow-up results showed that the incidence of infection in the intervention group significantly decreased after intervention with prevention program (P＜0.05). After reasonable nursing intervention, the incidence of infection in the intervention group after follow-up for 12 months was lower than that in the control group (P＜0.05). Pre-transplant infection and prophylactic use of antibiotics are factors influencing the infection after allogeneic hematopoietic stem cell transplantation. The incidence of infection can be reduced by reasonable infection prevention.

Development of diffuse large B-cell lymphoma from duodenal type follicular lymphoma: a retrospective study of 23 cases

The incidence and clinical characteristics of histological transformation (HT) from duodenal type follicular lymphoma (DFL) are unclear. A retrospective analysis was conducted to identify the incidence and clinical features of HT from DFL in 23 cases with DFL. The median follow-up duration was 4.6years (range, 0.8-20years). HT to diffuse large B-cell lymphoma was observed in 2 of 23 cases during follow-up (8.7%). One of two cases transformed at 21months later with increased serum lactate dehydrogenase (LDH; 1655 U/L) and abdominal lymphadenopathy. Partial response was achieved after R-THP (pirarubicin)-COP therapy, but the disease progressed. The other case transformed at 8.3years with an increase of serum LDH (4022 U/L), abdominal lymphadenopathy, and bone marrow involvement. The disease was refractory to DA-EPOCH-R and a high-dose methotrexate/cytarabine regimen. The patient received allogenic peripheral blood stem cell transplantation and finally achieved complete response. Both cases developed HT at nodal or other intestinal lesions with no progression of the primary duodenal lesion. No significant factors for the occurrence of HT were identified. Although the incidence is low, HT could occur in DFL with aggressive clinical manifestations.

Risk factors and associations with clinical outcomes of cytomegalovirus reactivation after haploidentical versus matched-sibling unmanipulated PBSCT in patients with hematologic malignancies.

In allogeneic hematopoietic stem cell transplantation recipients, cytomegalovirus (CMV) infection can cause overt CMV-associated disease, which is a main cause of transplantation-associated mortality. CMV infection correlates closely with donor's type. We therefore examined whether risk factors of CMV reactivation and clinical endpoints in patients with hematologic malignancies after allogeneic peripheral blood stem cell transplantation (PBSCT) differed between using matched-sibling donors (MSD-SCT) and haploidentical donors (HID-SCT). In this retrospective cohort study, we enrolled in 200 consecutive patients received an unmanipulated G-CSF-mobilized allogeneic PBSCT. Ninety (45%) patients received MSD-SCT and 110 (55%) received HID-SCT. Quantitative PCR was used for monitoring of CMV reactivation after transplantation. One-year cumulative incidence of CMV DNAemia was 55.0%, ranging from 23.5% in MSD-SCT group to 81.0% in HID-SCT group (p < 0.001). Although univariate analyses showed that non-myeloid malignancies, disease in complete remission status at transplantation, pretreatment with antithymocyte globulin, HLA-haploidentical donors, male donors, previous Epstein-Barr virus DNAemia, and absolute lymphocyte count on day 30 < 0.6 × 109/L were respectively associated with CMV reactivation after transplantation in total cohort of recipients (all p < 0.05), haploidentical donors were found to be the only independent predictor in multivariate analyses (Hazard ratio = 6.4, p < 0.001). Furthermore, univariate analyses revealed that non-myeloid malignancies and previous Epstein-Barr virus DNAemia were respectively associated with CMV reactivation in MSD-SCT recipients, and female was associated with CMV reactivation in HID-SCT recipients (all p < 0.05). In HID-SCT recipients, but not MSD-SCT recipients, previous CMV DNAemia was associated with a lower cumulative incidence of acute graft-versus-host disease (49.2% vs. 72.6%, p <0.001). CMV DNAemia did not play a role in the relapse rate, but it was strongly associated with an increased risk of non-relapse mortality either in total cohort of recipients (30.5% vs. 13.7%; p =0.003) or in the HID-SCT subgroup (36.0% vs. 16.7%; p =0.030). Relapse-free survival and overall survival in total cohort of recipients with CMV DNAemia were both inferior to those without CMV DNAemia (45.3% vs. 57.6% and 54.8% vs. 65.8%, respectively; both p < 0.05). However, in subgroup analysis according to donor's type, neither relapse-free survival nor overall survival was impacted by CMV status (both p >0.05). This study addressed differences in incidence, risk factors, and associations with clinical outcomes of CMV reactivation after haploidentical versus matched-sibling PBSCT.

Outcomes of 138 myelodysplastic syndrome patients with HLA-matched sibling donor allogeneic hematopoietic stem cell transplantation

目的评价人组织相容性抗原（HLA）匹配同胞供者外周血干细胞移植（MSD-PBSCT）治疗骨髓增生异常综合征（MDS）的疗效。方法回顾性总结2005年9月至2017年12月接受MSD-PBSCT治疗的138例MDS患者临床资料，观察患者总生存（OS）率、无病生存（DFS）率、复发（RR）率及非复发死亡率（NRM），分析影响移植预后的危险因素。结果①中位随访1 050（4~4 988）d，3年OS率、DFS率分别为（66.6±4.1）%、（63.3±4.1）%，3年累积RR率、NRM分别为（13.9±0.1）%、（22.2±0.1）%。②单因素分析显示，发生Ⅲ~Ⅳ度急性移植物抗宿主病（aGVHD）、造血干细胞移植合并症指数（HCT-CI）≥2分组和修订的国际预后积分系统（IPSS-R）极高危组的OS率均显著降低[（42.9±13.2）%对（72.9±4.2）%，χ2=8.620，P=0.003；（53.3±7.6）%对（72.6±4.7）%，χ2=6.681，P=0.010；（53.8±6.8）%对（76.6±6.2）%、（73.3±7.7）%，χ2=6.337，P=0.042]。MDS伴有原始细胞过多-2（MDS-EB2）和MDS转化急性髓系白血病（MDS-AML）患者，移植前接收化疗或去甲基化治疗不改善OS[（60.4±7.8）%对（59.2±9.6）%，χ2=0.042，P=0.838]。③多因素分析显示，HCT-CI是影响移植后OS和DFS的独立危险因素（P=0.012，HR=2.108，95%CI 1.174~3.785；P=0.008，HR=2.128，95%CI 1.219~3.712）。结论HCT-CI评价MDS患者移植后预后优于IPSS-R预后分组；发生Ⅲ~Ⅳ度aGVHD是影响移植后OS的不良预后因素；MDS-EB2和MDS-AML患者可以不化疗直接行MSD-PBSCT。

Systemic β-Adrenergic Receptor Activation Augments the ex vivo Expansion and Anti-Tumor Activity of Vγ9Vδ2 T-Cells.

TCR-gamma delta (γδ) T-cells are considered important players in the graft-vs.-tumor effect following allogeneic hematopoietic cell transplantation (alloHCT) and have emerged as candidates for adoptive transfer immunotherapy in the treatment of both solid and hematological tumors. Systemic β-adrenergic receptor (β-AR) activation has been shown to mobilize TCR-γδ T-cells to the blood, potentially serving as an adjuvant for alloHCT and TCR-γδ T-cell therapy. We investigated if systemic β-AR activation, using acute dynamic exercise as an experimental model, can increase the mobilization, ex vivo expansion, and anti-tumor activity of TCR-γδ T-cells isolated from the blood of healthy humans. We also sought to investigate the β-AR subtypes involved, by administering a preferential β1-AR antagonist (bisoprolol) and a non-preferential β1 + β2-AR antagonist (nadolol) prior to exercise as part of a randomized placebo controlled cross-over experiment. We found that exercise mobilized TCR-γδ cells to blood and augmented their ex vivo expansion by ~182% compared to resting blood when stimulated with IL-2 and ZOL for 14-days. Exercise also increased the proportion of CD56+, NKG2D+/CD62L–, CD158a/b/e+ and NKG2A− cells among the expanded TCR-γδ cells, and increased their cytotoxic activity against several tumor target cells (K562, U266, 221.AEH) in vitro by 40–60%. Blocking NKG2D on TCR-γδ cells in vitro eliminated the augmented cytotoxic effects of exercise against U266 target cells. Furthermore, administering a β1 + β2-AR (nadolol), but not a β1-AR (bisoprolol) antagonist prior to exercise abrogated the exercise-induced enhancement in TCR-γδ T-cell mobilization and ex vivo expansion. Furthermore, nadolol completely abrogated while bisoprolol partially inhibited the exercise-induced increase in the cytotoxic activity of the expanded TCR-γδ T-cells. We conclude that acute systemic β-AR activation in healthy donors markedly augments the mobilization, ex vivo expansion, and anti-tumor activity of TCR-γδ T-cells and that some of these effects are due to β2-AR signaling and phenotypic shifts that promote a dominant activating signal via NKG2D. These findings highlight β-ARs as potential targets to favorably alter the composition of allogeneic peripheral blood stem cell grafts and improve the potency of TCR-γδ T-cell immune cell therapeutics.

A Prospective Phase II Clinical Trial of CD26/Dipeptidyl Peptidase (DPP)-IV Inhibition for Prevention of Acute Graft Versus Host Disease (aGVHD) Following Myeloablative Allogeneic Peripheral Blood Stem Cell (PBSC) Transplantation.

<h3>Introduction</h3> DPP-IV is a homodimeric type II transmembrane receptor identical to the leucocyte surface antigen CD26. The interaction of CD26/DPP-IV on T cells with its ligand caveolin-1 on antigen-presenting cells (APC) enhances T cell activation, proliferation, and cytokine production. It also upregulates CD86 on APC resulting in co-stimulation. In a xenograft mouse model, reducing CD26 expression by a monoclonal antibody prevented aGVHD and preserved graft-versus-tumor effects (Hatano et al. <i>BJH</i> 2013). In a pilot trial testing sitagliptin for enhancement of cord blood engraftment, we observed a lower than expected rate of aGVHD (Farag et al. <i>Stem Cell Dev</i> 2013) and hypothesized that CD26/DPP-IV inhibition with sitagliptin may prevent aGVHD following allogeneic PBSC transplants. <h3>Objective</h3> Conduct a prospective phase II trial to test if sitagliptin can reduce the rate of grade II-IV aGVHD by day +100 following myeloablative allogeneic PBSC transplants (ClinicalTrials.gov, NCT02683525). The primary endpoint was grade II-IV aGVHD by day +100. <h3>Methods</h3> Patients received thiotepa (15 mg/kg) and cyclophosphamide (120 mg/kg), followed by G-CSF mobilized PBSC from matched related (6/6 HLA match) or unrelated (10/10 HLA match) donors. Sitagliptin (600 mg q12 hours) was given on days -1 to day +14, together with tacrolimus and sirolimus through day +100, then tapering until day +180. In a Simon two-stage design, <8 of a total of 36 patients developing grade II-IV aGVHD by day +100 would demonstrate a reduction of aGVHD from a historical rate of 30% to <15% with 80% power and type 1 error = 0.1. <h3>Results</h3> Thirty-six (17 M; 19 F) patients of median age 46 (20-59) years were enrolled. Patients had AML (n=19), ALL (n=9), MDS (n=4), and CML (n=4). Transplants were from matched related (13 patients) or unrelated (23 patients) donors. Acute GVHD occurred in 2 of 36 patients by day +100 (1 grade II; 1 grade IV), for cumulative incidences of 5.6% (95% confidence interval [CI], 0% - 13.2%) and 2.8% (95% CI, 0% - 8.2%) for grade II-IV aGVHD and grade III-IV aGVHD at day +100, respectively (Fig 1). An additional patient developed late-onset grade II aGVHD at day +140 following abrupt stopping of immunosuppression on day +100 for low donor chimerism in absence of relapse. Significant toxicities though day +30 included grades III-IV mucositis (n=15), acute kidney injury (4 with high tacrolimus levels, 1 sepsis), viral reactivation/infection (4 CMV, 2 BK, 1 EBV, 1 HHV6), and passenger lymphocyte syndrome (n=2). Non-relapse mortality was 0% at 12 months. With median follow-up of 699 (118-1312) days, the relapse-free survival was 77.2% (95% CI, 63.2% - 91.1%) and overall survival was 94.3% (95% CI, 86.7% - 100%) at 12 months (Fig 2a-b). <h3>Conclusion</h3> CD26/DPP-IV inhibition with sitagliptin is well-tolerated and significantly reduced the rate of aGVHD by day +100 in patients undergoing myeloablative allogeneic PBSCT transplantation.

Phase II Clinical Trial Evaluating the Standardization of CD3+ T-Cell Dose for Patients Receiving Allogeneic Peripheral Blood Stem Cell Transplants (PBSCT) from Matched Related Donors

<h3>Introduction</h3> Seminal studies of peripheral blood versus bone marrow grafts have elucidated the crucial role of CD3+ T-cells in mediating engraftment, immune reconstitution, disease control, and graft versus host disease (GVHD). An optimal dose-response relationship between the T-cell dose in the graft and outcomes is yet to be defined. Therefore, we performed a phase II clinical trial to evaluate whether T-cell dose standardization would adequately support engraftment and immune reconstitution while mitigating the risk of GVHD. <h3>Methods</h3> We conducted a clinical trial of dose standardization of T-cells between December 2014 and May 2018. Eligible adult patients (pts) with hematologic malignancies undergoing peripheral blood matched sibling allogeneic stem cell transplant were enrolled. Standardized T-cell dose was targeted 15-20 × 10e7. Tacrolimus and methotrexate were utilized for GVHD prophylaxis. The primary endpoint was to determine the incidence of grade II-IV acute GVHD. Secondary endpoints included overall survival (OS), progression-free survival (PFS), non-relapse mortality (NRM), and time to engraftment. Chronic GVHD was captured using conventional criteria. <h3>Results</h3> 17 pts were included in the study. Peripheral blood stem cell (PBSCT) graft from matched sibling donors was used in all pts. The mean age was 52 years (20-68 years). 53% pts were female and 82% were Caucasian. The median T-cell dose was 19.1 × 10e7 (range 9.1-21.8 × 10e7). Indications for PBSCT included AML/MDS (70.6%), ALL (17.6%), NHL and MPN (11.8 %). 35% pts received myeloablative and 65% received reduced-intensity conditioning. 59% had age-adjusted HCT-CI scores ≥3. 16 pts received tacrolimus and methotrexate for GVHD prophylaxis, with 1 patient receiving tacrolimus and mycophenolate. All pts successfully engrafted. The median time to engraftment was 15 days for neutrophils (range 10-20), and 12 days for platelets (range 9-22). The cumulative incidence of grade II-IV and grade III-IV acute GVHD at 1 year was 27% (95%-CI: 7-52) and 22.5 (95%-CI: 4.7-48.4) (no grade IV) and that of chronic GVHD was 47% (22-69) (N=8, all extensive by conventional criteria). 18% pts reactivated CMV (median - 40 days, range 33-50). 47% pts were alive in remission after a median follow-up of 18.1 months (3.3-52.2). The cumulative incidence of relapse at 1 year was 23.5% (95% CI: 7-46) (Figure 1). The 1 year PFS was 53% (95% CI: 28-73), and the OS was 65% (95% CI: 37-82). <h3>Conclusion</h3> Administration of a lower standardized T-cell dose is feasible, and when used in combination with standard immune suppression did not negatively affect outcomes. This study paves the way for a larger trial to evaluate the optimal T-cell dose and immune suppressive therapy to strike a favorable GVHD/GVL balance. Such a strategy could be used as a platform for additional interventions aimed towards improving the outcome of PBSCT for hematologic malignancies.

Very Low-Dose Anti-Thymocyte Globulin in HLA-Matched PBSCT – Results of a Phase II Study (JSCT-ATG 15) –

<h3>Background</h3> Allogeneic peripheral blood stem cell transplantation (PBSCT) is associated with an increased risk of severe acute graft-versus-host disease (GVHD) and chronic GVHD compared to bone marrow transplantation. Although several studies have shown that anti-thymocyte globulin (ATG) reduces severe acute and chronic GVHD in PBSCT following myeloablative conditioning (MAC), an optimal of ATG remains to be determined. <h3>Methods</h3> We conducted a multicenter phase II study to investigate safety and efficacy of very low-dose ATG in patients undergoing HLA-matched PBSCT after MAC (UMIN000018645). A total of 2mg/kg ATG (Thymoglobulin; 1mg/kg, days -2, -1) was given in combination with calcineurin inhibitor and methotrexate for prophylaxis of GVHD. The primary endpoint was grade III to IV GVHD at day100. <h3>Results</h3> From November 2015 to October 2018, a total of 77 patients were enrolled and 72 patients with a median age of 46.5 years were eligible for analysis. These included acute myeloid leukemia (n = 36), acute lymphoblastic leukemia (n = 19), myelodysplastic syndrome (n = 8), lymphoma (n = 5), and others (n = 4). All patients achieved neutrophil engraftment with a median of 13 days. The primary endpoint, cumulative incidence of grades III to IV acute GVHD at day100 was 1.4% (95% CI, 0.1 to 6.7%), which was greatly less than our pre-defined statistical threshold value in this study (18%), and the incidence of chronic GVHD at 1 year was also significantly low (all-grade; 15.3%, moderate to severe; 5.6%). Non-relapse mortality, relapse, overall survival, progression-free survival, and GVHD-free, relapse-free survival rate at 1 year were 4.2%, 20.8%, 84.7%, 75.0%, and 69.4%, respectively. <h3>Conclusion</h3> Our study demonstrated that GVHD prophylaxis using very low-dose ATG in HLA-matched PBSCT is feasible and effective for significant prevention of severe acute and chronic GVHD.

A Case of Donor Cell Leukemia after Allogenic Peripheral Blood Stem Cell Transplantation for Acute Promyelocytic Leukemia with PML-RARA

A Case of Donor Cell Leukemia after Allogenic Peripheral Blood Stem Cell Transplantation for Acute Promyelocytic Leukemia with <i>PML-RARA</i>

Analysis of factors associated with successful allogeneic peripheral blood stem cell collection in healthy donors

BackgroundThe collection of a sufficient number of stem cells is important for success of allogeneic hematopoietic stem cell transplantation (HSCT). This study aimed to investigate the factors associated with successful allogeneic peripheral stem cell (PBSC) collection in healthy donors. MethodsWe retrospectively reviewed clinical data of allogeneic PBSC collection in 175 donors from 2007 to 2017 at the National Cancer Center, Korea. This study analyzed factors associated with the CD34+ cell yield such as the characteristics of donors, including age, laboratory results before apheresis, and data of procedures on the first day. The CD34+ cell dose of ≥ 4.0 × 106/kg have recently been the accepted minimum recommended dose in allogeneic HSCT settings, and this was the target dose in our study. ResultsThe factors associated with the CD34+ cell yield were age (p = 0.007), baseline platelet (PLT) (p = 0.014), and pre-collection hematopoietic progenitor cells (HPCs) (p = 0.001) by multivariate analysis. This study represented that age, baseline platelet count, and pre-collection HPC count are important predictive factors as shown in other previous studies. ConclusionOur data suggest that young age, high baseline platelet counts and high HPC counts before collection might be useful for identifying successful mobilizers.

Allogeneic Peripheral Blood Stem Cell Transplant: Correlation of Donor Factors with Yield, Engraftment, Chimerism, and Outcome: Retrospective Review of a Single Institute During a 3-Year Period.

Donor factors have a variable correlation with cluster of differentiation (CD)34+ cell dose in allogeneic peripheral blood stem cell (PBSC) harvests. CD34+ cell dose affects the speed of hematopoietic recovery and percentage of donor chimerism in the recipient. A total of 25 allogeneic PBSC transplants performed during a 3-year period were included. All donors underwent mobilization with filgrastim. Leukapheresis, flowcytometric CD34+ cell enumeration, and chimerism analysis were performed and correlated with recipient outcome. Besides age, all other donor parameters had a positive correlation with CD34+ cell count. Engraftment kinetics and chimerism had a positive correlation with the CD34+ yield of the PBSC product. Acute graft-vs-host disease (GVHD) was observed in patients with complete chimerism at day 30 after transplantation. Adequate CD34+ cell yield happens in healthy donors, independent of donor demographic patterns with G-CSF only. A diverse population of donors can thus be approached for Matched Unrelated Donor (MUD) transplants. An accurate quantitative analysis of early donor chimerism in the recipient (at day 30) is an excellent tool for post-transplant monitoring for acute GvHD.

CD34+ Cell Dose Influences Survival after Allogeneic Peripheral Blood Stem Cell Transplantation with Post-Transplant Cyclophosphamide

Introduction: Higher infused total nucleated cell dose (TNC) in allogeneic bone marrow transplant (BMT) with post-transplant cyclophosphamide (PTCy) resulted in improved overall survival (OS) in a recent report (McCurdy, et al. BBMT. 2018). As many centers prefer peripheral blood stem cell grafts (PBSCT) with PTCy, the optimal cell dose with this platform requires elucidation. Methods: We retrospectively evaluated 144 consecutive adult patients with hematologic malignancies treated at the Moffitt Cancer Center between 2012-2018 with allogeneic T-cell replete PBSCT followed by PTCy-based graft-versus-host disease (GVHD) prophylaxis. Data were extracted from the Moffitt BMT Research &amp; Analysis Information Network (BRAIN) database. Both myeloablative (n=87) and reduced intensity (n=57) conditioning regimens were included. For analyses, CD34+ cell dose was stratified into low (&lt;5 x106/kg), intermediate (5-10 x 106/kg) and high (&gt;10x106/kg). TNC was stratified as higher or lower than the median. CD3+ T cell dose was evaluated as a continuous, linear variable. Associations with transplant related survival outcomes were assessed using univariate and multivariate Cox proportional hazard survival models. Fine and Gray regression models were used to assess associations of transplant related endpoints with competing risks. Kaplan Meier curves and cumulative incidence function curves were also plotted. RESULTS: The median follow-up for the entire cohort was 24 months. The median age at PBSCT was 58 (range: 21-76) years. Donors were haploidentical (n=72, 50%), matched unrelated (n=39, 27%), matched related (n=18, 13%), and mismatched unrelated (n=15, 10%). Median CD34+ cell dose was 8.12 x 106/kg (range: 2.27 - 22.4 x 106/kg). Stratified CD34+ dose was low for 16 patients (11.1%), intermediate for 93 patients (64.6%), and high for 35 patients (24.3%). Median CD3+ dose was 2.89 x 108 (range: 2.33 x 105 - 6.54 x 108/kg). Median TNC was 9.66 x 108/kg (range: 3.82 x 108 - 1.04 x 109/kg). Overall, successful neutrophil engraftment by day 30 was achieved in 94% (95% CI 91-98%) and platelet engraftment (&gt;20,000/mL) by day 100 in 87% (95% CI 81-93%) of all patients. The likelihood of neutrophil recovery was similar in the high and low CD34+ cell groups, while it was higher for the intermediate CD34+ cell group (HR=1.52, 95% CI 1.0-2.2; p=0.03). Platelet recovery was similar in the intermediate and high CD34+ cell groups, but significantly lower in low CD34+ cell group (HR=0.38, 95% CI 0.2-0.8; p=0.01). CuI of grade II-IV acute GVHD at day 100 was 39% (95% CI 32-48%) and of grade III-IV acute GVHD was 10% (95% CI 6-17%). CuI of chronic GVHD at 2 years was 50% (95% CI 41-59%). The CD34+ cell dose had no significant impact on either acute or chronic GVHD. Nonrelapse mortality (NRM) at 1 year was 19% (95% CI 13-27%). By CD34+ cell dose, the rates of NRM for low, intermediate, and high dose were 46% (95% CI 25-85%), 15% (95% CI 10-25%), and 15% (95% CI 7-34%), respectively (p=0.002). Relapse rate was 30% at 2 years with no differences across dose levels. Progression free survival (PFS) probability at 2 years was 47% (95% CI 39-57%) for the entire group, 0% (95% CI 0%) for the CD34+ low group, 53% (95% CI 42-65%) for the intermediate group and 51% (95% CI 35-73%) for the high dose group (p=0.0003). Two-year OS for the entire group was 57% (95% CI 49-67%), and was inferior in the low group (0%, 95% CI 0%) with no difference between the intermediate (61%, 95% CI 50-73%) and high (67%, 95% CI 52-87%) CD34+ cell dose groups (p=0.0002). In multivariable modeling, the low CD34+ cell dose group was associated with worse NRM (HR=4.1, 95% CI 1.2-14.5, p=0.03), PFS (HR=2.9, 95% CI 1.3-6.5, p=0.01), and OS (HR=3.2, 95% CI 1.4-7.6, p=0.01) compared with the high group, while there were no differences between the high and intermediate groups. Increasing CD3+ dose was also associated with improved NRM (HR=0.8, 95% CI 0.69-0.97, p=0.02), PFS (HR=0.7, 95% CI 0.5-0.9, p=0.02), and OS (HR=0.7, 95% CI 0.5-0.9, p=0.004). TNC had no impact on survival outcomes. CONCLUSION: In patients receiving allogeneic PBSCT with PTCy, CD34+ cell doses below 5 x 106 cells/kg yielded inferior OS and PFS, attributable to higher NRM. Doses of 5-10 x 106 cells/kg and &gt;10 x 106 cells/kg resulted in comparable outcomes. Higher CD3+ dose/kg was also associated with improved survival outcomes. Overall, this study supports targeting a CD34+ dose of &gt;5 x 106 cells/kg for allogeneic PBSCT with PTCy. Disclosures Nishihori: Novartis: Research Funding; Karyopharm: Research Funding. Bejanyan:Kiadis Pharma: Other: advisory board.

Mixed Chimerism and Secondary Graft Failure in Allogeneic Hematopoietic Stem Cell Transplantation for Aplastic Anemia.

Mixed chimerism (MC) and/or secondary graft failure (SGF) with recipient- or donor-type chimerism is a major obstacle in allogeneic transplantation for aplastic anemia (AA). From a registry database in Japan, patients with AA age >15 years who underwent a first allogeneic bone marrow or peripheral blood stem cell transplantation between 2000 and 2014 and achieved engraftment were included in this study. MC that did not require either granulocyte-colony stimulating factor (G-CSF) or transfusion support (group 1), MC (not SGF) that required G-CSF and/or transfusion support (group 2), SGF with MC or complete recipient-type chimerism (group 3), and SGF with complete donor-type chimerism (group 4) developed in 26, 16, 19, and 17 patients, respectively. The overall median duration of follow-up for survivors was 1727 days. The overall survival (OS) was 90.4% at 1 year and 83.5% at 5 years in patients without MC or SGF (n = 340), which was not different from the OS in groups 1 and 2. However, inferior OS was observed in group 3 (1 year, 52.1%; 5 years, 52.1%) and group 4 (1 year, 82.4%; 5 years, 56.3%). In multivariate analyses, the use of fludarabine (Flu) and the absence of irradiation in conditioning were associated with the development of SGF with MC or complete recipient-type chimerism, and the use of Flu in conditioning was associated with SGF with complete donor-type chimerism. In conclusion, the use of Flu may affect the occurrence of SGF with both recipient-type and donor-type chimerism.

1101P - Impact of FLT3-ITD mutation on post-transplant outcome of adult acute myeloid leukemia (AML) is modified by the concomitant NPM1 mutation and pre-transplant remission status: A report from Taiwan Bone Marrow Transplant Registry (TBMTR)

BackgroundThe impact of FLT3ITDmut on post-transplant outcome of adult AML remains controversial. A decreased leukemia-free survival (LFS) after allogeneic hematopoietic stem cell transplantation (HSCT) for adult AML in complete remission (CR) was observed in EBMT analysis but not CIBMTR. The impact of FLT3ITDmut on AML patients in later disease stage, as well as the influence of concurrent NPM1 mutation on post-transplant outcome, is less well studied. MethodsIn this study, only adults aged ≥ 18 years with a diagnosis of de novo AML who received allogeneic peripheral blood stem cell transplantation and with known FLT3ITD and NPM1 status in the registry were included. Kaplan-Meier estimates were used to calculate LFS and overall survival (OS). Multivariate analyses for LFS and OS were performed using Cox proportional hazards model. ResultsFor patients who received transplant in CR1, the 2 year LFS, OS, and relapse incidence (RI) were 33.1%, 48.7%, and 56%, respectively, for patients of FLT3ITDmutNPM1wt, which are much inferior to patients of FLT3ITDmutNPM1mut (74.3%, 77.8%, and 25.7%, respectively) and patients of FLT3ITDwt (53.5%, 71%, and 37.3%, respectively). In multivariate analysis, patients of FLT3ITDmutNPM1wt, but not patients of FLT3ITDmutNPM1mut, were associated with significant poor LFS (HR 2.672, p=0.007) and OS (HR 2.439, p=0.038) compared with patients of FLT3ITDwt. For patients who received transplant after CR1, FLT3ITDmut was associated with significant poor LFS (HR 1.775, p=0.013) and OS (HR 1.716, p=0.028) compared with patients of FLT3ITDwt. NPM1 mutation dose not influence the outcome. ConclusionsFor patients in CR1, the impact of FLT3ITD is markedly modified by NPM1 status. The post-transplant outcome remains poor for patients of FLT3ITDmutNPM1wt and highlights the need for a novel approach (such as maintenance FLT3ITD inhibitor after transplant). For patients after CR1, the post-transplant outcome is very poor for patients of FLT3ITDmut and is independent of NPM1 status. Legal entity responsible for the studyThe author. FundingHas not received any funding. DisclosureThe author has declared no conflicts of interest.

Validation of a formula predictive of peripheral blood stem cell yield and successful collection in healthy allogeneic donors

BackgroundAn efficient mobilization and collection of peripheral blood stem cells (PBSCs) are crucial to optimize engraftment in the recipient. We aim to validate a formula that predicted CD34+ cell yield and to describe variables that correlated with high yield mobilization and collection in healthy donors. MethodsWe retrospectively analyzed clinical and laboratory data from healthy donors who underwent PBSC collection from 2006 to 2015. The predicted number of collected cells was calculated using the following formula: Total number of CD34+ (cells×106/kg) yield=[(peripheral CD34+ cells/μL)×(0.43)/recipient body weight (kg)]×total liters processed. ResultsWe evaluated 338 collections from 307 allogeneic PBSC donors. The predicted versus the observed number of CD34+ cells/kg collected yielded an r-value of 0.775 (0.726–0.816; p<0.0001). Overall, 55.7% donors had an acceptable mobilization level. Donors with a body weight <67kg were less likely to yield a satisfactory CD34+ cell count (OR=0.44; 95% CI 0.24–0.81), while a white blood cell (WBC) count >40×109/L (OR=3.69; 2.11–6.46) and platelet count ≥200×109/L (OR=2.09; 1.26–3.47) on the day of collection predicted a good level of mobilization. Predictors of a CD34+ cell yield/kg of ≥4×106 with only one apheresis session were: circulating CD34+ cells/μL >40 (OR=16; 6.94–36.93), hemoglobin ≥14g/dL (OR=3.40; 1.53–7.57), WBC >40×109/L (OR=4.61; 2.10–10.10) on the first collection day, and a positive delta weight between donor and recipient (OR=3.10; 1.36–7.06). ConclusionThe formula for predicting CD34+ cell yield is accurate and suggests the optimal length of time for successful leukapheresis. Validation of the predictors of successful mobilization will help to further refine PBSC leukapheresis procedures.

IL12 and IFNγ secretion by donor mononuclear cells in response to host antigens may predict acute GVHD after HSCT

One persistent problem of allogeneic hematopoietic stem cell transplantation (HSCT) is acute graft versus host disease (GVHD). The role of cytokines in the pathogenesis of GVHD has been acknowledged.We aimed, in the current study, to investigate the possibility of prediction of acute GVHD through investigating the pattern of interleukin 12 (IL12) and interferon gamma (IFNγ) production of both patients' origin and donors' origin. A total of 45 patients, receiving allogeneic peripheral blood (PB) stem cells from an identical sibling, were included in the study. Patients' plasma was collected after conditioning, during aplastic phase (representing patients' origin) and after engraftment (representing donors' origin). In addition an aliquot from the graft was used as responders in mixed lymphocyte culture (MLC) for 3 days with patients' mitomycin-treated mononuclear cells as stimulators. Culture supernatant was used for detection of IL12 and IFNγ of donors' origin. Fourteen patients developed acute GVHD. In culture supernatant, IL12 was detectable in 7/14 cases with and in none of 31 cases without acute GVHD (p= <0.001). The corresponding figures for IFNγ were 10/14 and 3/31 with significantly higher IFNγ level in cases with than in cases without acute GVHD (p = 0.001). At engraftment the corresponding figures were 7/14 and 5/31 for IL12 and 11/14 and 7/31 for IFNγ with significantly higher cytokine levels in cases with acute GVHD (p = 0.008 and p = 0.001 respectively). At a cutoff of 0.89 pg/ml, IL12 in culture supernatant may predict acute GVHD with absolute specificity of 100% and a sensitivity of 50%. In conclusion, IL12 and IFNγ of donors' origin not of patients' origin may predict the occurrence of acute GVHD. The MLC model may allow prediction of acute GVHD upfront before conditioning of the patient or mobilization of the donor.