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Cytokine release syndrome (CRS) following haploidentical hematopoietic cell transplantation (HCT) resembles the CRS after chimeric antigen receptor (CAR)-T therapy. We conducted this single-center retrospective study evaluating the association of post-haploidentical HCT CRS with clinical outcomes and immune reconstitution. One hundred sixty-nine patients who underwent haploidentical HCT between 2011 and 2020 were identified. Of these, 98 patients (58%) developed CRS after HCT. CRS was diagnosed based on the presence of fever within the first 5 days after HCT without evidence of infection or infusion reaction, and graded according to established criteria. The development of post-haploidentical HCT CRS was associated with a lower incidence of disease relapse (p=0.024) but with an increased risk of chronic GVHD (p=0.01). The association of CRS with a lower incidence of relapse was not confounded by graft source or disease diagnosis. Neither CD34 nor TNC dose was associated with CRS independently of graft type. In patients developing CRS, CD4+ Treg (p

The ability of post-transplant cyclophosphamide (PTCY) to facilitate stem cell transplantation using HLA-haplotype-mismatched donors has spurred interest in whether PTCY can improve clinical outcomes in patients with HLA-matched unrelated donors undergoing peripheral blood stem cell transplantation (PBSCT). We investigated our institutional experience with 8/8 or 7/8 HLA-matched unrelated donor PBSCT using PTCY-based GVHD prophylaxis compared to conventional tacrolimus-based regimens. We compared overall survival (OS), progression-free survival (PFS), relapse, non-relapse mortality, and acute and chronic GVHD in 107 adult patients receiving a PTCY-based regimen versus 463 patients receiving tacrolimus-based regimens for GVHD prophylaxis. All patients were transplanted for hematologic malignancies. The two cohorts were well balanced for baseline characteristics except that more patients in the PTCY cohort received 7/8 matched PBSCT. There was no difference in acute GVHD. All-grade chronic GVHD and moderate-severe chronic GVHD were substantially reduced in patients receiving PTCY compared to tacrolimus-based regimens (2-year moderate-severe chronic GVHD: 12% vs 36%, p

To develop a prognostic model for patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HCT) for myelofibrosis (MF). We examined 623 patients undergoing allo-HCT between 2000 - 2016 in the USA (CIBMTR cohort). A Cox multivariable model was used to identify factors prognostic of mortality. A weighted score using these factors was assigned to patients transplanted in Europe (EBMT cohort) (n = 623). Age above 50 (hazard ratio [HR], 1.39; 95% confidence interval [CI], 0.98 -1.96), and HLA matched unrelated donor (HR, 1.29; 95% CI, 0.98-1.7) were associated with increased hazard of death and were assigned 1 point. Hemoglobin lower than 100g/L at time of transplant (HR, 1.63; 95% CI, 1.2- 2.19), and a mismatched unrelated donor (HR, 1.78; 95% CI, 1.25- 2.52), were assigned 2 points. The 3-year overall survival (OS) in patients with a low (1-2 points), intermediate (3-4 points) and high score (5 points) were 69% (95% CI, 61% -76 %), 51 % (95% CI, 46% -56.4 %), and 34% (95% CI, 21% - 49%), respectively (P. < 0.001). Increasing score was predictive of increased transplant related mortality (TRM) (P .0017) but not for relapse (P. 0.12). The derived score was predictive for OS (P. < 0.001) and TRM (P. 0.002) but not relapse (P. 17) in the EBMT cohort as well. The proposed system was prognostic of survival in two large cohorts, CIBMTR and EBMT, and can easily be applied by clinicians consulting patients with MF on transplant outcomes.

Supplemental Table 1. Multivariate analysis of late relapse, transplant-related mortality, overall survival after HCT for each disease (AML, ALL, CML, MDS)

Purpose: Malignancy relapse remains a major obstacle for successful allogeneic hematopoietic cell transplantation (HCT). Chronic graft-versus-host disease (cGVHD) is associated with fewer relapses. However, when studying effects of cGVHD on relapse, it is difficult to separate from acute GVHD effects as most cases of cGVHD occur within the first year after transplant at the time when acute GVHD is still active.Experimental Design: This study based on CIBMTR registry data investigated cGVHD and its association with the incidence of late relapse and survival in 7,489 patients with acute myelogenous leukemia (AML), acute lymphoblastic leukemia (ALL), chronic myelogenous leukemia (CML), and myelodysplastic syndromes (MDS), who were leukemia free at 12 months after myeloablative allogeneic HCT.Results: Forty-seven percent of the study population was diagnosed with cGVHD at 12 months after transplant. The protective effect of cGVHD on late relapse was present only in patients with CML [RR, 0.47; 95% confidence interval (CI), 0.37–0.59; P < 0.0001). cGVHD was significantly associated with higher risk of treatment-related mortality (TRM; RR, 2.43; 95% CI, 2.09–2.82; P < 0.0001) and inferior overall survival (RR, 1.56; 95% CI, 1.41–1.73; P < 0.0001) for all diseases. In patients with CML, all organ sites and presentation types of cGVHD were equally associated with lower risk of late relapse.Conclusions: These results indicate that clinically relevant antileukemia effects of cGVHD on late relapses are present only in CML but not in AML, ALL, or MDS. Chronic GVHD in patients who are 1-year survivors after myeloablative allogeneic HCT is primarily associated with higher TRM and inferior survival. Clin Cancer Res; 21(9); 2020–8. ©2014 AACR.See related commentary by Gill, p. 1981

Supplemental Table 4. Multivariate analysis showing impact of cGVHD characteristics on treatment related mortality, disease free survival, overall survival in patients with AML, ALL, MDS who developed cGVHD

Supplemental Table 2. Multivariate analysis showing impact of cGVHD characteristics in CML patients on relapse

Supplemental Table 3. Multivariate analysis showing impact of cGVHD characteristics on treatment related mortality, disease free survival and overall survival in patients with CML who developed cGVHD

Supplemental Figure 1. Cumulative incidence of cGVHD, relapse and death in patients with AML, ALL, CML, MDS

Steroid-refractory chronic graft versus host disease (cGVHD) remains a significant cause of morbidity and mortality following allogeneic transplantation. Abatacept is a selective co-stimulation modulator, used for the treatment of rheumatologic disease, and was recently the first drug to be approved by the FDA for the prophylaxis of acute graft versus host disease. We conducted a Phase II study to evaluate the efficacy of Abatacept in steroid-refractory cGVHD (clinicaltrials.gov #NCT01954979). The overall response rate was 58%, with all responders achieving a partial response. Abatacept was well-tolerated with few serious infectious complications. Immune correlative studies showed a decrease in IL-1-alpha, IL-21, and TNF-alpha as well as decreased PD-1 expression by CD4+ T cells in all patients after treatment with Abatacept, demonstrating the effect of this drug on the immune microenvironment. The results demonstrate that Abatacept is a promising therapeutic strategy for the treatment of cGVHD.

For myelodysplastic syndrome (MDS), allogeneic hematopoietic cell transplantation (alloHCT) is the only available curative therapy. The Blood and Marrow Transplant Clinical Trials Network study 1102 (BMT CTN 1102, NCT02016781) was a multicenter, biologic assignment trial based on matched donor availability in adults aged 50-75 with higher risk de novo MDS who were candidates for reduced-intensity conditioning (RIC) alloHCT. The primary analysis showed that those who received alloHCT had a survival benefit, but whether this is at the cost of worse quality of life (QOL) has not been described in detail. English- and Spanish-speaking trial participants completed the Functional Assessment of Cancer Therapy-General (FACT-G), the SF-36, and the EQ-5D, at enrollment, every 6 months until 24 months, and 36 months. We compared patient-reported outcome (PRO) scores between study arms using an inverse probability weighted-independent estimating equation (IPW-IEE) model. Between January 2014 and November 2018, 384 subjects (median age 66.7 years, range: 50.1-75.3) enrolled at 34 centers. PRO completion rates were generally high at 65%-78%. The PRO trajectories for both arms were similar, with most decreasing or stable from baseline to 6 months and improving thereafter. Baseline PRO scores were the most consistent independent predictors of subsequent QOL outcomes and survival, even after controlling for clinical and patient-level factors. For older adults with MDS, the survival advantage associated with donor availability and alloHCT did not come at the cost of worse QOL. These results should reassure older patients and clinicians who prefer a curative approach to treating MDS.

Chronic graft-versus-host disease (cGVHD) remains a frequent cause of nonrelapse morbidity and mortality after allogeneic hematopoietic stem cell transplantation. Despite recent advances, options for steroid-refractory (SR) cGVHD are limited. In previous trials of low-dose interleukin-2 (LD IL-2), the immunomodulatory properties of regulatory T cells (Tregs) have been harnessed to treat SR-cGVHD safely and effectively. In the present study, we combined a single infusion of Treg-enriched lymphocytes (Treg DLI) from the original stem cell donor with in vivo Treg expansion using LD IL-2 (1 × 106 IU/m2 per day for 8 weeks) in 25 adult patients with SR-cGVHD. Treg were not expanded ex vivo. Treg DLI was initiated at 0.1 × 106 cells per kg patient and escalated to a maximum dose of 1 × 106 cells per kg. Treg DLI plus LD IL-2 was well tolerated and led to partial responses (PR) in 5 of 25 patients (20%) after 8 weeks of therapy. Ten additional patients (40%) had stable disease with minor responses not meeting PR criteria. Patients at all dose levels had similar Treg expansion without significant changes in CD4+ conventional T cells or CD8+ T cells. High-throughput sequencing of the T-cell receptor β locus showed selective improvement of Treg diversity. A subset of DLI-derived Treg clones showed preferential expansion at week 8 and long-term persistence 1-year postinfusion. We demonstrate for the first time that infusion of polyclonal healthy donor Tregs followed by expansion with LD IL-2 is safe in patients with SR-cGVHD, thus establishing a foundation for future adoptive Treg therapies in the posttransplant setting. This trial was registered at www.clinicaltrials.gov as #NCT01937468.

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome marked by a severe hyperinflammatory state characterized by aberrant T- and natural killer-cell activity leading to prolonged hypercytokinemia and can be rapidly fatal if not diagnosed and treated early. While upfront therapy is aimed at reducing hyperinflammation and controlling possible triggers, allogeneic hematopoietic stem cell transplantation (HSCT) is indicated for primary and relapsed/refractory cases to attain sustained remission. While this has been explored extensively in the pediatric population, there are limited data on adults undergoing HSCT for HLH. We analyzed transplant outcomes in an adult HLH population in the modern era who were transplanted at Dana-Farber Cancer Institute from 2010 onwards. Patients were uniformly transplanted on a reduced intensity platform incorporating early administration of alemtuzumab with standard infectious and graft-versus-host disease (GVHD) prophylaxis. Engraftment was documented for all patients. At 3 years after transplantation, overall survival (OS) was 75% (95% confidence interval [CI], 51-89) while 3-year progression-free survival (PFS) was 71% (95% CI, 46-86). The 3-year cumulative incidence of relapse was 15% (95% CI, 3.4-33). There were no isolated HLH relapses without relapse of malignancy. The cumulative incidence of nonrelapse mortality at 3 years was 15% (95% CI, 3.5-34). Infectious complications and GVHD outcomes were comparable to standard reduced-intensity conditioning (RIC) transplantation at our institute. Mixed chimerism was common but did not correlate with transplant outcomes. Our data suggest that the immune defect in HLH can be abrogated with allogeneic transplantation using a reduced intensity regimen with early administration of alemtuzumab as preconditioning, providing a potentially curative option for this difficult disease.

The use of haploidentical donor hematopoietic cell transplantation (haploHCT) has expanded, but recent reports raise concern for increased rates of infectious complications. The incidence and risk factors for invasive fungal disease (IFD) after haploHCT have not been well elucidated. This study aimed to evaluate the incidence and risk factors for IFD after haploHCT. The identification of key risk factors will permit targeted prevention measures and may explain elevated risk for other infectious complications after haploHCT. This single-center retrospective study included all adults undergoing haploHCT between May 2011 and May 2021 (n = 205). The 30-day and 1-year cumulative incidences of proven or probable IFD and 1-year nonrelapse mortality (NRM) were assessed. Secondary analyses evaluated risk factors for invasive yeast infection (IYI) using univariate and multivariable Cox regression models. Twenty-nine patients (14%) developed IFD following haploHCT. Nineteen (9.3%) developed IYI in the first year, 13 of which occurred early, with a 30-day cumulative incidence of 6.3% (95% confidence interval [CI], 2.9% to 9.6%) and increased NRM in patients with IYI (53.9% versus 10.9%). The majority of yeast isolates (17 of 20; 85%) were fluconazole- susceptible. The incidence of IYI in the first 30 days after haploHCT was 10% in the 110 patients (54%) who developed cytokine release syndrome (CRS) and 21% in the 29 patients (14%) who received tocilizumab. On multivariable analysis, acute myelogenous leukemia (hazard ratio [HR], 6.24; 95% CI, 1.66 to 23.37; P = .007) and CRS (HR, 4.65; 95% CI, 1.00 to 21.58; P = .049) were associated with an increased risk of early IYI after haploHCT. CRS after haploHCT is common and is associated with increased risk of early IYI. The identification of CRS as a risk factor for IYI raises questions about its potential association with other infections after haploHCT. Recognition of key risk factors for infection may permit the development of individualized strategies for prevention and intervention and minimize potential side effects.

There have been no large studies comparing reduced-intensity/non-myeloablative conditioning (RIC/NMA) to myeloablative conditioning (MAC) regimens in T-cell non-Hodgkin lymphoma (T-NHL) patients undergoing allogeneic transplant (allo-HCT). A total of 803 adults with peripheral T-cell lymphoma, anaplastic large cell lymphoma and angioimmunoblastic T-cell lymphoma (age 18-65 years), undergoing allo-HCT between 2008-2019 and reported to the Center for International Blood and Marrow Transplant Research with either MAC (n = 258) or RIC/NMA regimens (n = 545) were evaluated. There were no significant differences between the two cohorts in terms of patient sex, race and performance scores. Significantly more patients in the RIC/NMA cohort had peripheral blood grafts, haematopoietic cell transplantation-specific comorbidity index (HCT-CI) of ≥3 and chemosensitive disease compared to the MAC cohort. On multivariate analysis, overall survival (OS) was not significantly different in the RIC/NMA cohort compared to the MAC cohort (hazard ratio (HR) = 1.01, 95% confidence interval (CI) = 0.79-1.29; p = 0.95). Similarly, non-relapse mortality (NRM) (HR = 0.85, 95% CI = 0.61-1.19; p = 0.34), risk of progression/relapse (HR = 1.29; 95% CI = 0.98-1.70; p = 0.07) and therapy failure (HR = 1.14; 95% CI = 0.92-1.41, p = 0.23) were not significantly different between the two cohorts. Relative to MAC, RIC/NMA was associated with a significantly lower risk of grade 3-4 acute graft-versus-host disease (HR = 0.67; 95% CI = 0.46-0.99, p = 0.04). Among chemorefractory patients, there was no difference in OS, therapy failure, relapse, or NRM between RIC/NMA and MAC regimens. In conclusion, we found no association between conditioning intensity and outcomes after allo-HCT for T-cell NHL.

Despite advances in the field, chronic graft-versus-host-disease (cGVHD) remains a leading cause of morbidity and mortality following allogenic hematopoietic stem cell transplant. Because treatment options remain limited, we tested efficacy of anticancer, chromatin-modifying enzyme inhibitors in a clinically relevant murine model of cGVHD with bronchiolitis obliterans (BO). We observed that the novel enhancer of zeste homolog 2 (EZH2) inhibitor JQ5 and the BET-bromodomain inhibitor JQ1 each improved pulmonary function; impaired the germinal center (GC) reaction, a prerequisite in cGVHD/BO pathogenesis; and JQ5 reduced EZH2-mediated H3K27me3 in donor T cells. Using conditional EZH2 knockout donor cells, we demonstrated that EZH2 is obligatory for the initiation of cGVHD/BO. In a sclerodermatous cGVHD model, JQ5 reduced the severity of cutaneous lesions. To determine how the 2 drugs could lead to the same physiological improvements while targeting unique epigenetic processes, we analyzed the transcriptomes of splenic GCB cells (GCBs) from transplanted mice treated with either drug. Multiple inflammatory and signaling pathways enriched in cGVHD/BO GCBs were reduced by each drug. GCBs from JQ5- but not JQ1-treated mice were enriched for proproliferative pathways also seen in GCBs from bone marrow-only transplanted mice, likely reflecting their underlying biology in the unperturbed state. In conjunction with in vivo data, these insights led us to conclude that epigenetic targeting of the GC is a viable clinical approach for the treatment of cGVHD, and that the EZH2 inhibitor JQ5 and the BET-bromodomain inhibitor JQ1 demonstrated clinical potential for EZH2i and BETi in patients with cGVHD/BO.

7537 Background: The recently reported ZUMA-7 and TRANSFORM trials demonstrate superior event-free survival among patients with primary refractory or early relapsed DLBCL compared to salvage chemotherapy with ASCT. However, given a cost of >$370,000, it is not known whether second-line CAR-T is cost-effective compared to ASCT. Thus, we developed a state-transition microsimulation model to simulate clinical outcomes and costs associated with therapy for DLBCL patients in first relapse, using ZUMA-7 and TRANSFORM data. Methods: The model begins at initiation of second-line therapy comparing salvage chemotherapy with ASCT or CAR-T therapy. We examined a three-year time horizon, including crossover to the alternative strategy therapy in the third line, as well as subsequent lines of therapy, using open-source Amua 0.3.0 software. Base case analysis was performed using 1000 first-order Monte Carlo simulations and probabilistic sensitivity analysis (PSA) was performed with 1000 simulations to test model uncertainty. Conditional probabilities of survival and disease progression were extracted from Kaplan-Meier curves from pivotal clinical trials using the WebPlotDigitizer tool. Costs were estimated from public sources in US Dollars ($) and effects were estimated in quality-adjusted life years (QALY) using published utility values. Results: Median overall survival was 15 months (95% confidence interval [CI] 13-19 months) with ASCT and 21 months (95% CI 17-29 months) with CAR-T. The PSA demonstrated costs and effectiveness per patient of $243,581 and 1.06 QALYs with ASCT and $470,150 and 1.22 QALYs with CAR-T with an incremental cost-effectiveness ratio (ICER) of $1,383,320/QALY. Incremental net monetary benefit of CAR-T versus ASCT, based on a willingness-to-pay (WTP) threshold of $200,000/QALY, was -$193,812. The break-even price for CAR-T and all subsequent therapies, based on a one-way sensitivity analysis, was $170,489. Conclusions: The model demonstrated improved survival and QALYs for the second-line CAR-T therapy, but was not cost-effective, as the ICER exceeded $1,000,000/QALY, which is higher than most accepted WTP thresholds. A limitation of these early data is that they only assess outcomes over three years. To estimate the full effect of these therapies, we will extrapolate the Kaplan-Meier curves for additional analyses. Clinical outcomes of second-line CAR-T are promising, but prices would need to be considerably lower to enable equitable access and affordability.[Table: see text]

Corticosteroid resistance after acute graft-versus-host disease (SR-aGVHD) results in high morbidity and mortality after allogeneic hematopoietic cell transplantation. Current immunosuppressive therapies for SR-aGVHD provide marginal effectiveness because of poor response or excessive toxicity, primarily from infection. α(1)-Antitrypsin (AAT), a naturally abundant serine protease inhibitor, is capable of suppressing experimental GVHD by downmodulating inflammation and increasing ratios of regulatory (T(reg)) to effector T cells (T(eff)s). In this prospective multicenter clinical study, we sought to determine the safety and response rate of AAT administration in SR-aGVHD. Forty patients with a median age of 59 years received intravenous AAT twice weekly for 4 weeks as first-line treatment of SR-aGVHD. The primary end point was overall response rate (ORR), the proportion of patients with SR-aGVHD in complete (CR) or partial response by day 28 without addition of further immunosuppression. Treatment was well tolerated without drug-related adverse events. A significant increase in serum levels of AAT was observed after treatment. The ORR and CR rates by day 28 were 65% and 35%, respectively, and included responses in all aGVHD target organs. At day 60, responses were sustained in 73% of patients without intervening immunosuppression. Infectious mortality was 10% at 6 months and 2.5% within 30 days of last AAT infusion. Consistent with preclinical data, correlative samples showed an increase in ratio of activated T(reg)s to T(eff)s after AAT treatment. These data suggest that AAT is safe and may be potentially efficacious in treating SR-aGVHD. This trial was registered at www.clinicaltrials.gov as #NCT01700036.

Umbilical cord blood transplantation (UCBT) is an alternative for patients who need hematopoietic stem cell transplant (HSCT), but lack HLA-matched adult donors. Rabbit anti-thymoglobulin (ATG) has been used in UCBT conditioning to achieve T cell depletion, but ATG-induced immunosuppression is associated with delayed immune reconstitution, increased infectious complications and higher non-relapse mortality. In a clinical trial of reduced intensity double-unit UCBT (dUCBT), we substituted low dose total body irradiation (TBI) for ATG to determine whether dUCBT without ATG would alter kinetics and quality of immune reconstitution. Thirty-one patients with hematopoietic malignancies and a median age of 58 yr were treated with Flu/Mel/TBI, followed by dUCBT and GVHD prophylaxis with tacrolimus and sirolimus. We examined reconstitution of immune cell populations, thymic regeneration by quantifying T cell receptor excision circles (TREC) and serum cytokines (IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, IFN-γ, TNF-α, IL-12p70, GM-CSF) using the LUNARISTM Human 11-Plex Cytokine Biochip384 from AYOXXA Biosystems. Assessments were done prior to and at 1, 2, 3, 6, 12 and 24 months after dUCBT. Results are based on 28 evaluable patients. The 2-yr overall survival and progression-free survival were 53% and 48%. Median time to neutrophil and platelet engraftment was 25 and 52 days, respectively. Before UCBT, the median values for most leukocyte subsets were below normal limits, except for monocytes. CD3+ cells remained depressed until 2 months post-transplant when gradually began to re-emerge. However, CD4+ and CD8+ subsets had distinct reconstitution kinetics (Figure 1). CD4+ T cells declined at 1 month but gradually increased and exceeded pre-transplant levels by 9 months after UCBT. In contrast, at 9 months, CD8+ lymphocytes remained depressed to 50% of pre-transplant levels, but increased thereafter and reached normal values by 2-yr. NK cells and monocytes reached normal values at 3 months post-UCBT. B cells were mostly undetectable for the first 6 months, followed by a 10-fold increase at 9 months and exceeded the upper normal limit by 2-yr. TREC, which were within normal range before transplant, decreased after UCBT but remained detectable between 1-6 months and recovered to normal levels by 9 months. Among cytokines, only IL-8, IL-6 and TNF-α displayed significant changes. IL-8 and IL-6 peaked at day 100 and 9 months, and subsequently declined. In contrast, TNF-α increased by day 100 and remained elevated thereafter. To evaluate functional immunity, we assessed correlations between viral reactivation and reconstitution of immune cell populations and thymic function. Nineteen patients experienced 24 clinically significant viral reactivations or infections, with 1-year cumulative incidence of 62%, which was comparable to 53% observed in dUCBT cohorts receiving ATG-containing conditioning. Although there was no difference in CMV, EBV, adenovirus and VZV reactivation, there was a significant increase in the incidence of HHV-6 reactivation. HHV-6 viremia was observed in 24 of 28 (86%) patients during the first month after dUCBT. Six of these 24 (25%) patients developed HHV-6-related encephalitis. There was a correlation between development of encephalitis and HHV-6 viral load ≥50.000 copies/ml (p=0.007). Pre-transplant TREC levels ≥1.200 copies/ml negatively correlated with subsequent HHV-6 reactivation (p=0.04), indicating that baseline reserve of thymic function has a significant role in post-transplant immune reconstitution. On days 30, 60 and 100 post-transplant, higher TREC levels correlated with lack of HHV-6 viremia (p Figure 1 Disclosures Defilipp: Incyte: Research Funding. Politikos:Angiocrine Bioscience Inc: Research Funding. Armand:Otsuka: Research Funding; Roche: Research Funding; Affimed: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Adaptive: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Infinity: Consultancy; Sigma Tau: Research Funding; ADC Therapeutics: Consultancy; Tensha: Research Funding; Genentech: Research Funding; Pfizer: Consultancy. Ho:Jazz Pharmaceuticals: Consultancy. Koreth:Amgen: Consultancy; Equillium: Consultancy; Cugene: Consultancy. Avigan:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Research Funding; Juno: Membership on an entity's Board of Directors or advisory committees; Partners Tx: Membership on an entity's Board of Directors or advisory committees; Partner Tx: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy; Parexel: Consultancy; Takeda: Consultancy. Rosenblatt:Celgene: Research Funding; Amgen: Other: Advisory Board; Merck: Other: Advisory Board; BMS: Other: Advisory Board ; Parexel: Consultancy; Imaging Endpoint: Consultancy; Partner Tx: Other: Advisory Board; Dava Oncology: Other: Education; BMS: Research Funding. Chen:Abbvie: Consultancy; Incyte: Consultancy; Magenta: Consultancy; Takeda: Consultancy; Kiadis: Consultancy. Soiffer:Gilead, Mana therapeutic, Cugene, Jazz: Consultancy; Juno, kiadis: Membership on an entity's Board of Directors or advisory committees, Other: DSMB; Mana therapeutic: Consultancy; Kiadis: Other: supervisory board; Jazz: Consultancy; Cugene: Consultancy. Cutler:Kadmon: Consultancy; Incyte: Consultancy; Pharmacyclics: Consultancy; Fate Therapeutics: Consultancy. Ritz:Equillium: Research Funding; Merck: Research Funding; Kite Pharma: Research Funding; Aleta Biotherapeutics: Consultancy; Celgene: Consultancy; Avrobio: Consultancy; LifeVault Bio: Consultancy; Draper Labs: Consultancy; Talaris Therapeutics: Consultancy; TScan Therapeutics: Consultancy.

The magnitude of risk associated with 9/10 mismatched unrelated donor (MMURD) hematopoietic stem cell transplantation and that of mismatches at the individual HLA loci remain unclear. We performed a meta-analysis to assess the difference in clinical outcomes between matched unrelated donor (MUD) and MMURD transplantation. A comprehensive search of Medline and Embase for manuscripts regarding transplantation outcomes in primarily adult patients with hematologic malignancies was performed. The pooled effect estimates were calculated using DerSimonian-Laird random effects models. A total of 13 studies were included, reporting on 13,446 transplants. 9/10 MMURD transplantation was associated with worse overall survival compared to 10/10 MUD transplantation (pooled HR: 1.27, 95% CI: 1.12-1.45; n = 7 studies). Mismatch at HLA-A, -B, or -C was associated with significantly worse overall survival compared to MUD transplantation, while there was no significant difference associated with -DQ or -DPB1 mismatch. Inferior survival associated with HLA-DRB1 mismatch could not be ruled out. Data on acute and chronic graft-versus-host disease were scarce but favored MUD transplantation. In summary, this meta-analysis of the available literature favored MUD over MMURD transplantation in hematologic malignancies and further quantifies the risks associated with specific HLA-allele mismatches. Am. J. Hematol. 91:551-555, 2016. © 2016 Wiley Periodicals, Inc.

The Blood and Marrow Transplant Clinical Trials Network conducted 2 parallel multicenter phase 2 trials for individuals with leukemia or lymphoma and no suitable related donor. Reduced intensity conditioning (RIC) was used with either unrelated double umbilical cord blood (dUCB) or HLA-haploidentical related donor bone marrow (Haplo-marrow) transplantation. For both trials, the transplantation conditioning regimen incorporated cyclophosphamide, fludarabine, and 200 cGy of total body irradiation. The 1-year probabilities of overall and progression-free survival were 54% and 46%, respectively, after dUCB transplantation (n = 50) and 62% and 48%, respectively, after Haplo-marrow transplantation (n = 50). The day +56 cumulative incidence of neutrophil recovery was 94% after dUCB and 96% after Haplo-marrow transplantation. The 100-day cumulative incidence of grade II-IV acute GVHD was 40% after dUCB and 32% after Haplo-marrow transplantation. The 1-year cumulative incidences of nonrelapse mortality and relapse after dUCB transplantation were 24% and 31%, respectively, with corresponding results of 7% and 45%, respectively, after Haplo-marrow transplantation. These multicenter studies confirm the utility of dUCB and Haplo-marrow as alternative donor sources and set the stage for a multicenter randomized clinical trial to assess the relative efficacy of these 2 strategies. The trials are registered at www.clinicaltrials.gov under NCT00864227 (BMT CTN 0604) and NCT00849147 (BMT CTN 0603).

Introduction: BK virus (BKV) seropositivity is highly prevalent (80-90%) in healthy adults, but BKV rarely causes significant clinical disease. However, immunologic control of BKV is often compromised after allogeneic hematopoietic stem cell transplantation (HSCT) and BKV reactivation can cause clinical disease, including hemorrhagic cystitis, in 5-68% of patients in the first year after HSCT. Immune reconstitution of BKV-specific T cells after HSCT has not been well defined, and the role of BKV-specific T cells in response to clinical infection has not been studied. Methods: From the DFCI 2010-2011 HSCT cohort (Rorije et al, BBMT 2014), 33 adult patients were selected who had urinary symptoms, were tested for urine BKV by PCR, and were diagnosed with BKV disease (cases; n=16) or did not have BKV reactivation (controls; n=17). Cases and controls were matched for cyclophosphamide use, acute GvHD and stem cell source. BKV-specific T cells were analyzed in 180 prospectively cryopreserved peripheral blood mononuclear cells (PBMC) samples (average 5.5/patient) across several timepoints (pre-HSCT and 1, 3, 6, 9, 12, 18 and 24 months post-HSCT) using cytokine flow cytometry (CFC). PBMC were stimulated for 6 hours with overlapping 15-mer peptides derived from BKV LT and VP1 proteins in the presence of brefeldin A, monensin and anti-CD28/49d. Results were compared with no-pepmix negative controls and Staphylococcal enterotoxin B positive controls. After stimulation, cells were stained with fluorochrome-conjugated antibodies specific for CD3, CD4, CD8, CD45RA, CCR7, CD57, CD107a, IFNγ, TNFα, IL-2, perforin (PERF) and granzyme B (GZMB). Laboratory assessments were blinded to clinical disease status. Results: Median age of the cohort was 51 years (IQR; 39-61); 79% were male and acute GvHD occurred in 64%. Conditioning included cyclophosphamide in 46% and ATG in 24%; cell source was peripheral blood stem cells in 81%, cord blood in 15% and bone marrow in 3%. Median time from HSCT to BKV testing was 60 days (23-181); median time to first positive test was 79 days (26-196) in BKV+ cases. Median duration of symptoms was 53 days (11-92) in cases, compared to 5 days in controls. The percentage of patients with BKV-specific T cells across timepoints is summarized in Figure 1. The frequency of BKV-specific degranulating (CD107a) T cells peaked at 6mo, where they could be detected in 37.5% and 58.3% of patients by reactivity of CD8+ and CD4+ T cells, respectively. Detection of BKV-specific T cells producing any cytokines (cytokine+) peaked at 9 mo (CD8+ in 19% and CD4+ in 38.1% of patients). BKV-specific IFNγ+, IL-2+, and TNFα+ T cells all peaked at 12mo after HSCT. Subsequently, detection of BKV-specific CD8+ T cells declined sharply while BKV-specific CD4+ T cells were maintained at higher levels 24 months after HSCT. Comparing BKV-specific immune responses in cases and controls, IFNγ+ CD8+ cells reconstituted faster in patients with clinical disease (first detected at 3 months vs. 9 mo), and were present in more patients at 9 months: 41.7% vs. 11.1%. A similar trend was noted for IL-2+ CD8+, IFNγ+ CD4+, and IL-2+ CD4+ T cells (Figure 2). BKV-specific CD8+ T cells were predominately central memory (CM) and terminally differentiated effector memory and their cytokine profile increased gradually after transplant; 19% produced at least two cytokines at 1 mo, compared to 71% at 12 mo. BKV-specific CD4+ T cells were predominately CM and effector memory and their cytokine profile also increased after transplant; 3.5% produced at least two cytokines at 1 mo, compared to 35% at 12 mo and 69.5% at 24 mo. PERF and/or GZMB were detected in 45-74% of BKV-specific CD107a CD8+ cells. CD107a CD8+ cells also produced IFNγ. Conclusion: BKV-specific T cells gradually reconstitute in the first 9 months after allogeneic HSCT. 30-40% of patients with clinical symptoms and 50-60% of patients with confirmed BKV disease had detectable BKV-specific T cells but BKV-specific immunity recovers more rapidly in patients with BKV disease. As CD8 and CD4 BKV-specific immunity recovers, T cells gradually become more functional with a memory phenotype. Our cohort is currently being expanded to assess the correlation between the development and expansion of BKV-specific T cells and clinical outcomes. Disclosures Koreth: kadmon corp: Membership on an entity's Board of Directors or advisory committees; takeda pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; amgen inc: Consultancy; LLS: Research Funding; prometheus labs inc: Research Funding; millennium pharmaceuticals: Research Funding. Armand:Otsuka: Research Funding; BMS: Consultancy, Research Funding; Infinity: Consultancy; Sequenta: Research Funding; Roche: Research Funding; Merck & Co., Inc.: Consultancy, Research Funding; Sigma Tau: Research Funding; Tensha: Research Funding. Soiffer:GentiumSpA/Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Ritz:Kiadis: Membership on an entity's Board of Directors or advisory committees.

BACKGROUND Randomized trials have shown that the transplantation of filgrastim-mobilized peripheral-blood stem cells from HLA-identical siblings accelerates engraftment but increases the risks of acute and chronic graft-versus-host disease (GVHD), as compared with the transplantation of bone marrow. Some studies have also shown that peripheral-blood stem cells are associated with a decreased rate of relapse and improved survival among recipients with high-risk leukemia. METHODS We conducted a phase 3, multicenter, randomized trial of transplantation of peripheral-blood stem cells versus bone marrow from unrelated donors to compare 2-year survival probabilities with the use of an intention-to-treat analysis. Between March 2004 and September 2009, we enrolled 551 patients at 48 centers. Patients were randomly assigned in a 1:1 ratio to peripheral-blood stem-cell or bone marrow transplantation, stratified according to transplantation center and disease risk. The median follow-up of surviving patients was 36 months (interquartile range, 30 to 37). RESULTS The overall survival rate at 2 years in the peripheral-blood group was 51% (95% confidence interval [CI], 45 to 57), as compared with 46% (95% CI, 40 to 52) in the bone marrow group (P = 0.29), with an absolute difference of 5 percentage points (95% CI, −3 to 14). The overall incidence of graft failure in the peripheral-blood group was 3% (95% CI, 1 to 5), versus 9% (95% CI, 6 to 13) in the bone marrow group (P = 0.002). The incidence of chronic GVHD at 2 years in the peripheral-blood group was 53% (95% CI, 45 to 61), as compared with 41% (95% CI, 34 to 48) in the bone marrow group (P = 0.01). There were no significant between-group differences in the incidence of acute GVHD or relapse. CONCLUSIONS We did not detect significant survival differences between peripheral-blood stem-cell and bone marrow transplantation from unrelated donors. Exploratory analyses of secondary end points indicated that peripheral-blood stem cells may reduce the risk of graft failure, whereas bone marrow may reduce the risk of chronic GVHD. (Funded by the National Heart, Lung, and Blood Institute–National Cancer Institute and others; ClinicalTrials.gov number, NCT00075816.)

The mTOR inhibitor sirolimus has been used in the prevention and treatment of GVHD after allogeneic hematopoietic stem cell transplantation (HSCT). In parallel, mTOR inhibitors have demonstrated clinical activity against various lymphoma histologies. In a retrospective study, we found that patients with lymphoma undergoing reduced intensity conditioning (RIC) HSCT who received a sirolimus-containing GVHD prophylaxis regimen had a lower rate of relapse (Armand et al, J Clin Oncol. 2008;26(35):5767). We therefore performed a multicenter, phase III, open label randomized trial comparing tacrolimus, sirolimus and methotrexate (Tac/Sir/Mtx, with sirolimus starting on day -3 of HSCT) for GVHD prophylaxis to conventional sirolimus-free regimens (tacrolimus + methotrexate (Tac/Mtx) or cyclosporine + MMF (Csa/MMF), pre-specified by center), in patients undergoing RIC HSCT for any lymphoma except Burkitt lymphoma. The primary endpoint was 2-year overall survival (OS); progression-free survival (PFS), acute and chronic GVHD were among the secondary endpoints. 139 patients were enrolled at five institutions between June 2009 and September 2012. The median age was 57 years (range, 23-70). 42 patients had aggressive B-NHL, 31 indolent B-NHL, 28 CLL, 19 T-NHL and 19 Hodgkin lymphoma. 66 were assigned to the Tac/Sir/Mtx arm, and 73 to the control arm (67 to Tac/Mtx and 7 to Csa/MMF). All patients but 1 received the allocated intervention, and all received peripheral blood stem cell products, as mandated by the protocol. Based on a planned interim analysis, the DSMB recommended reporting of the interim results at this time. Median follow-up for survivors is 22 months, and only 12% of living patients have less than 12 months of follow-up. There was no evidence of increased toxicity in the Tac/Sir/Mtx arm. At the time of this analysis, the Kaplan-Meier estimate of 2-year OS by intent to treat (Figure 1A) is 66% (95CI, 51-77) in the Tac/Sir/Mtx arm vs. 71% (95CI, 58-81) in the control arm (p=0.7); the corresponding 2-y PFS (Figure 1B) is 62% (95CI, 48-73) vs. 56% (95CI, 43-68) (p=0.9). The conditional power for finding a significant difference in the primary endpoint of 2y OS is In conclusion, the addition of sirolimus to the GVHD prophylaxis regimen in patients with lymphoma undergoing RIC HSCT is associated with a significant decrease in grade 2-4 acute GVHD after transplantation, without impacting toxicity, severe acute GVHD, chronic GVHD, progression-free or overall survival. These results should be broadly applicable to all recipients of RIC HSCT using T-cell-replete peripheral blood stem cells, and suggest that tacrolimus, sirolimus and methotrexate could be a preferred regimen in this patient population. Pre-specified subgroup analyses by histology and correlative studies will be performed when follow-up is complete in late 2014. Disclosures: Off Label Use: Sirolimus, tacrolimus, methotrexate, cyclosporin, mycophenolate for GVHD prophylaxis.

Background The National Care Determination for allogeneic hematopoietic stem cell transplantation (allo HSCT) for the treatment of myelodysplastic syndromes (MDS) stated that there is an absence of convincing evidence that allo HSCT improves health outcomes. A prospective data-gathering trial sponsored by the CIBMTR is ongoing; however, until such results are available, retrospective methods specifically comparing older populations are illustrative. Methods We analyzed outcomes for older patients with MDS undergoing HSCT with reduced intensity conditioning (RIC) at the Dana-Farber/BWH with uniform conditioning and graft versus host disease (GVHD) prophylaxis regimens from 2001 to 2011. Patients with CMML were excluded. Those aged 60-65, and those ≥ 66 were compared to assess overall survival (OS), progression free survival (PFS), and other HSCT-related outcomes. Aiming to build a better prognostic score using its significant components, we also assessed the association of the IPSS-R at transplantation as well as each of its components with OS, and fit multivariable Cox regression models with the new prognostic score as well as age. Results We identified 67 patients aged 60 or older who underwent RIC HSCT for MDS. All patients received fludarabine and intravenous busulfan as conditioning, and peripheral blood stem cells. GVHD prophylaxis included tacrolimus/rapamycin +/- MTX. The median age was 64 (60-74) years, and the majority (64%) had unrelated donors. 60% had advanced MDS (IPSS-R high risk or very high risk), 46% had poor risk cytogenetics, and 67% had high or very high disease risk index (DRI). The median age for the 60-65 group was 63; the median age for the ≥ 66 group was 69. We found no significant differences in PFS or OS by age category, as shown below (also see figure): In addition, rates of 6-month grade III-IV GVHD (p=.45) and 2-year incidence of cGVHD (p=0.78) did not significantly differ. The IPSS-R performed only modestly in predicting 4-year OS for this older cohort (p=.20); however, a new 3-level score (including collapsed cytogenetic categories, dichotomous platelet count [ ≥ 50 or < 50], percent blasts in marrow and dichotomous ANC) performed better (p=.008; see figure). In two multivariable models, one that included the IPSS-R and another that included the new score, age was not a significant predictor of OS (p=.78 and .77 respectively). Conclusions Our data suggest that age alone should not limit availability of RIC HSCT for patients with MDS, as older patients in our elderly cohort faired similarly to younger ones with respect to important HSCT-related outcomes. Our new prognostic score, if validated, may be able to help risk-stratify patients. Finally, continued efforts are needed to reduce relapse in high-risk elderly MDS patients. Disclosures: No relevant conflicts of interest to declare.

Chronic graft-versus-host disease (GVHD) is a major transplantation toxicity that impacts quality-of-life and long-term survival. Corticosteroids are standard-of-care for initial therapy of chronic GVHD despite limited efficacy and significant long-term toxicity. Proteasome-inhibition has immunomodulatory effects potentially beneficial in GVHD. We previously reported on peri-transplantation bortezomib (day +1, +3, +7) for GVHD prophylaxis. We now report on bortezomib plus corticosteroids for initial therapy of chronic GVHD. We undertook a single-arm prospective phase II trial for participants 18 years or older and 100 days or more after allogeneic transplantation from HLA-matched related, unrelated or mismatched donors (MRD, MUD, MMUD) with no active malignant relapse, and limited or extensive chronic GVHD requiring initiation of systemic therapy. IV bortezomib was dosed at 1.3 mg/m2 on days 1, 8, 15 and 22 of each 35 day cycle for 3 cycles (15 weeks). Concurrent prednisone dose was initially 0.5 mg/kg/d, but the study was later amended to allow up to 1 mg/kg/d. The suggested steroid taper after cycle 1 was 10-25% every 1-2 weeks. No addition or subtraction of other immunosuppressive medications was permitted. Topical GVHD therapies (e.g. eye, mouth) were allowed. The primary endpoint was week 15 overall response rate (ORR) per NIH chronic GVHD criteria, excluding ocular/oral sites where topical treatment was permitted. Secondary endpoints included the proportion of participants tolerating 50% or greater prednisone dose reduction at 15 weeks, prednisone dose requirement at 1 year, and long-term overall and progression-free survival (OS, PFS). Between March 2009 and November 2011, 22 participants with a median age of 51 years (range, 25-69) comprising 5, 13, and 4 recipients of 8/8 MRD, MUD, and 7/8 MMUD PBSC grafts, respectively, were enrolled. 45% were male. 18% had prior acute GVHD (1 gr. 1; 2 gr. 2; 1 gr. 3). The median time from transplantation to chronic GVHD onset was 215 days (range, 133-666), and to initiation of chronic GVHD therapy was 257 days (range, 186-2070). Participants had a median of 3 (range, 1-6) sites of chronic GVHD, with liver (73%), oral (68%), skin (64%), ocular (46%) and joint/muscle/fascia (J/M/F) (27%) the most common. The median follow up duration in survivors was 25 months (range, 19.3-48.5). Bortezomib plus prednisone as initial chronic GVHD therapy was well tolerated, with 1 grade 3 CTCAE (sensory neuropathy) possibly related to bortezomib. One participant died of relapsed AML after 2 cycles of treatment and was not evaluable for toxicity or response. Another died of fungal infection during cycle 1 and was not evaluable for response. 18 of 22 participants (82%) completed the 3 cycles of therapy. For the 20 participants evaluable for response, the week 15 ORR (per NIH chronic GVHD global score) was 80% (CR: 2 [10%], PR: 14 [70%]). Additionally, 1 participant (5%) had a mixed response, with CR at sentinel sites (liver, skin) but interval progression of pulmonary GVHD; 1 participant (5%) had stable disease; and 2 participants (10%) with prednisone starting dose of 0.5 mg/kg/d had progressive GVHD. The change of median NIH chronic GVHD global score from baseline to week 15 was 5.5 (range, 1-7) → 3 (range, 0-6), respectively. Sites of response included skin (n = 11; CR = 8 [73%], PR = 1, SD = 2); liver (n = 15; CR = 8 [53%], PR = 5, PD = 2); and J/M/F (n = 6; CR = 2 [33%], PR = 1, SD = 3). The change of median NIH chronic GVHD organ score from baseline to week 15 was: liver 3 (range, 1-3) → 0 (range, 0-2); skin 2 (range, 1-3) → 0 (range, 0-2); J/M/F 1 (range, 1-2) → 1 (range, 0-2). 14 participants (70%) tolerated a 50% or greater steroid dose reduction by week 15. The median steroid dose taper from baseline to week 15 was 50 mg (range, 30-100) → 20 mg (range, 5-40) (p Bortezomib plus prednisone for initial therapy of chronic GVHD was feasible and well tolerated, with an 80% ORR alongside substantial steroid dose taper. Proteasome-inhibition may offer steroid-sparing efficacy in chronic GVHD therapy, particularly for visceral and skin involvement. Of note, the need for weekly clinic visits for parenteral bortezomib was a barrier to accrual. Oral proteasome-inhibitors may be especially suitable for future trials in chronic GVHD. Disclosures: Off Label Use: Bortezomib is a proteasome inhibitor with a number of immunomodulatory effects that are potentially beneficial in GVHD. We studied bortezomib plus prednisone as initial therapy for chronic GVHD.

The treatment of hematological malignancies with umbilical cord blood transplantation (UCBT) is rapidly increasing for adult patients. Disadvantages of UCBT include insufficient cell numbers for adult patient reconstitution, a lack of antigen experienced cells, and deficits in T cell signal transduction mechanisms. Consequently, UCBT is frequently associated with impaired immune function and high infection-related mortality. To counter these difficulties, transplantation with two UCB units has been employed to improve immune reconstitution in adult patients. We evaluated both the quantitative and functional reconstitution of cellular immunity in a group of adult patients undergoing UCBT. Thirty-two patients with a median age of 50 years with hematopoietic malignancies were treated with reduced intensity conditioning (Flu/Mel/rATG) followed by infusion with two sequential UCB grafts and GvHD prophylaxis with tacrolimus and sirolimus. The grafts were at least a 4/6 match with each other and the recipient. Here we report the results of 27 patients who have completed at least one year of follow up. Assessments were done prior to transplant and at various time intervals until 12 months post UCBT. Neutrophil and platelet engraftment occurred at a median of 21 days and 42 days, respectively. CD3+ populations remained severely depressed until 8 wks post-transplant when they gradually began to re-emerge. However the CD4+ and CD8+ populations demonstrated distinctly different reconstitution kinetics. At 6 months the median value of absolute numbers of CD4+ lymphocytes was 35% of pre-transplant levels increasing to 42% at 1 yr post-transplant, a median value far below the normal range for adults. In contrast, at 6 months post-transplant CD8+ lymphocytes remained severely depressed to 12% of pre-transplant levels, but dramatically increased and reached normal levels by 1 yr after UCBT. Interestingly, both the CD14+ monocyte and the CD16+CD56+ NK cell populations expanded dramatically at 4 wks post-transplant and reached pre-transplant levels and were within the normal range by 6 months. CD20+ B cell repopulation began at 8 wks post-transplant, displayed a striking expansion leading to a 17-fold increase in the median value for B cell numbers over pre-transplant values at 1 year and resulting in a median value of absolute numbers near the top of the normal range. To evaluate functional T cell immune reconstitution in vivo, we performed IFN-γ ELISpot analysis on CMV stimulated PBLs and compared the results to a PCR-based assay for CMV viremia. Additionally, we assessed the reconstitution of thymopoiesis with the T cell receptor excision circle (TREC) assay and real-time PCR. 16/27 patients and 26/52 UCB products were CMV seropositive prior to transplant. In the post-UCB period, development of CMV-specific effectors as determined by ELISpot did not always correlate with clearance of CMV viremia. Specifically, prior to 8 weeks post-UCBT, 8 out of 12 (67%) patients with CMV-positive ELISpot displayed CMV viremia, between 8 weeks and 100 days post-UCBT 4 out of 11 (36%) patients with CMV-positive ELISpot displayed CMV viremia and after 100 days post-UCBT only 3 out of 10 patients (30%) who developed CMV-positive ELISpot remained positive for CMV viremia. Identification of functional CMV effectors was only associated with the numbers of CD8+CD45RA+ cells (p=0.01) and the development of high TREC concentrations (p=0.01) that were detected after 6 months of UCBT, and was independent of GvHD or mixed chimerism. Taken together these results indicate that reconstitution of T cell immunity after UCBT is characterized by delayed recovery of CD4+ and CD8+ T cells and correlates with reconstitution of thymopoiesis and increase of naïve CD8+CD45RA+ T cells that can develop into efficient pathogen-specific effectors.

Animal models of acute graft versus host disease (GVHD) suggested the critical role of host antigen-presenting cells (APC) in the pathogenesis of acute GVHD (Shlomchik et al Science285:412, 1999). Depletion of host B cells reduced the incidence of acute GVHD (Schultz et al BMT16:289, 1995). We hypothesized that B-cell depletion by prior rituximab (RTX) therapy in lymphoma pts might result in reduced incidence of acute GVHD (Ratanatharathorn et al Blood96:391a, 2000). We now analyzed the outcomes of allogeneic PBSCT in 435 B-cell lymphoma pts reported to CIBMTR from 1999 to 2004. Pts who had prior therapy with anti-CD52 or anti-T-cell antibody or recipients of conditioning regimens containing any of these antibodies were excluded. All patients received unmodified PBSC grafts. Pts were considered to have prior RTX therapy if they received RTX within 6 months of transplantation. There were 256 pts who did not receive RTX within 6 months of transplantation (No-RTX group) and 179 pts received RTX within 6 months of transplantation (RTX group). In RTX group, most pts (67%) received the last dose of RTX within 3 months of transplantation and 54% received at least two doses of RTX. Baseline characteristics of the two groups were similar except for significantly more unrelated donor (32% vs 19%, P=0.002)), tacrolimus use (47% vs 26%, P Clinical outcomes Relative risk (95% CI) P value Grade II-IV acute GVHD 0.72 (0.53–0.97) 0.03 Grade III-IV acute GVHD 0.55 (0.34–0.91) 0.02 Chronic GVHD 0.89 (0.67–1.18) 0.41 TRM 0.68 (0.46–1.0) 0.05 Progression or relapse 0.7 (0.42–1.19) 0.19 Progression-free survival 0.68 (0.50–0.92) 0.01 Overall survival 0.63 (0.46–0.86) 0.004