T-cell Replete Grafts Research Articles

Treosulfan Compared to Busulfan in Allogeneic Haematopoietic Stem Cell Transplantation for Myelofibrosis: A Registry-Based Study from the Chronic Malignancies Working Party of the EBMT

Background The optimal conditioning prior to allogeneic stem cell transplantation (HSCT) for myelofibrosis (MF) remains an ongoing matter of debate. There is a paucity of randomized trials robustly showing superiority of one over another. Registry studies comparing reduced intensity conditioning (RIC) versus myeloablative conditioning (MAC) regimens did not show significant differences in overall survival (OS). Recently, a multi-center phase 3 trial in MDS-AML reported an advantage of fludarabine-treosulfan (TREO) over fludarabine-busuflan (BU) RIC (Lancet Haematol Beelen et al 2020). The role of this large EBMT registry study was to compare outcomes of MF HSCT following TREO and BU based MAC or RIC regimens. Methods Patients with MF transplanted from a T-cell replete graft between 2010-2018 following BUMAC, BURIC or TREO were identified in the EBMT registry. Patients who were transformed into AML were excluded. Centers were contacted to participate in additional data collection. 63 centers included a total of 536 patients of whom 6 patients were excluded due to missing data for major endpoints (relapse or regimen). The role of TREO was tested in multi-variable models adjusted on major prognostic factors especially those who were not well balanced between groups and using multiple imputation for missing values. Results Most TREO (n=73) patients received it in combination with FLUDARABINE (95%) and most BU (n=457) received FLUDARABINE +/- other (93%). Median total dose received of TREO was 42 g/m2 and median dose of BU was 8mg/kg. Main differences between the 3 groups were: 1) Recipient age; patients were the oldest in the RIC group (median age 61 years, (IQR: 55-65), the youngest in BUMAC (56 years, (IQR: 51-62)), and intermediate in the TREO group (59 years, (IQR: 54-64); 2) Performance status; Karnofsky score was < 80 in 20%, 30%, 42% in the TREO, BUMAC and BURIC groups, respectively; 3) Comorbidity score (HCT-CI) was lowest in the MAC group (HCT-CT ‘low’ in 56%, 45% and 37% of BUMAC, BURIC and TREO groups); 4) Disease status; patients in the TREO group were more often transplanted with progressive disease (58% vs 30% in BUMAC and 34% in BURIC); 5) JAK inhibitor prior to HSCT; a higher proportion of patients in the TREO group were treated with a JAK inhibitor before HSCT (61% vs 50% in BUMAC and 42% in BURIC); 6) Cytomegalovirus (CMV) donor/ recipient status; CMV combinations were more frequently donor recipient -/- in the TREO cohort (41% vs 28% in MAC and 36% in RIC); 7) an HLA matched sibling donor was less frequently used in TREO group (18% vs. 28% in BURIC and 36% in BUMAC). The 3 groups were well balanced regarding period of transplantation, MF classification (primary versus secondary), splenomegaly at time of transplantation, chromosome abnormalities, MF related symptoms, DIPSS score, GVHD prophylaxis and use of ATG. Median time to neutrophil recovery was 17 days (range: 6-54), with no differences between the 3 groups. Cumulative incidence of engraftment at day 30 was 91.5% (95%CI: 89.1-93.9), with no differences between the 3 groups. Cumulative incidence of grade 2-4 acute GVHD at 120 days for the entire cohort was 23% (95%CI: 19-26%); similar in the 3 groups. Three-year OS was 62% (95% CI 58 -66), 3-year PFS was 49% (45-53). At 3 years, cumulative incidence of relapse was 26% (22-29) and NRM was 25% (21-29). Figure 1 shows OS, PFS, NRM and cumulative incidence of relapse (CIR) according to regimen. Multiple variables Cox models after selection are shown in Table 1. TREO group had a significantly better OS than BUMAC (HR: 0.61, 95%CI: 0.39-0.93), BURIC had similar OS to BUMAC (HR: 0.92, 95%CI: 0.68-1.26) and there was a trend for a better OS with TREO over BURIC (HR: 0.66, 95%CI: 0.41-1.05). The same trend was also observed for PFS with a significant advantage of TREO over BUMAC (HR: 0.57, 95%CI: 0.38-0.84) and BURIC (HR: 0.60, 95%CI: 0.39-0.91) while BURIC had a similar risk to BUMAC (HR: 1.05, 95%CI: 0.80-1.39). The improvement of OS and PFS was related to a lower NRM (HR: 0.44, 95%CI: 0.24-0.80 TREO vs BUMAC; HR: 0.54, 95%CI: 0.28-1.04 TREO vs BURIC) and same relapse risk with TREO over BU (TREO vs BUMAC, HR: 0.71, 95%CI: 0.42-1.20; TREO vs BURIC, HR: 0.63, 95%CI: 0.36-1.11). Conclusion TREO based regimens compared to BU based shows better PFS in MF HSCT. This advantage was also confirmed for OS and NRM when compared to BUMAC. More specific prospective studies are needed to confirm findings from this registry based study.

Selective Targeting of Immune Modulatory Proteins to Mitigate Fibrosis and Inflammation in Sclerodermatous Graft-Vs-Host Disease

Chronic graft-vs-host disease (cGVHD) is a major obstacle to the success of allogeneic hematopoietic stem cell transplantation (HCT) in patients. This debilitating condition is characterized by chronic inflammation, cell-mediated and humoral immunity, and ultimately tissue fibrosis. There is currently little or no understanding of the molecular pathogenesis of chronic cGVHD resulting in poor effective treatment strategies. Sclerodermatous GVHD (sclGVHD) is one of the more severe forms of cGVHD associated with poor prognosis and low sensitivity to immune suppressive therapy.Methods: To address the current gap in knowledge pertaining to the underlying pathophysiology of sclGVHD we used single cell RNA sequencing analyses on fresh patient biopsy specimens. In vivo studies were carried out by sub lethal irradiation of BALB.k recipients which underwent HCT from miAg-mismatched AKR/J donors. Recipient sclerodermatous-tissues were analyzed using FACS, IHC and IF staining. Human studies were conducted on (i) Primary samples from patients with severe sclGVHD using tissue microarrays (TMA) by Immuno-histofluorescence (IHF) and IF. (ii) Dermal fibroblasts from sclGVHD samples were subjected to ATACseq and ChiPseq CRISPR-Cas9 JUN deletion. (iii) Also, dermal fibroblasts from human scl-GVHD were implanted under the kidney capsule of NSG mice to study the effects of inhibiting pro-fibrotic pathways in vivo.Results: We show for the first time that in a mouse model of sclGVHD (male), recipients of female T-cell replete grafts developed severe scleroderma with massive skin thickening and collagen deposition. Fibroblasts strongly expressed JUN, which is part of AP-1, a transcription factor involved in the acute phase response that regulates gene expression in response to stimuli from cytokines, growth factors and pathogens. We have previously demonstrated JUN as a key player in the molecular pathogenesis of other fibrotic diseases (Wernig G et al. PNAS 2017, Cui et al. Nature comm. 2020, Lerbs et al. JCI i 2020). Likewise, CD47, an immune checkpoint protein that prevents removal of Mϕ, was strongly co-expressed in fibroblasts in sclGVHD - but not in the control mice (Fig A+B). Here we show that (i) In humans, (n = 45 sclGVHD patients), there is a strong expression and activation of JUN and CD47 in dermal fibroblasts which was not observed in control samples. Mixed inflammatory infiltrates were dominated by Mϕ and granulocytes. (ii) Isolated primary fibroblasts from fresh human sclGVHD skin biopsies analyzed for chromatin accessibility across the genome by ATAC-seq showed wide open accessibility to the JUN promoter, IL-6 promoter and CD47 enhancer and promoter indicating that they play a critical role in regulating the pathogenesis of sclGVHD. In contrast, normal fibroblasts displayed only minimal accessibility to the JUN promoter. We further validated our data using CRISPR-Cas9 knock-down studies on sclGVHD fibroblasts and show that the IL-6 promoter, enhancer and promoter of CD47 are regulated by JUN, with JUN deletion resulting in significant decrease in the promoter binding accessibility to IL-6 and CD47 (Fig C). Further, JUN activity appears to regulate key members of the Hh signaling pathway (GLI1, PTCH1 and PTCH2), as their chromatin accessibility was decreased with JUN deletion. These correlative findings were confirmed by JUN ChIP seq, an assay that identifies binding sites of DNA-associated proteins. (iii) To test our findings in vivo we established xenograft models of primary human sclGVHD by implanting cells under the kidney capsule of NSG mice.All treatments (except placebo) resulted in decreased fibrosis (Fig D), presumably by blocking the activation of JUN (pJUN) and its profibrotic downstream pathway members IL-6 and pSTAT3, as assessed by phospho flow. Conclusion: In our studies we demonstrate that in established SclGVHD, combinatorial therapy consisting of anti-CD47 antibody together with IL6 blockade has the highest potential to translate into a therapeutic intervention given its ability to be more effective than currently used antifibrotic and anti-inflammatory agents in clinic. The findings from our study are significant because we show an important mechanism underlying SclGVHD onset, identify a novel genetic signature that can be targeted, describe a new mouse model and a clinical assay that has a high throughput readout and suggest a treatment regimen for patients. [Display omitted] DisclosuresArai: Magenta Therapeutics: Research Funding. Shizuru: Forty seven Inc: Other: Inventor on a patent licenses by Forty Seven. Forty seven was acquired by Gilead in 2020; Jasper Therapeutics, Inc.: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Other: Chair of scientific advisory board.

CT-255: Progressive Substitution of Post-Transplant Cyclophosphamide with Bendamustine as GVHD Prophylaxis Reduces GVHD while Preserving GVL

Context Post-transplant cyclophosphamide (PTCy) is approved in haploidentical stem cell transplant setting. However, disease relapse and CMV or BK/JC viral reactivation veno-occlusive disease of the liver (VOD) remains a major challenge with the use of PTCy. Progressive substitution of PTCy with bendamustine (PT-BEN) may be a suitable option as evidenced by murine models. Objective To compare the outcomes for patients receiving PTCy with PT-BEN compared to historical cohorts receiving PTCy alone. Design This is a single arm, retrospective and prospective, single centre study in which all the patients undergoing allogeneic stem cell transplantation with a T-cell replete graft were recruited. Patients or Other Participants All patients received T-cell replete stem cells followed by PTCy 50mg/kg on day +3 and bendamustine 90mg/m2 on day +4. Calcineurin inhibitors with mycophenolate mofetil was given. Main Outcomes Measures The main outcome measures included myeloid and platelet engraftment, viral reactivations, disease status, incidence and severity of acute GVHD, incidence of veno-occlusive disease until D+28 post-transplant. Results Five patients have been recruited, all males, median age being 17 years. Two patients had relapsed/refractory (R/R) ALL after 2 lines of therapy, 1 had R/R AML, 1 had very severe aplastic anemia, 1 was high risk ALL in CR1. 3 fully matched a sibling, whereas 2 had haplomatched donors from mother. All the donors and recipients had seropositivity for CMV. Two patients received FluCyTBI, 2 received FluCyATG, and 1 received FluTreoTBI as conditioning. One patient expired due to neutropenic septic shock on D+8 and has been excluded from analysis. The median day for myeloid engraftment was 12 and platelet engraftment was 14. No patient had VOD, thrombotic microangiopathy, or culture positive bacterial infections. All the patients were in CR, 100% donor chimerism at D+28. Three patients had CMV reactivation, controlled with antivirals. One patient had Gr1 skin GVH and 1 patient had Gr1 gut GVH managed with topical and oral steroids respectively. Conclusions Progressive substitution of PT-BEN may ameliorate the toxicities associated with PT-Cy in post-transplant setting.

Haploidentical Hematopoietic Stem Cell Transplantation With Reduced Intensity Conditioning, T-Cell Replete Grafts and Post-Transplant Cyclophosphamide In Pediatrics

Hematopoietic stem cell transplants (HSCT) may be curative in the treatment of many hematological diseases. However, most patients do not have an HLA- matched sibling donor and an unrelated donor search may be a long process, during which the patients' disease may relapse or progress. Haploidentical transplants with in vitro T-cell depletion have been used in Pediatrics. However, it requires specialized laboratory infra-structure to manipulate the graft, increases the chances of graft failure and relapse. In vivo T-cell depletion can be achieved with the use of post-transplant cyclophosphamide, as reported by the Johns Hopkins and other groups. The results in adults are very promising and comparable to unrelated double cord blood transplants. Children, however, have not been included in any of the reported protocols. Our objective is to report the institutional experience with five consecutive children who received Haploidentical HSCT with reduced intensity conditioning, T-cell replete grafts and post transplant cyclophosphamide. MethodsChildren with clear indication to be treated with HSCT and no HLA-matched related or unrelated donor available were offered compassionate haploidentical transplants. Conditioning comprised cyclophosphamide 14.5 mg/kg/day on days -6 and -5, fludarabine 30 mg/m2/day for five consecutive days starting on day -6, and 2Gy total body irradiation given in a single fraction on day -1. Bone marrow was harvested from donors and infused into recipients on day 0. The target nucleated cell dose was 5 x10(8) mononuclear marrow cells/kg (i.e., peripheral blood count was substracted from the marrow cell count). There was no graft manipulation. GVHD prophylaxis consisted of cyclophosphamide 50 mg/kg IV on days +3 and +4 with 140% Mesna divided on hours 0, 4, 8 and 12 after each dose, Mycophenolate mofetil 15 mg/kg po every 8 hours (maximum 3 g/day) from day +5 to day +35, and tacrolimus from day + 5 to day +180 to keep levels between 5 and 10ng/ml. Prophylactic antimicrobial therapy was started on day +1 and included fluconazole and acyclovir. ResultsFive children with AML and T-ALL (three in CR2; one induction failure and one 4th relapse) were offered haploidentical transplants as the first HSCT. They had a median age of 10 years (4-16) and weight 41 kg (14-67), 2 girls. One graft was a peripheral blood stem cell collection per physician preference. The median total nucleated cell count was 12x10(8)/kg (10-27) with 10x10(6) CD34/kg (5-15). Mucositis was mild in three patients and none of them had sinusoidal obstruction syndrome. All patients engrafted after a median 14 days (13-17) but one of them, in 4th relapse of acute promyelocytic leukemia (APL), rejected the graft. Two of four evaluable patients had mild acute graft versus host disease (GVHD), and one mild chronic GVHD. The patient with APL died of two graft rejections on day+125, one T-ALL relapsed on day+180 and three children are disease-free with excellent clinical status one month to 1.7 years after transplant. We conclude that haploidentical HSCT with post-transplant cyclophosphamide is feasible to treat children without an available matched related or unrelated donor and should be prospectively studied. Disclosures:No relevant conflicts of interest to declare.

KIR- Ligand Mismatching Is Associated with Inferior Survival in Patients with Acute Leukemia Following T-Cell Replete Peripheral-Blood Stem Cell Haplo-Identical Transplantation with Post-Transplant Cyclophosphamide. a Study from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation (EBMT)

Background: Haplo-identical stem cell transplantation is increasingly been used in recent years in the treatment of acute leukemia. In particular, the use of T-cell replete grafts with post-transplant cyclophosphamide (PTCy) for prevention of graft-vs-host disease (GVHD) is becoming a valid treatment option with encouraging outcome. The initial studies used bone-marrow as the stem-cell source, but more recently, peripheral blood stem cells (PBSC) are also used. There is more limited data on the prognostic factors following haplo-identical transplantation with PBSC. Natural killer (NK) allo-reactivity as predicted by missing killer-cell immunoglobulin-like receptor (KIR) ligands in the recipients that are present in the donors has been shown to be an important factor in the outcome of T-cell depleted haplo-identical transplants. NK alloreactivity is associated with reduced relapse risk and improved survival in patients with AML, but not in patients with adult ALL. In addition, patients with donor NK alloreactivity had better engraftment and lower risk of GVHD. The role of NK cell allo-reactivity in the setting of T-cell replete haplo-identical transplant with PBSC and PTCy is unknown.Patients and Methods: The study included 238 patients, 139 male, 99 female, median age 45 years (range, 18-78) with AML (n=176) or ALL (n=62) who had T-replete haplo-identical transplant with PTCy between the years 2010-2015. All patients were given PBSC as their stem cell source. Patients were in CR1 (38%), CR2 (24%) or active disease (38%). Conditioning was myeloablative (47%) or reduced-intensity (53%). GVHD prevention included cyclosporine or tacrolimus with mycophenolate, in addition to PTCy, in 82%. KIR-ligand mismatching was predicted according to patient and donor HLA typing and correlated with transplantation outcomes. In all, 89 patients (37%) had a KIR mismatch in the GVHD direction, based on missing expression of C1, C2 or Bw4 ligands in the recipients that were expressed in their donors. There was no significant difference in patient characteristics between the group with and without KIR mismatch.Results: The median follow-up was 14 months (range, 1-50). Ninety-four percent of patients engrafted. The 2-year relapse and non-relapse mortality (NRM) rates in the entire group were 36% (95%CI, 29-42) and 22% (17-27), respectively. The leukemia-free (LFS) and overall survival (OS) rates were 43% (36-50) and 49% (42-56), respectively. Acute GVHD grade II-IV and chronic GVHD occurred in 34% (29-40) and 32% (26-39), respectively. The 2-year OS was 35% (22-47) in patients with KIR mismatch and 51% (42-60) in patients with no KIR-ligand mismatching (P=0.02). 2-year LFS rates were 27% (16-38) and 47% (38-56), respectively (P=0.003). Multivariate analysis identified AML (compared to ALL) (HR 0.51, P=0.008), active disease at transplantation (HR 5.03, P<0.001) and KIR mismatching (HR 1.60, P=0.03) as factors associated with 2-year OS. A center effect was also identified (P=0.05). The same factors predicted for LFS. KIR mismatching was associated with a higher incidence of relapse, 47% (34-58) and 32% (24-41), respectively (P=0.05). Multivariate analysis identified active disease at transplantation (HR 6.38, P<0.001), KIR mismatching (HR 1.97, P=0.03), female donors (HR 0.58, P=0.03) and reduced-intensity conditioning (HR 1.71, P=0.05) as factors associated with 2-year relapse. KIR mismatching was not associated with NRM, acute or chronic GVHD.Conclusions: Haplo-identical transplant with PTCy and PBSC graft is associated with favorable outcome in patients with acute leukemia. KIR ligand mismatching may be associated with increased relapse rate and worse survival in these patients. Donors with KIR mismatching should be avoided when possible in the PBSC haplo-identical setting. [Display omitted] DisclosuresCiceri:GSK: Other: B-thalassemia gene therapy was developed by Fondazione Telethon and Ospedale San Raffaele and has been inlicenced by GSK that provides funding for the clinical trial, Research Funding. Mohty:Sanofi: Honoraria, Speakers Bureau.

Key Aspects of the Immunobiology of Haploidentical Hematopoietic Cell Transplantation.

Hematopoietic stem cell transplantation from a haploidentical donor is increasingly used and has become a standard donor option for patients lacking an appropriately matched sibling or unrelated donor. Historically, prohibitive immunological barriers resulting from the high degree of HLA-mismatch included graft-vs.-host disease (GVHD) and graft failure. These were overcome with increasingly sophisticated strategies to manipulate the sensitive balance between donor and recipient immune cells. Three different approaches are currently in clinical use: (a) ex vivo T-cell depletion resulting in grafts with defined immune cell content (b) extensive immunosuppression with a T-cell replete graft consisting of G-CSF primed bone marrow and PBSC (GIAC) (c) T-cell replete grafts with post-transplant cyclophosphamide (PTCy). Intriguing studies have recently elucidated the immunologic mechanisms by which PTCy prevents GVHD. Each approach uniquely affects post-transplant immune reconstitution which is critical for the control of post-transplant infections and relapse. NK-cells play a key role in haplo-HCT since they do not mediate GVHD but can successfully mediate a graft-vs.-leukemia effect. This effect is in part regulated by KIR receptors that inhibit NK cell cytotoxic function when binding to the appropriate HLA-class I ligands. In the context of an HLA-class I mismatch in haplo-HCT, lack of inhibition can contribute to NK-cell alloreactivity leading to enhanced anti-leukemic effect. Emerging work reveals immune evasion phenomena such as copy-neutral loss of heterozygosity of the incompatible HLA alleles as one of the major mechanisms of relapse. Relapse and infectious complications remain the leading causes impacting overall survival and are central to scientific advances seeking to improve haplo-HCT. Given that haploidentical donors can typically be readily approached to collect additional stem- or immune cells for the recipient, haplo-HCT represents a unique platform for cell- and immune-based therapies aimed at further reducing relapse and infections. The rapid advancements in our understanding of the immunobiology of haplo-HCT are therefore poised to lead to iterative innovations resulting in further improvement of outcomes with this compelling transplant modality.

T-cell replete Haplo-identical HSCT with Post transplant Cyclophosphamide for Hemoglobinopathies: A retrospective analysis from a single center.

We report herein haplo-identical hematopoietic stem cell transplantation (haplo-HSCT) by T-cell replete graft infusion, with post-transplant cyclophosphamide (PTCy) in patients with hemoglobinopathies. Patients received a conditioning regimen consisting of either busulfan, fludarabine, cyclophosphamide, with antithymocyte globulin or Thiotepa, antithymocyte globulin, fludarabine, cyclophosphamide, and TBI. The median follow-up period was 14.3 months (range, 1-63 months). Overall survival (OS) and disease-free survival (DFS) were 80% and 62.8%, respectively. Incidence of secondary graft failure was 14%. Incidences of acute graft-versus-host disease (aGvHD) and chronic graft-versus-host disease (cGvHD) were 22.5% and 20%, respectively. Cytomegalovirus (CMV) reactivation was observed in 42.5% of cases. The 100-day mortality rate was 20%, with sepsis and aGvHD being the predominant causes of death.

Graft Failure after Haploidentical Hematopoietic Stem Cell Transplantation

Graft Failure after Haploidentical Hematopoietic Stem Cell Transplantation

Fevers post infusion of T-cell replete hla mismatched haploidentical hematopoietic stem cells with post-transplant cyclophosphamide: risk factors and impact on transplant outcomes.

Fever is a common early complication after infusion of stem cells in patients undergoing T-replete HLA haploidentical transplantation using post-transplant cyclophosphamide (PTCY). We analyzed the records of 172 haploidentical transplant patients to identify risk factors and to assess the impact of such fevers on transplant morbidity and mortality. One hundred and seventy-two patients received haploidential hematopoietic stem cell transplantation (haplo-HSCT) using PBSC (n = 103) or marrow (n = 69) grafts. One hundred and forty patients (81%) experienced fever (T ≥ 100.5 °F or >38 °C) with median onset on d + 2. Compared to patients who did not develop fevers, patients with fevers received higher median CD34+ cell dose (5.00 vs. 3.08 × 106/kg, p < 0.001), CD3+ cell dose (12.8 vs. 4.5 × 107/kg), were more likely to have received a myeloablative regimen (50% vs. 9%, p < 0.001), and PBSC source (71% vs. 9%, p < 0.001). Cox model showed that fever had no impact on TRM, GVHD, OS, and DFS. In the logistic regression to identify correlation with fevers, higher degree of HLA mismatches and use of PBSC were all predictors of developing fever. Fevers between infusion of the T-Cell replete graft and administration of PTCY are very common in Haplo-HSCT. This complication is transient and had no impact on post-transplant morbidity and mortality.

Upper gastrointestinal acute graft-versus-host disease adds minimal prognostic value in isolation or with other graft-versus-host disease symptoms as currently diagnosed and treated.

Upper gastrointestinal acute graft-versus-host disease is reported in approximately 30% of hematopoietic stem cell transplant recipients developing acute graft-versus-host disease. Currently classified as Grade II in consensus criteria, upper gastrointestinal acute graft-versus-host disease is often treated with systemic immunosuppression. We reviewed the Center for International Blood and Marrow Transplant Research database to assess the prognostic implications of upper gastrointestinal acute graft-versus-host disease in isolation or with other acute graft-versus-host disease manifestations. 8567 adult recipients of myeloablative allogeneic hematopoietic stem cell transplant receiving T-cell replete grafts for acute leukemia, chronic myeloid leukemia or myelodysplastic syndrome between 2000 and 2012 were analyzed. 51% of transplants were from unrelated donors. Reported upper gastrointestinal acute graft-versus-host disease incidence was 12.1%; 2.7% of recipients had isolated upper gastrointestinal acute graft-versus-host disease, of whom 95% received systemic steroids. Patients with isolated upper gastrointestinal involvement had similar survival, disease-free survival, transplant-related mortality, and relapse as patients with Grades 0, I, or II acute graft-versus-host disease. Unrelated donor recipients with isolated upper gastrointestinal acute graft-versus-host disease had less subsequent chronic graft-versus-host disease than those with Grades I or II disease (P=0.016 and P=0.0004, respectively). Upper gastrointestinal involvement added no significant prognostic information when present in addition to other manifestations of Grades I or II acute graft-versus-host disease. If upper gastrointestinal symptoms were reclassified as Grade 0 or I, 425 of 2083 patients (20.4%) with Grade II disease would be downgraded, potentially impacting the interpretation of clinical trial outcomes. Defining upper gastrointestinal acute graft-versus-host disease as a Grade II entity, as it is currently diagnosed and treated, is not strongly supported by this analysis. The general approach to diagnosis, treatment and grading of upper gastrointestinal symptoms and their impact on subsequent acute graft-versus-host disease therapy warrants reevaluation.

Immune reconstitution and survival of 100 SCID patients post–hematopoietic cell transplant: a PIDTC natural history study

AbstractThe Primary Immune Deficiency Treatment Consortium (PIDTC) is enrolling children with severe combined immunodeficiency (SCID) to a prospective natural history study. We analyzed patients treated with allogeneic hematopoietic cell transplantation (HCT) from 2010 to 2014, including 68 patients with typical SCID and 32 with leaky SCID, Omenn syndrome, or reticular dysgenesis. Most (59%) patients were diagnosed by newborn screening or family history. The 2-year overall survival was 90%, but was 95% for those who were infection-free at HCT vs 81% for those with active infection (P = .009). Other factors, including the diagnosis of typical vs leaky SCID/Omenn syndrome, diagnosis via family history or newborn screening, use of preparative chemotherapy, or the type of donor used, did not impact survival. Although 1-year post-HCT median CD4 counts and freedom from IV immunoglobulin were improved after the use of preparative chemotherapy, other immunologic reconstitution parameters were not affected, and the potential for late sequelae in extremely young infants requires additional evaluation. After a T-cell–replete graft, landmark analysis at day +100 post-HCT revealed that CD3 < 300 cells/μL, CD8 < 50 cells/μL, CD45RA < 10%, or a restricted Vβ T-cell receptor repertoire (<13 of 24 families) were associated with the need for a second HCT or death. In the modern era, active infection continues to pose the greatest threat to survival for SCID patients. Although newborn screening has been effective in diagnosing SCID patients early in life, there is an urgent need to identify validated approaches through prospective trials to ensure that patients proceed to HCT infection free. The trial was registered at www.clinicaltrials.gov as #NCT01186913.

Haploidentical Hematopoietic Cell Transplantation Using G-CSF Mobilized T-Cell Replete Grafts for for Acute Leukemia and MDS

▪The use of T-cell replete grafts from MHC-haploidentical donors with post-transplant cyclophosphamide (PTCy) to selectively deplete alloreactive T cells is efficacious in patients who do not have ready access to an HLA identical donor. The Johns Hopkins group that pioneered this regimen used non-myeloablative (NMA) conditioning and bone marrow (BM) grafts to help mitigate the risk of GvHD. Their results showed low rates of GvHD and treatment related mortality but outcomes were limited by a high relapse rate. However, for patients with active disease or other high risk characteristics new approaches are needed to help mitigate post-transplant relapse. For other transplant modalities, peripheral blood stem cell (PBSC) grafts are associated with lower relapse rates, faster engraftment, and improved overall survival when compared to BM derived grafts. To date, there are few small studies evaluating the outcomes G-CSF mobilized PBSC grafts for haplo-HCT with PTCy.To report our experience with T cell replete PBSC grafts with PTCy for haplo-HCT, we retrospectively analyzed the outcomes of patients with leukemia and MDS who underwent this transplant regimen. Between 2009 and 2015, 124 patients were transplanted at Washington University School of Medicine with this transplant platform and their outcomes were measured by retrospective chart review through June 2016. Donors were mobilized with G-CSF 10 mcg/kg daily for 5 days prior to beginning pheresis and no grafts were subjected to ex vivo T-cell depletion. Myeloablative conditioning was used for 54 patients and NMA regimens were used for 70 patients, after which, patients were infused with a median of 5.0 x 106 CD34+ cells/kg and 18.0 x 107 CD3+ cells/kg. For GvHD prophylaxis, all patients received PTCy 50 mg/kg on days +3 and +4, tacrolimus from day +5 to 180, and mycophenolate mofetil from day +5 to 35, as previously described.The median age at time of haplo-HCT was 53 years (range 19-73). Ninety three patients were transplanted for AML, 16 for ALL, and 15 for MDS. This was a high risk population with a median Hematopoietic Cell Transplantation-specific Comorbidity Index (HCT-CI) score of 3.5 (≥3 indicates high risk). Thirty two patients had prior transplants and 49 patients had active disease prior to their transplant.Median follow up for surviving patients was 553 days. Neutrophil count recovery occurred after a median of 17 days and platelet recovery after 29 days. 74 patient deaths occurred by June 2016. Relapse accounted for 36 deaths, infection for 17, acute GvHD for 9, graft failure for 3, and 9 patients died from other causes. The 1 year overall survival (OS) was 47.5% (95% CI 38.2-56.2%) and 1 year event free survival was 40.2 (31.2-48.9%). For patients transplanted in remission, 1 year OS was 50.8% (38.7-61.6%), while for patients transplanted with active disease 1 year survival was 42.9% (28.4-56.5%). Treatment related mortality at 6 months and 1 year was 20.2% (13.7-27.8%) and 31.4% (23.1-40.0%). The relapse rate at 1 year was 39.5% (28.7-50.1%). For patients transplanted in remission, the 1 year relapse rate was 31.4% (18.7-44.9%) and for those transplanted with active disease it was 50.7% (32.5-66.3%). Univariate analysis showed increased risk of relapse when going into transplant with active disease or receiving NMA regimens.The 180 day cumulative incidence of grades II-IV acute GvHD was 39.3% (30.0-48.9%) and grade III-IV acute GvHD was 10.8% (3.1-23.7%). 1 year cumulative incidence of chronic GvHD was 49.0 (35.8-60.9%) and severe chronic GvHD was very low at 4.0% (1.0-10.4%).In conclusion, using G-CSF mobilized grafts from PBSC for haplo HCT with PTCy is feasible for patients with leukemia and MDS who do not have ready access to an HLA identical donor. The use of PBSC grafts with higher numbers of CD3+ cells led to rapid engraftment, low rates of graft failure, and acceptable rates of acute and chronic GvHD. The 1 year OS was almost 1 year, which is encouraging considering most patients had a HCT CI score > 3 and many had active disease at transplant or already failed a prior transplant. Disease relapse post-transplant remains the primary cause of post-transplant mortality for these leukemia patients. In this cohort relapse was associated with having active disease at time of transplant and receiving NMA conditioning. Our results show using PBSC may be a valid alternative to bone marrow grafts for haplo HCT with PTCy. DisclosuresNo relevant conflicts of interest to declare.

Human Herpesvirus 6 replication predicts Cytomegalovirus reactivation after allogeneic stem cell transplantation from haploidentical donor

Background and objectivesSince HHV-6 reactivation after transplant has been reported to increase the risk of CMV infection, we tested this hypothesis in the HLA-haploidentical hematopoietic stem cell transplantation setting. Study designFrom February 2011 to October 2015, 75 patients received hematopoietic stem cell transplantation using a T-cell replete graft from a HLA-haploidentical donor at our Institution. ResultsInterestingly, 87% of HHV-6 reactivations were followed by a CMV reactivation, at a median of 15days between the two viruses. Incidence of CMV reactivation was 14.5-fold higher in those patients with prior HHV-6 reactivation vs. those without it (p-value<0.001). ConclusionThe present results suggest that HHV-6 can be considered as a predicting indicator of cellular immunosuppression preceding the onset of CMV infection.

Outpatient Haploidentical Peripheral Blood Stem-Cell Transplantation with Post-Transplant Cyclophosphamide in Children and Adolescents

Patients with high-risk hematological malignancies have a poor prognosis without a hematopoietic stem cell transplant. An HLA- haploidentical donor is available in 95% of the cases, and post-transplant cyclophosphamide permits the use of T-cell replete grafts in settings were ex-vivo manipulation is not available. The experience with HLA-haploidentical HSCT with PBSC and post-tranplant Cy in the pediatric and adolescent population is limited; we report the following experience.We retrospectively collected data on 25 patients (0 to 21 years old) with hematological malignancies, who underwent ambulatory haploidentical HSCT with post-transplant Cy from November 2011 to November 2014. The different conditioning regimens are described in Table 1. All patients received high-dose Cy(50mg/kg) on days +3 and +4. Cyclosporine A (CYA; 6mg/kg/d per os) and mycophenolate mofetil (MMF; 15mg/kg two times daily per os) were started on day +5. MMF was discontinued on day +35 and tapering of cyclosporin started day +90 in the absence of GVHD. All patients received anti-microbial prophylaxis for bacteria, fungal, herpes infection and Pneumocystis jiroveci according to institutional practices. First chimerism was performed at day +30, and second chimerism at day +100. Primary graft failure was defined when neutrophil counts did not exceed 0.5 x 109/L by day +30. Acute and chronic GVHD were graded according to NIH criteria.Patient, donor and stem-cell harvest characteristics are described in Table 1. All patients had high risk hematological malignancies. There were 5 patients who underwent their first transplant on 1st CR, 4 with ALL with high risk cytogenetics and 1 with AML. All other patients were defined as high risk because they were refractory/relapsed.Twenty-three patients (92%) had neutrophil engraftment after a median 17 (7-24) days. Platelet engraftment was observed in 20 (80%) patients after a median of 14.5 (11-23) days, 3 (12%) patients did not have platelet counts below 20,000/mcL. One patient was catalogued as a primary failure for not achieving neutrophil and platelet engraftment by day +30. One patient died before engraftment at day +10 of septic shock. Four patients (16%) died before day +30. The only patient that did not have a complete chimerism, had a diagnosis of AML and 30% of donor cells by day +30, by day +45 relapse of disease was documented.After a median follow-up of 157 days, 13 patients (52%) remain alive, with an estimated 1-year OS of 52% (95%CI: 30.4 - 65.6%).Nine patients (36%) died of complications (mainly infectious) not related to relapse at a median time of 66 days (10-579 days) from stem cell infusion. Nine patients (36%) relapsed in a median time of 105 days (45-288 days); three of those patients died at days +150, +113 and + 370 from transplant. Estimated 1 year event-free survival is 40.2% (95%CI: 41.3 - 75.8%) (Figures 1 and 2). Patients transplanted on 1st CR had a median follow-up of 664 days with an OS and EFS of 80% (4 patients), which was statistically different from the rest of the population (p=0.03) (Figure 3).Among those who engrafted (n=21), 9 cases (42.9%) had grade 2-4 acute GVHD and 4 cases (19%) of grade 3-4 acute GVHD. Three patients (14.3%) developed chronic GVHD, two had mild skin or liver cGVHD. One patient had severe (NIH stage 3) skin cGVHD, she was alive and with a grade 2 cGVHD until last follow up at day +893.Outpatient procedure, HLA-haploidentical HSCT including PBSC as a stem cell source, and post-transplant T-cell in vivo depletion using high-dose cyclophosphamide is feasible in children and adolescents, with acceptable rates of response and GVHD.Table 1Patient, donor and harvest characteristicsVariableN=25Age, median(range in years)10 (1-21)Gender, n(%) Male Female17 (68%) 8 (32%)Diagnosis, n(%) ALL-B ALL-T AML CML16 (64%) 2 (8%) 5 (20%) 2 (8%)Time from diagnosis to transplant (months)17.2 (1.9-153.5)Conditioning regimen, n(%) Cy 1500mg/m2 + Flu 75mg/m2 + Bu 9.6mg/kg (IV) Cy 1050mg/m2 + Flu 75mg/m2 + Bu 12 mg/kg (oral) Cy/VP-16/RT Cy/Flu/Mel16 (64%) 6 (24%) 2 (8%) 1 (4%)Donor, n(%) Mother Father Sister20 (80%) 3 (12%) 2 (8%)Donor age, median(range in years)38 (17-49)Infused CD34+ x 106/kg, median(range)11 (3.2-20) [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Long-Term Outcomes after Myeloablative Allogeneic Hematopoietic Cell Transplantation for Adult Acute Lymphoblastic Leukemia

Allogeneic hematopoietic cell transplantation (alloHCT) is a curative therapy for high-risk acute lymphoblastic leukemia (ALL). However, long-term outcomes after alloHCT for adult ALL have not been well described. We conducted a retrospective cohort study of 72 consecutive adult ALL patients who underwent a first myeloablative alloHCT at our institution from January 2000-December 2013. Median age at HCT was 38 yrs (range, 18-62), 40 (56%) were male, 18 (38%) had high HCT CI score, 14 (19%) had prior CNS leukemia and 35 (49%) had BCR-ABL+ disease. Donor source was HLA-matched related donor for 50% patients and 90% received PBSC as graft source. All patients were transplanted in CR (72% were in 1st or 2nd CR) and 92% received T-cell replete grafts. Median time from diagnosis to alloHCT was 5 months (range, 2-90). The incidences of grade II-IV and III-IV acute GvHD, chronic GvHD and extensive chronic GvHD were 43%, 13%, 51% and 36%, respectively. The median follow-up for our cohort is 76 months. At 6 years after HCT, probability of overall survival (OS) was 33% (95% CI, 21-44%) and relapse-free survival (RFS) was 30% (95% CI, 19-42%), and the cumulative incidence of relapse was 36% (95% CI, 25-48%) and non-relapse mortality (NRM) was 37% (95% CI, 26-49%). The most common causes of death were relapse (43%) and infection (21%); majority of relapses occurred within the first 2-years post-transplantation. There were no second cancer related deaths. In multivariable analyses, factors significantly associated with OS were HCT CI score (HR 2.69 for high vs. low/int., P=0.002) and CMV status (HR 2.62 for donor+ vs. others, P=0.05). HCT CI score was the only predictive factor for RFS (HR 2.26 for high, P=0.007). We also compared outcomes by BCR-ABL status. BCR-ABL+ patients were older (median age 42 vs. 36 yrs, p=0.02), had low HCT CI score (34% vs 22%, p=0.01), were more likely to be in CR1 (74% vs. 32%, p=0.002), and as a result, proceeded to HCT sooner after diagnosis (median 4 vs 7 months, p=<0.001). For BCR-ABL+ and BCR-ABL- patients, 6 year OS was 41% and 25%, RFS was 40% and 21%, relapse was 27% and 45% and NRM was 38% and 36% (P=NS for all comparisons). Myeloablative alloHCT can provide long-term survival for selected high-risk adult ALL patients. Relapses are relatively uncommon after 2 years post-transplant. Long-term NRM is high in this population and we did not observe a plateau in its incidence until 7.5 years post-transplant, suggesting the need for long-term follow up to prevent and manage late complications of alloHCT. [Display omitted] DisclosuresMajhail:Gamida Cell Ltd.: Consultancy; Anthem Inc.: Consultancy.

Fludarabine Busulfan Compared to Fludarabine Melphalan Is Associated with Increased Relapse Risk in Reduced Intensity Conditioning Transplant Despite Pharmacokinetic Dosing

Background: Fludarabine plus busulfan (FB) and fludarabine plus melphalan (FM) are two commonly used reduced intensity conditioning (RIC) regimens for allogeneic hematopoietic stem cell transplantation (SCT). A recent analysis showed that both regimens had similar overall survival (OS) but relapse incidence (RI) was significantly higher with FB with a trend towards higher non-relapse mortality (NRM) in FM (Baron et al., Cancer 2015). However, that cohort included patients treated with oral and intravenous busulfan without pharmakokinetic targeting of intravenous which may impact anti-leukemic activity.Aim: Compare transplant related outcomes of FB vs. FM using intravenous (IV) busulfan targeted to the area under the curve (AUC).Methods: After due IRB approval, patients with acute myelogenous leukemia (AML) and myelodysplastic syndromes (MDS) receiving RIC-SCT from 2008-2014 were identified. All baseline and laboratory features were retrospectively extracted. Busulfan dose in FB was 0.8 mg/kg IV for 10 doses with therapeutic AUC target of 900-1500 mcmol/L (min). All patients received T-cell replete grafts. Categorical and continuous variables were compared using Pearson's chi-squared and Wilcoxon/Kruskal-Wallis, respectively. Survival estimates were calculated using the Kaplan-Meier method and curves were compared using the log-rank test. Cumulative incidence was computed as competing events using Grey's model. Univariate and multivariate analyses were performed using Cox regression modeling.Results:A. Baseline characteristics and AUC monitoring: 134 pts were identified (47 FB and 87 FM). Median follow up of the entire cohort was 40 months (0-63.3) and at last follow up, 60% and 29% have died or relapsed, respectively. Baseline characteristics stratified according to conditioning regimen are shown in table 1. Younger age (60 yrs FB vs. 61 yrs FM, p = 0.015) and a trend towards a higher CMV R-/D- status (28% FB vs. 14% FM p = 0.064) were the only significant differences identified. All patients in the FB group received intravenous busulfan and 46/47 patients had evaluable AUC data with a range of 732-1354 mcmol/L (min). A total of 19 patients were outside of range, all <900 mcmol/L (min) and required a median dose increase of 28.1% (3.3-50.2%)B. Engraftment and toxicity data: The median time for platelet engraftment was 19 days (0-48) for FB vs. 16 days (14-183) for FM (p = 0.0023) whereas the median time to absolute neutrophil count (ANC) engraftment was 18 days (7-30) for FB and 15 days (11-40) for FM (p = 0.077). Cumulative incidence of grade II-IV, III-IV acute GVHD and chronic GVHD at 2-yr was 57.3%, 11% and 52.8% for FB and 48.6%, 17% and 63.4% for FM (p = 0.73, 0.4 and 0.21, respectively). Two patients in the FM group died of cardiac causes (heart failure and sudden cardiac arrest). No cases of sinusoidal obstructive syndrome were observed in either armC. Transplant outcomes: A significantly higher 2-yr relapse incidence (RI) was associated with FB vs. FM at 35.6% vs 17.3%, respectively (p = 0.0058). 2-yr progression free survival (PFS) was also significantly lower in the FB vs. FM at 51.2% vs. 65.1%, respectively (p 0.031). However, 2-yr OS and NRM was similar for FB vs. FM (53.1% and 22.9% vs 63.9% and 21.9%, respectively p = 0.26 and 0.89). Necessitating a dose adjustment based on AUC did not increase the risk for relapse or affect NRM. In multivariate analysis, FB was associated with increased RI with hazard ratio (HR) 2.29 (1.07-4.88; p = 0.033). Other factors significantly associated with RI on multivariate analysis were secondary/therapy related disease with HR 2.84 (1.34-6.02; p = 0.0067) and CR1 vs. other with HR 0.39 (0.17-5.32; p = 0.019). The significance of the results remained unchanged after exclusion of MDS patients (data not shown)Conclusion: Despite AUC dose adjustment, FB compared to FM was associated with increased RI with a similar OS and NRM. AUC dose adjustment did not impact transplant outcomes and its routine use in RIC should be further evaluated. Given the wide use of FB as a conditioning regimen, these important observations should be prospectively studied in a randomized fashion. [Display omitted] [Display omitted] [Display omitted] DisclosuresAl-Kali:Novartis: Research Funding. Wolf:Janssen Scientific Affairs, LLC: Consultancy.

Haploidentical stem cell transplantation (Haplo-HSCT) with nonmyeloablative conditioning regimen (NMAC) and postinfusion cyclophosphamide in advanced non-Hodgkin lymphoma (NHL) patients.

7039 Background: In patients lacking HLA identical (HLA-id) donors, haploidentical (Haplo) donors is increasingly considered as a valid alternative stem cell source.The introduction of post-infusion Cyclophosphamide (Cy) as prophylaxis for immunological complications using T-cell replete graft is one of the most usual strategy. However, efficacy is still a matter of debate. Here we reviewed the outcome of 28 consecutives Haplo-HSCT patients with advanced NHL that we compared to an historical control cohort of patients transplanted from HLA-id donors. Methods: 28 Haplo-HSCT were performed between 04/06/2010 and 27/09/2013. Diagnoses were aggressive NHL in 22 patients and low-grade NHL in 6. Median age was 48 years (19-67). At transplant, 64% were in complete remission, 29% in partial remission and 7% in stable disease. These 28 patients were fully matched to 61 HLA-id patients. Conditioning regimen varied according to donor source. Haplo-HSCT patients received a NMAC associating of Fludarabine (150mg/m² to...

T-cell replete haploidentical donor transplantation using post-transplant CY: an emerging standard-of-care option for patients who lack an HLA-identical sibling donor.

Availability of an HLA-identical sibling (MRD) or suitably matched unrelated donor (MUD) has historically been a limiting factor in the application of allogeneic hematopoietic transplantation. Although almost all patients have an HLA-haploidentical family donor, prior attempts at transplantation from such donors using T-cell replete grafts and conventional immunosuppression were associated with unacceptable rates of GVHD, and when stringent ex vivo T-cell depletion was used to control GVHD, rates of graft rejection and post-transplant infections were prohibitive. The recent approach to HLA-haploidentical donor transplantation developed in Baltimore that uses T-cell replete grafts and post-transplant CY (Haplo-post-HCT-CY) to control post-transplant allo-reactivity appears to have overcome many of the obstacles historically associated with haploidentical donor transplantation. In particular, TRM rates of <10% are usual and rapid reconstitution of immunity leads to a low rate of post-transplant infections and no post-tranplant lymphoproliferative disorders (PTLD), consistent with the hypothesis that post-transplant CY selectively depletes proliferating alloreactive T cells responsible for GVHD and graft rejection while preserving resting memory T cells essential for post-transplant immunologic recovery. In parallel trials using similar non-myeloablative conditioning regimens, Haplo-post-HCT-CY produced similar overall survival to double umbilical cord blood transplantation(DUCBT) in adult patients (62% vs 54%), with low rates of TRM (7% vs 24%), severe acute GVHD (0% vs 21%) and chronic GVHD (13% vs 25%). Furthermore, recent non-randomized comparisons adjusted for risk factors show that Haplo-post-HCT-CY achieve at least equivalent outcomes to conventional MRD and MUD transplants. Although most experience has been obtained using BM, emerging data suggest that a G-CSF mobilized PBSC graft can also safely be used for Haplo-post-HCT-CY. Haplo-post-HCT-CY also avoids the graft acquisition costs of DUCBT and MUDs and the cost of cell selection associated with T-depleted grafts. Although randomized comparisons will be forthcoming, Haplo-post-HCT-CY can already be considered a valid standard-of-care in patients who lack conventional donors thus extending the availability of allogeneic transplants to almost all patients. This donor source may also challenge the routine preference for a MUD in patients lacking an MRD.

Sequential Therapy Combining Clofarabine and HLA-Haploidentical Hematopoietic Stem Cell Transplantation In The Treatment Of Refractory and Advanced Lymphoma: Feasibility, Toxicity and Early Outcome

Allogeneic hematopoietic stem cell transplantation (HSCT) is a valuable treatment option for patients with relapsed or refractory lymphoma including patients with relapse after a first autologous HSCT. However, outcome in non-remission patients is still poor. Here we report the feasibility and efficacy of a protocol using the concept of sequential therapy with clofarabine induction chemotherapy followed by a HLA-haploidentical HSCT in the treatment of patients with advanced non-remission lymphoma. 16 adults (11 male, median age: 53 years, median comorbidity index: 3) with MCL (n=7), CLL (n=1), AITL (n=2), secondary DLBCL (n=2), DLBCL (n=2), follicular lymphoma (n=1), B- lymphoblastic lymphoma (n=1) were treated between September 2010 and February 2013. After induction-chemotherapy with clofarabine (5x30 mg/m² IV), followed by 3 days of rest, a reduced intensity conditioning (RIC) consisting of fludarabine/cyclophosphamide plus melphalan 110 mg/m2 IV was performed prior to a T-cell replete HLA-haploidentical HSCT. High dose cyclophosphamide (Cy) was administered for post-grafting immuno-suppression followed by mycophenolate mofetil and tacrolimus. The median number of immuno-chemotherapy attempts prior to haploidentical HSCT was 4 including 8 autologous HSCT. None of the patients were in complete remission (CR) prior to haploidentical HSCT. After salvage therapy and prior to haploidentical HSCT, progressive disease (PD) was documented in 9 patients with one patient being primarily refractory, while in 7 patients a partial remission (PR) was observed. Neutrophil engraftment was achieved in 16 patients (100%) within a median of 21 days (range 14-36) and platelet engraftment in 14 patients (88%) within a median of 30 days (range 18-115). No primary graft rejection occured. By day +30 CR was achieved in 4 patients (25%) and PR in 11 patients (69%), whereas 1 patient (6%) showed PD. Full donor chimerism on day +30 was detected in all 16 patients. By day +100, 8 of the 14 evaluated 14 patients (57%) achieved CR, 4 (29%) PR, and only 2 (14%) had relapsed. Full donor chimerism was detected in 13 (93%) patients. The rate of acute GvHD grade II-IV was 31%, while chronic GvHD occurred in 3 of 14 (21%) evaluable patients (21%). Non hematologic regimen-related grade III-IV toxicity was observed in 9 patients (56%), and included most commonly transient elevation of liver enzymes (38%), mucositis (19%), and nausea and vomiting (19%). Creatinine elevation (6%), hand-foot syndrome (6%) and haemorrhagic cystitis (6%) were rare. After a median follow up of 14.5 months (range 5.7-35) 4 patients had relapsed, and 4 patients had died, while death was lymphoma-associated only in one patient. Causes of non-relapse mortality (NRM) were haemorrhagic cerebral bleeding in one patient (day +101), and toxicity/infection in 2 patients (day +141; day +156). Cumulative incidence of NRM was 0% on day +100 and increased up to 20% (7-50) on day +360. Estimated one-year overall survival and progression-free survival were 75% (95 CI 46-90) and 56% (95 CI 30-76), respectively. Sequential therapy combining cloforabine induction-chemotherapy and HLA-haploidentical HSCT using RIC, a T-cell replete graft and high dose Cy post-transplant is feasible, shows a favourable toxicity profile and furthermore achieves significant anti-lymphoid activity in patients with advanced non-remission lymphoma. These early results are promising, but longer follow up is needed. Disclosures: Off Label Use: Clofarabine off label use in adults. Hausmann:Sanofi: Travel support Other. Tischer:Sanofi: Travel support Other.

Post-Transplantation Cyclophosphamide (PT-CY) After Myeloablative Conditioning Regimen (MAC) In Unmanipulated Haploidentical Bone Marrow Transplantation (hBMT) Is Highly Effective As Gvhd Prophylaxis and Disease Free Survival In Pediatric and Adult Patients With High Risk Leukemia

Introduction BMT from HLA haploidentical family members (hBMT), using either T-cell depleted or T-cell replete grafts, is increasingly employed in patients who urgently need (but lack) a donor. After the promising results in hBMT obtained by the Baltimore group (Luznik et al., Biol Blood Marrow Transplant 2008, Blood 2010) introducing post-transplant high-dose cyclophosphamide (PT-CY) following a non-myeloablative conditioning regimen, the Genoa group (Raiola et al., Biol Blood Marrow Transplant 2013) has shown, in the haploidentical setting that a myeloablative conditioning (MAC) with PT-CY (on day +3 and +5), cyclosporine from day zero and mycophenolate mofetil (MMF) from day +1, is associated with a high rate of engraftment, acceptable TRM and GVHD, and induces durable remission with low incidence of relapse in a high proportion of patients with high-risk hematologic malignancies. We now report a series of 13 heavly pretreated high-risk leukemia patients who underwent a MAC protocol consisted of TBF regimen: Thiotepa (10 mg/kg), Busulfan (9,6 mg/kg) and Fludarabine (150 mg/mq). As graft versus host disease (GVHD) prophylaxis, 2 patients received a 5 drugs combination (ATG-Fresenius, CSA, MTX, MMF and Basiliximab) and stem cells source was G-CSF-primed haploidentical bone marrow (hBM) cells (Di Bartolomeo et al., Blood 2013). In 11 patients stem cells source was non-primed unmanipulated hBM cells, and GVHD prophylaxis consisted of PT-CY (50mg/kg) iv on day +3 and +4, CSA 2.5 mg/kg/day and MMF 45 mg/kg/day from day +4. Results From 2008 to 2013, 11 adult patients (M/F=8/3; median age 40 years, range 23 to 62) and 2 pediatric patients (M/F=1/1, age 4 and 7 years) with high risk ALL (1 pediatric; 2 adult), AML (1 pediatric; 8 adults) and one Richter evolution of CLL, underwent T replete hBMT. At time of transplant 10 patients were in CR (CR1=9, CR2=1), 1 in a good PR and 2 had refractory disease. Grafts contained a median of 5.68 x 108/kg nucleated BM cells (range 0.7-62.1), 2.14x106/kg CD34+ cells (range 0.55-7.09) and 34.7x106/kg CD3+ cells (range 16-93.4). 12 patients are evaluable for engraftment. This occurred in 100% for neutrophils and 93% for platelets, with a median time to neutrophil recovery (&gt; 0.5 x 109/L) of 22.5 days (range, 13-40) and to platelet recovery (&gt; 20.0 x 109/L) of 27.5 days (range, 17-49). All patients had full donor chimerism by day +30. Non relapse mortality (NRM) was 23%: 2 pt died for sepsis (one before engraftment), 1 for aGVHD. 4 patients had grade I and 3 grade II aGvHD, respectively. Only one patient had a grade III, and another had grade IV fatal GVHD. 3 patients had only limited chronic GvHD. Up to now, only 3 patients have relapsed and of these 2 have died. 8 patients (61.5%) are currently surviving, 7 of them are disease-free with median follow-up time of 165 days (range 32-896 days) from transplant. Conclusion Our preliminary results confirm that haplo-BMT following a MAC regimen, is a feasible treatment in pediatric and adult patients, and that PT-CY is highly effective as GVHD prophylaxis, producing a high rate of stable engraftment with encouraging non relapse mortality and relapse-free survival. Disclosures: No relevant conflicts of interest to declare.