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Introduction - primary refractory AML is associated with a dismal prognosis. Only 30% of patients will respond to salvage chemotherapy and continue to allogeneic hematopoietic cell transplantation (HCT) with a 10-20% long- term overall survival. Following from the FLAMSA protocol, we implemented a modified RIC regimen - FITCy (fludarabine, cytarabine +/- idarubicin and 4 Gy TBI) in all primary refractory patients with a donor available for transplant. Methods - all patients who were admitted with AML, were identified by the transplantation coordinator nurse and underwent donor evaluation within 2 days from diagnosis. Patients who received induction chemotherapy had a day 14 marrow examination and where leukaemia blasts were identified, donor search was prioritized. These patients went on to have a day 28 bone marrow examination to confirm refractory disease. Patients who were treated with azacitidine ±venetoclax had a 2-month BM evaluation and donor search was prioritized in case of refractory disease. All consecutive patients, diagnosed with primary refractory AML, underwent HCT with the FITCy regimen in the Tel Aviv Sourasky Medical Center. Patients who underwent sequential therapy for relapsed disease (either chemosensitive or refractory) or a second HCT were excluded from this analysis. The protocol was amended on January 2018 to include ATG for all patients after interim analysis showed a high rate of GVHD. Results - Between January 2014 and June 2021, 48 patients were identified with primary refractory disease and were eligible for the protocol. Median age was 63 (range, 22-75) years (Table). Median follow-up for surviving patients was 33 (range, 1-81) months. Prior to HCT, 12 (25%) patients had ongoing documented infections (either microbiology or clinically). Median days to engraftment of neutrophils (>500/dL) and to complete engraftment of platelets (>20000/dL) were 10 (range, 7-20) days, and 16 (9-35) days, respectively. 7 patients with early progression/non relapse mortality were not evaluated for this outcome. No patient had primary/secondary graft rejection. Severe mucositis was observed in only 7 patients (15%) and was mostly observed in the upper gut. 18 patients (38%) developed microbiology documented infections during the neutropenic period and in 7 (40%) this directly contributed to mortality. Only 2 patients (4%) developed sinusoidal obstruction syndrome. Complete remission was documented on day 30, in all but 1 patient with a median whole marrow donor chimerism of 98% (range, 73-100%).Cumulative incidences of grade 2-4 and 3-4 acute GVHD at day 100 were 55% and 15%, respectively. Cumulative incidences of overall chronic GVHD and moderate-severe chronic GVHD at 1 year after HCT were 64% and 24%, respectively. Cumulative incidences of relapse at 1 year and 2 years post HCT were 24% and 30%, respectively. Non-relapse mortality rates, at 30 days, 100 days and 1 year post HCT were 13%, 20%, and 32%, respectively. Cumulative incidences of 1, 2, and 3 years overall survival were 50%, 42%, and 42%, Figure. Cox regression analysis for overall survival identified increased time from diagnosis (HR-1.03, p=.046), mismatched donor (HR-1.4, p=.05) and the use of ATG (HR=.33, p=.006) to impact survival, while age, sex and comorbidity index were not predictive. Conclusions - Sequential therapy in patients with primary refractory AML provides a remarkable anti- leukemic effect. A timely donor search program is essential for the succession of this approach. Nevertheless, infection control and GVHD prophylaxis is still suboptimal and future protocols should focus on these domains while preserving graft vs. leukemia function. Figure 1 Figure 1. Disclosures Moshe: AbbVie: Membership on an entity's Board of Directors or advisory committees, Other: Lectures; Astellas: Membership on an entity's Board of Directors or advisory committees, Other: Lectures; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Lectures. Avivi: Novartis: Speakers Bureau; Kite, a Gilead Company: Speakers Bureau. Ram: Novartis: Honoraria; Gilead: Honoraria. OffLabel Disclosure: Off label Cellcepet for prophylaxis of GVHD

Autologous Stem Cell Transplantation (ASCT); is a universal accepted therapy for rescuing relapsed Hodgkin (HL) and non-Hodgkin (NHL) lymphoma patients and for consolidation of mantle cell lymphoma (MCL). The most used preparative regimens in this setting are BEAM and CBV. both of them include carmustine, a medication with serious shortage and cost problems, therefore , is very important to find alternative regimens. During the nineties the combination of high dose of carboplatin plus cyclophosphamide and etoposide (CEC) was explored, however, it was abandoned due to high toxicity. We present our experience with 108 patients using this regimen but with intermediate dose of carboplatin (Inter CEC) Methods: We did a retrospective descriptive longitudinal observational study. All consecutive patients who met the inclusion criteria; age above 18 years, diagnosis of HL, NHL, M CL, and transplanted with Inter CEC were included. The preparative regimen consisted of carboplatin 900 mg/m2, etoposide 900 mg/m2, and cyclophosphamide 6.000 mg/m2, split in five days (fig 1). All patients received peripheral blood stem cells, and from d + 5 until neutrophil recovery, daily filgrastim. Every patient signed informed consent and the study was approved for institutional ethical committee. Results: From Oct 2013 to May 2020, 108 patients were included; median age was 45 years (18-70), 43.5% were female, 20% were older than 60 years and 79.6% had advanced disease at diagnosis. Thirty-five (32.4%) had HL, 35 (32.4 %) NHL (28 diffuse large B cell, 7 follicular), 29 (26,9%) had MCL, and 9 (8.3%) had other lymphomas. 34% of HL patients and 48% of cases were transplanted in CR1 after being refractory to first line therapy, while 44% and 14% of HL and NHL respectively had active disease at the time of transplantation. Regarding MCL cases; 21 (72,4%) had MIPI above 3 points and 96.5% were transplanted in first remission. All of the evaluable patients at day + 30 had hematopoietic recovery, median time to achieve 500 neutrophil /ul or more was 12.3 days (10-30) and for self-sustained platelet counts, 20.000/ul or more, was 15.3 (10-34). After a median follow up for surviving patients of 42,2 months the overall survival (OS) (Kaplan-Meier) at 48 months for the entire group was 74% (CI 63-82) and the event free survival (EFS) was 57% (CI 43-69). When the OS and EFS were discriminated for diseases, it was; for HL 76% (CI 56-88) and 43% (CI 17-66), for NHL 78% (CI: 57-90) and 68% (CI 42-83), and for MCL 69% (48-83) and 57% (CI 32-76) respectively (Fig 2). Eleven out of 18 patients (61%) transplanted with active disease achieved complete remission and 14 out of the entire group relapsed during the first years of transplant The transplant related mortality (TRM) at 1 year was 2.8%, the relapse associated deaths were 13% and, in 5 patients, who died after one year of transplant, the cause was not found. The main toxicity was mucositis; 46%, (grade II-IV: 22%), 30 patients (28%) had confirmed infections; bacteremia 17 cases, pneumonia 5, and others infections 6. Renal toxicity occurred in 24 cases (22%), grade 1; 15.8%, grade 2; 4.6% and grade 3; 1.8% Discussion Comparing results among trials is always difficult; however, despite that, in our series 58% of the cases were transplanted with active disease, our outcomes compare favorably with the results informed after the use of BEAM or CBV presented by CIBMTR in the largest trial published so far (table 1). The use of intermediate dose of carboplatin plus etoposide and cyclophosphamide produces a very good control of the lymphoma activity with acceptable toxicity, and achieves good OS and EFS. Other advantage of this regimen is that is carmustine free. The next step in our study is to do a matched paired analysis with patients transplanted with BEAM or CBV Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Background: High-dose chemotherapy followed by autologous hematopoietic cell transplantation (auto HCT) is considered to be the standard of care treatment for transplant-eligible patients with multiple myeloma (MM). The most commonly used conditioning regimen in this setting is high-dose melphalan by intravenous administration. Conventional melphalan formulations, when administered at high doses, can put patients at risk of potential propylene glycol-associated toxicities. Melphalan for injection (Evomela) is propylene glycol free (PGF), can be dissolved directly using saline, and as a PGF reformulation of Alkeran, incorporating Captisol brand of beta-cyclodextrin sulfobutyl ethers sodium salts, overcomes previous formulation limitations. In 2016 Evomela was the first product approved by the US FDA for high-dose conditioning treatment prior to HCT in MM patients and it is also indicated for the palliative treatment of patients with MM for whom oral therapy is not appropriate. Reconstituted Evomela solution can be stored in the vial for up to 1 hour at room temperature or up to 24 hours at 2-8 °C with no significant degradation. After storage in the vial, it remains stable for an additional 3 to 29 hours after, preparation of admixture solution in infusion bags at concentrations of 0.25 to 5.0 mg/mL, respectively. As well, Evomela solution in saline, at concentration of 5.0 mg/mL melphalan, was bacteriostatic through 72 hours when stored at 2-8 °C. This stability allows for less frequent handling by pharmacy and nursing staff, resulting in a concomitant decrease in exposure risks, increased convenience and administration flexibility, suggestive of an improved ease of handling and administration, when compared to Alkeran. Further, Evomela may actually be less toxic due to the absence of propylene glycol. Although increased melphalan doses have previously demonstrated signals of improved response, the most commonly used dose of melphalan is 200 mg/m2, primarily due to concerns of toxicity. Emerging data regarding higher stability and potentially less toxicity of PGF melphalan (Evomela) supports dose escalation evaluation in order to improve the outcomes. Previous trial data have shown that continuous infusion or frequent fractionated-dose delivery increases the antitumour activity of several drugs. Due to the instability of currently available Alkeran at the room temperature, infusional studies have not been feasible. This limitation is overcome by Evomela, being that the compound is stable for several hours at the room temperature, thus allowing evaluation of infusional schedules in addition to the traditional 30-60 minute bolus doses. Here, we describe a trial designed to assess whether the above noted characteristics of Evomela allow for the escalation of dose and prolongation of infusion time, in order to increase the efficacy of melphalan in patients undergoing auto-HCT. Study Design/Methods: This is a two-stage phase I-II trial to optimize the dose and schedule of Evomela given as a single agent preparative regimen for auto-HCT. Up to 60 participants may be included if they are 18-70 years of age, with non-relapsed MM, have a Karnofsky performance score ≥70%, who have received at least two cycles of initial systemic therapy, and are within 2 to 12 months of the first dose. Patients will be randomized 1:1 to two different infusion schedules (30-60 minute infusion or 8-9 hour infusion) using Evomela (2mg/ml) at two dose cohorts (200mg/ml2 or 225mg/m2). Because 2 mg/mL Evomela is stable for 10 hours, patients receiving the 8-9 hour infusion will receive the total dose in one single infusion bag. The primary objectives are to determine the optimal dose and schedule of Evomela before auto-HCT for MM and collect pharmacokinetic data and compare the exposure-response evaluations between the two infusion schedules. Secondary outcomes will include incidence of treatment-related mortality, rate of minimal residual disease negative complete response at 90 days post auto-HCT, progression-free survival and overall survival after auto-HCT in newly diagnosed myeloma patients treated on different schedules and doses of Evomela. The active study follow-up period will be up to one-year post auto-HCT. Figure Disclosures Bashir: Acrotech: Research Funding; StemLine: Research Funding; Takeda: Other: Advisory Board, Research Funding; Celgene: Research Funding; KITE: Other: Advisory Board; Amgen: Other: Advisory Board; Purdue: Other: Advisory Board. Qazilbash:Amgen: Research Funding; Bioclinica: Consultancy; Angiocrine: Research Funding; Bioline: Research Funding; Janssen: Research Funding.

Background Allogeneic stem cell transplantation (allo-SCT) using an HLA-matched sibling donor remains the only curative treatment for young patients with acquired severe aplastic anemia (SAA) [1]. When a matched sibling is not available and a patient does not achieve a response to immunosuppressive therapy (IST), allo-SCT from an unrelated donor (URD-SCT) is the preferred alternative. However, haplo-SCTs are increasing as a graft from a related mismatched donor is readily available for most patients and has the advantage of allowing for prompt transplantation. Therefore, haplo-SCT is a front-line therapy option for very SAA (VSAA) when the patient is not able to receive a SCT from emergent compatible donors. Methods We collected clinical data on 38 consecutive patients with aplastic anemia (AA) all of whom were treated at the Lu Daopei Hospital between December 2013 and July 2020. Patients had a median age of 8 (range: 1-34 years), 21 patients were male and 17 were female. Of the enrolled patients, 4 had 4 congenital AA, 34 had acquired AA and 3 had hepatitis-associated SAA. Median time from diagnosis to transplant was 9 months (range: 1-282 months). Eleven (28.9%) patients failed to receive ATG/ALG treatment. Twenty-six patients received a haploid-SCT, three patients received a sibling HLA-matched SCT and 9 patients received a URD-SCT. The sources of donor stem cell were parents in 11 cases, brothers and sisters in 6 cases, and unrelated donors in 9 cases. Median age of the donors was 32 (range: 11-57 years). Moreover, there was 13 donors that were incompatible in blood type with the patients. With regard to HLA matching type, 16 patients were HLA 5/10 and 22 patients were ≥ HLA 6/10. The stem cells were derived from BM+PBSC in 29 cases and from PBSC in 9 cases. The median dosage of MNC transfusion was 12.385x108/kg (range: 4.97-29.44x108/kg), CD34+ cell transfusion was 9.42x106/kg (range: 2.64-22.4 x106/kg) and CD3+ cell transfusion was 2.26 x106/kg (range: 1.11-7.92 x106/kg). Preparative regimen were Flu/Cy/ATG+TBI 200cGy for 30 patients, Bu for eight of the patients and three patients received BU+TBI. Additionally, all patients were treated with CSA/FK506 + MMF + sMTX to prevent GVHD. Results The median follow-up was 26.5 months (range: 1-103 months). All 36 cases were engrafted and no primary graft failure occurred. There was only one case of secondary graft failure. The median day of leukocyte engraftment was day +13 (range: +10 to +23), the median day of platelet engraftment was day +10.5 (range: 6-167). An Evaluation of bone marrow at one month after transplantation showed all patients were fully donor type. The overall survival (OS) rate was 92.1%, OS for haplo-SCT was 88.5%, and OS for HLA-identical SCT (sibling HLA-matched SCT + URD-SCT) was 100% (Figure 1). Conclusions In conclusion, the outcomes of haplo-SCT with TBI 200 cGy/Flu/Cy/ATG indicate that haplo-SCT can be an effective alternative option for SAA patients when fully matched or unrelated matched donors are not available, or for patients with VSAA who need an urgent transplant. Figure Disclosures No relevant conflicts of interest to declare.

Background: Granulocyte colony-stimulating factor (G-CSF) is used after hematopoietic cell transplantation (HCT) to enhance neutrophil recovery in patients rendered neutropenic by the agents used in the preparative regimen (PMID: 9187067). G-CSF is contraindicated in patients with sickle cell disease (SCD) due to reported life-threatening complications ascribed to sickle vasculopathy, presumably secondary to leukocytosis and granulocyte activation (PMID: 11880644). Complications include severe vaso-occlusive pain crises, splenic engorgement, rupture, and death (PMID: 19513902). Individuals with sickle trait tolerate G-CSF without toxicity (PMID: 29743574, PMID: 27167356).The safety/toxicity of using G-CSF to enhance neutrophil recovery following HCT for SCD has not been previously described in the context of vasculopathy that is present in recipients but whose hematologic milieu is altered by transfusions and donor product infusion. Aim/Method: The hypothesis that G-CSF use would be safe in SCD patients following HCT was tested in a multicenter trial (NCT 03128996). Patients underwent HCT from matched or one-antigen mismatched (at HLA-A, -B, -C, -DRB1 if marrow; -A, -B, -DRB1 loci if cord) related or unrelated donor products between 2004 and 2019 following reduced intensity conditioning (RIC) which included hydroxyurea, alemtuzumab, fludarabine, melphalan +/- thiotepa. The regimen results in short-term marrow suppression followed by recovery. GVHD prophylaxis included tacrolimus, short-course methotrexate or mycophenolate or prednisone, and since 2018, abatacept. All patients underwent transfusions prior to commencing conditioning to reduce Hemoglobin S (Hb S) levels to 1.5x103 cells/mL on 3 successive days. The clinical course, outcomes, and toxicities in the first 100 days post-HCT were evaluated as best representing the period of G-CSF influence on SCD recipients. Results: Sixty-four patients with SCD were evaluated post-HCT. The median age at HCT was 10.67 years (range, 1-21). HCT was performed for stroke/increased transcranial doppler velocity (N=32), acute chest syndrome (N=24) and vaso-occlusive episodes (VOE) (N=38). Twenty-nine and 35 patients received related and unrelated donor HCT respectively; 24 were mismatched at one antigen or allele locus. Graft sources included marrow (46), cord (12), peripheral blood (3), marrow + cord (2) and CD34 selected graft with T cell add-back (1). G-CSF was administered for a median of 9.4 days (range 6-33 days) post HCT. Neutrophil engraftment occurred at a median of 14.35 days (range 10-38), platelets at median of 25.2 days (range 12-89). Three patients recovered platelets beyond day 100. Seven patients had primary graft rejection and autologous reconstitution of hematopoiesis. Chimerism analysis in the remaining patients included a median of 93% (range 41-100% in the myeloid lineage; N=30), 89% (range 26-100% in the lymphoid lineage; N=36) and 93% (range 48-100% in whole blood; N=45) on day 100. The incidence of grade I-II and III-IV acute GVHD was 23.4% and 17% respectively during first 100 days. A total of 23 episodes of bloodstream and 7 non-bloodstream sites of bacterial infection were observed in 22 patients. No patient developed SCD related symptoms following post-HCT G-CSF administration. Organ toxicities noted in 17 of the 64 patients were variable [most common were hypertension (4), posterior reversible encephalopathy (3), and renal dysfunction (3)] and expected as part of the transplant process. Conclusion: In this cohort of SCD patients who underwent HCT from different donor sources following RIC and G-CSF to enhance neutrophil recovery, we noted no toxicities attributable to G-CSF. Specifically, no SCD related symptoms or extended hospitalization were encountered in any patient attributable to G-CSF administration. Commencing conditioning at a Hb S level Disclosures No relevant conflicts of interest to declare.

Background: In recipients of allogeneic hematopoietic stem cell transplantation (HSCT), organ toxicity is a barrier to administering high-intensity conditioning regimens. We hypothesized that determinants of acute organ toxicity are specific to individual conditioning regimens. We sought to characterize toxicities across common transplantation regimens, evaluate their prognostic implication, and derive predictors of severe toxicity at the regimen level. Methods: This retrospective study included adults undergoing first allogeneic HSCT at a single center between the years of 2001 and 2014 (median: 2010). Patients received grafts from matched sibling or unrelated donors and were conditioned with any of the following regimens: Cyclophosphamide + TBI (Cy/TBI), Busulfan + Cyclophosphamide (Bu/Cy), Fludarabine + 12.8 mg Busulfan (Flu/Bu4), Fludarabine + 6.4 mg Busulfan (Flu/Bu2), Fludarabine + 36-42 gr/m2 Treosulfan (Flu/Treo), and Fludarabine + 100-140 mg/m2 Melphalan (Flu/Mel). Toxicities were defined by the KDIGO scale for acute kidney injury (AKI) and by the CTCAE v. 5.0 for increases in total bilirubin, AST, ALT, and alkaline phosphatase (Alk. Phos.) The incidence of toxicities from the start of conditioning through 30 days post-transplantation was tabulated by regimen. Risk factors for severe organ toxicity were assessed within each regimen cohort using multivariable logistic regressions. Results: In a cohort of 707 patients, the median age was 52 years. The main indications for transplantation were acute leukemia (57%), myelodysplastic syndrome (13%), and aggressive lymphoma (9%). Graft-versus-host-disease prophylaxis included methotrexate in 80% of patients, and 56% received anti-thymocyte globulin (ATG). The most common regimens were Flu/Treo (n = 160) and Bu/Cy (n = 141). As expected, patient characteristics varied between regimens. The incidence of AKI and increased serum bilirubin in each regimen is shown in Figure 1A and 1B, respectively. Sinusoidal-obstructive syndrome (6% overall) accounted for only 17% of gr. ≥ 3 bilirubinemia in the entire cohort. Elevations in AST, ALT, and Alk. Phos of gr. ≥ 3 were not common ( Conclusion: Allogeneic stem cell transplantation recipients are at high risk for acute organ damage. We describe patterns of renal and liver toxicity across several regimens. Determinants of acute severe organ toxicity, defined as those associated with short-term mortality, are regimen dependent. Our findings suggest that these factors should be considered when selecting the preparative regimen. While requiring validation, the newly-defined composite endpoint of acute severe organ toxicity (ASOT) may be valuable in studying transplantation strategies. Figure 1 Disclosures No relevant conflicts of interest to declare.

Introduction: Allogeneic hematopoietic stem cell transplant is curative in several benign and malignant hematological disorders with predominant complications of graft versus host disease (GVHD) and infections. Antithymocyte globulin (ATG) has been shown in a number of prospective trials to be effective in decreasing acute and chronic GVHD. Recently, it has been suggested that recipient peripheral blood absolute lymphocyte count (ALC) on the day of ATG administration interacts with the dose of ATG administered and predicts transplantation outcomes. This interaction may depend on the preparative regimen and the dose of ATG used. We sought to determine if ALC at time of administration of ATG could impact clinical outcomes in a population treated with busulfan fludarabine myeloablative regimen and a fixed dose of 4mg/kg of ATG. Methods: Seventy consecutive pts who underwent a matched unrelated donor transplant with ATG at the University of Iowa were retrospectively analyzed. All pts received rabbit ATG (Thymoglobulin®) at 0.5 mg/kg on day -3, 1.5 mg/kg on day -2 and 2 mg/kg on day -3 in addition to tacrolimus and methotrexate. All received a myeloablative preparative regimen with busulfan (130 mg/m2 days -6 to -3) and fludarabine (40 mg/m2 daily for 4 days). All but one pt received peripheral blood as graft source. The effect of patient, disease, and transplant characteristics on 2-year outcomes was evaluated using Cox and Fine and Gray regression models. For relapse, GVHD, and infections, death was considered a competing risk. Estimated effects of predictors are reported as hazard ratios (HR) along with 95% confidence intervals. Results: Median age was 59 years (range 20-68). Underlying diagnoses were AML (n=47), MDS (n=20) and CML (n=3). Disease Risk index showed 25 high risk, 24 intermediate risk and 21 low risk patients in this study. The median peripheral blood ALC on day -3 was 100 × 102/µL (range 0-1144 × 102/µL). Univariate analysis showed no significant impact of ALC (100+ vs Conclusion: Our single center experience using busulfan and fludarabine myeloablative regimen and rabbit ATG dosed at 4 mg/kg showed no interaction between the recipient peripheral blood ALC and ATG to predict GVHD, infections, overall and relapse free survival. Disclosures Farooq: Celgene: Honoraria; Kite Pharma: Research Funding.

HLA-haploidentical (haplo) stem cell transplantation is now widely used for patients lacking a suitably matched related or unrelated donor (MUD). Conventionally, T-replete Haplo transplantation has been performed using non-myeloablative conditioning and a bone marrow graft. Subsequently, our group has developed the use of myeloablative conditioning and PBSC grafts for Haplo (Solomon et al BBMT 2015, 2019). However, some patients with hematologic malignancies who are unable to tolerate a fully myeloablative regimen may benefit from intermediate intensity conditioning. We conducted a prospective phase II trial utilizing melphalan based preparative regimen ( fludarabine 30mg/m2 days -6 to -2, melphalan 140 mg/m2 day -1) followed by infusion of unmanipulated peripheral blood stem cells (PBSCs) ,capped at 5x10 6 CD34+/kg,from a haploidentical first degree family donor. Graft-versus-host disease (GVHD) prophylaxis consisted of Cy 50mg/kg on days 3 and 4, MMF through day 35, and tacrolimus through day 180. The primary endpoint was to estimate the incidence of graft rejection following Fludarabine/Melphalan conditioning. For the graft failure endpoint we tested the hypotheses H0: p=10% versus Ha: p Haplo transplant using fludarabine/melphalan with PBSCs is a valid option for some patients lacking a timely access to a matched donor. It is well tolerated and provides full and rapid donor myeloid and T-cell chimerism. Figure 1:Overall Survival and Disease Free Survival In Matched Cohorts of Flu/Mel versus Flu/Cy/TBI Figure 1 Disclosures No relevant conflicts of interest to declare.

Background: Traditionally, pre-transplant conditioning regimen is given over 4-6 days before hematopoietic cell transplant (HCT). Delivering higher dose chemotherapy preparative regimen over a longer time period has not been tested previously. We hypothesized that the delivery of myeloablative dose of busulfan over a 3-week period may reduce toxicity and non-relapse mortality (NRM), without affecting relapse, and tested this in a prospective phase II study. Methods: Patients between 18 and 70 years of age with hematological malignancies and adequate organ function, with 8/8-HLA matched related or unrelated donor were eligible. They received a fixed dose of busulfan 80mg/m2 as outpatient on days -20 and -13. Then, fludarabine 40mg/m2 was given on days -6 to -2 followed by busulfan dosed to achieve target area under the curve (AUC) of 20,000 mol/min for the whole course based on pharmacokinetic studies. GVHD prophylaxis was cyclophosphamide (PTCy) 50mg/kg on days 3 and 4 and tacrolimus. Mycophenolate mofetil (MMF) was added to later unrelated donor recipients. All patients received standard supportive care. The primary endpoint was day 100 NRM. Results: We enrolled 52 patients with a median age of 62 (range, 39-69) years. Almost half (n=25, 48%) had AML or MDS and the other half (n=26, 50%) had had CML or MPD; 1 (2%) had multiple myeloma. Low, intermediate, high and very-high disease risk index (DRI) was present in 3 (6%), 34 (65%), 14 (27%) and 1 (2%). HCT-comorbidity index was >3 in 23 (44%) and 1-2 (n=23, 44%). A majority (n=32, 62%) had an unrelated donor. With a median follow up of 14 months (range, 3-23), NRM at day 100 was 1.9% (n=1) and 8% (95% CI, 0-15) at 1 year. Overall survival, progression-free survival and relapse at 1-year were 83% (95% CI, 73-95%), 78% (95% CI, 67-91%), and 14% (95% CI, 4-24%), respectively [Table]. There were no graft failures. The median time to neutrophil engraftment was 17 days (range, 13-33) and that of platelets (> 20K/µL, n=45) was 24 days (range, 9-266). Day 100 grade II-IV and III-IV acute GVHD rates were 37% (95% CI, 23-50%) and 6% (95% CI, 0-12%), respectively; 1-year chronic GVHD and extensive chronic GVHD rates were 9% (95% CI, 0-17%) and 7% (95% CI, 0-14%), respectively. Overall survival at 1-year differed significantly among patients with low/intermediate DRI (94%; 87-100%) and those with high/very high DRI (53%; 31-91%), P=0.001. Conclusion: Myeloablative fractionated busulfan regimen with PTCy GVHD prophylaxis is feasible in older patients, has low incidence of severe acute GVHD, chronic GVHD, and NRM and results in promising overall survival. Table Disclosures Popat: Bayer: Research Funding; Incyte: Research Funding; Jazz: Consultancy. Bashir:Imbrium: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Kite: Membership on an entity's Board of Directors or advisory committees; Spectrum: Membership on an entity's Board of Directors or advisory committees; StemLine: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Acrotech: Research Funding; Celgene: Research Funding. Ciurea:Miltenyi: Research Funding; Spectrum: Membership on an entity's Board of Directors or advisory committees; MolMed: Membership on an entity's Board of Directors or advisory committees; Kiadis Pharma: Membership on an entity's Board of Directors or advisory committees, Other: stock holder. Kebriaei:Amgen: Research Funding; Pfizer: Honoraria; Jazz: Consultancy; Kite: Honoraria. Nieto:Astra-Zeneca: Research Funding; Affimed: Research Funding; Affimed: Consultancy; Novartis: Research Funding. Oran:AROG pharmaceuticals: Research Funding; Astex pharmaceuticals: Research Funding. Qazilbash:Autolous: Consultancy; Bioclinica: Consultancy; Speaker: Other: Speaker; Amgen: Other: Advisory Board. Molldrem:M. D. Anderson & Astellas Pharma: Other: Royalties. OffLabel Disclosure: Fludarabine & Busulfan as conditioning agent prior to transplant

Introduction: Graft failure remains a major obstacle to the success of allo-HSCT. Rates of graft failure are reported to be 2% in recipients of HLA identical grafts, 9% in those with an unrelated donor, and up to 12.3% in those with an HLA-mismatched related donor (0-3 antigen mismatched). Graft failure is associated with high mortality due to prolonged cytopenia's leading to significant anemia, bleeding, and infection. Successful management of graft failure usually requires a second transplant to restore normal hematopoiesis. The selection of a preparative regimen presents a challenge in these patients who have recently undergone myelosuppressive therapy prior to the failed transplant maneuver. We have employed the use of a minimally myelosuppressive regimen consisting of a single dose of pentostatin with a low dose of total body irradiation (TBI) as conditioning prior to a second allogeneic transplant for patients who experienced primary graft rejection. Methods: Under an IRB-approved retrospective study, we describe 4 consecutive patients with graft failure after allogeneic stem cell transplantation, who received a re-conditioning regimen consisting of pentostatin and low-dose TBI prior to second allo-HSCT. The median age of patients was 38 years (23-51). The conditioning regimens of the first transplant were myeloablative doses of cyclophosphamide/rabbit ATG; busulfan/fludarabine rabbit ATG/; busulfan/fludarabine; and fludarabine/melphalan (Table 1). Median cell doses for the first transplant were 7.7 x 10E6 CD34+ cells/kg and 104 x 10E6 CD3+ cells/kg. Two patients had primary graft rejection and 2 patients had secondary graft rejection. Patients with secondary graft rejection had initial hematopoietic engraftment of neutrophils on a median of 21 days and platelets on a median 61 of days post-transplant with subsequent declines in peripheral blood counts and chimerism studies showing loss of donor cell engraftment. The donor for the second transplant was the same in one patient and different in three patients and included a HLA-matched sibling in 2/4 patients and HLA-matched unrelated donor (URD) in 2/4 patients. One patient had two transplants from the same donor followed by a third transplant from a different HLA matched sibling donor. Conditioning for the second transplant in these cases consisted of pentostatin 4 mg/m2 as a single dose on day -3 and two fractions of 200 cGy TBI on days -2 and -1 as shown in Table 2. Results: Patients underwent the second (or third) donor allogeneic transplant at a median of 99 days following the first transplant. The second donor allograft contained a median of 9.6 x 10E6 CD34+ cells/kg and 390 x 10E6 CD3+ cells/kg. All recipients of the pentostatin-TBI conditioning regimen engrafted following transplantation of allogeneic stem cells (Table 2). Engraftment following the second transplant (or third transplant, in patient #1) occurred at a median of 22 days for neutrophils and 54 days for platelets, and all patients achieved 100% myeloid and lymphoid chimerism. Patients did not experience VOD/SOS or have severe mucositis, enteritis, or pulmonary toxicity, and were hospitalized a median of 39 days from the second transplant. All four patients achieved normal blood counts following the second transplant. One patient died unexpectedly of an apparent infection following full donor hematopoietic reconstitution. Three of the four patients undergoing a second transplant using pentostatin/TBI conditioning are alive without evidence for disease relapse or graft rejection at a median follow-up of 3.5 years, with none of these patients experiencing severe acute or chronic GvHD. Conclusion: Single dose pentostatin combined with low-dose TBI represents an effective and well-tolerated conditioning regimen that facilitates engraftment of a second allogeneic transplant in patients who experienced primary or secondary graft rejection. The enhanced therapeutic efficacy of this reduced-intensity regimen that allowed consistent donor-derived hematopoietic engraftment after initial allo-graft rejection warrants further study. Disclosures Langston: Astellas Pharma: Other: Research Support; Incyte: Other: Research Support; Jazz Pharmaceuticals: Other: Research Support; Chimerix: Other: Research Support; Takeda: Other: Research Support; Kadmon Corporation: Other: Research Support; Novartis: Other: Research Support; Bristol Myers Squibb: Other: Research Support. Waller:Pharmacyclics: Other: Travel expenses, Research Funding; Cerus Corporation: Other: Stock, Patents & Royalties; Chimerix: Other: Stock; Cambium Oncology: Patents & Royalties: Patents, royalties or other intellectual property ; Amgen: Consultancy; Kalytera: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. OffLabel Disclosure: the use of pentostatin as part of a conditioning regimen

Fanconi anemia (FA) is an inherited bone marrow failure syndrome characterized by chromosomal fragility, progressive marrow failure, and cancer predisposition. Hematopoietic cell transplantation (HCT) is curative for FA-related marrow failure or leukemia, but both radiation exposure during transplant and graft-versus-host disease (GVHD) may increase risk of later malignancies of the head and neck and anogenital area. In this study, we tested a radiation-free conditioning regimen with a T-cell-depleted graft to eliminate radiation exposure and minimize early and late toxicities of transplant. Forty-five patients (median age, 8.2 years; range 4.3-44) with FA underwent HCT between June 2009 and May 2014. The preparative regimen included busulfan, cyclophosphamide, fludarabine, and rabbit anti-thymocyte globulin. Busulfan levels were monitored to avoid excess toxicity. All grafts were CD34-selected/T-cell-depleted using the CliniMacs CD34 columns (Miltenyi). Thirty-four patients (75.6%) with marrow failure and 11 (24.4%) with myelodysplastic syndrome underwent HCT using matched unrelated (n = 25, 55.5%), mismatched unrelated (n = 14, 31.1%), or mismatched related donors (n = 6, 13.4%). One year probabilities of overall and disease-free survival for the entire cohort, including patients with myeloid malignancy and those receiving mismatched related/haploidentical grafts, were 80% (±6%) and 77.7% (±6.2%), respectively (median follow-up 41 months). All young children (

Background αβ T- and B-cell depleted HLA-haploidentical HSCT (αβ haplo-HSCT) is an alternative promptly available and virtually applicable to any children with malignant and non-malignant disorders lacking an HLA-matched donor or in need of an urgent allograft (Locatelli et al. 2017). Through this approach, recipients can benefit immediately after transplantation from the anti-leukemia effect mediated by donor natural killer (NK) and γδ T cells, which confers protection also against infections. Nonetheless, even with this type of HSCT, the recovery of adaptive immunity is suboptimal. We have developed a further refinement of the approach based on the post-transplant infusion of a titrated number of donor T cells transduced with the inducible suicide gene iC9 (BPX-501 cells). This strategy has the potential to accelerate the recovery of adaptive immunity and to restore an efficient T-cell mediated graft-versus-leukemia (GvL) effect without the risk of inducing uncontrollable graft-versus-host disease (GvHD). Since reconstitution of a naïve T- and B-cell repertoire plays a key role in the long-term ability to respond to a broad range of pathogens, as well as to tumor antigens, we quantified T-cell receptor and kappa chain-deleting recombination excision circles (TREC and KREC), which represent reliable surrogate of T and B-cell neogenesis respectively. Study design and patients We analyzed samples of 48 children (M/F: 26/22) with acute leukemia (31 ALL, 17 AML) given an ab T-cell and B-cell depleted haplo-HSCT after a myeloablative regimen followed by the infusion of a titrated number of donor BPX-501 cells (1 million/Kg) after a median of 27 days (range: 11-87). Median age at transplantation was 8.3 years (range, 0.9-18). Thirty-two and 16 patients did or did not receive a preparative regimen containing total body irradiation (TBI). Anti-T lymphocyte globulin (ATLG Grafalon®, Neovii Biotech, 12 mg/Kg) was administered from day -4 to -2 for preventing graft rejection and GvHD. Moreover, to reduce the risk of EBV-related PTLD, on day -1, patients received rituximab (200 mg/m2). We analyzed T-cell reconstitution by measuring the TREC, small DNA excision circles of the TCR d locus deleted during recombination of the a-locus and present in the majority of functional ab-T-cells (sjTREC), and during the TCR b-chain recombination (bTREC). We also analyzed B-cell reconstitution by measuring coding-joint (Cj), signal-joint KREC (sjKREC) which reflect newly produced naïve B cells and the mean number of B-cell division (n) using the formula n=LOG(Cj/sjKREC)/LOG2. We performed real-time quantitative PCR, as recently described (Arruda et al. 2018), on genomic DNA extracted from PBMC collected at 6 different time points (before and 1, 3, 6, 12 and 18 months after the allograft). Results Recovery of thymic function started at 3 months after transplant: sjTREC and bTREC amounts reached and overcame pre-transplant values at 6 months, continuing to increase until 18 months after HSCT. Number of B-cell divisions obtained by the measurement of cj and sjKREC found in peripheral blood matched with the newly-generated B-cells bone marrow output and showed the same kinetics of sj and bTREC, rising from the 3rd month after HSCT. All these data correlate with immunophenotyping findings, which show a progressive increase over time of both total CD3+ and ab-T-cells. Furthermore, we observed a negative impact on both T- and B-cell neogenesis played by aGvHD (occurring in 14 patients), which became significant from 3 months after HSCT for sjTREC (p=0.013) and at 6 months for sjKREC (p= 0.03). We did not observe any impact of the use of TBI during the preparative regimen on T- and B-cells generation in this cohort. Conclusions BPX-501 cell infusion aims to contribute to the acceleration of immune reconstitution after a/b haplo-HSCT. In this study, we show that naïve T- and B- cells are quickly and efficiently generated in the early post-transplant period. This finding represents an interesting result considering the fully myeloablative conditioning regimens with the large use of TBI and the Ta/b and B-cells depletion (also in vivo by the administration of Rituximab) received by the patients. We observed an expected detrimental effect of aGvHD on immune reconstitution, but we emphasize the low frequency of this complication in this transplant setting despite the absence of any post-transplant pharmacological prophylaxis. Disclosures Foster: Bellicum: Employment, Equity Ownership. Locatelli:bluebird bio: Consultancy; Miltenyi: Honoraria; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Prior to a patient receiving a dose of an adoptive cell transfer such as engineered autologous or allogeneic CAR-T cells, it is common to perform a lymphodepletion step often using high dose chemotherapy. This process is considered important to create sufficient space in the immune microenvironment, e.g. bone marrow, to allow the transferred cells to engraft. Further, it appears to elicit a favorable cytokine profile for establishment and proliferation of the donor lymphocytes. Anti-CD45 radioimmunotherapy (RIT) is being investigated in a Phase III clinical trial as a myeloablative targeted conditioning regimen prior to allogeneic hematopoietic cell transplantation in AML patients. In this study, a low 131I-CD45 RIT dosimetric dose is administered to each patient and imaging performed to define a personalized therapeutic dose. Results from studies performed post-dosimetric dose demonstrate that lower doses of 131I-anti-CD45 RIT may be suitable for use as a preparative conditioning or lymphodepleting regimen prior to cell therapy such as CAR-T. Significantly, targeted conditioning with pan-CD45 antibody, which selectively targets all nucleated immune cells, is anticipated to deplete not only lymphocytes, but also macrophages, as well as immune suppressive regulatory T cells (T-regs) and myeloid-derived suppressor cells in the immune microenvironment. It may also exert a direct anti-tumor effect on CD45+ hematopoietic cancers. We hypothesized that targeted lymphodepletion may result in a more suitable immune homeostatic environment for the reception of adoptive cell therapies, and possibly reduce the incidence of cytokine release syndrome. We have performed preclinical studies using a 131I- labeled surrogate anti-mouse pan-CD45 antibody (30F11) to investigate in a mouse model the response of targeted RIT lymphodepletion on particular immune cell types and resulting changes in immune cytokine expression. Following single dose administration of non-myeloablative doses of CD45-RIT, peripheral blood, bone marrow and spleen samples were collected from 8-12 week C57Bl/6 mice at 48 and 96 hours post-treatment for immunophenotyping to evaluate lymphoid and myeloid subsets for lymphodepletion, and serum for cytokine profiling. CD45-RIT was shown to effect a considerable reduction in both lymphocyte and myeloid cell counts, inclusive of immune suppressive T regs and MDSCs. Further, the cytoreduction by CD45-RIT was shown to induce the expression of immune homeostatic cytokines including IL-15. Studies are in progress to evaluate CD45-RIT as a targeted lymphodepletion regimen in E.G7 lymphoma tumor bearing mice prior to adoptive cell transfer with OVA-specific CD8+ T cells. Disclosures Ludwig: Actinium Pharmaceuticals: Employment, Equity Ownership. Berger:Actinium Pharmaceuticals: Employment, Equity Ownership. Ekaterina:Actinium Pharmaceuticals: Consultancy, Research Funding; Radimmune Therapeutics: Consultancy, Research Funding.

Background: High dose chemotherapy (HDT) followed by autologous hematopoietic stem cell transplantation (auto-HSCT) is an effective choice of treatment for relapsed/refractory non-Hodgkin lymphoma (NHL) and Hodgkin lymphoma (HL). Historically, carmustine, etoposide, cytarabine, and melphalan (BEAM) has been the most widely used conditioning regimen, shown to significantly improve progression free survival (PFS) and overall survival (OS) with relatively low toxicity. However, high doses of carmustine and etoposide combined with melphalan (BEM), despite increased risks of pulmonary toxicity and severe mucositis, has also demonstrated efficacy as a more intensive preparative regimen with acceptable tolerability in younger populations. We performed a single institution descriptive study in order to compare the outcomes of patients with both NHL and HL treated with either consolidative BEAM or BEM preparative regimens and auto-HSCT. Methods: We identified 65 patients who were treated at USC Norris Comprehensive Cancer Center for relapsed/refractory NHL or HL with HDT and auto-HSCT between 2013 and 2018. 14 patients were excluded from statistical analysis due to insufficient data. The primary outcome was 1-year OS and the secondary outcomes were 100-day mortality and 1-year relapse rate (RR). BEAM consisted of carmustine 150mg/m2, etoposide 200mg/m2, cytarabine 200mg/m2, and melphalan 140mg/m2, while BEM was carmustine 12mg/kg, etoposide 60mg/kg, and melphalan 140mg/m2. Patient baseline characteristics, including age, sex, and diagnosis, were identified to describe the population. The T-test was used to describe groups with continuous outcomes and the Fisher's exact test was used to describe groups with categorical outcomes. A p-value of < 0.05 was considered statistically significant. Results: 22 patients who received BEM and 29 patients who received BEAM were included for statistical analysis. The patient's baseline characteristics are shown in Table 1. There was an insignificant trend towards increased 1-year OS (100% vs. 93.10%; p = 0.4996) but a higher 1-year RR (35.29% vs. 33.33%; p = 0.77) in BEM than BEAM. All patients were alive at 100 days; so, no difference was observed between BEAM and BEM with regards to 100-day mortality. Notable differences in demographics between the patients treated with BEAM versus BEM were observed primarily in age and diagnosis. Compared to BEAM, BEM was utilized significantly more in younger patients (mean age at transplant 41.7 vs. 58.6 years old; p < 0.0001) with a significantly larger percentage of HL diagnosis (48.28% vs. 5.56%; p = 0.0001). There was no significant difference in the 1-year OS, 100-day mortality or 1-year RR between HL and NHL (p = 0.5333, p = 1, and p = 0.7287, respectively) or between age < 50 and age ≥ 50 (p = 0.5271, p = 1, and p = 1, respectively). Conclusions: Both BEAM and BEM HDT for auto-HSCT to treat relapsed/refractory NHL or HL resulted in similar outcomes with no difference observed in 100-day mortality and only minor differences in 1-year OS and 1-year RR. However, significant differences in age and diagnoses of patients treated with these conditioning regimens serve as obstacles for more direct and applicable comparisons. Further analyses including tighter-matched patient cohorts, induction and salvage therapy prior to auto-HSCT, maintenance therapy, as well as treatment-related toxicities are necessary to better differentiate these two preparative regimens and provide additional utility in the clinical setting. Nonetheless, despite the much wider usage of BEAM as a preparative regimen for auto-HSCT in patients with relapsed/refractory lymphomas, BEM appears to be an efficacious alternative, and, therefore, warrants further consideration for future studies. Disclosures No relevant conflicts of interest to declare.

The addition of antithymocyte globulin (ATG) to a regimen of high-dose cyclophosphamide has been advocated to enhance engraftment after allogeneic bone marrow transplantation (BMT) for severe aplastic anemia (SAA). In a prospective clinical trial, 134 patients were randomly assigned to receive cyclophosphamide alone or in combination with ATG. All patients received T-cell–replete bone marrow from an HLA-matched sibling. With a median follow-up of 6 years, the 5-year probabilities of survival were 74% for the cyclophosphamide alone group and 80% for the cyclophosphamide plus ATG group (P = .44). Graft failure and graft-versus-host disease (GVHD) rates were similar in both groups. With the survival rates achieved, this study is not adequately powered to detect significant differences between the 2 treatment groups. In conclusion, the results of allogeneic BMT for SAA have improved over time related to advances in supportive care. The addition of ATG to the preparative regimen did not significantly improve the outcome.

Umbilical cord blood (UCB) is increasingly used as an alternative source of hematopoietic stem cells for transplantation for patients who lack a suitable sibling donor. Despite concerns about a possible increased risk of Epstein-Barr virus (EBV) posttransplantation lymphoproliferative disorder (PTLD) after UCB transplantation, early reports documented rates of PTLD comparable to those reported after HLA-matched unrelated marrow myeloablative (MA) transplantations. To further investigate the incidence of EBV PTLD after UCB transplantation and potential risk factors, we evaluated the incidence of EBV-related complications in 335 patients undergoing UCB transplantation with an MA or nonmyeloablative (NMA) preparative regimen. The incidence of EBV-related complications was a 4.5% overall, 3.3% for MA transplantations, and 7% for NMA transplantations. However, the incidence of EBV-related complications was significantly higher in a subset of patients treated with an NMA preparative regimen that included antithymocyte globulin (ATG) versus those that did not (21% vs 2%; P < .01). Nine of 11 patients who developed EBV PTLD were treated with rituximab (anti-CD20 antibody), with the 5 responders being alive and disease free at a median of 26 months. Use of ATG in recipients of an NMA preparative regimen warrants close monitoring for evidence of EBV reactivation and potentially preemptive therapy with rituximab.

We compared the safety and efficacy of allogeneic stem cell transplantation (allo-SCT) after reduced-intensity conditioning using either unrelated umbilical cord blood (UCB) donors or matched-sibling donors (MSDs) for 21 adults at high risk with advanced Hodgkin lymphoma (UCB, n = 9; MSD, n = 12). Both groups were comparable except for younger age in the UCB cohort (median, 28 vs 42 years; P = .02). Neutrophil recovery occurred earlier in the MSD group (median, 7 vs 10 days; P = .02). All patients had sustained donor engraftment by day 60. Cumulative incidence of acute severe graft-versus-host-disease (33% vs 33%; P = .99), chronic graft-versus-host-disease (11% vs 33%; P = .24), and 100-day treatment-related mortality (11% vs 17%; P = .80) were comparable. With median follow-up periods of 17 and 24 months, the 2-year progression-free survival rates were 25% (95% confidence interval [95% CI], 0%-55%) for UCB and 20% (95% CI, 0%-44%) for MSD allo-SCT (P = .67). Our results suggest comparable outcomes for reduced-intensity allo-SCT using UCB or MSD in adults at high risk with advanced Hodgkin lymphoma.

In this issue of Blood , Lindemans et al report on the impact of thymoglobulin (antithymocyte globulin [ATG]) during the preparative regimen for pediatric unrelated umbilical cord blood transplantation (UCBT). Survival and chronic graft-versus-host disease (GVHD) were similar whether or not patients

Hematopoietic stem cell transplantation (HSCT) is followed by profound immunodeficiency. Thymic function is necessary for de novo generation of T cells after HSCT. Circulating CD45RA+ naive T-cell levels are predictive of antigen-specific T-cell responses in the absence of graft-versus-host disease (GVHD). These T cells may not represent recent thymic emigrants, since naive T cells may maintain this phenotype if not antigen-activated. To accurately measure thymic output after HSCT and determine the factors that influence thymic function, T-cell receptor excision circles (TRECs) were examined in CD4+ and CD8+ cells from a cross-section of patients following HSCT. TREC levels rose weeks after HSCT and could be detected in patients 6 years after HSCT. TREC levels correlated with the frequency of phenotypically naive T cells, indicating that such cells were not expanded progeny of naive T cells present in the donor graft. Chronic GVHD was the most important factor that predicted low TREC levels even years after HSCT. Patients with a history of resolved GVHD had decreased numbers of TREC, compared with those with no GVHD. Because few adults had no history of GVHD, it was not possible to determine whether age alone inversely correlated with TREC levels. Recipients of cord blood grafts had no evidence of decreased TREC induced by immunosuppressive prophylaxis drugs. Compared with unrelated donor grafts, recipients of matched sibling grafts had higher TREC levels. Collectively, these data suggest that thymopoiesis is inhibited by GVHD. Larger studies will be needed to determine the independent contributions of age and preparative regimen to post-transplant thymopoietic capacity.

The toxicity of preparative regimens render neonatal bone marrow transplantation (BMT) for progressive childhood diseases a controversial treatment. Ablative BMT in neonatal mice with or without the lysosomal storage disease mucopolysaccharidosis type VII (MPS VII) show high morbidity and developmental disruption of both brain and bone structure. In this investigation, BMT was performed with a high dose of congenic, normal bone marrow into nonablated newborn mice. Recipients had lifelong, multilineage, peripheral blood chimerism with the donor β-glucuronidase-positive (GUS+) cells that was both well tolerated and therapeutic. Three daily injections of normal adult marrow increased the average life span by at least 6 months and corrected the functional breeding deficits typical of the MPS VII mice. Twelve months after injection, several structural features of femurs were more like that of normal mice than of untreated MPS VII mice. Periosteal circumference and bone cortical thickness were significantly improved in males and cortical density did not differ significantly from values in normal females. Significant reduction of lysosomal glycosaminoglycan storage corresponded directly with GUS enzyme activity and percentage of histochemically GUS+ cells in visceral organs and hematopoietic tissues such as thymus, spleen, peripheral blood, and bone marrow. By all criteria tested, BMT into neonatal MPS VII mice in the absence of any preparative regimen is a successful therapy.

Relapsed pre-B acute lymphoblastic leukemia (ALL) portends a poor prognosis even with hematopoietic stem cell transplantation (HSCT). CD19 chimeric antigen receptor (CAR) T cells have shown promise in early studies although morbidity related tohigh gradecytokine release syndrome (CRS) and/or neurotoxicity could limit its wide applicability in patients with high disease burden. The lympho depleting chemotherapy regimen may affect both toxicity and response and has not been well studied. Relapse rates among complete responders to CD19 CAR therapy occur in nearly half of patients in the first year. We report outcomes from our completed clinical trial of 53 children and young adults with relapsed/refractory ALL (n=51) or lymphoma (n=2) with a median follow up (mF/U) of 18.7 months. The first 21 patients received a low dose fludarabine (25 mg/m2/day Days -4 to -2) and cyclophosphamide (900 mg/m2 Day -2) preparative regimen (LDflu/cy) and results are reported in Lancet 385:517-28. The regimen for the subsequent 32 patients, who all received 1x106 CAR+ T cells/kg, was stratified based on disease burden. Subjects with low burden ALL (lowALL; 25% marrow blasts or lymphomatous disease) received an alternative regimen [FLAG (n=6), ifosfamide/etoposide per AALL0031 (n=2) or fludarabine (30mg/m2/day Days -6 to -3) and cyclophosphamide (1200 mg/m2/day Days -4 and -3) (HDflu/cy; n=8)] in an attempt to mitigate severe CRS risk and improve response. Four highALL subjects received LDflu/cy due to comorbidities including Trisomy 21. CRS was graded and anti-cytokine therapy was instituted as per Blood 124:188-95. Date for data cutoff was July 31, 2016. Of the 53 subjects 11 had primary refractory ALL, 5Ph+, 3 with Trisomy 21, 4 with CNS2 and 2 with CNS3 ALL including one with extensive leptomeningeal and parenchymal involvement. Cells were manufactured in 7-11 days and none underwent a test expansion. One patient was not infused due to rapidly progressive fungal pneumonia but was accounted for in all analyses. Of 51 ALL patients, 31 (60.8%) achieved a complete response (CR) with 28/31 (90%) of responders negative for minimal residual disease (MRD-). All 6 subjects with CNS ALL were rendered into CNS1 status with resolution of leptomeningeal enhancement, where appropriate, and CAR cells in CSF. The median leukemia free survival (mLFS) of MRD- CR responders is 18 months with a 49.5% probability of LFS beginning at 18 months (mF/U 22.6 months). Grade 3 (n=5) and 4 (n=2) CRS combined for a severe CRS incidence of 13.5%. Three grade 3 neurotoxicities(1 each: dysphasia, delirium, headache) and 2 seizures (one grade 1, one grade 2) occurred. There were no grade 4 neurotoxicities, even in the subject with extensive CNS disease. Subjects with low ALL had a significantly higher CR rate (18/21; 85.7%) than those with high ALL (13/32; 40.6%) (p=0.0011) and use of a flu/cy regimen correlated with higher response (29/44; 65.9% vs 2/8; 25%; p=0.0301). Overall survival in all subjects receiving a flu/cy regimen was 13.3 months with a 34.7% probability of survival beginning at 38 months (mF/U 18.7 months), which is significantly longer than those who did not receive a flu/cy regimen (5.5 months, no survivors beyond 11 months). The hazard ratio (HR) of not receiving a flu/cy regimen was 6.35 (1.906-21.14; p=0.0026). mLFS of subjects with MRD- CR who received a flu/cy regimen was not reached with a 53.3% probability of LFS beginning at 18 months (mF/U 22.6 months). Of the 28 subjects achieving MRD- CR, 21 had a subsequent HSCT with a median time to HSCT of 54 days from CAR infusion. 8/28 (28.6%) relapsed with CD19+ (n=2), CD19-/dim (n=5), CD19 unknown (n=1) blasts. Relapse was significantly more common in subjects who did not have a HSCT after CAR therapy (6/7; 85.7%) compared to those who did (2/21; 9.5%) (p=0.0001). Even accounting for transplant related mortality, them LFS in the HSCT group was not reached with a 62% probability of LFS beginning at 18 months. This is significantly longer than them LFS of 4.9 months in MRD- CR subjects who did not proceed to HSCT (p=0.0006) with a HR of 16.9 (3.37-85.1) of not having a subsequent HSCT. In all, CD19 CAR T cell therapy was effective and safe with a low incidence of severe CRS and neurotoxicity. In this nonrandomized series, the rate of durable remission was higher when a flu/cy preparative regimen was used and consolidation HSCT was employed. Figure 1 Figure 1. Figure 2 Figure 2. Disclosures Lee: Juno: Honoraria. Kochenderfer:bluebird bio: Patents & Royalties, Research Funding; Kite Pharma: Patents & Royalties, Research Funding. Rosenberg:Kite pharma: Research Funding. Mackall:NCI: Patents & Royalties: B7H3 CAR.

Allogeneic hematopoietic stem cell transplantation (HSCT) has emerged as standard therapy for children suffering from various life-threatening inherited metabolic disorders (IMD). Historically, successful outcomes have been limited by high rates of both graft failure and regimen-related toxicity. Real-time busulfan pharmacokinetic monitoring, combined with once daily dosing, has allowed for more precise delivery of targeted exposures during transplant conditioning. Recently, the Utrecht group reported highly favorable outcomes following a high-dose busulfan and fludarabine-based preparative regimen in patients with a variety of diagnoses, particularly in comparison to historical regimens that employ two or more alkylating agents. We report our experience using the same regimen specifically in patients with IMD. Since July 2014, 24 children undergoing first HSCT for IMD were conditioned with once daily IV busulfan (4 days; total regimen exposure of 90 mg x h/L) and once daily IV fludarabine (40 mg/m2/day x 4 days). Busulfan pharmacokinetic monitoring was performed on each of the first 3 doses (days); subsequent doses were altered to achieve the desired total regimen exposure. Serotherapy use was donor-dependent: HLA-matched related donor (MRD, n = 5), none; unrelated UCB (n = 16), thymoglobulin (2.5 mg/kg/day, days - 8 to -5); HLA-matched unrelated donor (MUD, n = 1), thymoglobulin (2.5 mg/kg/day, days - 5 -to -2); and, related HLA haploidentical marrow (n = 2), alemtuzumab (0.5 mg/kg divided days -11 and -10), +/- rituximab (375 mg/m2, day -12). All patients received CSA for GvHD prophylaxis. Additional GvH prophylaxis depended upon the allograft source: UCB, prednisolone; MRD/MUD, MMF; related haploidentical, MMF and post-transplant cyclophosphamide. Growth factor support was administered to recipients of UCB or haploidentical grafts. IMD diagnoses were as follows: Hurler syndrome (n = 10); cerebral adrenoleukodystrophy (n = 9); metachromatic leukodystrophy (n = 1); osteopetrosis (n = 1); fucosidosis (n = 1); alpha-mannosidosis (n = 1); and, beta-mannosidosis (n = 1). At a median follow-up of 229 days (range, 15 - 743), 22 of 24 patients survive, with a Kaplan Meier estimate of survival at one year of 86%. Causes of death were pulmonary bronchiolitis obliterans (BOS, n = 1) and graft failure (n = 1). Twenty-two patients had initial donor neutrophil recovery at a median day +14 (range, +11 to +21); for these patients, the median duration of severe neutropenia (ANC < 500/μL) was 7.5 days (range, 4 to 16 days). Of 20 patients who at the time of analysis are ≥ 30 days from HSCT, 18 had platelet engraftment (≥20,000/μL, transfusion unsupported) at a median day +22.5 (range, +10 to +94). One patient developed Grade II aGvHD (haploidentical marrow graft) which was successfully treated; no patients developed Grade III-IV aGvHD. One patient developed chronic GvHD with fatal BOS (UCB). Regimen-related complications were as follows: veno-occlusive disease, n = 0; hemorrhagic cystitis, n = 1; diffuse alveolar hemorrhage n = 1; idiopathic pneumonia syndrome, n = 1; immune-mediated cytopenias, n = 2; CMV viremia, n = 3; and, adenovirus infection, n = 1. Twenty patients (83%) have demonstrated durable, complete donor myeloid engraftment following the regimen. Of these, all have demonstrated mixed donor-recipient T-cell chimerism. Four patients, (all UCB grafts), have experienced graft failure: aplastic graft failure, n = 3, and autologous hematopoietic recovery, n = 1. Three of these patients underwent second HSCT and 2 are alive and engrafted while the other died of complications following second transplant. One patient awaits second transplant. In summary, this regimen of high-exposure, targeted daily busulfan and fludarabine in children with IMD provides favorable engrafted survival with minimal toxicities. Disclosures No relevant conflicts of interest to declare.

Introduction Relapse, graft-versus-host disease (GvHD) and GvHD-associated mortality are major obstacles to success of transplantation from unrelated and haploidentical donors in children with acute lymphoblastic leukemia. Future directions will focus on optimizing conditioning regimens and enhancing graft-versus-leukemia effect. Negative depletion of α/β(+) T cells and CD19+ B lymphocytes, which permits to maintain mature donor-derived natural killer cells and γδ(+) T cells in the graft may improve GvHD control, immune reconstitution and prevent the relapse. Patients and methods : A total of 67 pediatric patients with acute lymphoblastic leukemia (T-ALL- 26, B-ALL-41, 29 female, 38 male, median age 9,4 years, range 0,15-20) underwent allogeneic HSCT between May 2012 and May 2016. Forty two patients received haploidentical graft, 25 - a graft from matched unrelated donor. Disease status at transplant was CR1 in 19pts., CR2 in 35 pts. and CR>2 13 pts. Transplantation in CR1 was performed according to risk stratification scheme in the current institutional ALL protocol.Fifty patients recieved treosulfan-based myeloablative preparative regimen (74%), TBI-based regimen was used in 17 patients (26%). Two regimens of GvHD prophylaxis were used: regimen 1 (n=28): ATG (horse, ATGAM) 50mg/kg, post-grafting immunosuppression consisted of short course Tacro/MTX (n=20) before day +30 or no post-transplant prophylaxis (n=8[ММ1] ); regimen2 (n=39): ATG (rabbit, thymoglobuline) 5mg/kg, rituximab 200mg/m2 (n=30), bortezomib (n=24) and post- transplant bortezomib (n= 19) or Tacro (n=19). All patients with TBI- based regimen received rabbit ATG. TCRαβ+/CD19+ depletion of HSCT with CliniMACS technology was implemented in all cases according to manufacturer's recommendations. The median dose of CD34+ cells in transplant was 10 x106/kg (range 3,9-18,8), TCRα/β - 19x103/kg (range 0,2-300). Results Primary engraftment was achieved in 64 of 67 pts. (two patients died before engraftment), the median time to neutrophil and platelet recovery was 13 and 14 days, respectively. All evaluable patients achieved sustained complete donor T cell and myeloid chimerism by day +30. Early (100 day) mortality was pTRM was 7,5% (95% CI: 0,3-17),2-year pTRM - 17% (95%CI: 9-30). The 3 early deaths included bacterial sepsis (n=2) and viral infections (n=1), seven late: viral infection in four pts. (ADV=2, ADV+CMV=1, CMV=1), bacterial sepsis in two pts. and rhinocerebral mucormycosis in 1 pt., all late deaths were associatedwith chronic GvHD and prolonged corticosteroid therapy. Cumulative incidence of acute graft-versus-host disease (GvHD) grades II - IV and III - IV was 23,9% (95% CI: 16-36), and 7,5% (95% CI: 3-17) respectively. CI of cGvHD was 22,9% (95% CI: 14-36). Regimen 2 was more effective in prevention of aGvHD II-IV: CI at 2 year after HSCT was 12,8% vs 35,7% in regimen 1, p=0,05 and in cGvHD 8,8% vs 35,7%, p=0,028. No correlation between graft composition, donor type in aGvHD and cGvHD was noted Cumulative incidence of relapse at 2 years was 32% (95%CI: 22-47). Two years pEFS (event=death or relapse) was 49,6% (95%CI: 36-63), 2-year pOS - 50% (95%CI: 40-67). In patients, who received TBI-based conditioning pEFS was 62% (95%CI: 37-86), as compared with treosulfan-based 46,5% (95%CI: 31-62), p=0,65. There was no significant difference in survival and relapse rate according leukemia subtype and donor type. Median time of follow-up for survivors was 2 years (range, 0,3 - 4). Discussion: We confirm that the depletion of TCR-alpha/beta and CD19 lymphocytes from the graft ensures high engraftment rate and acceptable transplant-related mortality in pediatric ALL patients. Viral infections and leukemia relapse await further improvement of control. All major outcomes were equivalent between transplantation from unrelated and haploidentical donor. Disclosures No relevant conflicts of interest to declare.

Background: Telmisartan (TMS) is an angiotensin receptor blocker (ARB), approved in 1998 for treatment of hypertension. Additional mechanisms of action were described post-approval, including PPARɣ agonism (by physical binding) and Rho Kinase inhibition (indirectly, at the level of gene expression). A third function is suppression of NADPH oxidase, causing increased Nrf2, a master regulator of anti-oxidant genes like superoxide dismutase. TMS's effect on blood pressure plateaus at 80 - 160 mg/day, and is minimal in normotensive subjects. Elimination of intact bioactive drug is via intestine and biliary tract, without liver enzyme involvement. Importantly, TMS is anti-inflammatory and Treg inducing in various pre-clinical disease models, but has not been associated with immunosuppression or increased cancer risk during two decades of use. Given its excellent safety profile, described mechanisms of action, intact gut elimination, and pre-clinical effects, we reasoned that treatment prior to and during the acute post-transplant period could prevent severe acute graft-vs.-host-disease (GvHD) targeting the bowel, in recipients of related or unrelated donor (RD or URD) allogeneic hematopoietic stem cell transplants (allo-HSCTs) matched for 7/8 or 8/8 HLA. Methods: An open label Phase I/II trial is designed to enroll 60 adult allo-HSCT patients for treatment with TMS 160 mg daily, starting 2 days pre-transplant, and continuing for 99 consecutive days. Subjects receiving > 28 consecutive days of TMS are considered evaluable. Patients can receive myeloablative or reduced-intensity regimens, and mobilized PBPC or marrow. Post-HSCT immunosuppression is tacrolimus and methotrexate. GvHD is evaluated at least weekly using standard grading / staging. Safety stopping criteria are non-relapse mortality (NRM), relapse or progression, failure to engraft, and drug intolerance (excluding reversible hypotension) within the first 180 days post-HSCT. The study is historically controlled vs. recent 3 year data from the John Theurer Cancer Center, and powered to detect 50% and 20% reductions in, respectively, Grade 3-4 (26%, historic) and Grade 2 (74%, historic) GvHD, as primary effect endpoints. Exploratory endpoints include: Endotoxin Activity Assay (EAA, Spectral) for LPS in blood, soluble ST2 (a marker of inflammation previously associated with acute GvHD, PreSage EIA, Critical Diagnostics). Early Results: To date, 12 patients (10 male and 2 female, ages 24 - 70) have been enrolled (Table 1). Ten have reached the 100 day post-transplant point. Six of 12 patients discontinued drug - 5 for non-medical reasons, prior to day 100 ("too many" pills and/or samples, forgot to take, did not feel good) - three of them after > 28 days of treatment. One other patient required dose reduction to 80 mg/d. Among all 12 enrollees, including those with < 28 days of TMS, there was one MDS progression to AML and one persistence of MDS. There was no graft failure or NRM. Among 8 evaluable patients (i.e., > day 100 post-HSCT, > 28 days' TMS), there have been no cases of Grade 4 GvHD. Two patients receiving > 28 days of treatment experienced Grade 3 GvHD. One patient had only skin rash involvement; a second (Pt #3) had, at separated time points, rash, diarrhea, and elevated LFTs, with rapid response to steroid therapy. No patients developed Grade 2 GvHD during the 100 day acute period, although three patients developed chronic Grade 2 rashes after 100 days. Exploratory endpoints revealed an increase in LPS (Fig. 1) and sST2 (Fig. 2) during the pre-transplant preparative regimen, reaching septic levels in some cases, but generally returning to normal or sub-septic levels during the post-transplant phase. Discussion: Early results suggest safety of TMS, and possible reduced frequency and severity of GvHD with 28 - 100 days of treatment. The study continues, with close attention to day 180, 1 year, and longer term outcomes, in relation to blood markers and lymphocyte subsets. Retention of out-patient subjects is challenging due to complexity of post-HSCT regimens and symptoms, which may be overwhelming for some patients. Also, the absence of GvHD symptoms, possibly due to early acute phase TMS treatment, may reduce the incentive to continue TMS in some cases. Figure 1 Characteristics of Study Patients Figure 1. Characteristics of Study Patients Figure 2 EAA (requires adequate leukocyte counts, typically unavailable at wk 1 post-HSCT) Figure 2. EAA (requires adequate leukocyte counts, typically unavailable at wk 1 post-HSCT) ST2 ST2 Disclosures Schwartz: Hackensack University Medical Center: Patents & Royalties: provisional patent for use of telmisartan to prevent or treat GvHD. Iyengar:Hackensack University Medical Center: Patents & Royalties: I am on a provisional patent for the use of Telmisartan to treat Graft v. Host Disease.

Blood stem cell transplantation (BSCT) results in rapid hematopoietic recovery in both the allogeneic and autologous transplant settings. Because of the large numbers of progenitor cells in mobilized blood, the administration of growth factors after transplantation may not provide further acceleration of hematopoietic recovery. A randomized, double-blind, placebo-controlled study was performed to determine the effects of filgrastim (granulocyte colony-stimulating factor; G-CSF) administration on hematopoietic recovery after allogeneic BSCT. Fifty-four patients with hematologic malignancies undergoing a related, HLA-matched allogeneic BSCT were randomly assigned to receive daily filgrastim at 10 μg/kg or placebo starting on the day of transplantation. A minimum of 3 × 106 CD34+ cells/kg in the allograft was required for transplantation. All patients received a standard preparative regimen and a standard regimen for the prevention of graft-versus-host disease (GVHD). The median time to achieve an absolute neutrophil count greater than 0.5 × 109/L was 11 days (range, 9-20 days) for patients who received filgrastim compared with 15 days (range, 10-22 days) for patients who received placebo (P = .0082). The median time to achieve a platelet count greater than 20 × 109/L was 13 days (range, 8-35 days) for patients who received filgrastim compared with 15.5 days (range, 8-42 days) for patients who received placebo (P = .79). There were no significant differences for red blood cell transfusion independence, the incidence of acute GVHD, or 100-day mortality between the groups. The administration of filgrastim appears to be a safe and effective supportive-care measure following allogeneic BSCT.

Therapy-related myelodysplasia (t-MDS) and acute myeloid leukemia (t-AML) after high-dose chemotherapy (HD-CT) and autologous stem cell transplantation (ASCT) for malignant diseases have become an important problem. The actuarial risk has varied, but has often been high if compared to the risk after conventional therapy. Prior chemotherapy with large cumulative doses of alkylating agents is the most important risk factor. In addition, patient age and previous radiotherapy, particularly the use of total body irradiation (TBI) in the preparative regimen for ASCT, have been identified as risk factors. In 3 studies, patients transplanted with CD34+ cells from peripheral blood after chemotherapy priming showed a higher risk of t-MDS or t-AML than patients transplanted with cells isolated from the bone marrow without priming. To what extent this higher risk relates to the prior therapy with a different contamination with preleukemic, hematopoietic precursors of the CD34+ cells obtained by the 2 methods, or is a direct result of chemotherapy priming, or of an increasing awareness of these complications, remains to be determined. The latent period from ASCT to t-MDS and t-AML has often been short, 12 months or less in 27% of the patients. Bone marrow pathology of early cases of t-MDS after ASCT has often been neither diagnostic nor prognostic, but most patients presented chromosome aberrations, primarily deletions or loss of the long arms of chromosomes 5 and 7. The prognosis was in general poor, although 17% with indolent t-MDS survived more than 18 months from diagnosis, and most of these presented a normal karyotype or a single chromosome aberration.

Nonmyeloablative allogeneic stem cell transplantation has recently been explored as a safer alternative to conventional high-dose transplant regimens. Although a high incidence of mixed chimerism after nonmyeloablative procedures has been reported, the exact kinetics of engrafting donor cells in specific cellular lineages has yet to be defined. We investigated lineage-specific chimerism in 15 patients receiving an allogeneic peripheral blood stem cell (PBSC) transplant from an HLA-identical (n = 14) or a 5/6 antigen-matched sibling donor after a preparative regimen of cyclophosphamide and fludarabine. Donor chimerism was assessed weekly in T lymphocytes and myeloid cells by polymerase chain reaction (PCR) of minisatellite regions. Eight patients survived between 121 to 409 days after transplant. Ten of 14 patients surviving more than 30 days (71.4%) had delayed disease regression consistent with a graft-versus-malignancy (GVM) effect. One patient rejected the transplant with subsequent recovery of autologous hematopoiesis. Hematological recovery was rapid (median, 11 days to ≥500 neutrophils/μL) and was initially predominantly recipient in origin. Donor myeloid chimerism gradually supplanted recipient hematopoiesis and became fully donor in all survivors by 200 days after transplantation. In contrast, T-cell engraftment was more rapid, with full chimerism in 7 patients by day 30 and in 6 further patients by day 200 after cyclosporine withdrawal and donor lymphocyte infusion. Full donor T-cell engraftment preceded donor myeloid engraftment, acute graft-versus-host disease, and disease regression, consistent with a requirement for 100% donor T-cell chimerism for full expression of the alloresponse. These results emphasize the importance of lineage-specific chimerism analysis to successfully manipulate engraftment after nonmyeloablative allogeneic PBSC transplantation.

Donor CD8+ T cells capable of host reactivity inhibit marrow graft rejection, but also generate graft-versus-host disease (GVHD). To evaluate whether the Tc1- and Tc2-type subsets of CD8 cells might inhibit rejection without host reactivity, we established an F1 into-parent murine bone marrow transplant model. Donor Tc1 and Tc2 cells were generated that preferentially secreted type I or type II cytokines; both subsets possessed potent cytolytic function, and clonally deleted host-type allospecific precursor CTL in vitro. B6 hosts receiving 950 cGy irradiation did not reject the donor marrow (F1 chimerism of 78.6%; n = 10), whereas hosts receiving 650 cGy rejected the donor marrow (3.8% chimerism; n = 8). At 650 cGy irradiation, the addition of Tc2 cells to the F1 marrow resulted in extensive F1 chimerism (70.8%) in 8 of 8 recipients; in contrast, alloengraftment was not consistently observed in mice receiving Tc1 cells or unmanipulated CD8 cells. Furthermore, when the preparative regimen was further reduced to 600 cGy, only hosts receiving the Tc2-type cells did not reject the F1 marrow. We conclude that Tc2 cells potently inhibit marrow graft rejection without inducing an alloaggressive response and that non–host-reactive Tc2 cells therefore facilitate engraftment across genetic barriers with reduced GVHD.

Primary graft rejection after marrow transplantation occurs more frequently in patients receiving HLA-haploidentical compared with HLA-identical sibling transplants. Both human and experimental animal data suggest that the cells responsible for this phenomenon are either host natural killer (NK) cells, T cells, or both. To investigate the mechanisms of graft rejection, we have developed a canine model of marrow transplantation, which uses DLA-nonidentical unrelated donors in the absence of postgrafting immunosuppression. In this model most animals rejected their marrow grafts after a preparative regimen of 9.2 Gy total body irradiation (TBI). However, engraftment of DLA-nonidentical marrow can be facilitated when the recipients are pretreated with monoclonal antibody (MoAb) S5, which recognizes CD44. In this report, we extended these observations by first cloning the canine CD44 and, next, mapping the epitope recognized by S5, which was located in a region conserved among human and canine CD44 and was distinct from the hyaluronan binding domain. However, in vitro binding of S5 caused a conformational change in CD44, which allowed increased hyaluronan binding. Then, we reexamined the in vivo model of marrow transplantation and compared results with MoAb S5 to those with two other anti-CD44 MoAbs, IM7 and S3. Only MoAb S5 significantly increased the engraftment rate of DLA-nonidentical unrelated marrow, whereas the two other anti-CD44 MoAbs were ineffective. The enhanced in vivo effect was not related to differences in the MoAbs' avidities, since both S5 and IM7 had equivalent binding to CD44, but most likely related to the specific epitope that S5 recognizes. Thus, this study shows that the effect of the anti-CD44 MoAb S5 in facilitating engraftment is epitope specific and if one is to use an anti-CD44 to facilitate engraftment of marrow in humans, one cannot assume that any anti-CD44 would work.

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disorder of immune regulation leading to widespread lymphocytic and hemophagocytic infiltration of vital organs. Apparent cure has only been achieved with allogeneic bone marrow transplantation (BMT). This report describes 20 consecutive patients, who underwent either matched sibling donor (n = 4) or unrelated donor (URD; n = 16) BMT. Age at the time of BMT was 0.4 to 5.3 years (median, 0.8 years). Central nervous system disease was present at diagnosis in 13 patients. At BMT, 14 patients were in a clinical remission, whereas 6 patients had active HLH. All patients were engrafted after cytoreduction with busulfan, cyclophosphamide, and etoposide. The probability of grade II-III acute graft-versus-host disease (GVHD) for all patients was 57% (95% confidence limit [CL], 0.28, 0.86), and 73% (95% CL, 0.44, 1.0) in URD patients. The overall probability of survival at 3 years was 45% (95% CL, 0.23, 0.67) and 44% (95% CL, 0.19, 0.68) when URD BMT was evaluated separately. Favorable BMT outcome was associated with clinical remission status at the time of BMT. The preparative regimen was well tolerated, and in the 9 surviving patients it provided durable engraftment and was effective at eradicating the underlying disease.

From 1990 to 1993 we performed a prospective study of busulfan (16 mg/kg) and cyclophosphamide (120 mg/kg) in 30 patients with refractory anemia (RA) undergoing related (n = 17) or unrelated (n = 13) donor marrow transplantation. Nineteen patients survive disease free (63% 3-year actuarial disease-free survival [DFS]) and no patient relapsed. These results were compared to those of 38 historical controls with RA treated with cyclophosphamide and total body irradiation, of whom 22 are disease-free survivors and 1 relapsed. After correcting for significant variables between the two treatment groups, we found no statistically significant difference in outcome based on preparative regimen. Combining data from these 68 patients plus 2 additional patients with RA treated before 1993 with busulfan and cyclophosphamide, we identified four variables independently associated with improved survival: younger age, shorter disease duration, lower neutrophil count pretransplant, and lower hematocrit pretransplant. We also found that 15 patients 40 to 55 years of age had a 46% 3-year actuarial DFS and 26 patients receiving unrelated or mismatched related donor marrow had a 50% 3-year actuarial DFS. We conclude that there does not appear to be any significant difference in outcome based on preparative regimen in this patient population. In addition, allogeneic bone marrow transplantation may be a reasonable approach to therapy of RA early after diagnosis. However, whether early intervention with transplantation prolongs survival over that expected without transplantation cannot be ascertained with certainty from available data.

From March 1988 to March 1991, 19 French bone marrow transplant (BMT) centers participated in a prospective randomized trial comparing two conditioning regimens for patients with chronic myeloid leukemia transplanted in first chronic phase with an HLA identical sibling donor. A total of 120 consecutive patients were randomized to receive either 120 mg/kg of cyclophosphamide followed by total body irradiation (CY-TBI; n = 55) or 16 mg/kg of busulfan followed by 120 mg/kg of CY (BU-CY; n = 65). Two different TBI regimens were used. Thirteen patients received a 10-Gy single-dose TBI (SDTBI), and 42 received a fractionated TBI (FTBI). Median time between diagnosis and BMT was 315 days. Overall 5-year actuarial survival was 62.9% (65.8% +/- 12.5% for CY-TBI and 60.6 +/- 11.7% for BU-CY; P = .5), and overall disease-free survival was 55% (51% +/- 14% for CY-TBI and 59.1% +/- 11.8% for BU-CY; P = .75). All patients conditioned with CY-TBI experienced sustained engraftment; in contrast, 4 of 65 patients conditioned with BU-CY rejected the graft (P = .18). There was no significant statistical difference between the two groups regarding transplant-related mortality (29% for CY-TBI and 38% for BU-CY; P = .44). So far, with a median follow up of 42 months, 11 patients have relapsed; 9 relapses occurred after CY-TBI, mostly after FTBI (8 of 9) and 2 after BU-CY (P = .02). The actuarial risk of relapse was 4.4% +/- 6.7% after BU-CY, 11.1% +/- 20.8% after SDTBI, and 31.3% +/- 18.1% after FTBI (P = .039). In addition, independently of the conditioning regimen, the increase of posttransplant immunosuppression in 16 patients with an anti- interleukin-2 receptor monoclonal antibody (MoAb) in addition to a short course of methotrexate and cyclosporine was shown to increase the actuarial risk of relapse (57% +/- 30% with MoAb v 9% +/- 7.3% without MoAb; P = .001). We conclude that BU is an acceptable alternative to TBI for patients with chronic myeloid leukemia in first chronic phase receiving BMT from HLA identical sibling donors. Both BU-CY and CY-TBI regimens gave similar transplant-related mortality, and the antileukemic efficiency of BU-CY regimen was either similar or even higher than that of CY-TBI.

Relapse is a major cause of treatment failure following allogeneic bone marrow transplantation (BMT) for acute myeloid leukemia (AML). To reduce the risk of relapse following BMT for patients with hematologic malignancy, our group developed a novel preparative regimen which combines high-dose etoposide with cyclophosphamide and total body irradiation (VPCyTBI). We now report the outcome of therapy with VPCyTBI followed by allogeneic BMT for 40 patients with AML in untreated first relapse. With the exception of increased stomatitis, the toxicity of this regimen was similar to that reported by others for CyTBI. Forty-four months after transplant the actuarial probabilities of disease-free survival (DFS), persistent or recurrent leukemia, and transplant related mortality were .29, .44, and .47 respectively. DFS was improved (P < .01) and risk of persistent or recurrent leukemia reduced (P = .005) among patients with significant (grade > or = 2) acute GVHD. Patients with 30% or more blasts on pre-BMT bone marrow examination were not at increased risk for persistent or recurrent leukemia. We conclude that VPCyTBI with allogeneic BMT is effective therapy for AML in untreated first relapse and that a randomized trial comparing this regimen with CyTBI is warranted.

In an attempt to decrease the relapse rate after bone marrow transplantation (BMT) for advanced acute leukemia, we initiated studies using 131I-labeled anti-CD45 antibody (BC8) to deliver radiation specifically to hematopoietic tissues, followed by a standard transplant preparative regimen. Biodistribution studies were performed in 23 patients using 0.5 mg/kg trace 131I-labeled BC8 antibody. The BC8 antibody was cleared rapidly from plasma with an initial disappearance half-time of 1.5 +/- 0.2 hours, presumably reflecting rapid antigen- specific binding. The mean radiation absorbed doses (cGy/mCi131I administered) were as follows: marrow, 7.1 +/- 0.8; spleen, 10.8 +/- 1.4; liver, 2.7 +/- 0.2; lungs, 2.1 +/- 0.1; kidneys, 0.7 +/- 0.1; and total body, 0.4 +/- 0.03. Patients with acute myelogenous leukemia (AML) in relapse had a higher marrow dose (11.4 cGy/mCi) than those in remission (5.2 cGy/mCi; P = .001) because of higher uptake and longer retention of radionuclide in marrow. Twenty patients were treated with a dose of 131I estimated to deliver 3.5 Gy (level 1) to 7 Gy (level 3) to liver, with marrow doses of 4 to 30 Gy and spleen doses of 7 to 60 Gy, followed by 120 mg/kg cyclophosphamide (CY) and 12 Gy total body irradiation (TBI). Nine of 13 patients with AML or refractory anemia with excess blasts (RAEB) and two of seven with acute lymphocytic leukemia (ALL) are alive disease-free at 8 to 41 months (median, 17 months) after BMT. Toxicity has not been measurably greater than that of CY/TBI alone, and the maximum tolerated dose has not been reached. This study demonstrates that with the use of 131I-BC8 substantially greater doses of radiation can be delivered to hematopoietic tissues as compared with liver, lung, or kidney, which may improve the efficacy of marrow transplantation.

Background: Allogeneic stem cell transplant (alloSCT) is indicated for patients with acute myeloid leukemia (AML) with high-risk disease on presentation or in relapsed or refractory cases. Durable elimination of leukemic burden after achieving a complete remission (CR) is thought to be an important prerequisite for successful transplant. Typically, this is achieved with consolidation treatments with cytarabine (ARA-C) in repeated cycles in non-refractory cases. Previous reports have suggested there is no apparent advantage for post-remission consolidation chemotherapy before reduced intensity transplant, provided a donor is readily available. Aim: To study the impact of the total cumulative dose of ARA-C in the pre-transplant setting before alloSCT either with reduced-intensity conditioning (RIC) or full myeloablative conditioning (MAC). Methods: We conducted a retrospective chart review at the University of Oklahoma and affiliated hospitals in patients with AML in complete remission from October 2006 to December 2014. Appropriate IRB approval was obtained in accordance with Helsinki declaration. Simple descriptive statistics were created for all covariates [mean, SD for continuous covariates and n (%) for categorical variables]. A Cox proportional hazards model was used to assess the association of each covariate with overall survival. Results: Sixty five patients were identified through our local leukemia registry with a mean age of 43, 57 (87.7%) were white, and 42 (64.6%) were male. Based on cytogenetics and molecular markers, 36 patients (55.3%) were intermediate risk and 20 patients (30.7%) were unfavorable risk status. For transplant preparative regimen, MAC was utilized in 50 cases (76.9%) and RIC was utilized in the other 15 (23.0%). Bone marrow stem cells were used in 28 cases (43.0%), peripheral blood cells were used in 26 cases (40.0%), and cord blood cells were used in the remaining 11 cases (16.9%). The mean dose of ARA-C given in consolidation was 43 g/m2 with standard deviation 31.5 g/m2. After adjusting for age and risk status, ARA-C consolidation was not associated with increased overall survival (OS) in the patients (p-value = 0.1776). When only considering those patients with myeloablative conditioning, ARA-C consolidation was still not associated with increased OS (p-value = 0.7533). Conclusions: Prior published data indicates that further ARA-C therapy given during consolidation does not correlate with improved outcomes post-transplant in patients with AML who received a reduced intensity preparative regimen. However, we attempted to expand this data to include patients who received a full myeloablative preparative regimen. Our experience using our single institution retrospective data suggests further ARA-C therapy given in consolidation does not benefit patients who underwent either RIC or MAC in terms of post-transplant survival. This provides further evidence that there should be no delay in moving patients to transplant, provided a suitable donor is available. Disclosures No relevant conflicts of interest to declare.

Background: Melphalan 200mg/m2 is the standard preparative regimen in MM and addition of other cytotoxic drugs has not been found to result in superior activity. The novel agents have improved outcome in MM significantly, but data on their role in preparative regimens are scarce. The purpose of this study was to understand the toxicity and efficacy of triple therapy with VDT in combination with high-dose melphalan. Methods: An IRB approved retrospective analysis was performed on all patients who received an ASCT with the VDT-Mel during 2012-2014. Mel: 100 mg/m2 was given on days -4 and -1; V: 1 mg/m2 on days -4, -1, +2 and +5; T: 100 mg daily from -5 to +5; and D: 20 mg/day from -4 to -1 and +2 to +5. End points were treatment-related toxicity during the first 100 days and quality of response at 6 months post-transplant; 98 patients had follow-up ≥ 6 months. Patients in sCR were also minimal residual disease negative (MRD-) by 10-color flow cytometry with a sensitivity of 10-4. Results: 100 patients received 153 transplants; 47 patients underwent single and 53 had tandem transplants (TT); 64 patients received early (≤ 12 months of induction therapy) and 36 salvage transplantation. Median age was 61 y; median followup was 16.2 months. Only 1patient had achieved a sCR and 11 a CR prior to transplantation. Best responses at 6 months were 53% sCR (and MRD-), 24% CR, and 9% VGPR. The sCR rate after single transplant was 47% (overall) and 54% (early transplant) vs 59% and 60% after TT. Grade 3-5 non-hematologic toxicities were almost entirely related to infections (38% and 53% in single and TT, respectively); the 100-day mortality rate was 2.6% (4/153), 1.8% for early transplants and 4.5% for salvage transplants. Median time to ANC recovery > 500/µL was 12 days in both early and salvage transplantation. Conclusion: VDT-Mel is well-tolerated and resulted in minimal additional toxicity and a similar mortality rate when compared to historic data of MEL alone. Importantly, the sCR rate with MRD- by flow cytometry at 6 months in our study was very high compared to published reports. The ultimate sCR rate will be higher as at this time an additional 13 patients attained a sCR during further follow up past 6 months for a total of 66% sCR. Since both sCR and MRD- are proven early surrogate markers for progression-free and overall survival, it appears highly likely that this regimen will be superior to Mel alone and should become the new standard for ASCT in myeloma. Figure 1. Figure 1. Disclosures No relevant conflicts of interest to declare.

Background Limitations in umbilical cord blood (UCB) transplantations result from decreased cell numbers available for infusion at time of transplant. Delayed engraftment and higher rates of engraftment failure subsequently increase the need for post-transplant growth factor use and transfusion support. Hyperbaric oxygen (HBO) has been shown to improve engraftment in an animal model of UCB transplantation. These experiments proved sufficient to initiate a first-in-human trial of HBO for UCB transplantation. Objectives This study compared growth factor use and time to packed red blood cell (PRBC) and platelet transfusion independence between the HBO study population and historical UCB cases from the same institution. The effects of conditioning regimen and the number of cord units infused at time of transplant were analyzed. Study Design Subjects underwent HBO therapy at the University of Kansas Medical Center after reduced intensity conditioning (RIC) (n=9) or myeloablative conditioning (MAC) (n=6) regimens. Six hours following HBO therapy, they received single (n=8) or double (n=7) UCB units. Charts of HBO-treated patients and historical controls (n=44) were reviewed for post-transplant growth factor use and transfusion requirements. These were further stratified by preparative regimen and number of UCB units infused. Kaplan-Meier curves were compared between HBO and control subjects using log-rank tests as some observations were right-censored if the patient experienced relapse or expired within the first 100 days post-transplant. A small quantity was imputed to values of 0 to facilitate including these subjects in the analyses. Results By days +66 and +74 post-transplant, 100% of HBO-patients were PRBC and platelet independent, respectively. This compares to incomplete platelet (88.63%) and PRBC (86.36%) independence in the control cohort at day 100. Though time to transfusion independence (TTI) for PRBCs was consistently shorter in the HBO cohort, it was only statistically significant in the RIC setting and approached significance in the single cord setting (Table-1). TTI for platelets was shorter for the HBO cohort and approached statistical significance in the single cord setting. Similarly, the consecutive days of filgrastim support post-transplant were consistently fewer for HBO patients, with values approaching statistical significance in the MAC and single cord settings. Conclusions In vitro data with HBO and UCB showed improved rates of engraftment in animal models. Similarly, data in this small pilot study suggests that HBO facilitates less growth factor use and shorter TTI. However, these effects did not reach statistical significance in all settings, most likely due to small sample size of the HBO cohort. Further studies are needed to examine the effect of HBO on growth factor use, PRBC and platelet independence post-UCB transplantation. Table 1. A comparison of supportive transfusion means, between standard and HBO-UCB transplant recipients. These data are segregated for conditioning regimens and units of UCB infused for transplant. Group PRBC Units Platelet Units Days G-CSF Support TTI - PRBC TTI - Platelets HBO-total (n=15) 9 (p=0.30) 16.35 (p=0.31) 29.4 (p=0.08) 32.87 (p=0.07) 33.53 (p=0.11) Standard-Total (n=44) 9.29 17.14 35.02 56.09 54.8 HBO-Ablative (n=6) 5.43(p=0.23) 7.86 (p=0.16) 26.63 (p=0.07) 24 (p=0.53) 25.5 (p=0.45) Standard-Ablative (n=23) 11.93 22.29 35.65 66.13 67.78 HBO-RIC (n=9) 6.13 (p=0.66) 11.89 (p=0.78) 31.67 (p=0.44) 22.56 (p=0.02) 25.56 (p=0.11) Standard-RIC (n=21) 7.52 13.71 34.33 45.09 40.57 HBO-Single UCB (n=8) 5.43 (p=0.19) 7.87 (p=0.26) 26.63 (p=0.06) 24 (p=0.06) 25.5 (p=0.06) Standard-Single UCB (n=4) 10.25 24 36.2 74.4 70.2 HBO-Double UCB (n=7) 12.57 (p=0.87) 24.86 (p=0.95) 33.57 (p=0.70) 43 (p=0.74) 42.71 (p=0.95) Standard-Double UCB (n=40) 9.19 16.19 34.87 53.74 52.82 Disclosures No relevant conflicts of interest to declare.

INTRODUCTION: High dose busulfan (Bu) is an integral component of many commonly-used preparative regimens for both allogeneic and autologous transplantation. Data on the efficacy and toxicity of q6 vs. q24 hour dosing are of significant clinical interest. In order to facilitate a therapeutic dose-monitoring protocol, we transitioned from q6 to q24 Bu dosing as part of our standard Bu/Cy/VP ASCT preparative regimen for patients with Hodgkin (HL) and Non-Hodgkin Lymphoma (NHL) in July 2012. We present comparative outcomes of q24 Bu dosing vs historical controls receiving q6 Bu. METHODS We retrospectively reviewed 400 consecutive eligible lymphoma patients who underwent ASCT from 2007-2013 with Bu/Cy/VP. All patients received Cy 60 mg/kg IV over 4 hours on days -3 and -2 and VP 60 mg/kg as continuous infusion on days -5 and -4. Bu was given at a dose of either 0.8 mg/kg q6 (N = 307) x 14 doses for patients transplanted between 2007-July, 2012 or 2.8 mg/kg q 24 hours (N = 93) on days -9 through -6 for subsequent patients. Outcomes assessed from date of transplant were: relapse, non-relapse mortality (NRM), relapse-free survival (RFS) and overall survival (OS). Toxicity was assessed using pulmonary and liver function tests (PFTs and LFTs) at specified time-points before and after ASCT. In addition, for a subset of 22 patients receiving q24 Bu, we measured serial Bu serum levels after the first dose of Bu with an in-house liquid chromatography-tandem mass spectrometry assay using turbulent flow online extraction technology (Bunch, et al. J Chromatogr B Analyt Technol Biomed Life Sci, 2010. 878(31): p. 3255-8) and subsequently determined the cumulative Bu area-under the curve (AUC). RESULTS Baseline patient and disease characteristics of patients dosed with q6 and q24 Bu were similar. The median age was 55 (range 20-78) years; 63% were males. 18% had HL and 82% had NHL with a comparable distribution of subtypes in both groups. Patients in both groups had comparable rates of prior chemotherapy regimens and of complete/partial remission at the time of ASCT. Due to a change in institutional guidelines, plerixafor was more commonly incorporated in peripheral blood stem cell mobilization regimen in the q24 group compared to q6 cohort (70% vs. 39%, P CONCLUSIONS Q24 Bu dosing in combination with Cy/VP is more convenient than q6 hours, has equivalent outcomes, and results in no increase in either hepatic or pulmonary toxicity. Consistent with previous reports, there is a significant range of Bu AUC levels, with a standard deviation of 12%. These data provide rationale for our prospective clinical trial of real-time therapeutic dose monitoring with q24 Bu dosing. Table 1. Q6 dosing Q24 dosing P-value OS 78% 80% 0.79 RFS 63% 61% 0.99 NRM 5% 3% 0.95 Relapse 30% 36% 0.46 18 month outcomes of q6 vs q24 Bu dosing Figure 1. RFS and OS for lymphoma patients undergoing ASCT with Bu/Cy/VP treated with q6 vs. q24 hour weight-based Bu dosing. Figure 1. RFS and OS for lymphoma patients undergoing ASCT with Bu/Cy/VP treated with q6 vs. q24 hour weight-based Bu dosing. Figure 2. Figure 2. Disclosures Hill: Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Majhail:Gamida Cell Ltd.: Consultancy; Anthem Inc.: Consultancy.

INTRODUCTION: Despite recent advances in treatment for MDS, allogeneic hematopoietic stem cell transplantation (alloHCT) remains the only curative therapy. Historically, patients (pts) 65 and older with Medicare did not have coverage for HCT. On August 4th 2010, the Centers for Medicare and Medicaid services (CMS) established coverage for HCT for MDS through coverage with evidence development (CED). A Center for International Bone Marrow Transplant Research (CIBMTR) study comparing outcomes of pts 55-64 vs. 65 and older was approved. Herein we report the survival outcomes of the first 688 pts enrolled on the study. RESULTS: From 12/15/2010 to 5/14/2014, 688 pts 65 years and older (65+) underwent alloHCT for MDS compared with 592 pts 55-64 years (55-64). Median follow-up was 12 and 18 months for the 65+ and 55-64 group respectively. Median age was 68 and 61 for the 65+ and 55-64 group respectively. In the 65+ group, 76%, 22% and 2% were ages 65-69, 70-74 and > 74 years old. At the time of diagnosis, 30%, 10%, 42% were diagnosed with RA/RARS/RCMD/RCMDRS/5q-, CMML and RAEB respectively. The IPSS score at diagnosis was Low risk/intermediate-1 and intermediate-2/high risk in 39% and 31% respectively, and 23% had t-MDS. In the 55-64 group, 43% and 57% were 55-59 and 60-64 years old respectively. Otherwise, patient and disease characteristics were similar in both groups. More patients in the 55-64 group compared to 65+ group received a myeloablative alloHCT (49% vs. 29%). The donor was an HLA identical sibling in 24% vs. 34% in the 65+ vs. the 55-64 groups. Because of confounding between age and selection of transplant procedures (including preparative regimen intensity, graft source, gvhd prophylaxis) we chose to adjust only for patient and disease characteristics in the multivariate analysis (MVA). Age group 65+ vs. 55-64 had no significant impact on 100-day mortality (HR 1.26; CI 0.91-1.75 p=0.16) or overall survival (HR 1.14; CI 0.98-1.33 p=0.1) in the MVA. The adjusted 100 day survival was 84% vs. 87%, one year survival was 60% vs. 56% and 2 year survival was 42% vs. 46% in the 65+ group vs. 55-64 group respectively. As expected, MVA for 100 day mortality identified that poor cytogenetics (HR 1.85; CI 1.28-2.68) compared to good cytogenetics, patients with stable disease/no response to therapy (HR 3.35; CI 1.59-7.07), disease progression/relapsed disease (HR 2.91; CI 1.13-7.51), patients who did not receive any therapy prior to preparative regimen (HR 2.9; CI 1.17-7.21) compared to patients in complete remission and platelet count CONCLUSION: In patients who are eligible for alloHCT, there was no difference in 100 day mortality or overall survival for patients 55-64 compared to patients 65 years and older. Age alone should not be a determinant for alloHCT eligibility. Figure 1. Figure 1. Disclosures Deeg: Medac: Research Funding; Medac: Consultancy.

Background: FLT3 ITD mutated acute myeloid leukemia remains a therapeutic challenge with very few patients experiencing prolonged disease free survival after standard therapies. FLT3 inhibitors have thus far demonstrated limited single agent activity in this disease. However, administration of FLT3 inhibitors during a state of minimal residual disease and a reconstituting immune system offers a promise of improved disease control. Methods: We designed a prospective trial for patients FLT3 ITD AML undergoing allogeneic transplant, to evaluate the safety, tolerability and outcome of the FLT3 ITD inhibitor sorafenib administered pre- and post-allogeneic transplant. To be eligible, patients needed to be in remission prior to transplant. At the discretion of the treating physician, sorafenib could be started prior to transplant after confirmation of remission and continued until three days prior to the start of the preparative regimen. Otherwise, all patients were started on sorafenib 200 mg twice a day, no earlier than Day +30 and no later than Day +120 post-transplant, after documented engraftment (Plts >50K, ANC >500). Dosing of sorafenib was based on individual patient tolerance: in tolerant patients sorafenib was escalated to 400 mg twice a day while dose reductions occurred for Grade 3 or 4 toxicities in a stepwise manner (200 mg BID, 200 mg QD, 200 mg QoD) until a tolerable dose was identified. Results: We have accrued to date 28 patients with a median age of 54, with FLT ITD AML undergoing allogeneic transplant who were started on sorafenib in the peri-transplant period (8 pre-transplant). Ten patients underwent myeloablative conditioning and received a transplant from a matched related donor (5), a matched unrelated donor (2) or a haploidentical donor (3). Eighteen patients underwent non-myeloablative conditioning and transplant using either a haploidentical donor (10), a matched sibling donor (4), a matched unrelated donor (3) or an umbilical cord blood donor (1). The median duration of post transplant follow up for active patients is 450 days (range, 107-1192 days). The median duration of sorafenib therapy for all patients is 252 days (range, 52-1081). The tolerability of sorafenib in the peri-transplant period varied among patients: 6 patients tolerated the maximum dose of sorafenib at 400 mg twice a day, 14 patients were maintained on 200 mg twice a day, seven patients were maintained on 200 mg daily and one patient was maintained on 200 mg every other day. Six patients died in the post-transplant period with three deaths due to relapsed leukemia and three from transplant-associated toxicity. No primary or secondary graft failures were observed but 9 patients developed grade 2 or higher GVHD (1-4 weeks after starting sorafenib) requiring escalation of immunosuppression therapy. Overall 5 pts have relapsed so far. Three of these patients were off therapy at the time of relapse. One patient relapsed with FLT3 ITD leukemia 117 days after stopping sorafenib at the 24 month planned stoppage time and is now back in remission after resuming sorafenib. Correlative studies evaluating FLT3 inhibition via a plasma inhibitory activity (PIA) assay showed consistent inhibition of FLT3 at all tolerability-determined dosing levels, suggesting that dosing can be safely adjusted in patients having adverse events without loss of FLT3 inhibition. Consistent with this finding was the fact that the adjusted sorafenib trough concentration exposure accounting for the active metabolite (sorafenib + (14.59*sorafenib N-oxide)) was highly variable (70% CV) and not statistically different across all dosing levels. Exploratory analysis of minimal residual disease monitoring, and of T regulatory cell populations and their relation to GVHD in the pre- and post-treatment peripheral blood, are ongoing. Conclusion: Sorafenib is well tolerated in the post-transplant setting irrespective of the conditioning intensity or the donor source. Our findings indicate that sorafenib dosing should be individualized in the post-transplantation setting according to patient tolerability. This approach results in effective in vivo FLT3 inhibition, and yields encouraging survival results, with 15 of 28 patients currently on therapy without relapse. This data supports the further study of sorafenib in a larger cohort to determine its overall effectiveness in preventing FLT3 ITD AML relapse post allogeneic transplant. Figure 1. Figure 1. Figure 2. Figure 2. Disclosures Off Label Use: Sorafenib for off label usage in Acute Myeloid Leukemia.

Previous studies have shown that tumor-specific bcr-abl mRNA can often be detected by polymerase chain reaction. (PCR) for months to years after allogeneic bone marrow transplantation (BMT) for chronic myelocytic leukemia (CML). Nevertheless, the presence of bcr-abl mRNA by itself does not invariably predict for clinical relapse post-BMT. This has led to the hypothesis that bcr-abl mRNA might be expressed in cells that have lost either proliferative or myeloid differentiation potential. To directly characterize the cells detected by PCR in patients with CML after allogeneic BMT, we first identified five individuals in whom PCR-positive cells could be detected at multiple times post-BMT. Bone marrow samples from these individuals were cultured in vitro and single erythroid, granulocytic, and macrophage colonies, each containing 50 to 100 cells, were examined for the presence of bcr-abl mRNA by PCR. PCR-positive myeloid colonies could be detected in four of five individuals in marrow samples obtained 5 to 56 months post-BMT. Overall, 7 of 135 progenitor cell colonies (5.2%) were found to be PCR-positive. The expression of bcr-abl mRNA appeared to be equally distributed among committed erythroid, macrophage, and granulocyte progenitors. These patients have now been followed-up for an additional 20 to 33 months from the time of progenitor cell PCR analysis but only one of these individuals has been found to have cytogenetic evidence of recurrent Ph+ cells. These results show that long-term persistence of PCR-detectable bcr-abl mRNA after allogeneic BMT can be caused by the persistence of CML-derived clonogenic myeloid precursors that have survived the BMT preparative regimen. These cells continue to have both proliferative and myeloid differentiation capacity in vitro. Nevertheless, these PCR-positive cells do not appear to either expand or differentiate in vivo for prolonged periods, suggesting the presence of mechanisms for suppression of residual clonogenic leukemia cells in vivo.

A prospective comparative trial of allogeneic versus autologous bone marrow transplant (BMT) was conducted. Sixty-six consecutive patients (median age, 41; range, 15 to 60; female:male ratio = 21:45) entered this clinical trial. Priority for allogeneic BMT was given to patients who were 55 or younger and had a major histocompatibility complex- matched or 1-antigen-disparate sibling donor. Autologous BMT was offered to all other patients whose age was 60 or younger. Patients who had no sibling donor and who had BM involvement at the time of evaluation were not eligible. Thirty-one patients received an allograft, and 35 patients received an autograft. Thirteen patients received a BM graft purged with 4-hydroperoxycyclophosphamide because of previous BM involvement. Patients who had previous radiation to the thoracic and/or abdominal areas of more than 20 Gy received a preparative regimen consisting of cyclophosphamide (1,800 mg/m2/d for 4 days), VP-16 (200 mg/m2 every 12 hours for 8 doses), and 1,3-bis(2- chloroethyl)-1-nitrosourea (600 mg/m2 as 1 dose). Other patients received cyclophosphamide 1,800 mg/m2/d for 4 days followed by total body irradiation of 12 Gy administered as a single daily fraction over 4 days. With a median follow-up of 14 months, the progression-free survival (PFS) for autograft and allograft recipients was 24% +/- 8% (+/- SE) and 47% +/- 9%, respectively, (P = .21). However, the probability of disease progression was significantly higher in the autologous group (69% +/- 9%) than in the allogeneic group (20% +/- 10%; P = .001). When other confounding prognostic factors were adjusted in the multivariate analysis, chemosensitive disease and allograft were found to have a significant favorable influence on probability of disease progression (P = .03 and .003), but only chemosensitive disease had a significant influence on the PFS (P < .002). Our results suggest the existence of graft-versus-lymphoma effect and also support the rationale of using immunotherapy after autologous BMT. Allogeneic BMT should be preferable to autologous BMT in younger patients with lymphoma.

Despite prophylaxis with immunosuppressive drugs, severe acute graft- versus-host disease (GVHD) remains a major cause of morbidity and mortality in patients transplanted with unmodified bone marrow (BM) grafts from HLA-identical siblings. Although T-cell depletion of the BM graft has evolved as the most effective method to prevent severe acute GVHD, this beneficial effect is counterbalanced by an increased rate of graft failure and relapse of the disease. To find an approach to T-cell depletion that may avoid these extreme risks, we gave BM recipients a fixed low number of 1 x 10(5) donor T cells per kilogram of recipient's body weight in the graft. This corresponds with 99% T-cell depletion and is achieved by the addition of T cells to the graft that was previously depleted of T cells. A total of 70 patients with hematologic malignancies or aplastic anemia, including 40 patients with standard- risk leukemias, received BM grafts, depleted of T cells according to this approach, from HLA-identical siblings. The preparative regimen consisted of cyclophosphamide and total body irradiation. The patients also received a short course of cyclosporine posttransplant. Graft failure did not occur. Acute GVHD, only grade I or II, was seen in 70% of the patients and was limited to the skin in all patients. Chronic GVHD occurred in 31% of the patients and, with the exception of 1 patient, was limited to the skin as well. Relapse occurred in 3 of 40 (8%) patients with standard-risk leukemias, resulting in a projected survival at 5 years of 80%. Patients with standard-risk diseases had a procedure-related mortality of 11%. Quality of life, determined 1 year after BM transplant, was good in almost all patients with standard-risk diseases. Thus, this approach of T-cell depletion may be an approach that avoids the development of severe acute and chronic GVHD without damaging the function or antileukemic effect of the graft and that has a low transplant-related morbidity and mortality.

Forty patients with multiple myeloma received thiotepa (750 mg/m2), busulfan (10 mg/kg), and cyclophosphamide (120 mg/kg) (TBC) followed by autologous bone marrow or blood stem cell support. Granulocyte-Colony stimulating factor (G-CSF) was administered to accelerate hematopoietic recovery. Sixty-five percent of all patients responded to this treatment. Eighty-eight percent of patients transplanted in partial remission had a further reduction of the myeloma and 53% achieved a complete remission. Forty-eight percent of patients with refractory myeloma responded. All responding patients transplanted during partial remission or with primary refractory myeloma remain free of progression for a period of 4 to 24 months post-transplant, but the remission duration of patients treated in refractory relapse was short (4 months). Five of 24 patients transplanted with marrow and none of 16 receiving blood stem cells died of treatment-related complications. Use of blood stem cells resulted in more rapid granulocyte and platelet recovery. We conclude that TBC is an effective, relatively well tolerated, preparative regimen for patients with multiple myeloma.

Current intensive chemotherapy for acute nonlymphoblastic leukemia (ANLL) results in a complete remission in the majority of patients. Unfortunately, the duration of remission is short and most of the patients will experience a relapse of their underlying disease. Autologous bone marrow (BM) transplantation is being explored as a treatment modality designed to improve relapse-free survival. We have conducted a phase II trial exploring the combination of busulfan (16 mg/kg) and etoposide (60 mg/kg) in an attempt to improve antitumor efficacy using this novel preparative regimen. To date, 50 patients (48 with ANLL and 2 patients with biphenotypic acute leukemia) have been treated. The first 20 patients received unmanipulated BM; 28 patients subsequently received 4-hydroperoxycyclophosphamide (4–HC) (60 micrograms/mL)-purged bone marrow, and 2 patients with biphenotypic acute leukemia received both 4–HC (60 micrograms/mL) and etoposide (5 micrograms/mL)-purged BM. Thirty-four patients were in first complete remission (CR1), 12 patients in second complete remission (CR2), and 4 patients in relapse. The median time from first complete remission to BM harvest was 3 months (range, 0.8 to 4) compared with median time of 2 months (range, 1.5 to 5.0) for patients in second complete remission. The median time from harvest to transplant was 1 month for both groups (range, 0.4 to 36). A median of 0.7 x 10(8) (range, 0.2 to 1.4) mononuclear cells were infused. Patients achieved an absolute neutrophil count of > or = 500/microL at a median of 26 days (range, 13 to 96), an untransfused platelet count > or = 20,000/microL at a median of 56 days (range, 15 to 278) and a sustained hematocrit > or = 30% at a median of 50 days (range, 19 to 116). Twenty-six patients are alive and in continued CR. Follow-up of the surviving patients ranged from 6 months to 66 months with a median follow-up of 31 months. Patients receiving purged BM have an actuarial disease-free survival of 57% with a relapse rate of 28% compared with patients receiving unpurged BM whose actuarial disease-free survival is 32% with a relapse rate of 62% (P = .06 for relapse rate). The most significant extramedullary toxicities for this regimen are hepatic and cutaneous (including mucositis). The BU/VP-16 regimen is associated with a significant proportion of patients surviving disease free, especially in the group receiving purged BM. Whether this regimen offers a substantial improvement in disease-free survival over currently used regimens will require a prospective randomized study.

We have studied the use of a new preparative regimen for the treatment of patients in remission of acute myeloid leukemia (AML) with autologous bone marrow transplantation. Chemotherapy consisted of busulfan 1 mg/kg every 6 hours for 4 days (total dose, 16 mg/kg) on days -7 through -4 followed by an intravenous infusion over 6 to 10 hours of etoposide 60 mg/kg on day -3. Autologous bone marrow, treated in vitro with 100 micrograms/mL of 4-hydroperoxycyclophosphamide, was infused on day 0. We have treated 58 patients up to the age of 60 years, 32 in first remission, 21 in second or third remission, and 5 with primary refractory AML unresponsive to high-dose Ara-C, but achieving remission with aggressive salvage regimens. Of the first remission patients, there has been 1 treatment related death and 5 relapses. With median follow-up of 22 months, the actuarial relapse rate is 22% +/- 9% and disease-free survival is 76% +/- 9% at 3 years. Patients with favorable French-American-British (FAB) subtypes (M3 or M4 EO) did especially well, with no relapses seen in 15 patients observed for a median of 30 months. Actuarial relapse rate at 3 years was 48% for first remission patients with less favorable FAB subtypes. Of patients in second or third remission, there were 5 treatment related deaths and 4 relapses. With median follow-up of 22 months, the actuarial relapse rate is 25% +/- 11% and disease-free survival is 56% +/- 11% at 3 years. Four of five primary refractory patients died during treatment and 1 remains in remission with short follow-up. These preliminary data are very encouraging and, if confirmed, support the use of autologous purged bone marrow transplantation using aggressive preparative regimens as one approach to improve the outcome of adults with AML.

We report nine children with relapsed (n = 8) or high-risk (n = 1) peripheral T-cell lymphoma (PTCL) who underwent autologous (n = 6) or allogeneic (n = 3) bone marrow transplantation (BMT). These children received transplants as part of a prospective phase I/II study of thioTEPA (TT) and total body irradiation (TBI) with escalating doses of VP-16. The median age of these patients at time of BMT was 6.5 years (range 2.5 years to 14 years). Three were transplanted with active disease after failing salvage chemotherapy. Of the other six, one was transplanted in first complete remission (CR) and five in second or subsequent CR. Of these nine patients, eight are free of disease a median of 25 months after BMT (range, 6 to 48 months), with an estimated 2-year relapse-free survival (RFS) of 89%. Six of these eight patients have been followed for 12 or more months after BMT, and in each their current remission exceeds their longest previous remission duration. The toxicity of the TT/TBI +/- VP-16 regimens was significant but manageable, predominantly consisting of severe mucositis. For a comparison, we reviewed retrospective data on the six additional children and adolescents with PTCL who underwent BMT during the 3-year period preceding this phase I/II study. The median age at BMT of these six patients was 19 years (range 15.5 years to 20 years). These patients were prepared for BMT with a variety of other regimens. One had no response to BMT and the other five relapsed at 1.5 to 5 months after BMT (median, 3 months) with an RFS of 0%. Our data suggest that thioTEPA plus TBI, with or without VP-16, is an effective preparative regimen for BMT for young patients with relapsed or high-stage PTCL and leads to prolonged RFS.

One hundred twenty-seven patients with acute myelocytic leukemia (AML) were given busulfan 4 mg/kg on each of 4 days and cyclophosphamide 60 mg/kg on each of 2 days (BuCy2) followed by allogeneic bone marrow transplantation from an HLA-identical or one antigen disparate sibling. For 71 patients in first complete remission, 23 in second complete remission or initial relapse, and 33 patients with primary refractory disease, second or subsequent relapse, or a preceding hematologic disorder, the 3-year leukemia-free survival (LFS) is 63.1%, 32.6%, and 24.2% respectively. The actuarial probability of relapse for each group is 14.1%, 40.6%, and 61.0%. In multivariate analyses, relapse and decreased LFS were associated with advanced disease phase and with M4/M5 French-American-British classification. The LFS of first remission patients was adversely associated with a short time interval from diagnosis to transplantation. This study indicates that BuCy2 is an attractive preparative regimen for marrow transplantation in patients with AML and that prognostic factors for relapse and LFS are similar those described for regimens containing total body irradiation.

Graft-versus-tumor effects can be achieved after allogeneic bone marrow transplantation in patients with malignancies of the kidney or hematopoietic system but are often accompanied by severe graft-versus-host-disease (GVHD). We sought to maximize graft-versus-tumor while minimizing GVHD using tumor-specific allogeneic effector T cells rather than open-repertoire T cells. We transferred allogeneic CD8+ pmel-1 or CD4+ TRP-1 T cells specific for the melanoma-associated antigens, glycoprotein 100 (gp100) and tyrosinase-related protein-1 (TRP-1), respectively, into B16-melanoma–bearing mice. Mice receiving a preparative regimen of nonmyeloablating (5 Gy) total body irradiation experienced the rapid rejection of tumor-specific allogeneic lymphocytes with no impact on tumor growth. However, when mice were given more intense total body irradiation conditioning regimens combined with autologous bone marrow transplantation, adoptively transferred allogeneic tumor-specific T lymphocytes persisted at detectable levels for several weeks and mediated significant regression of large, vascularized tumors. We found that the risk of GVHD was low when tumor-specific T cells were transferred and significant toxicity was observed only when substantial numbers of open repertoire allogeneic naive T cells were mixed with the tumor-specific lymphocytes. Taken together, these data indicate that the use of tumor-specific allogeneic CD8+ T cells or CD4+ can result in significant antitumor effects in the absence of measurable GVHD.

We have little information on chronic graft-versus-host disease (GVHD) after cord blood transplantation (CBT). We investigated its clinical features in 1072 Japanese patients with hematologic malignancies who received a transplant through the Japan Cord Blood Bank Network. The primary end point was to investigate the incidence of any chronic GVHD. Median age of the patients was 33 years (range, 0-79 years). The cumulative incidence of chronic GVHD 2 years after transplantation was 28%. Chronic GVHD was fatal in 29 patients. Multivariate analysis demonstrated that development of chronic GVHD was favorably associated with both overall survival and event-free survival. Multivariate analysis identified risk factors of chronic GVHD: higher patient body weight, higher number of mismatched antigens for GVHD direction, myeloablative preparative regimen, use of mycophenolate mofetil in GVHD prophylaxis, and development of grades II to IV acute GVHD. Although chronic GVHD is a significant problem after CBT, it is associated with improved survival, perhaps due to graft-versus-malignancy effects.