Noël, Pierre

Abstract Background The prognosis for AML or MDS patients (pts) with monosomal karyotype (MK) is dismal. Although a benefit for allogeneic hematopoietic cell transplantation (allo-HCT) compared to chemotherapy or autologous HCT has been demonstrated in young (≤ 60) pts (Cornelissen, 2012), the curative potential of allo-HCT in older (≥ 60) pts with monosomal karyotype AML/MDS is not known. Patients and methods In this retrospective review, we analyzed outcomes for 69 AML (n = 49) or MDS (n = 20) pts ≥ 60 who underwent allo-HCT at Mayo Clinic Arizona between 2005 and 2013, based on cytogenetic grouping as follows: cytogenetically normal (CN, n = 23), cytogenetically abnormal but not MK (CA, n = 32), and MK (n = 14). Monosomal karyotype was defined (Breems, 2008) as a karyotype with at least two autosomal monosomies or a single autosomal monosomy in combination with at least one structural abnormality. Univariate and multivariate statistical analyses were performed to evaluate the impact of these 3 cytogenetic groupings on outcome (primary endpoint progression-free survival). The median age for all pts was 66 (60-76), and median follow-up for surviving pts was 22 months (range 70 days – 7.1 years). Thirty-seven pts had high-risk disease (MDS > 5% blasts or AML not in CR), while 32 were considered standard risk (MDS <5% blasts or AML in CR). The majority of pts had good performance status (KPS ≥ 90% in 66), but 34 pts (49%) had an HCT-CI score of ≥ 3. Conditioning was myeloablative (Bu-Cy) in 4, reduced toxicity FBM (Fludarabine, BCNU, Melphalan) in 36, and RIC/NMA in 29. Donors were matched related in 18, matched unrelated in 36, and mismatched unrelated in 15. GVHD prophylaxis included tacrolimus in all pts combined with mycophenolate mofetil (37) or methotrexate (32); 49 pts received in-vivo T-cell depletion with rabbit anti-thymocyte globulin (rATG, Thymoglobulin, Genzyme, Cambridge, MA). Results The Kaplan-Meier estimate of progression-free survival (PFS) at 2 yrs was 59% (CN), 39% (CA), and 1.5% (MK); P = 0.004 (Fig. 1). The cumulative incidence of relapse at 2 yrs (with death without relapse as a competing risk) was 34% (CN), 25% (CA), and 94% (MK); P= 0.009). In a Cox proportional hazards analysis adjusted for age (≤ 66 vs. > 66), risk status (standard vs. high), conditioning (myeloablative [Bu-Cy + FBM] vs. RIC/NMA), use of ATG (yes/no), donor type (unrelated vs. related), and HCT-CI (0-2 vs. ≥ 3), the only factor predictive for inferior PFS was cytogenetic status (MK vs. CN, HR 4.64 [95% CI, 1.7 – 13]; P = 0.003); (MK vs. CA, HR 2.4 [95% CI 0.97 – 5.9]; P = .057). Conclusions Standard allo-HCT in AML or MDS pts ≥ 60 with a monosomal karyotype appears to have limited curative potential. Although larger studies will be required to confirm our results, novel transplant approaches or post-transplant strategies to prevent relapse should be a focus of future studies in this incurable pt population. Disclosures: Reeder: Novartis: Research Funding; Celgene: Research Funding; Millennium: Research Funding.

Introduction Allogeneic hematopoietic stem cell transplant (HCT) patients are at risk for having a low Vitamin D (VD) level. VD level has been correlated with cancer incidence, pulmonary disease and infection. VD also has immunomodulatory properties and reports suggest that a low VD level increases the incidence of chronic GVHD and may impact mortality in HCT. HCT morbidity and mortality is attributed to infection, organ system toxicity, GVHD and recurrent disease. Identifying a correctable factor that would reduce the occurrence or severity of these complications would be beneficial. It is possible that VD may have significant effect on outcome after HCT due to its described properties. Normal VD level may infer better outcome for HCT patients by improving response in or preventing infection, protecting organ function, decreasing risk of relapse and/or decrease incidence or severity of GVHD. We hypothesize that there is a relationship between VD level and morbidity and mortality after HCT. We therefore studied VD levels pre- and post-HCT to determine if there was an impact of VD level on these outcomes. Patients and Methods Two hundred and fifty patients underwent myeloblative or non-myeloablative HCT between 3/12/2009 and 10/29/2012 at our institution. Baseline demographic data, disease characteristics, transplant variables and outcomes data were obtained from the transplant database. These data were supplemented by retrospective chart review for VD levels prior to transplant, at day 100 and 1 year post-HCT. Data were collected through day 100 for occurrence of infection and admissions to the ICU. Categories for VD level included normal (≥30 ng/ml) or abnormal (<30 ng/ml). Patient characteristics were compared using the Chi-square test or Wilcoxon rank sum test. The logrank test was used to compare the survival curves between groups, and the Cox proportional hazard model was used to measure the association between outcomes (mortality, relapse, acute or chronic GVHD) and VD level. Results Of the 250 patients undergoing HCT VD level was performed on 180 (72%) patients pre-HCT, 149 (60%) patients at day 100 post-HCT and 81 (32%) patients at 1 year post-HCT. The rate of acute or chronic GVHD was not significantly associated with VD level pre or post-HCT. Overall infection risk was not significant pre or post-HCT but when sorted by type of infection bacterial infection (p=0.01), radiologic evidence of pulmonary nodules/consolidation (p=0.03), and ICU admissions (p=0.0313) within the first 100 days post-transplant were significantly increased in patients who had a low VD level at day 100 post -HCT. Pre-HCT and 1 year post-HCT VD level did not impact mortality or relapse but there was a significant increase in one year mortality (p=0.02, HR = 5.99) and relapse (p = 0.03, HR=9.47) in patients who had a low VD level at day 100 post-HCT. Discussion This study shows that VD may play a significant role in bacterial infection, pulmonary infection, ICU admission, mortality and relapse after HCT. Those patients with a low VD level at day 100 post-HCT had significantly worse outcomes for relapse and mortality. Those patients with a low VD level at day 100 post-HCT had a higher incidence of lung infection, bacterial infection and admission to the ICU. In contrast to previous studies, we found no correlation between VD level and incidence of acute or chronic GVHD. This study is one of the largest reported and the first to our knowledge that reports decreased risk of certain types of infection (bacterial and lung), mortality and relapse in those with an adequate VD level receiving HCT. It is possible that supplementation of VD to keep levels ≥30 would reduce these complications of HCT. Future prospective study of VD is warranted. Finding a low cost and easy to administer therapy (such as VD replacement) that would reduce morbidity, mortality and relapse in the HCT population is needed. Disclosures: Reeder: Celgene: Research Funding; Novartis: Research Funding; Millenium: Research Funding.

Background Steroid-refractory (SR) acute graft-versus host disease (aGVHD) is a serious complication of allogeneic HCT, for which there is no established standard treatment. Both ECP and cytokine inhibitors such as Infliximab have apparent single agent activity in the therapy of SR aGVHD, but there are no published data that address the efficacy of combination anticytokine therapy and ECP in this setting. We report here results in 18 adult patients (pts) with grade III or IV SR aGVHD who were treated with concurrent Infliximab and ECP. Patients All pts underwent allogeneic HCT (first transplant, n=15, second transplant, n=3) for a hematologic malignancy at Mayo Clinic Arizona between March 2012 and May 2013. The median age was 61 (range 22-70), and the median follow-up of 6 surviving pts is 263 days (range 79-433). Donors were related in 3, matched unrelated in 8, and mismatched unrelated in 7. GVHD prophylaxis consisted of tacrolimus and mycophenolate mofetil in 13 pts and tacrolimus/methotrexate in 5; in addition, 17 pts received in vivo T-cell depletion with Thymoglobulin 2.5 – 7.5 mg/kg. All pts developed grades III-IV aGVHD at a median day 27 post-transplant (range 10-107) and failed to respond to a course of high-dose corticosteroids (methylprednisolone or equivalent 2 mg/kg daily) for at least 5 days. Treatment Regimen At diagnosis of SR aGVHD, pts were scheduled to receive weekly Infliximab 10 mg/kg (maximum 4 doses), concurrent with ECP performed twice or thrice weekly for one month, followed by a pre-specified taper schedule (anticipated total treatment duration of 6-9 months). To minimize infectious risk and morbidity, corticosteroids were tapered rapidly after the start of Infliximab/ECP therapy. Results Thirteen pts (72%) responded to the Infliximab/ECP combination; complete response (CR; resolution of all GVHD symptoms for at least 30 days and able to discontinue corticosteroids) was observed in 6 pts (33%), and partial response (PR; improvement in GVHD symptoms, partial taper of corticosteroids, and no additional agent for at least 30 days) in 7 pts (39%). At the time of this report, 6 pts are alive, and the Kaplan-Meier estimate of one-year survival is 22.5 % (95% CI, 8.8%-47%). Only pts who achieved CR had good outcomes (5/6 surviving and clinically well); among 13 pts with PR (7) or no response/progression (6) to Infliximab/ECP, 12 have died and one is day 79 post transplant and remains on ECP and low-dose prednisone. Eleven of the 12 deaths were related to GVHD or complications of its treatment (infection, multi-organ failure). Conclusions In this retrospective study of adult pts with severe (grade III/IV) SR aGVHD, treatment with 4 doses of weekly Infliximab and concurrent ECP resulted in an overall response rate of 72%, with one-third of pts achieving CR; the regimen was well-tolerated and facilitated early taper and rapid discontinuance of corticosteroids. Unfortunately, the overall survival of 22.5% at one year does not appear superior to other single agent or combination therapies reported in the literature, or to historical data from our program. Although a small percentage of pts appear to be long-term survivors, the majority of pts succumb to complications of progressive GVHD or infection. Given poor results with available therapies, and the dismal prognosis of pts with SR aGVHD, future research should focus on better preventative strategies for this devastating complication of allogeneic HCT. Disclosures: No relevant conflicts of interest to declare.

Abstract A favorable prognosis and a low rate of leukemic transformation has been attributed to the 5q- syndrome, a myelodysplastic syndrome (MDS) characterized by macrocytic anemia, hypolobulated micromegakaryocytic hyperplasia, and an interstitial deletion of chromosome 5. We examined the characteristics and outcome of 43 consecutive patients in our institution strictly defined by morphologic criteria and a solitary 5q- cytogenetic defect. The median age at diagnosis was 68 years, with a clear female predominance (7:3). Eighty percent of the patients were red blood cell transfusion-dependent at diagnosis and all untransfused patients had macrocytic indexes. In contrast, significant neutropenia or thrombocytopenia was rare. The French-American-British (FAB) class distributions were RA (72%), RARS (7%), RAEB (16%), and RAEB-IT (5%). At a median follow-up of 31 months, 56% of the patients survive, with a projected median survival of 63 months. The incidence of acute leukemia was 16% and was uniformly fatal. Clinical hemosiderosis occurred in 28% of the patients, resulting in two deaths. Neither survival nor the risk of leukemic transformation was predictable from initial clinical parameters, including FAB classification, Bournemouth score, and degree of aneuploidy. The lack of significant neutropenia and thrombocytopenia seemed to account for a very low incidence of infection and bleeding resulting in a prognosis equal or superior to historical patients with MDS. Therapeutic endeavors, including the use of corticosteroids, androgens, cis-retinoic acid, pyridoxine, and danazol, were largely unsuccessful.

A favorable prognosis and a low rate of leukemic transformation has been attributed to the 5q- syndrome, a myelodysplastic syndrome (MDS) characterized by macrocytic anemia, hypolobulated micromegakaryocytic hyperplasia, and an interstitial deletion of chromosome 5. We examined the characteristics and outcome of 43 consecutive patients in our institution strictly defined by morphologic criteria and a solitary 5q- cytogenetic defect. The median age at diagnosis was 68 years, with a clear female predominance (7:3). Eighty percent of the patients were red blood cell transfusion-dependent at diagnosis and all untransfused patients had macrocytic indexes. In contrast, significant neutropenia or thrombocytopenia was rare. The French-American-British (FAB) class distributions were RA (72%), RARS (7%), RAEB (16%), and RAEB-IT (5%). At a median follow-up of 31 months, 56% of the patients survive, with a projected median survival of 63 months. The incidence of acute leukemia was 16% and was uniformly fatal. Clinical hemosiderosis occurred in 28% of the patients, resulting in two deaths. Neither survival nor the risk of leukemic transformation was predictable from initial clinical parameters, including FAB classification, Bournemouth score, and degree of aneuploidy. The lack of significant neutropenia and thrombocytopenia seemed to account for a very low incidence of infection and bleeding resulting in a prognosis equal or superior to historical patients with MDS. Therapeutic endeavors, including the use of corticosteroids, androgens, cis-retinoic acid, pyridoxine, and danazol, were largely unsuccessful.

Abstract Introduction Although allogeneic hematopoietic cell transplantation (HCT) is an expensive modality of treatment for hematological disorders, very little is known about the financial burden for the patients themselves. We analyzed factors associated with financial burden and its impact on health behaviors of allogeneic HCT recipients. Patients and Methods A questionnaire was mailed to adult patients who were alive after allogeneic HCT performed between 1/06 to 6/12 at Mayo Clinic to collect information regarding financial concerns, household income, employment status, insurance, out-of-pocket expenses and health and functional status. A multivariable logistic regression analysis was performed to determine socio-demographic and clinical factors associated with financial hardship. Results Of 482 patients, 268 responded (response rate 56%). Respondents were more likely to be older and Non-Hispanic Whites. No significant differences were seen in disease or transplant characteristics between the two groups except that respondents were more likely to have received reduced intensity conditioning. Median follow-up after HCT was 2.3 years (range 0.7-6.7 years). All the patients for whom the insurance information was available (missing n=13) were insured. Median physical and mental component score, as derived from the SF-12, were 36.8 [Interquartile range (IQR) 29.3-49.0] and 53.1 (IQR 42.1-57.1) respectively, where the general population score is 50, and lower scores indicate worse functioning. The proportion of patients that reported being on medical disability increased from 8% prior to HCT to 29% after HCT. 73% of the respondents reported that being sick had hurt them financially. 54% experienced adverse financial consequences such as decrease in household income by &gt;50% due to the HCT, need to sell/mortgage home, withdraw money from retirement accounts or having to pay more for medical care than they could afford. 3% declared bankruptcy. 12% had out-of pocket costs for the past 3 months that were&gt; $5000. Median monthly medication copayments were $100 (range $ 0-3000). 36% patients felt that their insurance coverage was poor which was strongly correlated with adverse financial consequences (p=0.0013). Other risk factors for financial burden were poor physical functioning reflected by the physical component score &lt;40 (OR 3.2; p=0.005), lower household income (OR 3.08; p=0.006) and lack of commercial/private insurance (OR 4.2; p&lt;0.001) while adjusting for patient and transplant related characteristics. Time from transplant was a significant predictor (OR 1.2; p=0.03) in the univariate analysis, but lost its significance in the multivariate analysis. 18 to 27% patients reported deleterious health behaviors due to financial constraints such as not taking prescribed medications, not using a recommended medical service or not making physician appointments. Conclusions A significant proportion of allogeneic HCT survivors experience adverse financial consequences with a few reporting severe outcomes like bankruptcy, despite having health insurance coverage. Future research should investigate potential interventions such as early financial counseling and connecting with sources of financial support to help at-risk patients and prevent long-term adverse financial outcomes after this life-saving procedure. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 3513 To identify targets for rational combination therapies with 5-Azacytidine (5-Aza) in myeloid malignancies, we utilized high-throughput RNA-interference (RNAi) viability screening. A siRNA library targeting 572 kinases and a custom collection of 289 putative cancer targets, including cell cycle and apoptosis regulatory genes, were screened alone and in combination with 5-Aza in TF-1 and ML-2 myeloid leukemia cell lines to identify synergistic interactions in reducing cell viability. Of the 572 kinases that were individually silenced, less than 1% significantly increased sensitivity to 5-Aza. The kinase library was also screened in combination with 5-Aza in a third myeloid cell line, THP-1, confirming that few kinases sensitize to 5-Aza when inhibited. While few kinases sensitized to 5-Aza, the anti-apoptotic Bcl-2 family of genes emerged as potent sensitizers to 5-Aza from RNAi screens. Therefore, silencing by siRNA of BCL-XL, BCL-2, BCL-W, MCL-1 and BFL-1 was evaluated in combination with 5-Aza treatment in an expanded panel of myeloid cell lines including TF-1, HEL, THP-1, ML-2 and MDS-L. BCL-XL validated as a vulnerability and potent sensitizer to 5-Aza in erythroid leukemia cell lines TF-1 and HEL, whereas MCL-1 was a strong vulnerability in the monocytic leukemia cell line THP-1 and also a moderate sensitizer to 5-Aza in ML-2, THP-1, TF-1 and HEL. Published proteomics data from our group indicate that M6 and M7 leukemias exhibit higher levels of BCL-XL, while additional unpublished data suggest elevated levels of MCL-1 in M4 and M5 leukemias, supporting our functional observations. Additionally, data from the public database Oncomine suggest that BCL-XL expression is elevated in M6 and M7 leukemias while MCL-1 shows a trend towards elevation in M4 and M5 leukemias. Based on RNAi screening results, siRNA validation experiments and proteomic/mRNA expression data, we evaluated the BCL-2/BCL-XL/BCL-W inhibitor ABT-737 in combination with 5-Aza. ABT-737 resulted in dose-dependent sensitization to 5-Aza in all AML-derived cell lines examined (including M7, M6, M5, M4 and M2 FAB subtypes) and in the MDS cell line MDS-L; however, no sensitization was observed in the CML cell line K562. In extensive ex vivo experiments with 17 primary specimens, potent synergy between 5-Aza and ABT-737 was observed in AML, MDS and MPN samples, but not in most CML samples examined. Calculations with CalcuSyn software demonstrate synergy, with combination index values as low as 0.2, between 5-Aza and ABT-737 both ex vivo and in vitro. The combination of 5-Aza with ABT-737 resulted in substantial induction of apoptosis, measured by the induction of cleaved caspase 3 in TF-1 and HL-60 cells, as compared to either compound alone. Interestingly, although siRNA silencing of MCL-1 in combination with 5-Aza was potent across several cell lines, and silencing of BCL-XL preferentially in an erythroid differentiation background, ABT-737 with 5-Aza sensitized across a variety of cell lines and all myeloid primary specimens ex vivo. We suggest that inhibition of anti-apoptotic Bcl-2 family members is a most promising rational combination strategy with 5-Aza for the treatment of leukemias. Our results also highlight the potential utility of more specific anti-apoptotic Bcl-2 family inhibitors in the lineage-specific treatment of myeloid malignancies. Disclosures: Off Label Use: AraC in AML. Experimental Agent MK1775. Mesa:Incyte: Research Funding; Lilly: Research Funding; SBio: Research Funding; Astra Zeneca: Research Funding; NS Pharma: Research Funding; Celgene: Research Funding.

Abstract Abstract 229 Introduction: Optimal rational combination targets with Cytarabine (AraC) have not been identified. After the development of a high-throughput, small-interfering RNA (siRNA) platform for suspension cells, we performed the first RNAi sensitizer screen of the human kinome with AraC in myeloid cell lines. Herein we present the final data of this first siRNA-sensitizer screen in leukemias in combination with AraC. Our results include full validation of the selected targets as well as ex vivo data assessing the first in class clinically tested WEE1 inhibitor MK1775 with AraC providing a pre-clinical rationale for using the combination of AraC with WEE1 inhibitors in leukemias. RNAi Screens and siRNA Validation: In siRNA sensitizer screens, we silenced 572 kinases of the human kinome in combination with AraC. Few kinases strongly sensitized to AraC and the targets CHEK1 and the WEE1 related kinase PKMYT1 emerged as the most potent genes whose silencing sensitized leukemia cells to AraC. In secondary siRNA validation experiments, silencing of WEE1 kinase was found to be more potent than silencing of CHEK1, PKMYT1 or other kinases (i.e. ATR, BRCA, AURKB) in combination with AraC treatment. Importantly, the sensitizing activity observed with WEE1 inhibition was universal across all AML cell lines examined, whereas it was not for CHEK1 inhibition. siRNA assays were robust, exhibiting little (<10%) non-specific toxicity and siRNA silencing was specific for individual genes (i.e. WEE1 or CHEK1) as demonstrated by selective reduction of mRNA and protein level for the respective genes; confirming the validity of the siRNA assay. Pharmacological WEE1 Inhibitor Experiments In vitro and Ex vivo: In vitro treatment of eight AML, ALL and CML cell lines with commercial and the first clinically developed WEE1 kinase inhibitor MK1775, demonstrated strong sensitization to AraC up to 97-fold in individual cell lines. Ex vivo, MK1775 substantially reduced viability in 13 of 14 AML, MDS and CML patient samples compared to AraC alone. The optimal dose to achieve maximum sensitization was observed for AraC between ∼10–120 nM and for MK1775 between 200–400 nM. Synergy at these optimal concentrations was confirmed in all ex vivo samples tested for which sufficient data for analysis with CalcuSyn Software was available (n=7): with Combination Indices (CI) ranging from 0.21–0.45. At higher AraC and MK1775 concentrations antagonism was observed both ex vivo and in vitro. Thus, we have also established optimal suggested concentration dose ranges for the currently ongoing design of a clinical trial. Clinically relevant, WEE1 is expressed in primary AML, ALL and advanced CML specimens with a trend towards higher expression in relapsed samples. However, there was no direct correlation with WEE1 mRNA expression or TP53 status. Our initial in vitro experiments further suggest that inhibition of WEE1 with MK1775 in combination with AraC at optimal concentrations was associated with higher degree of caspase 3 cleavage, DNA damage induction as measured by gamma-H2AX, and greatest inhibition of proliferation. Thereby establishing a context of optimal drug concentration ranges with molecular correlates and anti-leukemic activity directly informing design of the clinical trial and correlative biomarkers. In conclusion, data from this first siRNA sensitizer screen of the kinome in leukemias identifies inhibition of WEE1 kinase as the most potent sensitizing target to AraC. Inhibiting WEE1 with pharmacological inhibitors in combination with AraC is a rational treatment strategy for myeloid and lymphoid leukemias that warrants clinical investigation. Furthermore, our RNAi loss-of-function genomics approach has high potential to rapidly identify and validate crucial genes whose inhibition modulate the response to cytotoxic agents. Establishment of the siRNA sensitizer platform allows accelerating the development of new rational combinations for leukemia therapy. Disclosures: Off Label Use: AraC in combination with the experimental Wee1 inhibitor MK1775. Mesa:NS Pharma: Research Funding; Astra Zeneca: Research Funding; SBio: Research Funding; Lilly: Research Funding; Incyte: Research Funding; Celgene: Research Funding. Demuth:Merck and CO: Employment.

Abstract Abstract 1749 BACKGROUND: We have previously reported that transformation of a myeloproliferative neoplasm (MPN) to acute leukemia or blast phase (MPN-BP) is accompanied by a median survival of 2.6 months (range 0–24.2 months) (Mesa et. al. Blood 2005) despite treatment. Allogeneic stem cell transplantation (ASCT) offers a potential for cure. We reviewed 13 patients with MPN – BP who were candidates for ASCT, and 8 of those patients received ASCT after induction chemotherapy. METHODS: Retrospective analysis of individuals who had a clear antecedent myeloproliferative neoplasm (essential thrombocythemia (ET), polycythemia vera (PV), or myelofibrosis (MF) (either primary (PMF) or post ET/PV)), transformed to MPN-BP, and were candidates for ASCT. Clinical characteristics at each phase of illness, therapy at each phase of illness, and outcome of ASCT were assessed. RESULTS: Patients (MPN details): Thirteen patients (8 male, 5 female, median age at diagnosis of MPN 42 years in those who underwent ASCT and 64 years in those who did not receive ASCT (combined median 53 years, range 26–70)) were identified who met the inclusion criteria, of whom 2 had ET, 4 PV, 2 Post-ET MF, 1 Post-PV MF and 4 PMF. Jak2-V617F mutation was present in 7 of 8 patients tested. Treatments used during the MPN phase included hydroxyurea in 9 (+ busulfan in 1 and + anagrelide in 1), and thalidomide/prednisone in 2 (two patients received no treatment prior to MPN-BP). Patients (MPN-BP details): Transformation of an MPN to blast phase (from diagnosis of MPN) occurred after a median of 11 years in those who underwent ASCT and 8 years in non-ASCT (range 3 months to 30 years). At the time of MPN-BP diagnosis, 9 patients had an abnormal karyotype, 3 with complex karyotypes, 3 with trisomy 8 (sole abnormality), 1 with del(7q), 1 with del(13q). Leukemic induction consisted of standard anthracycline/cytarabine combination therapy (+/− etoposide), except for one patient received a study medication voreloxin. One patient who did not receive ASCT had remission after induction, but later expired from relapse, two expired soon after leukemic transformation, and two were too ill to receive induction. In the ASCT group (N=8), 5 patients achieved complete remission (CR) of their leukemia/return to MPN chronic phase (one of the five patients required a second induction to achieve CR), while 3 patients were considered primary induction failures due to persistence of > 5% blasts in the blood (2) or marrow (1) at the time of pre-transplant response assessment. The median time from diagnosis of MPN-BP to ASCT was 128 days. ASCT Details and Outcomes: Patients (median age of 55 years at time of ASCT; range 44–73) underwent ASCT (all HLA identical, 3 matched unrelated donors, 5 matched sibling donors) with either reduced intensity conditioning (n=6) or fully myeloablative conditioning (n=2). After a median follow-up of 488 days (range 127 – 1206), 6 of 8 patients are alive and free of disease. MPN-BP recurred in two patients at day 69 and 77 post-transplant; both patients eventually died of progressive leukemia, one after a second transplant. Acute GVHD occurred in 3 patients (1 grade III, 2 grade II), and chronic GVHD in 4 (2 mild, 2 moderate). All five patients who achieved CR (marrow and PB blasts < 5%) after induction therapy remain in continuous CR, while 2 of the 3 patients with evidence of persistent leukemia relapsed and died of MPN-BP. No patient died of transplant-related causes and all patients engrafted promptly. CONCLUSION: Rapid induction followed by ASCT can offer a curative path for individuals with MPN-BP. Although limited by small numbers, our data suggest that leukemic clearance (marrow blast percentage < 5%) prior to ASCT is associated with improved outcome. Disclosures: Mesa: Incyte: Research Funding; Lilly: Research Funding; SBio: Research Funding; Astra Zeneca: Research Funding; NS Pharma: Research Funding; Celgene: Research Funding.

Abstract Abstract 1977 Introduction: Transplant options are limited for adult patients (pts) who lack a fully matched related or unrelated donor. We hypothesized that in-vivo T-cell depletion with r-ATG would allow safe allo-SCT from mismatched, unrelated donors, thus expanding the potential donor pool for pts with hematologic malignancies who require allo-SCT. Patients and Methods: Thirty seven adult pts (age 20 – 70, median 45) underwent a first unrelated, mismatched, allo-SCT between 1/1/2006 and 6/30/2011 at Mayo Clinic Arizona for hematologic malignancy (35 PBSC, 2 marrow). All pts had at least a one allele or one antigen mismatch (MM) at HLA-A, -B, -C, or -DRB1, and all except one pt received r-ATG as part of the GVHD prophylaxis strategy (dose range 2.5 – 10 mg/kg in daily dose of 2.5 mg/kg depending on degree of mismatch, with the last dose generally given on day −1). One pt received Campath after experiencing anaphylaxis to r-ATG. Pts were transplanted for acute myeloid leukemia (n = 19; 10 CR1, 6 CR2, 3 other), acute lymphoblastic leukemia (n = 8; 4 CR1, 4 CR>/= 2), chronic myeloid leukemia (n = 1), myelodysplastic syndrome (n = 5), or non-Hodgkin lymphoma (n = 4). Conditioning was myeloablative in 20, reduced intensity in 16, and non-myeloablative in 1. Mismatches were as follows: 1-allele MM (n = 7); 1 antigen MM (n = 15); 2 allele MM (n = 4); 1 antigen, 1 allele MM (n = 7); and 2 antigen MM (n = 4). Additional GVHD prophylaxis included tacrolimus plus either methotrexate (n =21), mycophenolate mofetil (n = 14), or other (n = 2). Results: The median follow-up for surviving pts is 12 months. As of 6/30/11, 31 pts were alive, and 6 had died of the following causes: multiorgan failure (n = 1), relapse (n = 3), and veno-occlusive disease (n = 2). To date, there have been no deaths related to acute or chronic GVHD. The 1- and 2-year estimated rates of overall survival are 84.5%/78.8% (Fig. 1); of progression-free survival 79.7%/72.0%. The estimated rate of relapse at 1 and 2 years is 11.8%/18.7%, and of non-relapse mortality 8.1%/10.5%. Four pts (10.8%) have developed severe (grades III-IV) acute GVHD by day 100 (days 19, 27, 30, 43; one pt after withdrawal of prograf due to transplant-associated microangiopathy). No late onset severe acute GVHD has been seen. Moderate to severe NIH-defined chronic GVHD occurred in a single pt at risk (cumulative incidence estimate 2.4% at 1 year, 4.7% at 2 years; Fig. 2). Four pts have reactivated EBV, with one developing PTLD (all have been treated with Rituximab). CMV reactivation was seen in 24 pts (65%), CMV disease in 4, with no deaths directly related to CMV. Conclusions: In vivo T-cell depletion with r-ATG abrogates severe acute and chronic GVHD, and allows use of mismatched unrelated donors for allo-SCT in adult pts with otherwise incurable hematologic malignancies. Long-term survivors are generally free of severe chronic GVHD, with good quality of life. There does not appear to be an increased incidence of disease relapse, and non-relapse mortality is low. This approach is safe, effective, and considerably expands the donor pool for adult pts who require allo-SCT. Disclosures: Reeder: Celgene: Research Funding; Millennium Pharmaceuticals Inc.: Research Funding; Novartis: Research Funding. Mesa:Incyte: Research Funding; Lilly: Research Funding; SBio: Research Funding; Astra Zeneca: Research Funding; NS Pharma: Research Funding; Celgene: Research Funding.