ALBERT

Description: Graft-versus-host disease (GVHD) represents the major nonrelapse complication of allogeneic hematopoietic cell transplantation. Although rare, the CNS and the eye can be affected. In this study, manifestation in the retina as part of the CNS and T-cell epitopes recognized by the allogeneic T cells were evaluated. In 2 of 6 patients with posttransplantation retina diseases and 6 of 22 patients without ocular symptoms, antigen-specific T-cell responses against retina-specific epitopes were observed. No genetic differences between donor and recipient could be identified indicating T-cell activation against self-antigens (graft versus self). Transplantation of a preexisting immunity and cross-reactivity with ubiquitous epitopes was excluded in family donors and healthy individuals. In summary, an immunological reaction against retina cells represents a mechanism of graft-versus-host interaction following hematopoietic cell transplantation.

Description: Abstract 3540 Historically, allogeneic hematopoietic cell transplantation (HCT) has been offered only to patients with good performance status and below the age of 60. However, the peak incidence of most hematologic malignancies is above 60 years of age. The introduction of reduced intensity conditioning (RIC) regimens enabled successful allogeneic HCT in patients with considerable comorbidities and older than 60 years. The impact of age on outcome of allogeneic HCT in patients ≥60 years has not been evaluated extensively. We retrospectively analyzed 109 consecutive patients (f=43, m=66) aged≥60 who received allogeneic HCT 2000–2010 at our institution. Median age of the patients was 65 years (range, 60–76). Patients were grouped in two cohorts depending on age: group 1 aged 60–65 years (n=60, median age=63) and group 2 aged 66–76 years (n=49, median age=68). Diagnoses were acute leukemia (AML n=65, ALL n=1), myelodysplastic syndrome (n=14), osteomyelofibrosis (n=7), non-Hodgkin lymphoma (n=9), multiple myeloma (n=8), aplastic anemia (n=1), chronic myeloid leukemia (n=2) and chronic lymphatic leukemia (n=2). At time of HCT, 41 of the patients were in complete remission (CR), 68 in partial remission (PR) (group 1: CR 21, PR 39; group 2: CR 20, PR 29) and 18 patients had a preceding HCT, 14 in group 1. Conditioning regimens were grouped in high (TBI/Bu+Cy, n=5, all group 1), intermediate (FLAMSA, Flu/Mel/BCNU, n=28, group 1=11, group 2=17), low (FLU+alkylans, n=48, group 1=32, group 2=16) and minimal (2GyTBI/Flu, n=28, group 1=12, group 2=16) intensity. Intermediate intensity conditioning was particularly used for high risk patients in PR (25/28). 22 patients were transplanted from matched related (MRD), 46 from matched unrelated (MUD) and 41 from mismatched unrelated donors (MMUD). Kaplan-Meier-estimated 3-year overall survival (OS) was 45% for all patients, 32% for group 1 and 62%, for group 2, respectively (p=0.02), with more patients with high risk constellation in group 1. 3-year OS for patients transplanted with MUD was 57%, with MMUD 46% vs. with MRD 0% (p=0.01). Non-relapse-mortality was 28% for all patients, 40% in group 1 and 12% in group 2, probably due to the higher intensity in conditioning in group 1. The outcomes with intermediate, low and minimal intensity conditioning were comparable, while all patients after high intensity conditioning died. Table 1 describes Kaplan-Meier estimated 3-year-OS and statistical univariate analysis by log-rank test in the different subgroups. Table 1. 3-year OS (in%) All Group 1 Age 60–65 Group 2 Age 66–76 Remission CR 52 p=0.25 31 p=0.76 77 p=0.15 PR 40 32 50 Conditioning high 0 p=0.5 0 p=0.08 – p=0.38 intermediate 52 50 53 low 48 43 57 minimal 45 17 67 Donor MRD 0 p=0.01 0 p=0.06 73 p=0.45 MUD 57 53 65 MMUD 46 40 33 GVHD acute no 18 p=0.003 13 p=0.008 33 p=0.27 ≥II 43 53 58 chronic no 39 p=0.25 36 p=0.70 52 p=0.08 limited 52 30 100 extensive 50 30 67 In group 1 the outcome of minimal conditioning was inferior compared to intermediate and low conditioning while patients in group 2 had a better outcome with minimal vs. low and intermediate conditioning. Incidences of acute GVHD ≥II, limited and extensive chronic GVHD (cGVHD) were 10%, 28% and 13%, respectively. In group 1, acute GVHD ≥II occurred in 13% and cGVHD in 35%, in group 2 in 5% and 41% of the patients, respectively. Acute GVHD ≥II was associated with inferior outcome (3-year OS of 18% vs. 43%, p=0.003) while cGVHD had a positive impact on OS. In group 2 patients with limited cGVHD showed better 3-year OS than patients without cGVHD (67% vs. 52%, p=0.12). Age alone had no major impact on outcome of allogeneic HCT. Patients aged ≥60 seemed to benefit from the use of MUD rather than an older MRD. Chronic GVHD had a positive influence on survival. Our data indicate that the regimen used should be tailored to disease risk and patient performance status. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 348 We previously reported results of 3 sequential trials of GVHD prophylaxis with mycophenolate mofetil (MMF) BID/TID and cyclosporine (CSP) BID with various taper schedules in patients (pts) with advanced hematologic malignancies given unrelated G-CSF-mobilized peripheral blood stem cell (PBSC) grafts after fludarabine 90 mg/m2 and 2 Gray total body irradiation. Cumulative incidences of grades II-IV acute GVHD in the 3 trials were 52, 53 and 77%, respectively. The goal of the current protocol was to evaluate, in a phase II randomized 3-arm study, which drug combination or schedule was most promising in preventing acute GVHD. Tacrolimus (Tac) was used in place of CSP and each of the 3 arms used MMF TID until day 30 and then BID, but the subsequent duration of MMF varied. In Arm1, pts received Tac until day 180 and MMF until day 96. In Arm2, Tac was given until day 150 and MMF until day 180. In Arm3, Tac was given until day 150 and MMF until day 180 with the addition of rapamycin from days -3 through 80. One hundred seventy-five pts ineligible for myeloablative conditioning were enrolled on this multi-institutional study between Jan/05 and Aug/09, and results on the first 159 pts (Arm1 n=56; Arm2 n=51; Arm3 n=52) are reported here with a median follow-up of 18.4 months for surviving pts. The median age of pts was 60 (range 13-75) yrs. Sixty-six (42%) had previous autologous (n=55) or allogeneic (n=11) HCT. All pts were matched for HLA-DRB1 and -DQB1 at the allele level: 16 had single allele mismatches at HLA-A, -B or –C and the remainder (n=143) were fully HLA-matched. Diagnoses included AML (n=72), NHL (n=36), MM (n=19), ALL (n=10), CLL (n=9), MDS (n=8), HL (n=4), and CML (n=1). Randomization was based upon transplant center (FHCRC vs other), number of prior chemotherapy treatments (0-2 vs 3+), and age (

Description: NK-cells have been shown to play a pivotal role in haploidentical hematopoietic cell transplantation (HHCT) for engraftment, GvL effects and to combat infectious complications. Different strategies have been employed to hasten NK-cell recovery after HHCT. Here we compare the immune recovery of 17 patients after CD34 selected HHCT receiving additional adoptive CD3-depleted CD56-enriched NK cells 2 days after HHCT (adoptive NK-cells), with 18 patients receiving CD3/CD19 depleted grafts (CD3/CD19) for HHCT. Transplantations were performed at two different institutions with a median follow-up of 〉1 year. Conditioning consisted of 12 Gy TBI, thiotepa (10mg/kg), fludarabine (150 mg/m2) and OKT3 (day −4 to +2) in the group receiving CD34 selected grafts and adoptive NK-cell transfusions. All patients in the CD3/CD19 group received conditioning with fludarabine (150–200 mg/m2), thiotepa (10 mg/kg), melphalan (120 mg/m2) and OKT-3 (day −5 to +14). No postgrafting immunosuppression was used in both groups. Seven out of the 17 patients in the adoptive NK-cell group received IL-2 activated NK cells. Median age was 37 years in the adoptive NK-cell group compared to 40 years in the CD3/CD19 group. Diagnoses in the adoptive NK-cell group included AML (n=10), ALL (n=3), CML (n=2), and Hodgkin’s disease (n=1) and MDS (n=1). Diagnoses in the CD3/CD19 group were AML (n=10), ALL (n=5), NHL (n=1), CML (n=1) and multiple myeloma (n=1). The grafts contained a median of 12.5x10E6 CD34+ cells/kg and 1.1×10E4 CD3+ cells/kg in the CD34 selected group versus 9.2×10E6 CD34+cells/kg and 2.3×10E4 CD3+cells/kg in the CD3/CD19 group. The number of transferred CD56+ cells was 8.3×10E6/kg in the adoptive NK-cell group and 7.2×10E7/kg cells in the CD3/CD19 group. Hematopoietic recovery was similar in both groups. Among the patients receiving adoptive NK-cells we observed a striking difference in immune recovery between the patients receiving IL2-activated and those treated with non-activated NK cells: patients receiving activated NK cells showed significantly lower numbers of NK- and T cells during the first months post transplant (p=

Description: Allogeneic hematopoietic cell transplantation (HCT) using reduced intensity conditioning (RIC) regimens offers a potential curative therapy to patients with advanced NHL. RIC HCT induces potent graft-versus-lymphoma effects with best results in patients with low tumor burden at time of HCT. Combined use of radioimmunotherapy (RIT) with RIC may increase anti-lymphoma activity of RIC while HCT provides rescue from hematologic toxicity of RIT. This may allow dose escalation of RIT. A multicenter phase I/II study of allogeneic HCT combining RIT using yttrium-90-ibritumomab tiuxetan (Y90-CD20) with two RIC regimens for treatment of patients with NHL has been initiated. Patients with indolent NHL (Arm A) receive RIT with Y90-CD20 (0.4 mCi/kg) on day −14 combined with RIC using fludarabine (30 mg/m^2 day −4 to−2) and 2 Gy TBI (day 0). Patients with aggressive NHL (Arm B) receive an escalated dose of Y90-CD20 (0,6–0,8 mCi/kg) on day −14 combined with RIC using fludarabine (30 mg/m^2 day −8 to−4), melphalan (140 mg/m^2 day −3) and campath (20–30 mg day −3 to−2). For postgrafting immunosuppression either CSA/MMF (Arm A) or CSA alone (Arm B) is used. To date, 31 patients have been enrolled (Arm A=23, Arm B=8). Diagnoses in Arm A were FL (n=12), MCL (n=6), CLL (n=4) and Immunocytoma (n=1). Diagnoses in Arm B were DLBCL (n=6), blastoid MCL (n=1) and transformed CLL (n=1). Median age was 55 (range, 34–67) years. PBSC grafts were either from matched related (n=10) or matched unrelated donors (n=21). All patients were high risk with refractory disease or relapse after preceding HCT. Disease status after salvage therapy at time of HCT was in Arm A: CR=1, PR=18, SD=4 and in Arm B: PR=8. No additional toxicity due to RIT was observed. Engraftment was rapid and sustained with no graft rejections. In Arm A median time to 〉500 granulocytes/μL was 13 (range, 0–69) days and to 〉20000 platelets/μL 3 (range, 0–69) days (in 11 patients platelets never dropped 500 granulocytes/μL was 17 (range, 9–23) days and to 〉20000 platelets/μL 11 (range, 8–29) days. TRM in the first 100 days was 3%, overall 19%. Incidence of grade II-IV GVHD in Arm A was 35% (II=3, III=4, IV=1) and in Arm B 25% (II=2). Best disease response observed was in Arm A: CR=18, PR=5 and in Arm B: CR=3, PR=5. To date, 16/23 patients in Arm A and 6/8 patients in Arm B are alive with a median follow-up of 271 (range, 20–390) days, resulting in a Kaplan-Meier 1 year survival estimate of 65% in Arm A and 62% in Arm B. Causes of death were infection=5, GVHD=1, relapse=1 in Arm A and relapse=2 in Arm B. A combination of RIT with RIC is feasible with no additional toxicity due to RIT and stable engraftment in all patients. Preliminary response data suggest that this strategy may improve early post-transplant disease control, but long-term disease-free survival remains to be determined.

Description: To improve the results of allogeneic SCT for high-risk AML and MDS, the FLAMSA-RIC conditioning regimen for allogeneic SCT combines cytoreductive chemotherapy (fludarabine, HD AraC, amsacrine), followed three days later by reduced intensity conditioning (4Gy TBI/EDX). Since in particular patients with an unfavorable karyotype seemed to benefit from this approach (Schmid et al., JCO, 2005), we analysed the outcome of 172 patients with poor risk cytogenetics according to NCCN criteria, who had been allografted following FLAMSA-RIC conditioning in 11 European centres between 1999 and 2008. Median time from diagnosis to transplantation was 5 months. Donors were matched siblings, matched unrelated, or mismatched unrelated donors in 34%, 47%, and 19%. Patients suffered from progressive MDS (10%), de novo AML (47.5%), or secondary AML (43.5%). SCT was performed upfront, after primary induction failure, in CR1 and in relapsed disease in 17%, 33%, 22% and 28% of patients, respectively. Median patient age was 53 (18–71) years. 95 patients (56%) had a complex aberrant karyotype, 55 and 65 had abnormalities of chromosome 5 (−5/5q-) and 7 (−7/7q-), respectively. After a median follow up of 20 months, overall survival (OS) at 2 and 4 years was 46.4% and 40.5%, the respective leukemia-free survival was 37.7% and 32.0%. Causes of death were leukemia in 30%, and non-relapse mortality in 21%. Encouraging results were observed in patients with chromosome 7 aberrations or with a complex karyotype leukemia (4y OS=49.3% and 40.3%). In contrast, results were inferior in patients with chromosome 5 aberrations (4y OS=30%), mainly due to an increased rate of leukemia-associated death (p=.008). Patiens with MDS, who received allogeneic SCT as first line treatment, achieved a 4y OS of 80% despite unfavorable cytogenetics. Unlike, patients with secondary AML after MDS had an inferior outcome (4y OS=28%, p=.018). In a Cox regression model, a stage of remission at transplantation, a 8/8 or 10/10 matched family or unrelated donor, and lack of monosomy 5 or deletion 5q were associated with superior OS (p=.025, .05, and .05). In conclusion, allogeneic SCT following the FLAMSA-RIC regimen is a highly effective treatment for MDS and AML with unfavorable karyotype, comparing favourably with published data. In MDS, SCT should be performed before transformation into sAML. Long term remission is achieved in a substantial percentage of patients with complex karyotype disease and aberrations of chromosome 7. Aberrations of chromosome 5 may require alternative or additive strategies.

Description: Haploidentical hematopoietic cell transplantation (HHCT) after high dose conditioning with a megadose of CD34-selected stem cells has been complicated by regimen related toxicities, slow engraftment and delayed immune reconstitution leading to high treatment related mortality (TRM). A new regimen using reduced intensity conditioning (RIC) and immunomagnetic CD3/CD19 graft depletion may allow HHCT with lower toxicity and faster engraftment. CD3/CD19 depleted grafts not only contain CD34+ stem cells but also graft-facilitating cells, CD34- progenitors, dendritic and natural killer cells which may allow stable engraftment even without a megadose of CD34+ cells. A multicenter phase I/II study of HHCT using RIC with fludarabine (150–200 mg/m2), thiotepa (10 mg/kg), melphalan (120 mg/m2), OKT-3 (5 mg/day, day -5 to +14) and CD3/CD19 graft depletion has been initiated. No post grafting immunosuppression was applied if the graft contained 500 granulocytes/μL of 12 days (range, 9–50) and to 〉20000 platelets/μL of 11 days (range, 7–38). Full donor chimerism was reached after 2–4 weeks in all but four patients (median of 14 days (range, 7–215)). Four patients experienced rejection/non-engraftment, two were rescued by a second CD3/CD19 depleted graft from another haploidentical donor. Incidence of grade II-IV acute GVHD was 51% with grade II=16, III=6 and IV=4. So far there are six cases of limited chronic GVHD and one case of extensive chronic GVHD. TRM in the first 100 days was 11/51 (22%) and overall 20/51 (39%). Overall survival is 17/51 patients (33%) with deaths due to relapse (n=14), infection (n=15), PML (n=2), GVHD (n=2) and cardiac failure (n=1), with a median follow-up of alive patients of 397 days (range, 62–1180). This results in a Kaplan-Meier estimate 1-year survival of 37%. So far, we did not observe a statistical significant survival advantage for patient transplanted from a KIR-mismatched donor (28/51 patients). This regimen with low toxicity as well as fast and sustained engraftment is promising in high risk patients lacking a suitable donor. To investigate the treatment protocol earlier in course of disease a new study for high-risk patients with acute leukemia in first complete remission is in preparation.

Description: Median ages of pts with most hematological malignancies are beyond 60 years. The advent of nonmyeloablative conditioning regimens has extended the use of allogeneic HCT to these older pts. Here, we retrospectively investigated outcomes among 280 pts aged ≥60 years, given HCT between 1998 and 2006. Results were broken down in 3 age groups 60–64 (n=166), 65–69 (n=90), and ≥70 (n=24) years old, respectively. Pts aged ≥70 years had less preceding chemotherapy, less often failed autologous HCT, more often had related grafts, and had higher comorbidity scores compared to pts in the other two age groups (table 1). Acute leukemias were more frequent and lymphoma/multiple myeloma were less frequent among pts aged ≥70 years old, resulting in higher risk for relapse (Table 1). After HCT, non-relapse mortality, relapse, and progression free survivals at 5-years for all pts were 26%, 41%, and 32% respectively. Five-year Kaplan Meier rate of overall survival was 35%, of those 12% vs. 23% were with vs. without chronic GVHD requiring immunosuppressive therapy, respectively. There were no statistically significant differences in outcomes among the three age groups except for more infections and days of hospitalization among pts aged 65–69 years compared to the other two age groups (Table 2). In multivariate analyses of risk factors, high HCT-comorbidity index (1–2 and ≥3) independently predicted higher NRM (HR: 2.84 and 3.0, respectively, p=0.01) and, not surprisingly, previously defined high relapse risk predicted relapse (HR: 2.17, p=0.06); both predicted worse OS (p=0.005 and p=0.0009, respectively) and PFS (p=0.01 and p=0.02, respectively). Pts given unrelated grafts did as well as recipients of related grafts. In conclusion, nonmyeloablative allogeneic HCT can be curative among pts older than 60 years with resolution of chronic GVHD among a majority of pts. Comorbidities and relapse risk rather than age should be used for benefit-risk assessment. Continued enrollment of elderly pts in prospective studies including unrelated donors is warranted. Table 1: Pt characteristics Age groups, years (60–64) (n=166) (65–69) (n=90) (70–74) (n=24) Median Interval from Dx to HCT, months 19 15 8 Median (range) # of prior regimens 3 (0–14) 3 (0–13) 2 (0–10) Median CD34+ cell number x 106/kg 6.7 6.7 6.5 Median CD3+ cell number x 108/kg 2.9 3.1 3.4 % Prior radiotherapy 18 11 13 Prior HCT Failed 19 12 4 Planned 8 6 4 Positive patient CMV sero-status 58 65 79 HLA-matched related 54 53 83 Donor HLA-matched unrelated 41 44 17 HLA-mismatched unrelated 5 3 0 Conditioning 2 Gy TBI 12 13 21 2 Gy TBI + FLU 88 87 79 HCT-CI scores 0 27 27 15 1–2 30 39 25 3–4 30 17 40 ≥5 13 17 20 Diagnoses Acute leukemia 35 47 62 Chronic leukemia 15 13 13 Lymphoma/myeloma 21 23 8 Myelodysplastic/myeloproliferative 16 16 17 Others 3 1 0 Disease status at HCT CR 46 41 38 PR 15 30 21 Refractory 28 21 33 Relapse 11 8 8 Relapse risk Low 19 17 8 Standard 48 51 38 High 33 32 54 Table 2: Outcomes per age groups HCT Outcomes Age groups, years P* (60–64) (n=166) (65–69) (n=90) (70–74) (n=24) FUO indicates fever of unknown origin *Test for trend μBased on hazard ratio analysis Bacterial 1.4 2.3 1.7 .0004 Rates of Infection episodes per person Viral 0.7 1.1 0.7 NS within 100 days FUO 0.3 0.4 0.1 NS Fungal 0.3 0.2 0.3 NS Median (range) days of hospitalization 1 (0–60) 4.5 (0–179) 0.5 (0–47) NS % Acute GVHD Grades II–IV 52 49 54 NSμ Grades III–IV 16 12 13 NSμ Chronic extensive GVHD 39 45 54 0.05μ NCI-CTC criteria grades III–IV non-hematological toxicities 42 57 50 NSμ Pts with Full donor chimerism at 1-year CD3/CD33/BM 68/ 84/ 80 66/ 83/ 77 67/ 79/ 71 NSμ CR at 2-years 40 47 63 NSμ 5-years Relapse/progression 38 46 46 NSμ 5-years NRM 28 22 29 NSμ 5-years OS 37 36 23 NSμ 5-years PFS 34 31 25 NSμ Patients alive and off all immunosuppression 24 25 5 NSμ

Description: To lower treatment-related mortality and toxicity of conventional marrow transplantation, a nonmyeloablative regimen using 200 cGy total-body irradiation (TBI) and mycophenolate mofetil (MMF) combined with cyclosporine (CSP) for postgrafting immunosuppression was developed. To circumvent possible toxic effects of external-beam γ irradiation, strategies for targeted radiation therapy were investigated. We tested whether the short-lived (half-life, 46 minutes) α-emitter bismuth 213 (213Bi) conjugated to an anti-CD45 monoclonal antibody (mAb) could replace 200 cGy TBI and selectively target hematopoietic tissues in a canine model of nonmyeloablative DLA-identical marrow transplantation. Biodistribution studies using iodine 123–labeled anti-CD45 mAb showed uptake in blood, marrow, lymph nodes, spleen, and liver. In a dose-escalation study, 7 dogs treated with the 213Bi–anti-CD45 conjugate (213Bi dose, 0.1-5.9 mCi/kg [3.7-218 MBq/kg]) without marrow grafts had no toxic effects other than a mild, reversible suppression of blood counts. On the basis of these studies, 3 dogs were treated with 0.5 mg/kg 213Bi-labeled anti-CD45 mAb (213Bi doses, 3.6, 4.6, and 8.8 mCi/kg [133, 170, and 326 MBq/kg]) given in 6 injections 3 and 2 days before grafting of marrow from DLA-identical littermates. The dogs also received MMF (10 mg/kg subcutaneously twice daily the day of transplantation until day 27 afterward) and CSP (15 mg/kg orally twice daily the day before transplantation until 35 days afterward). The therapy was well tolerated except for transient elevations in levels of transaminases in 3 dogs, followed by, in one dog, ascites. All dogs had prompt engraftment and achieved stable mixed hematopoietic chimerism, with donor contributions ranging from 30% to 70% after more than 27 weeks of follow-up. These results will form the basis for additional studies in animals and later the design of clinical trials using213Bi as a nonmyeloablative conditioning regimen with minimal toxicity.

Description: Abstract 3450 Objective: Allogeneic hematopoietic cell transplantation (HCT) following a variety of reduced-intensity conditioning regimens has been reported to produce encouraging results in patients with AML. In these studies disease relapse was the main cause of treatment failure, with 2–4 year relapse rates ranging between 32–61% resulting in overall survivals of 28–45% at 2–4 years. Our goal here was to examine whether pre-HCT variables could identify patients at high risk for relapse following nonmyeloablative allogeneic HCT, who thus would become candidates for additional interventions to reduce the risk of AML relapse. Methods: The data were derived from 274 consecutive Seattle Consortium patients (median age: 60 years) with de novo or secondary AML who underwent allogeneic HCT from related or unrelated donors after conditioning with 2 Gy total body irradiation (TBI) with or without fludarabine (90 mg/m2) as recently reported (Gyurkocza et al., JCO 2010 Jun 10;28(17):2859–2867). Cox regression was used to perform multivariate analysis of risk factors for relapse in a subset of 231 patients in morphologic leukemia-free state (defined as less than 5% marrow blasts) with (n=134) or without (n=97) peripheral blood cell count recovery (defined as platelets 〉 100,000/ml and neutrophils 〉 1,000/ml) at the time of HCT. In this multivariate model, AML beyond 1st complete remission (CR1), unfavorable cytogenetics (according to SWOG criteria), incomplete peripheral blood cell count recovery before HCT, and shorter time between diagnosis and HCT were associated with statistically significantly higher risk of relapse (Table 1). From this multivariate model we developed a relapse risk score that summarizes the contribution of multiple risk factors by assigning weights based on the relative magnitude of the log hazard ratios associated with the principal risk factors. From a starting score of 0, points were added or subtracted based on the following factors: 2nd CR: +1 point; 3rd or later CR: +2 points; unfavorable cytogenetics: +1 point; absence of pre-HCT peripheral blood cell count recovery: +0.5 points; time from diagnosis to HCT 〉 18 months, -2 points (Table 2). Patients were then stratified into 2 relapse risk groups according to whether the total risk score was ≤0 (low-risk) or 〉0 (high-risk). Results: Stratification of patients according to the proposed Relapse Risk Score resulted in a clear separation of the two risk groups, with 5-year relapse rates of 50% and 17% in the high- and low-risk groups, respectively (Figure 1A). Five-year overall survival rates were 26% and 50% in the high- and low-risk groups, respectively (Figure 1B). Conclusion: Our Relapse Risk Score may be a useful tool to identify patients with AML at high risk for relapse, who could potentially benefit from additional interventions to reduce the risk of relapse following allogeneic HCT. We are currently attempting validation in an independent cohort of patients with AML to make this Risk Score more generalizable. Relapse/Progression (A) and Overall Survival (B) rates stratified by Relapse Risk Score. Disclosures: Off Label Use: Off label usage of fludarabine, cyclosporine, tacrolimus and mycophenolate mofetil is discussed.