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Background While racial disparities in the clinical outcomes of hematopoietic stem cell transplant (HSCT) patients have been explored, racial disparities in quality of life (QoL) during the readjustment phase after transplant has yet to be investigated in pediatric patients. The objective of this study was to examine the role of patient race in QoL at least two years after pediatric HSCT. Procedure We conducted a retrospective chart review of patients under 21 years of age at diagnosis that received an allogeneic transplant at our institution between January 2007 and December 2017. Patient QoL was assessed using the PedsQL TM 4.0 at least two years post-transplant. Patient demographic, treatment, and transplant outcome data were obtained for subsequent analysis, where patient race was categorized as either Black, White, Hispanic, or Native American. Results Data were collected on 86 pediatric patients who underwent HSCT. Forty patients (46.5%) were non-Hispanic White, 29 (33.7%) Hispanic, 10 (11.6%) Black, and 7 (8.1%) Native American. Where preliminary analyses indicated a difference in QoL by patient race, there were no significant differences in physical, emotional, social, and school functioning by patient race after adjusting for transplant characteristics (age at transplant, sex, diagnosis, donor type and conditioning regimen) and determinants of socioeconomic status (insurance type, estimated household income). Conclusions Pediatric patients had comparable QoL, regardless of race, at a median of three years after HSCT in our study cohort.

Vitamin D deficiency remains common among pediatric patients undergoing hematopoietic stem cell transplant (HSCT) despite both aggressive and standard of care strategies. This study examined the safety and efficacy of single high-dose oral vitamin D therapy (Stoss therapy) for treatment of vitamin D deficiency in HSCT recipients. Patients ages 1–21 years presenting for HSCT were randomized to receive either Stoss regimen plus weekly/daily supplementation or standard of care, per US Endocrine Society guidelines. Among the total 48 subjects, 22 (46%) were randomized to Stoss and 26 (54%) to control arms. Baseline 25-hydroxyvitamin D (25-OHD) levels were insufficient/deficient in total of 34 (71%) patients, without difference between treatment groups. The Stoss regimen was well tolerated and no toxicity was observed. At Day +30, mean 25-OHD levels were significantly higher (P = 0.04) with Stoss (42.3 ± 12 μg/l) compared to controls (35.6 ± 14.3 μg/l), and a higher proportion of Stoss patients had adequate vitamin D levels than controls (85% vs 65%). Stoss therapy is a safe and efficacious treatment option for vitamin D deficiency in children undergoing HSCT and may achieve sufficient levels more rapidly than standard of care. This trial was registered at www.clinicaltrials.gov as NCT03176849.

Reduced-intensity/reduced-toxicity conditioning and allogeneic T-cell replete hematopoietic stem cell transplantation are curative in patients with hemophagocytic lymphohistiocytosis (HLH). Unstable donor chimerism (DC) and relapses are clinical challenges . We examined the effect of a reduced-intensity conditioning regimen based on targeted busulfan to enhance myeloid DC in HLH. The European Society for Bone and Marrow Transplantation–approved reduced-intensity conditioning protocol comprised targeted submyeloablative IV busulfan, IV fludarabine, and serotherapy comprising IV alemtuzumab (0.5-0.8 mg/kg) for unrelated-donor and IV rabbit anti–T-cell globulin for related-donor transplants. We assessed toxicity, engraftment, graft-versus-host disease (GHVD), DC in blood cell subtypes, and overall survival/event-free survival. Twenty-five patients from 7 centers were treated (median age, 0.68 year). The median total dose and cumulative area under the curve of busulfan was 13.1 mg/kg (6.4-26.4) and 63.1 mg/L × h (48-77), respectively. Bone marrow, peripheral blood stem cell, or cord blood transplants from HLA-matched related (n = 7) or unrelated (n = 18) donors were administered. Donor cells engrafted in all patients (median: neutrophils d+20/platelets d+28). At last follow-up (median, 36 months; range, 8-111 months), the median DC of CD15(+) neutrophils, CD3(+) T cells, and CD16(+)56(+) natural killer cells was 99.5% (10-100), 97% (30-100), and 97.5% (30-100), respectively. Eight patients (32%) developed sinusoidal obstruction syndrome, resolving after defibrotide treatment. The 3-year overall survival and event-free survival rates were both 100%. None of the patients developed acute grade III to IV GHVD. Limited chronic GVHD was encountered in 4%. This regimen achieves excellent results with stable DC in patients with HLH.

This prospective observational study evaluated the impact of adequate vitamin D levels by day +30 after vitamin D supplementation on early post-HSCT outcomes, including acute graft-versus-host disease (aGVHD), immune recovery, infection rates, and overall survival. Forty children (age 2 to 16 years) undergoing hematopoietic stem cell transplantation (HSCT) were given vitamin D supplementation, were followed prospectively from day +30 post-transplantation, and had day +30 vitamin D levels measured. Thirty patients with normal vitamin D levels (≥30 ng/mL) were compared with 10 patients with low day +30 vitamin D levels (30 ng/mL). The times to neutrophil and platelet engraftment was similar in both day +30 vitamin D groups (P = .13 and .32, respectively). At day +100, slower immune recovery in CD4

Alopecia is a common sequela in children undergoing chemotherapy, radiation, and hematopoietic stem cell transplantation. In most cases, this is a transient state in which full hair regrowth eventually occurs, but permanent or persistent alopecia, defined as the presence of incomplete hair regrowth more than 6 months after cessation of treatment, is possible and can be psychologically distressing. We sought to characterize the risk factors that can lead to permanent alopecia following the aforementioned treatments in pediatric populations, as well as diagnostic and treatment options that may be considered, as part of a scoping review of the literature. A general algorithm for approaching these patients was developed based on our findings.

Post-hematopoietic stem cell transplantation (HSCT) maintenance therapy using azacitidine and prophylactic donor lymphocyte infusions (DLI) was implemented for high-risk acute myeloid leukemia. Azacitidine was started on day +60 as a 5 day course every 28 days for 6 cycles. DLI was given every 6 weeks for 3 doses starting after day +120. Ten patients were treated on this protocol. With a 90% one-year disease free survival, we report this post-HSCT maintenance therapy is feasible, safe, and well tolerated.

During pediatric hematopoietic stem cell transplant (HSCT), there is significant reduction in physical activity, leading to loss of strength and function, along with decline in quality of life (QoL). This study evaluates the effects of a supervised exercise program on functional ability, mobility, strength, and QoL during and following pediatric HSCT.Patients ages 4-21 years presenting for HSCT were randomized to either an intervention group, who underwent exercise routines three times weekly and once weekly on discharge for 6 weeks supervised by a physical therapist, or the control group, which was treated per standard of care. Forty subjects were recruited for the study, 20 in each arm. Physical therapy and QoL assessments were conducted at three time points: pre-HSCT (baseline), on the day of hospital discharge, and 6 weeks after discharge.Exercise capacity and endurance using Six-Minute Walk test (p = .023) and strength using manual muscle testing (p = .005) were improved in the exercise group, compared to the control group. There was evidence that some QoL outcomes (measured using the Patient Reported Outcomes Measurement Information System) were improved 6 weeks post discharge, with observed decreases in anxiety (p = .0009) and fatigue (p = .037).Supervised exercise program during pediatric HSCT has positive effects on endurance, functional mobility, and muscle strength, and may also result in improvements in some aspects of QoL. This trial was registered at www.gov as NCT04663503.

Eighteen pediatric oncology or bone marrow transplant (BMT) survivors who had liver iron content of >12 mg/g dry weight also underwent Cardiac MR (CMR) to quantify cardiac iron content. Despite high transfused packed red blood cell volumes (mean 383 ml/kg) patients all had cardiac T2* relaxation times in normal ranges (T2* relaxation time mean 35.1 msec ± 7.1 [normal >20 msec]).

Vitamin D deficiency remains common among pediatric patients undergoing hematopoietic stem cell transplant (HSCT) despite both aggressive and standard of care strategies. This study examined the safety and efficacy of single high-dose oral vitamin D therapy (Stoss therapy) for treatment of vitamin D deficiency in HSCT recipients. Patients ages 1-21 years presenting for HSCT were randomized to receive either Stoss regimen plus weekly/daily supplementation or standard of care, per US Endocrine Society guidelines. Among the total 48 subjects, 22 (46%) were randomized to Stoss and 26 (54%) to control arms. Baseline 25-hydroxyvitamin D (25-OHD) levels were insufficient/deficient in total of 34 (71%) patients, without difference between treatment groups. The Stoss regimen was well tolerated and no toxicity was observed. At Day +30, mean 25-OHD levels were significantly higher (P = 0.04) with Stoss (42.3 ± 12 μg/l) compared to controls (35.6 ± 14.3 μg/l), and a higher proportion of Stoss patients had adequate vitamin D levels than controls (85% vs 65%). Stoss therapy is a safe and efficacious treatment option for vitamin D deficiency in children undergoing HSCT and may achieve sufficient levels more rapidly than standard of care. This trial was registered at www.clinicaltrials.gov as NCT03176849.

Background After hematopoietic stem cell transplantation (HSCT) autoimmune hemolytic anemia (AIHA) is a known and fairly common complication. It is often refractory to conventional therapies including corticosteroids, intravenous immunoglobulin, splenectomy, and the more recently described use of monoclonal antibodies. The high morbidity associated with these severe persistent cases elucidates the gaps in alternative therapies available for treatment. Study design and methods We described the successful use of abatacept for severe refractory AIHA after HSCT in three patients. Results Three pediatric patients with refractory AIHA after allogeneic stem cell transplantation were observed to be unresponsive to multitude immunosuppressive therapies, resulting in persistent transfusion dependency. Treatment with abatacept, a fusion protein that inhibits T-cell activation by binding to CD80/CD86 on antigen-presenting cells (APCs), thus blocking the required CD28 interaction between APCs and T cells, resulted in the resolution of hemolysis. Conclusion Abatacept may provide significant clinical benefit in the management of AIHA after HSCT.

We analyzed late cardiovascular outcomes of 661 patients who survived at least 2 years from hematopoietic cell transplantation for childhood hematologic malignancy between 1995 and 2008. Center for International Blood and Marrow Transplant Research data was supplemented with surveys focused on cardiotoxicity and potential risk factors. The median duration of follow-up was 97 months (range 24-230). 4.2% of survivors experienced at least one of the primary outcomes including coronary artery disease (0.2%), cerebrovascular accident (0.6%), cardiomyopathy (3%), and cardiac-related death (0.5%). Patients who received anthracycline chemotherapy (HR 4.67, p = 0.036) or cranial or chest radiation (HR 5.58, p

Introduction The effects of RIC for HSCT on male fertility remain unknown. We investigated spermatogenesis and gonadal hormonal status among adolescent male patients who received RIC HSCT for non-malignant diseases. Patients and methods Patients with non-malignant disease who had undergone a RIC HSCT were recruited and evaluated for spermatogenesis via semen analysis and gonadal hormonal function via serum hormone levels. Those who had received prior chemotherapy or radiation were excluded from the study. We reviewed the charts to record demographic factors, conditioning regimen and complications during and after transplant. Results Five patients were enrolled. The median age at the time of transplant was 15 years (range, 11-19 years), and the median time between bone marrow transplant and semen analysis was 5 years (range, 3-11 years). Median age of patients was 20 years (range, 18-25 years) at the time of the study. Serum FSH and LH levels were elevated in four patients, and inhibin B levels were low for age in three patients. Semen analysis showed two patients had azoospermia, and the remaining three patients showed severe oligozoospermia. Normal morphology and motility were seen in only one patient. Conclusion This case series suggests that RIC transplants may be associated with impaired spermatogenesis and sequential follow-up is necessary given the potential for either permanent impairment or delayed recovery. Further larger studies are needed to confirm these findings.

After hematopoietic stem cell transplantation (HSCT) autoimmune hemolytic anemia (AIHA) is a known and fairly common complication. It is often refractory to conventional therapies including corticosteroids, intravenous immunoglobulin, splenectomy, and the more recently described use of monoclonal antibodies. The high morbidity associated with these severe persistent cases elucidates the gaps in alternative therapies available for treatment.We described the successful use of abatacept for severe refractory AIHA after HSCT in three patients.Three pediatric patients with refractory AIHA after allogeneic stem cell transplantation were observed to be unresponsive to multitude immunosuppressive therapies, resulting in persistent transfusion dependency. Treatment with abatacept, a fusion protein that inhibits T-cell activation by binding to CD80/CD86 on antigen-presenting cells (APCs), thus blocking the required CD28 interaction between APCs and T cells, resulted in the resolution of hemolysis.Abatacept may provide significant clinical benefit in the management of AIHA after HSCT.

We analyzed late cardiovascular outcomes of 661 patients who survived at least 2 years from hematopoietic cell transplantation for childhood hematologic malignancy between 1995 and 2008. Center for International Blood and Marrow Transplant Research data was supplemented with surveys focused on cardiotoxicity and potential risk factors. The median duration of follow-up was 97 months (range 24-230). 4.2% of survivors experienced at least one of the primary outcomes including coronary artery disease (0.2%), cerebrovascular accident (0.6%), cardiomyopathy (3%), and cardiac-related death (0.5%). Patients who received anthracycline chemotherapy (HR 4.67, p = 0.036) or cranial or chest radiation (HR 5.58, p 0.0001; HR 2.18, p = 0.0087) were at increased risk for developing one of the primary outcomes. Dyslipidemia was diagnosed in 18% of survivors. Pre-transplant anthracycline (HR 1.74, p 0.0001) and chest radiation (HR 1.34, p = 0.0371) were risk factors for dyslipidemia. Overweight/obese body mass status was present in 63% of patients at baseline, 65% at 2 years, and 52% at most recent evaluation. Diabetes was diagnosed in 7% of subjects. In conclusion, severe cardiovascular complications were infrequently reported. The incidence of risk factors including obesity and dyslipidemia were significant and will likely increase the risk of cardiovascular disease over time in transplant survivors.

Background Pediatric patients undergoing hematopoietic stem cell transplantation (HSCT) are frequently diagnosed with vitamin D deficiency, which may impact outcomes. Objectives : To estimate the prevalence of vitamin D deficiency and examine its association with short-term survival in pediatric HSCT patients. Methods Patients undergoing HSCT at Phoenix Children's Hospital were retrospectively identified. Routine serum 25-hydroxyvitamin D measurements were described prior to transplant and at 100 days and 1-year post-HSCT. Associations of pre-HSCT vitamin D groups (i.e., normal ≥30 ng/ml, insufficient 20–29 ng/ml, and deficient

Twenty children with leukemia were provided with daily massage therapy by their parents and were compared to a standard treatment control group. Following a month of massage therapy, depressed mood decreased in the children's parents, and the children's white blood cell and neutrophil counts increased.

Background The aim of this study was to evaluate serum 25-hydroxyvitamin D (25OHD) concentrations in survivors of childhood cancer and compare levels by underlying diagnosis and as a function of time. Procedure A retrospective review of 201 pediatric cancer survivors enrolled in a hospital-based cancer survivor registry. Demographic characteristics and 25OHD levels were extracted from the registry. Vitamin D status was determined during routine clinical care and was categorized as normal, insufficient, or deficient. Results 25OHD levels differed significantly across diagnoses (P = 0.017), with the lowest levels found in patients treated for osteosarcoma, retinoblastoma, hepatoblastoma, and myeloid leukemias. Age was inversely correlated with 25OHD levels (P = 0.03). Average 25OHD level at study entry was 29.8 ng/ml (range: 5–79.7), with 14.4% vitamin D deficient, 39.3% insufficient, and 46.3% normal. 25OHD concentrations decreased 11.4% over time (P

Introduction Myelofibrosis (MF), both primary myelofibrosis (PMF) and post essential thrombocytosis/polycythemia vera myelofibrosis (post ET/PV-MF), are chronic myeloproliferative neoplasms that are incurable with standard medical therapy. The only potential curative therapeutic modality remains allogeneic stem cell transplant (ASCT), but the optimum conditioning regimen has yet to be defined and may vary due to pre-ASCT factors such as age, donor source, and comorbidities. In the past, traditional myeloablative (MA) regimens have proven toxic. Reduced intensity conditioning (RIC) regimens have generally become the accepted standard of care for patients with PMF or Post PV/ET MF in need of ASCT, but with the potential for increase in relapse especially for high risk disease. The optimal conditioning regimen has yet to be defined. The regimen of Fludarabine, BCNU, and melphalan (FBM) is considered a reduced toxicity regimen that may afford the benefit of reduction in relapse without increase in toxicity and may “bridge the gap” between MA and RIC especially in older patients. Patients with MF have high inflammatory cytokine levels which may act as mediators of MF symptom burden and may further aggravate mediators of acute GVHD, which is one of the most frequent and severe complications of ASCT. Selection of conditioning regimen and GVHD prophylaxis are keys to MF transplant outcomes. We report here the results of 16 patients who received conditioning with FBM with rATG (FBM-A) with PMF and post PV/ET MF. Methods We conducted a retrospective review of all patients from October 2009 to November 2012 with PMF or post ET/PV-MF who underwent an ASCT with FBM-A. Patient demographic and transplant data were analyzed from a comprehensive database. The use of such data for reporting purpose was approved by the Mayo Clinic Arizona Institutional Review Board. Overall survival was estimated using Kaplan-Meier. Results There were 16 patients analyzed who had PMF or post PV/ET MF or overlap syndromes. The median follow-up of surviving patients is 20.4 months (range 8 months – 46 months). The median age was 60 (range 47-68 yrs) with 56% of patients being ≥ 60yrs. There were 8 males and 8 females. The JAK2 V617F mutation was present in 64% of patients. 86% were high risk according to the DIPSS system with 14% being intermediate-2 risk. None of the patients underwent splenectomy prior to transplant. The median HCT-CI score was 1.5 with 6 (38%) of the patients having an HCT-CMI ≥3. Donors were related in 10 patients (8 matched, 2 mismatched at 1 antigen) and unrelated in 6 (matched, n=3, 1-antigen mismatch, n=3). GVHD prophylaxis consisted of tacrolimus, MMF, and ATG 2.5 – 5.0 mg/kg. The cumulative incidence of acute GVHD grades III-IV was 15.3% at 6 months, and the cumulative incidence of NIH-defined moderate-to-severe chronic GVHD was 25% at 2 years. No patient has relapsed, and no patient has developed graft failure. There have been 4 deaths, 3 from GVHD, and 1 from infection. Among the 3 patients who died from GVHD, all were unrelated donor transplants, and 2 were mismatched unrelated transplants. The 2-year Kaplan-Meier estimate of overall survival (OS) is 72% (95% CI, 45 – 91%). The cumulative incidence of TRM was 12.6% (95% CI 3.9%-34%) at 1 year. Conclusion The reduced-toxicity regimen of FBM-A in PMF, Post ET/PV MF and overlap syndromes appear to provide the benefit of an ablative regimen with the tolerance of a RIC. The 2-year overall survival of 72% in our series is encouraging in an older population of predominantly high-risk patients. Treatment failure was related predominately to GVHD, which continues to be a significant obstacle to better long-term outcomes, especially in unrelated and mismatched patients. Reduced toxicity ASCT conditioning regimens in the setting of MF warrant further investigation. Disclosures: Reeder: Celgene: Research Funding; Novartis: Research Funding; Millenium: 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 ( 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.

Abstract 1954 Introduction: Vitamin D (VD) deficiency can cause osteomalacia, aching bone pain, muscle weakness, fatigue, increase risk of fracture and precipitate or exacerbate osteopenia/osteoporosis. Allogeneic hematopoietic stem cell transplant (HCT) patients are susceptible to low VD level secondary to poor oral intake, decreased exposure to sunlight and treatment related malabsorption. VD level has been correlated to cancer incidence and VD metabolites have been used in the treatment of myeloid leukemia. VD shows promising immunomodulatory properties and correction of low VD level may mitigate manifestations of graft versus host disease (GVHD). Reports have suggested that low VD level appears to increase the incidence of GVHD. We hypothesize that there is a relationship between low VD level and morbidity (specifically incidence of acute GVHD), mortality and relapse incidence after HCT. We therefore studied VD levels pre- and post-HCT to determine if VD level impacts these outcomes. Patients and Methods: 241 patients underwent myeloblative or non-myeloablative HCT between January 1, 2009 and January 31, 2011 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 pre- and post-transplant VD level. Categories for VD level included normal (>30 ng/ml) or abnormal ( Results: 131 (54%) of patients who underwent myeloblative or non-myeloablative HCT had their VD level evaluated either pre-transplant, post-transplant or both. Pre-HCT 57 (56%) patients, 100 days post-HCT 55 (59%) patients and 365 days post-HCT 12 (32%) patients had a low VD level. 51 (38%) of patients had a reduced intensity HCT and 80 patients (62%) had an ablative conditioning regimen. 11 (8.4%) patients had acute GVHD. Comparison of VD level among those with acute GVHD did show a higher incidence of acute GVHD between those with a low or normal VD level (HR=3.14, 95% CI: 0.35–28.33) however this association was not statistically significant (p=0.3079). Survival analysis in those with a low VD level pre-HCT showed there was not a higher risk of mortality (HR=1.14, 95% CI: 0.18–7.38) after adjusting for post- VD level, and this association was not statistically significant (p=0.8921). Survival analysis in those with a low VD level post-HCT did show a higher risk of mortality (HR=2.59, 95% CI: 0.26–25) after adjusting for pre-HCT VD level, however, this association was not statistically significant (p=0.4155). The relationship between VD level and relapse at 1 year post-HCT was not able to be examined because the VD level for patients who relapsed was not available. Conclusions: Half of patients undergoing HCT had VD testing pre- or post- HCT. Just over half of the patients tested had a low VD level pre- and 100 days post-HCT. It is notable that 365 days post HCT the number of patients with low VD level had decreased. This could be attributable to less time in the hospital thus increasing sun exposure, increasing performance status allowing better ingestion and absorption of VD in the gastrointestinal tract or proper supplementation of a low level noted previously. There was no significant difference in incidence of acute GVHD by VD level though there was a trend for increased risk. Pre- and post-HCT VD level did not significantly impact mortality but there was a trend toward higher risk in those with a low VD level post-HCT. This is the first study, to our knowledge, to evaluate the impact of VD level on mortality post-HCT. Our study confirms that many patients have a low VD level pre-and post-HCT. These findings, especially the trend towards a higher mortality risk and higher incidence of acute GVHD in those who have a low VD level post-HCT, warrant further prospective investigation. VD supplementation may be a low cost, easy to implement addition to routine post HCT care that might reduce HCT associated mortality. Disclosures: Reeder: Celgene: Research Funding.