Abstract: Interleukin-7 (IL-7) is an essential cytokine for T-cell homeostatic proliferation and maintenance. Clinical studies have shown the potential benefits of IL-7 therapy in various diseases associated with lymphopenia. However, the kinetics of the T-cell response to a single administration of IL-7 in humans have not been fully elucidated. Here, we investigated the effects of Fc-fused long-acting recombinant human IL-7 (hIL-7-hyFc, efineptakin alfa) on lymphocytes in healthy adults after a single subcutaneous or intramuscular administration. Administration of hIL-7-hyFc increased the CD8+ and CD4+ T-cell numbers up to 2.5-fold, with corresponding upregulation of Ki-67 and Bcl-2 expression, peaking at day 3 or 7. Regulatory T cells (Tregs) did not expand. Among CD8+ and CD4+ T cells, all T-cell subsets (TN, TEM, TCM, TEMRA, and TSCM) increased for 56 days. The T-cell receptor repertoire diversity of naive CD8+ and CD4+ T cells was increased by hIL-7-hyFc, whereas the memory T-cell subsets did not differ between day 56 and day 0. Transcriptomic analysis revealed that hIL-7-hyFc induced robust T-cell expansion without changes in gene expression profiles associated with T-cell functions or genes related to T-cell exhaustion, senescence, and anergy. The effector functions of antigen-specific CD8+ T cells were preserved after hIL-7-hyFc administration. Our results suggest that hIL-7-hyFc administration induced a sustained increase in the numbers of CD8+ and CD4+ T cells, but not Tregs, without qualitative changes. These results support the potential of hIL-7-hyFc as a treatment for patients with compromised T-cell immunity or as a vaccine adjuvant.

Abstract: Lee and colleagues investigated the role of the intestinal microbiota in steady-state hematopoieisis, demonstrating that microbiota-derived DNA circulates to the bone marrow, where uptake by mononuclear cells leads to inflammatory cytokine production favoring myeloid-cell maturation of hematopoietic progenitors.

Abstract: Background: CT-P10 is a biosimilar candidate to the reference rituximab product, EU-approved MabThera® and US-licensed Rituxan®. CT-P10 has an identical amino acid sequence and highly similar physicochemical and in vitro functional properties to its reference drug. In patients with rheumatoid arthritis, CT-P10 has demonstrated compelling similarity in pharmacokinetics (PK), pharmacodynamics (PD), efficacy, safety and immunogenicity (Yoo DH, et al. Arthritis Rheum. 2013;65(10):1736). Objective: The goal of this study was to demonstrate PK similarity of CT-P10 to rituximab, each administered in combination with cyclophosphamide, vincristine, and prednisone (CVP) in patients with newly diagnosed Advanced Follicular Lymphoma (AFL) (NCT02162771) (Kim WS et al. Blood. 2015;126(23): 5111). The results of PK, PD, safety and immunogenicity up to Core Cycle 4 (12 weeks) are presented here from this ongoing study. Methods: Patients with AFL were randomized 1:1 to receive infusion (375mg/m2) of either CT-P10 or rituximab, at a 3-week interval, in combination with CVP. PK analysis was conducted in terms of AUCtau and Cmax at steady state, Core Cycle 4, as primary PK endpoints. PK parameter values considered as outliers determined by robust regression outlier testing were excluded from the pharmacokinetic primary analysis. Results: In total, 121 patients were randomly assigned to receive either CT-P10 (n=59) or rituximab (n=62) in combination with CVP. Result of CT-P10 PK at Core Cycle 4 was similar to that of rituximab. The ratios (90% CI) of geometric least square means (CT-P10 to rituximab treatment group) were 102.3% (94.1%-111.2%) for AUCtau and 100.7% (93.8%-108.0%) for CmaxSS at Core Cycle 4. The 90% CIs of ratio of geometric LS means for both AUCtau and CmaxSS were entirely contained within the equivalence margin of 80% to 125% (Table 1 and Figure 1). Mean serum concentrations of the study drug were highly similar for the 2 treatment groups at each time point (Core Cycle 1 to 4). The B-cell kinetics was similar up to Core Cycle 4 in the 2 treatment groups. Median number of B-cells decreased to below the lower limit of quantification (LLoQ) (20 cells/μL) 1 hour after the end of infusion at Core Cycle 1 and remained below the LLoQ at each subsequent cycle, up to and including Core Cycle 4. The proportion of patients with a positive anti-drug antibody up to Core Cycle 4 at post-treatment visits was similar between the 2 treatment groups; 3/59 (5.1%) patients and 2/62 (3.2%) patients in the CT-P10 and rituximab groups, respectively. In addition, CT-P10 was well tolerated and the safety profile of CT-P10 up to Core Cycle 4 was similar to that of rituximab. The number of patients who experienced at least 1 treatment emergent adverse event (TEAE) was 43 (72.9%) patients and 41 (66.1%) patients in CT-P10 and rituximab treatment groups, respectively. The proportion of patients who experienced at least 1 treatment emergent serious adverse event considered by the investigator to be related to the study treatment was similar between the 2 treatment groups; 2/59 (3.4%) patients and 2/62 (3.2%) patients in the CT-P10 and rituximab groups, respectively. The frequencies of adverse events special interest (AESI) were similar between the 2 treatment groups (Table 2). Conclusion: This study demonstrated similarity of PK in terms of AUCtau and CmaxSS between CT-P10 and rituximab in AFL patients. The B-cell kinetics and immunogenicity were comparable between the two treatment groups. CT-P10 was well tolerated with a safety profile comparable to that of rituximab up to and including Core Cycle 4 (12 weeks). Table 1 Statistical Analysis of Rituximab Pharmacokinetic Primary Endpoints for Core Cycle 4 at Steady State: Pharmacokinetic Population Table 1. Statistical Analysis of Rituximab Pharmacokinetic Primary Endpoints for Core Cycle 4 at Steady State: Pharmacokinetic Population Figure 1 Mean (±SD) Serum Concentration of Rituximab Versus Time for Cycle 4 at Steady State (Linear Scale): Pharmacokinetic Population Figure 1. Mean (±SD) Serum Concentration of Rituximab Versus Time for Cycle 4 at Steady State (Linear Scale): Pharmacokinetic Population Table 2 The Incidence Rates of Adverse Events Special Interest: Safety Population Table 2. The Incidence Rates of Adverse Events Special Interest: Safety Population Disclosures Coiffier: Celltrion, Inc.: Consultancy, Honoraria. Sancho:Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celltrion, Inc: Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Jurczak:Celltrion, Inc: Research Funding; Gilead Sciences: Research Funding; Acerta: Research Funding; Bayer: Research Funding; Janssen: Research Funding. Kim:Celltrion, Inc.: Research Funding. Nagarkar:Celltrion, Inc.: Research Funding. Zhavrid:Celltrion, Inc.: Research Funding. Hernandez Rivas:Celltrion, Inc.: Research Funding. Prokharau:Celltrion, Inc.: Research Funding. Zodelava:Celltrion, Inc.: Research Funding. Osmanov:Celltrion, Inc.: Research Funding. Ogura:SymBio Pharmaceuticals: Consultancy, Honoraria; Celltrion, Inc.: Consultancy, Honoraria. Buske:Celltrion, Inc.: Consultancy, Honoraria. Kwak:Celltrion, Inc.: Consultancy. Kim:Celltrion, Inc.: Consultancy, Honoraria.

Abstract: We previously reported the interim analysis on the clinical outcome of nilotinib (Tasigna®, Novartis Pharma, Basel, Switzerland), when combined with multi-agent chemotherapy for newly diagnosed Philadelphia-positive acute lymphoblastic leukemia (Ph+ALL) in adults. Herein, we reported the final results of the multicenter prospective phase2 trial of Adult Acute Lymphoblastic Leukemia Working Party, the Korean Society of Hematology. Newly diagnosed Ph+ALL patients aged 18 years old or more were eligible when they had adequate organ function. Diagnosis of Ph+ALL was performed via confirmation of the presence of Ph chromosome by conventional GTL-band technique, and/or positive molecular analysis with nested RT PCR for detection of BCR-ABL fusion transcripts. Written informed consent was obtained from all subjects. All patients received induction treatment consisting of vincristine, daunorubicin, oral or parenteral prednisolone, and nilotinib. After achieving complete remission (CR), subjects received either 5 courses of consolidation followed by 2-year maintenance with nilotinib, or allogeneic hematopoietic cell transplantation (alloHCT) depending on the donor availability, his/her tolerability, and patient’s wish. Nilotinib was administered twice a day with a single dose of 400mg (800mg per day) from day8 of induction until the initiation of conditioning for alloHCT or the end of maintenance therapy. Minimal residual disease (MRD) monitoring was performed at the central lab with quantitative RT-PCR assays for peripheral blood BCR-ABL RNA using LightCycler® Technology in serial; at the time of diagnosis, at hematologic CR(HCR), and every 3 months thereafter. BCR-ABL quantification was expressed relative to the amount of glucose-6-phosphate dehydrogenase (G6PDH) mRNA. The molecular response was defined as complete (MCR, MRD-negative) if the BCR-ABL/G6PDH ratio was less than 1x10-6. Toxicity was graded according to National Cancer Institute Common Toxicity Criteria (version 2.0). Subjects had been followed up for 2 years after alloHCT or during maintenance therapy. Data were frozen up in June, 2013. A total of 91 subjects (male: female = 45: 46) were enrolled onto the study between January 2009 and May 2012. The median age was 47 (range 18-71) years old. Type of BCR breakpoint was minor (e1a2) in 71% of patients. The median BCR-ABL/G6PDH ratio was 6.09 (bone marrow) and 3.28 (peripheral blood) at diagnosis. During induction, all subjects required blood product transfusion, and incidence of nonhematologic adverse events (AE) over grade 3 was 17% (jaundice), 18% (ALT elevation), 13% (lipase elevation), and 2% (pancreatitis). Neither QTc prolongation over 500ms nor significant arrhythmia happened among any subject and any cycle. HCR rate was 90% and median time to HCR was 27 days (range, 13-72); most of failure was due to death in aplasia (n=8). MCR rate at HCR was 55%, Cumulative MCR rate was 84%, and median time to MCR was 1.1 months (range, 0.6-15.8). Most common cause of dropout from study was treatment-related death (n=22; during induction/consolidation vs. after alloHCT = 12 vs. 10), and HREL (n=15). Nilotinib was interrupted 75 times among 64 subjects, reduced 14 times among 12 subjects, and discontinued permanently due to hematologic relapse (HREL, n=14), AE (n=6, over gr3:3), and other cause (n=2). Fifty nine patients underwent alloHCT, 34 with myeloablative and 25 with reduced-intensity conditioning. Incidences of acute graft-versus-host disease (GVHD) and chronic GVHD were 41% and 29%, respectively. With a median follow-up of 20.7 months of surviving subjects, estimated hematologic relapse-free survival (RFS), and overall survival (OS) rate at 2 years were 74% and 70%, respectively. Among subject achieving MCR, 2-year molecular RFS rate was 56%. When events were defined as ‘dropout due to AE, isolated molecular / extramedullary relapse, HREL, and death from any cause’, median event-free survival was 12.5 months. In this prospective study, nilotinib was shown to be effective for adult Ph+ALL, and concurrent administration of nilotinib with cytotoxic drug was well-tolerable, although death in aplasia during induction was the most common cause of failure of achieving HCR. In terms of MRD, potential of nilotinib to achieve and maintain MRD negativity were satisfactory (Clinicaltrials.gov NCT00844298). Disclosures: Off Label Use: Nilotinib for Ph+ALL-sientific and academic purpose.

Abstract: Nilotinib plus multiagent chemotherapy was feasible and showed a comparable outcome to previous results with imatinib for Ph-pos ALL. The achievement of deep MR with nilotinib at postremission correlated well with the clinical outcomes for Ph-pos ALL.

Abstract: Abstract 2072 Poster Board II-49 Backgrounds Currently, there are many efforts to design risk-adapted strategies in newly diagnosed acute promyelocytic leukemia (APL) by modulating treatment intensity and those seem to be an efficient approach to minimize treatment-related morbidity and mortality (TRM) while maintain the potential in cure for each relapse-risk group. We had postulated that maintaining of Ara-C during induction therapy might have acceptable toxicities yet obtaining good CR in newly diagnosed APL, and idarubicin alone during consolidation periods might have excellent LFS and OS with low relapse rate. Patients and Methods Eighty six patients with newly diagnosed APL were enrolled in the “multicenter AML-2000 trial” after informed consents were obtained during the period of January 2000 to July 2007. For remission induction therapy, patients received oral ATRA (45mg/m2/d, maintained until CR) combined with idarubicin (12mg/m2/d, D1-D3) plus Ara-C (100mg/m2/d, D1-D7). After CR achievement, patients received 3 monthly consolidation courses consisting of idarubicin (12mg/m2/d, D1-D3) alone and maintenance therapy with ATRA (45mg/m2/d, D1-D15, every 2 month) alone had continued for 2 years. Total patients were divided into low-risk, intermediate-risk and high-risk groups according to a predictive model for relapse risk (Sanz score) based on pretreatment WBC and platelet count and the treatment outcomes were compared in the different risk groups. Results The median age of our cohort was 40 years old (range; 6-80) and median follow-up was 27 months (range; 1-90). The distribution of patients in the 3 risk groups was as follows ; 28 (32.6%) patients in low-risk, 40 (46.5%) in intermediate-risk and 18 (20.9%) in high-risk. Overall, CR was achieved in 78 (90.7%) of 86 patients. The CR rate according risk groups was 96.4% in low-risk, 87.5% in intermediate-risk, and 88.9% in high-risk group and there was no significant statistical difference among the different risk groups. During induction therapy, 48 (55.8%) patients experienced grade 3-4 treatment-related toxicity (TRT), mostly fever and infection (38.8% of all patients) and 6 (7.0%) patients died of treatment-related complications. During 3 consolidation courses, 25 (29.1%) of 78 patients experienced grade 3-4 TRT in 1st course, 27 (36.0%) of 75 patients in 2nd course, and 14 (28.0%) of 50 patients in 3rd course. Overall, 3 (3.5%) patients died of treatment-related complications in CR. The incidence of TRT and treatment-related mortality (TRM) during induction or consolidation therapy showed no significant statistical difference among the different risk groups. The relapse occurred in 6 (7.0%) patients; 2 cases in intermediate-risk and 4 cases in high-risk. However, none had relapsed in low risk group, 5 patients of relapsed patients relapsed during consolidation courses and only one patient, however, relapsed during maintenance therapy. The overall survival (OS) and leukemia-free survival (LFS) rate at 7 years in all of patients was 76.7% and 83.5%, respectively. The OS rate at 7 years was 92.9% in low-risk, 78.6% in intermediate-risk and 53.6% in high-risk group (P:0.04) and the LFS rate at 7 years was 96.4%, 83.4% and 62.2% respectively, showing the significant difference between 3 different risk groups (P:0.046). Conclusions This study indicates that our protocol composed of induction therapy with “3+7” chemotherapy plus ATRA followed by consolidations with three courses of idarubicin alone and maintenance therapy with ATRA alone yields a high CR rate and low relapse rate but minimal acceptable toxicities. Despite of adding Ara-C during induction therapy, we did not find much significant toxicities but having good CR rates, and despite of not adding any additional low/intermediate dose chemotherapies(ie, 6MP), we were able to observe significantly high relapse rate in low and intermediate risk group with excellent LFS and OS. Meanwhile, in high-risk group, the relapse rate was significantly higher than other risk groups and most of the relapses occurred in the middle of consolidation courses. This data suggests that our consolidation therapy composed of anthracycline alone may be not enough to minimize risk of relapse in high-risk group in contrast with the low and intermediate-risk groups. More intensive consolidation therapy combined with other effective, but get tolerable chemotherapies or hematopoietic stem cell transplantation in first CR or the combination of arsenic trioxide or others in front-line therapy should be considered in the patients with high-risk of relapse. Disclosures: No relevant conflicts of interest to declare.

Abstract: Cytogenetics is still being considered the most powerful single prognostic factor, which is useful to determine the types of post-remission therapy in AML, though various molecular markers are available for predicting the prognosis of AML patients. Most phase III studies have failed to demonstrate a clear advantage of allografting over chemotherapy in terms of overall survival because of significant risk of transplant-related mortality. Optimal post-remission therapies in terms of frequencies (number of treatment) or intensities are not decided yet. In this study, since 2000, we investigated that outcomes of post-remission therapies(high-dose cytarabine (HDAC) vs autologous stem cell transplantation (AutoSCT) vs allogeneic stem cell transplantation from sibling or unrelated donors (AlloSCT)) based on cytogenetic risk (GPG, Good prognosis group; IPG, Intermediate prognosis group; PPG, Poor prognosis group by MRC definition) on the AML patients who achieved complete remission after induction chemotherapy. The aims of this prospective intention to treat analysis was to compare the CR, recovery kinetics, DFS and OS in the different prognostic groups. Three plus seven (idarubicin 12mg/m2, D1–D3; cytarabine 100mg/m2, D1–D7) were given to de novo AML, secondary AML and therapy-related AML. Then, HDAC or AutoSCT was given after intermediate dose (8gm/m2) of cytarabine to the patients with GPG. Three times of post-remission therapy including HDAC, or AutoSCT followed by two times of post-remission therapy were given to IPG or PPG. If HLA-identical sibling was available, then AlloSCT underwent after 1st post-remission therapy. Since January, 2000, 506 patients(18 centers) were enrolled up to December, 2007. Among them, 92.3% was de novo AML, and GPG, IPG and PPG were, 23.1%, 62.1% and 14.8% respectively. Over all complete remission rate after 1st induction was 79.0% and CR rate in GPG, IPG, PPG were 92.0%, 81.0% and 43.9% respectively(P & lt;0.001) in 476 patients who were eligible to this study. In Good Prognosis Group (GPG), survivals were not different between different treatment groups (5 year LFS: HDAC 34.2%, AutoSCT 63.5%, AlloSCT 54.8%, p=0.270; 5 year OS: HDAC 54.5%, AutoSCT 62.5%, AlloSCT 53.3%, p=0.676). However, beneficial effect of AlloSCT in post-remission therapy therapy was observed by multivariate analysis in terms of LFS compared to HDAC (HR of relapse for HDAC 3.198 compared to AlloSCT, p=0.045). Outcomes of HDAC group were inferior in GPG in terms of OS and LFS compared to other studies. This results may be due to low cumulative dose of Ara C, because patients of HDAC group in GPG treated just 1 cycle of IDAC before HDAC therapy. In addition, in our cohort, majority (80%) of GPG have t(8;21), which are known as having inferior survival results, compared to inv(16) group. In Intermediate Prognosis Group (IPG), survivals were not different among different types of treatment (5 year LFS: HDAC 31.1%, AutoSCT 42.4%, AlloSCT 55.0%, p=0.131; 5 year OS: HDAC 39.2%, AutoSCT 42.5%, AlloSCT 46.5%, p=0.491). AlloSCT group showed a trend of being superior to other therapeutic modalities in terms of LFS (p=0.07). AutoSCT group showed a trend of being superior to other therapeutic modalities in OS by multivariate analysis (HR of death for AutoSCT 0.539 compared to AlloSCT, p=0.085). In Poor Prognosis Group (PPG), though data showed slightly beneficial effect of AlloSCT in AML therapy, however, there were no significant statistical differences on OS/LFS in 3 types of consolidation therapy modalities (4 year LFS: HDAC 48.3%, AutoSCT 0%, AlloSCT 39.1%, p=0.379; 4 year OS: HDAC 21.4%, AutoSCT 33.3%, AlloSCT 56.1%, p=0.638). Based on this trial, Allo- or Auto-SCT over HDAC may have beneficial effects in some subgroup with high risk and young age, among the patients with good and intermediate cytogenetic risk. In GPG, “sufficient cumulative dose” of Ara C seems to be necessary to have a good outcome. However, GPG seems to be heterogenous group in terms of biology having poor prognosis when one has additional CG abnormalities on top of t(8;21) or inv(16), which ones need to investigate further. While finding more effective anti-AML molecules/monoclonal Ab’s are necessary, good therapeutic rationales in terms of choosing AlloSCT vs AutoSCT vs HDAC should be established. Same time, identifying for better cellular and molecular prognostic factors over cytogenetics are still relevant for designing “effective therapies, but minimal toxicities”.

Abstract: Abstract 1691 Dasatinib and nilotinib have been founded to be effective and well-tolerated in patients who develop resistance or intolerance to imatinib. Not enough data are currently available to recommend one over the other as the preferred second-line therapy based on efficacy data. Therefore we planned a multicenter retrospective study to analyze the efficacy and safety of dasatinib and nilotinib in patients with imatinib-resistant or –intolerant chronic myeloid leukemia in chronic phase. In this Korean multicenter study, 126 patients imatinib-resistant or –intolerant chronic myeloid leukemia in chronic phase were treated with dasatinib (n=76) or nilotinib (n=50) The purpose of this study was to compare rates of cytogenetic and molecular response rate, event-free survival (EFS), progression-free survival (PFS) and overall survival (OS), and toxicities of nilotinib and dasatinib treatment of imatinib-resistant or –intolerant chronic myeloid leukemia in chronic phase. PFS was defined as the time from the start of treatment to the earliest date of any of following event: loss of complete hematologic response (CHR), loss of major cytogenetic response (MCyR), progression to accelerated phase (AP) or blastic phase (BP), discontinuation due to treatment failure as assessed by the clinician, and death from any cause on therapy. Event was defined by any one of the following: loss of CHR, loss of MCyR, progression to AP or BP, discontinuation due to treatment failure as assessed by the clinician, treatment discontinuation due to toxicity, and death from any cause on therapy. For dasatinib and nilotinib group, median ages (51 years old vs. 53), median durations of CML (23.7 months vs. 19.8 ) before receiving dasatinib or nilotinib and duration of prior imatinib treatment (21.7 months vs 17.7) were comparable. Nilotinib group had a higher proportion of intermediate and high sokal scores at the time of diagnosis than dasatinib group (41.5 vs 29.3% (high), 41.5% vs 32.5%(intermediate), 17.1% vs 37.9(low), p= 0.04). After median follow-up durations of 20.2 months of dasatinib group and 25.3 months of nilotinib group, the rates of major molecular response were 50.0% for dasatinib group and 59.6% for nilotinib group (p=NS) and the rates of MCyR (complete and partial cytogenetic response) were 78.4% for dasatinib group and 74.5% for nilotinib group (p=NS). The estimated EFS at 24 months was 67% and 48% in dasatinib and nilotinib group, respectively. (p 〈 0.05). The estimated PFS at 24 months was 85% and 56% in dasatinib and nilotinib group, respectively. (p 〈 0.05) Overall survival rates were comparable in both treatment groups (24-months OS; dasatinib 91%, nilotinib 94%; p=0.65). Both were generally well tolerated. Hematologic toxicities were more frequent among patients receiving dasatinib. 10 patients (13%) had pleural effusion in dasatinib; 9 events were grade 1 or 2. Elevated liver enzyme were more frequent among patients receiving dasatinib. In conclusion, In this study population, nilotinib and dasatinib showed similar cytogenetic and molecular response rates and survival. Toxicity profiles of two drugs were different and both drugs showed tolerable toxicities. In terms of event-free survival and progression-free survival, dasatinib was superior to nilotinib, but caution is warranted in interpretation because baseline characteristics including hematologic and cytogenetic response at the time of start with dasatinib and nilotinib and sokal scores at the time of diagnosis were different. Disclosures: No relevant conflicts of interest to declare.

Abstract: Abstract 4513 Introduction Severe chronic neutropenia (SCN) is a rare hematologic disorder defined by an absolute neutrophil count less than 0.5×109/L for several months or years. They usually suffer from recurrent infections. Principal subtypes of SCN are congenital, cyclic, idiopathic and primary autoimmune neutropenia (AIN). Patients and Methods Medical records collected from a national survey were retrospectively analyzed on newly diagnosed SCN patients in Korea between January, 1999 and December, 2008 in respect to the diagnosis, clinical manifestations, treatments and prognosis of the patients. Results There were 64 patients (Male, 20; Female 44) reported from 16 hospitals: congenital, 19; cyclic, 16; idiopathic, 25; and immune in origin, 4. The main clinical manifestation was various types of bacterial infections. Two cases (1 congenital, 1 cyclic) were diagnosed by family histories. The median age at diagnosis was 12 months (11 days-158 months). A bone marrow examination was done in 45 patients (70.3 %) at the median age of 26 months (1 day-158 months), with the interval between the initial CBC and BM study being 7.3 months (9 days-138 months). The ELA2 mutation, done in 6 patients, was not detected. Only one patient with congenital SCN evolved to AML at 54 months after diagnosis, who is under chemotherapy. Most patients were treated with G-CSF (5-10 μg/kg/day) during infection episodes. The median follow up duration was 23 months (11 days – 176 months). Two patients of congenital SCN died of infection (pneumonia, meningitis) and 8 patients were lost to follow up, and the remaining are alive. Conclusions SCN is a rare hematologic disease with inherent vulnerability to infections, thus early detection with proper management should be important for survival of SCN patients. We propose a nation-wide, prospective study to delineate the prevalence, molecular diagnosis, natural history, the optimal use of G-CSF, and prognostic factors in Korean patients with SCN. Disclosures: No relevant conflicts of interest to declare.

Abstract: Abstract 1179 Poster Board I-201 Introduction: Intravenous (iv) busulfan can yield a more consistent dosing and pharmacokinetic profile than oral formulation, but there is still inter-patient variability in systemic exposure with iv busulfan. GST gene polymorphisms may explain the variability because busulfan is metabolized in liver through conjugation with GST family. Thus, we investigated the influence of polymorphisms of 3 GST genes, GSTA1, GSTM1, and GSTT1 on the clearance of iv busulfan in adult patients undergoing hematopoietic cell transplantation (HCT). Patients and Methods: We analyzed the PK data from 60 patients, who were included in a randomized trial of 4-times-daily (0.8 mg/kg q 6 h) versus once-daily (3.2 mg/kg once a day) iv busulfan in a conditioning therapy for HCT (Biol Blood Marrow Transplant 2007;13:1095). Limited sampling strategy was used for PK studies, which were performed for the first busulfan dosing using a validated LC with tandem MS. Busulfan plasma clearance (CL) was derived from 1 compartment model. GSTA1 was genotyped by PCR followed by RFLP, and GSTM1- and GSTT1-null genotypes were identified by PCR procedure. Results: GSTA1 genotyping revealed GSTA1*A/*A in 46 patients (77%) and GSTA1*A/*B in 14 (23%). GSTM1-null genotype was found in 25 patients (43%) and GSTT1-null genotype in 34 (59%). Each polymorphism of GST genes was not associated with sex or age of the patients. In univariate analysis, clearance (CL, mL/min/kg) of iv busulfan was significantly associated with GSTA1 polymorphisms (*A/*A vs. *A/*B, 2.036 ± 0.340 vs. 1.789 ± 0.295, P=0.017), but not with GSTM1 (present vs. null, 2.012 ± 0.390 vs. 1.915 ± 0.279, P=0.274) or GSTT1 (present vs. null, 2.047 ± 0.286 vs. 1.917 ± 0.380, P=0.064) polymorphisms. Actual body weight in kilogram was also significantly associated with CL of iv busulfan (Pearson's correlation coefficient, -0.420; P=0.001). Linear regression analysis demonstrated that GSTA1 gene polymorphism (regression coefficient, -0.255; 95% CI, -0.440 to -0.071; P=0.008) and actual body weight (regression coefficient, -0.012; 95% CI, -0.091 to -0.005; P=0.001) were independently significant factors for CL of iv busulfan. Null genotype of GSTM1 and/or GSTT1, although each polymorphism was not a significant factor, showed decreased clearance of iv busulfan both in patients with GSTA1 *A/*A and those with GSTA1 *A/*B (Figure 1). The CL was similar between in patients with GSTA1 *A/*A with null genotype of both GSTM1 and GSTT1 and in those with GSTA1 *A/*B with present genotype of both GSTM1 and GSTT1. Conclusion: GSTA1 gene polymorphism was an important determining factor for the clearance of iv busulfan. Polymorphisms of GSTM1 and GSTT1 genes also appeared to have a supplementary role in the pharmacokinetics of iv busulfan. Disclosures: No relevant conflicts of interest to declare.