Abstract: Background: Allogeneic stem cell transplantation (SCT) is the most intensive therapeutic modality for children with acute lymphoblastic leukemia (ALL) who are resistant to the conventional chemotherapy. The preparative regimen given to those patients is mostly myeloablative conditioning (MAC) and it is the major cause of short or long term post-transplant complications in spite of the potent anti-leukemic effect. Reduced intensity conditioning (RIC) regimen is commonly applied to elderly patients who are ineligible to MAC regimen but only a small number of children received RIC regimen to date and the precise transplant outcome of SCT with RIC regimen for children with ALL is not well understood. To interpret the clinical implication of RIC regimens in children, we have conducted nationwide retrospective analysis by comparing the transplant outcomes with RIC and MAC regimens in children with ALL. Patients and Methods: From 2000 to 2010, 1334 children with ALL undergone their first allogeneic SCT either by RIC (n=133) or MAC (n=1201) regimen in Japan. Clinical outcomes of SCT was accumulated in the database of The Japan Society for Hematopoietic Cell Transplantation (JSHCT) and the definition of RIC or MAC was based on the internationally recognized criteria in which MAC was defined as 〉 8Gy of fractionated TBI, 〉 5Gy of single TBI, 〉 8mg/kg or 〉 280mg/m2 of busulfan, otherwise categorized as RIC. Disease status at transplant for RIC/MAC was first complete remission (CR, 60/508), 2nd CR (27/347), and more advanced stages (42/329), respectively, (P=0.125). Stem cell source for RIC/MAC was related bone marrow (BM, 33/380), unrelated BM (36/410), related peripheral blood (11/78), and unrelated cord blood (53/333), respectively, (P=0.017). Serological HLA compatibility of RIC/MAC was matched (66/750), or mismatched (62/426), respectively, (P=0.007) Results: In univariate analysis, five year overall survival (OS) of RIC and MAC in each disease status were not significant different, i.e. 75.2% and 73.4% at first CR (P=0.991), 50.5% and 56.7% at 2nd CR (P=0.748), and 26.7% and 30.3% at more advanced stages (P=0.683), respectively. Five year relapse free survival (RFS) of RIC and MAC in each disease status were also not different, i.e. 62.3% and 68.2% at first CR (P=0.249), 46.6% and 54.0% at 2nd CR (P=0.519), and 14.9% and 27.0% at more advanced stages (P=0.295), respectively. Neutrophil engraftment was obtained 91.7% in RIC and 96.2% in MAC by day 100 (P=0.491). Five year relapse rate was significantly higher in RIC than MAC, i.e. 43.1% vs 33.6%, P=0.020, but five year treatment related mortality (TRM) of RIC and MAC was not significantly different, i.e. 15.7% vs 15.3%, respectively (P=0.952). In multivariate analysis adjusted by other covariates, conditioning regimen of RIC compared to MAC did not significantly affect OS (HR=1.10, P=0.488), RFS (HR=1.25, P=0.093), relapse (HR=1.11, P=0.530), TRM (HR=0.89, P=0.621) or engraftment (HR=0.99, P=0.983). In 133 RIC patients, poor prognostic factors of OS identified in multivariate analysis were advanced stages at SCT (HR=3.91, P 〈 0.001), other than unrelated BMT (HR=0.457, P=0.040), and that of RFS was age of younger than 1 year old (HR=2.28, P=0.006), advanced stages at SCT (HR=5.49, P 〈 0.001) and conditioning regimen without TBI (HR=0.484, P=0.012). Conclusion: Our data showed that SCT with RIC for children with ALL showed similar transplant outcome compared to those who received MAC. These data suggest that RIC regimen could be considered as one of the therapeutic modality of SCT for children with ALL who needs allogeneic SCT. RIC may have a role also for children, since it may reduce late effects of MAC regimen or high-dose TBI for long-term survivors. To confirm these results, prospective randomized study with multi-institutional basis is mandatory. Disclosures No relevant conflicts of interest to declare.

Abstract: Purpose It is difficult to decide whether children with leukemia who could not achieve complete remission (CR) after relapse or primary induction failure should undergo transplantation. Nonetheless, allogeneic hematopoietic stem cell transplantation (HSCT) is a possible approach for refractory acute leukemia including acute lymphoblastic leukemia (ALL). Even after refractory to conventional chemotherapy, a graft versus leukemia (GVL) effect could be expected to some extent. This approach is considered to be experimental because the mortality rate of HSCT is extremely high. A previously conducted large-scale study showed that age younger than 10 years was a factor of good prognosis; however, the details in children are unclear. The purpose of this retrospective analysis was to describe the outcomes and risk factors of HSCT for children with refractory ALL. Patients and Methods The data was collected through the Transplant Registry Unified Management Program (TRUMP) system, the registry of The Japan Society for Hematopoietic Cell Transplantation. In total, 325 patients with ALL younger than 21 years old when HSCT was performed between January 2001 and December 2015 and who harbored blasts in peripheral blood and/or bone marrow were analyzed. Both myeloablative regimens and reduced-intensity conditioning regimens were analyzed. Patients were classified as having poor-risk cytogenetics with either t(4;11), t(9;22), t(8;14), hypodiploidy or near triploidy, or more than 5 cytogenetic abnormalities. Other ALL cytogenetic findings were classified as other abnormalities or normal. Myeloablative conditioning was defined as total body irradiation (TBI) of 〉 8 Gy and the administration of 8 mg/kg of busulfan (BU), 〉 140 mg/m2 of melphalan, or 〉 10 mg/kg of thiotepa. All other regimens were analyzed as reduced-intensity conditioning HSCT, including low-dose TBI (≤8 Gy) and low-dose BU (≤8 mg/kg). The graft included bone marrow, peripheral blood stem cells, or cord blood. Overall survival (OS) was used as a primary outcome because for HSCT during relapse, post-HSCT CR was not always achieved or reliably documented. Results The median follow-up time of survivors was 1145 days (range 110-3710). The median age was 11 years. Thirty-five percent of patients had a pre-HSCT performance status (PS) of 0, which corresponds to a Karnofsky PS of ≥90. The rate of pre-HSCT fungal infection was 14%. Fifty-nine patients had more than 25% marrow blasts when HSCT was performed. When HSCT was performed, 10%, 60%, and 30% of patients exhibited primary induction failure, first relapse, and second or later relapse, respectively. Ninety-one percent of patients had neutrophils and 67% exhibited platelet recovery by day 100. The cumulative incidence of grade II-IV acute graft-versus-host disease (aGVHD) on day 100 was 43%. The cumulative incidence of chronic GVHD (cGVHD) at 3 years after HSCT was 19%. Two hundred and forty-seven patients died. The causes of death were leukemia progression (57%), followed by graft failure (11%), GVHD (10%), hemorrhage (6%), and infection (5%). The 3-year OS rate in all the patients was 22% (95% confidence interval (CI), 18-27). Age, white blood cell count at diagnosis, prior history of central nervous disease, disease status, conditioning regimens, donor-recipient human leukocyte antigen match, graft type, or year in which HSCT was performed did not affect the OS. Grade ≥2 aGVHD did not affect OS. Whereas Patients with chronic GVHD had better 3-year OS (49%, 95% CI 35-61%) compared to that in patients without chronic GVHD (22%, 95% CI 16-29%) (p = 0.001) (Figure 1). Multivariate analysis showed that other than cGVHD, low PS (relative risk (RR): 2.53), blasts in bone marrow greater than 25% (RR: 1.43), T cell phenotype (RR: 1.86), high-risk or normal cytogenetics (RR: 1.42), and a history of HSCT (RR: 1.90) were significant adverse pre-HSCT variables (Table 1). Patients who had 0 or 1 (n = 113), 2 (n = 113), and 3-5 pre-HSCT variables (n = 99) had 42% (95% CI, 32-51), 17% (95% CI, 10-25), and 6% (95% CI, 2-13) 3-year OS, respectively (Figure 2). Conclusion Some patients with refractory pediatric ALL achieved relatively long survival following HSCT in the relapsed period, especially when a GVL effect was obtained. A scoring system using pre-HSCT variables should help decide whether HSCT should be performed or not. HSCT is worth considering for children who have undergone ≤2 pre-HSCTs. Disclosures No relevant conflicts of interest to declare.

Abstract: Recently, intravenous busulfan (iv-BU) has replaced oral-BU, which can suppress variety of bioavailability. Also, iv-BU showed less hepatic toxicity by avoiding the hepatic first-pass effect of oral-BU. Previous reports showed that the use of iv-BU reduced early complications and decreased early non-relapse mortality (NRM). Some reports demonstrated that iv-BU may provide better overall survival (OS) in adult with malignant diseases. Although several reports have been published on pediatric patients using iv-BU, the number of patients included was small, and the reports mainly focused on acute toxicity or early clinical outcome because of a short follow-up period. Thus, the role of iv-BU in HSCT for pediatric patients with acute leukemia is yet to be determined. In this study, to compare clinical outcome of HSCT with iv-BU and oral-BU, we retrospectively analyzed HSCT based on data reported to the Japan Society for Hematopoietic Cell Transplantation (JSHCT) registry. The patients were selected according to the following criteria: (1) patients diagnosed with either acute lymphoblastic leukemia (ALL) or acute myeloblastic leukemia (AML), (2) aged 15 years or younger when receiving HSCT, (3) BU-based myeloablative (more than 8 mg/kg) preconditioning regimens, and (4) HSCT performed between 2000 and 2010. Therefore, we analyzed 460 children with iv-BU (n = 198) or oral busulfan (BU) (n = 262) receiving hematopoietic stem cell conditioning transplantation (HSCT) with BU-based myeloablative conditioning for acute leukemia. The median age at HSCT was 4 years (range, 0–15 years). The median follow-up period was 1,828 days (range, 85–4,619 days) after HSCT in all the surviving patients, and 1,185 days (range, 100–3,759 days) after HSCT in the iv-BU patients. Although OS with iv-BU and oral-BU at day 100 after HSCT was 72.5 ± 3.2% and 66.9 ± 2.9%, respectively, OS at 3 years after HSCT was similar (iv-BU, 53.4 ± 3.7%; oral-BU, 55.1 ± 3.1% ), and the log-rank test for OS did not show statistically significant difference (p = 0.77) (Figure 1a). The result was concordant even when an analysis was limited to patients with ALL or AML. OS at 3 years for patients with ALL using iv-BU (n = 90) and oral-BU (n = 151) was 56.4 ± 5.5% and 54.6 ± 4.1, respectively (p = 0.51) (Figure 1b). OS at 3 years for patients with AML using iv-BU (n = 108) and oral-BU (n = 111) was 51.0 ± 5.0% and 55.8 ± 4.8%, respectively (p = 0.83) (Figure 1c). The similarity of OS was reproduced even with the limited cohort of 247 patients who received HSCT after 1st CR or 2nd CR without prior HSCT. OS at 3 years was 78.3 ± 4.2% for iv-BU patients (n = 98) and 78.7 ± 3.4% for oral-BU patients (n = 149) and the difference was not statistically significant (p = 0.66). Multivariate analysis also showed no significant survival advantage with iv-BU. Cumulative incidence of relapse at 3 years with iv-BU was similar with that of oral-BU (39.0 ± 3.6% and 36.4 ± 3.1%, respectively) (p = 0.67). Cumulative incidence of NRM at 3 years was 16.6 ± 2.7% with iv-BU and 18.3 ± 2.5% with oral-BU (p = 0.51). The iv-BU group showed a tendency toward higher engraftment probability at day 60 (96.0 ± 1.5%) compared with the oral-BU group (89.3 ± 2.0%), but the difference was not statistically significant (p = 0.22) This study was a retrospective study using registry data, and there are some limitations of our data. For example, as selection of iv-BU or oral-BU was strongly associated with the transplantation period, which may have introduced bias. Further prospective studies are required to establish an optimal allogeneic HSCT treatment strategy for pediatric patients with acute leukemia. In conclusion, our study provides valuable information on the role of iv-BU in myeloablative HSCT for pediatric acute leukemia. In children, iv-BU could not show significant survival improvement in outcome of acute leukemia. Disclosures: No relevant conflicts of interest to declare.

Abstract: Introduction: Adult T-cell leukemia/lymphoma (ATL) is an aggressive peripheral T-cell lymphoma caused by human T-cell lymphotropic virus type I. In younger patients, allogeneic hematopoietic stem cell transplantation (HSCT) has been shown to improve prognosis through a graft-versus-ATL (GvATL) effect. On the other hand, elderly patients with ATL are often not amenable to HSCT, and the prognosis is extremely poor with existing chemotherapy. The most widely used chemotherapy for ATL, CHOP (combination of cyclophosphamide-doxorubicin-vincristine-prednisone) and similar chemotherapy, have shown a complete response (CR) rate of about 20% and a long-term prognosis of less than 10%. In a phase II study of mogamulizumab, a humanized defucosylated anti-C-C chemokine receptor 4 monoclonal antibody, in concurrent combination with chemotherapy (mLSG15), the primary endpoint of CR was 52% in the mLSG15 + mogamulizumab group compared to 33% in the mLSG15 alone group. However, no improvement was observed in overall survival (OS) or progression-free survival (PFS). In addition, mLSG15 is a potent chemotherapy and not feasible in majority of elderly patients. Considering the possibility that mogamulizumab may unlock the tumor immune evasion mechanism by removing regulatory T cells and exert an immunological effect like GvATL, we investigated its usefulness as an immunological consolidation therapy following chemotherapy, with the aim of suppressing recurrence. Methods: New-onset treatment-naive ATL patients who were not eligible to HSCT received 3 courses of CHOP (combination of cyclophosphamide div 750 mg/m 2/day1, doxorubicin iv 50 mg/m 2/day1, vincristine iv 1.4 mg/m 2/day1 [max. 2.0 mg/body, and prednisone po/iv 100 mg/body/day1-5) at 21-day intervals, and then the first course of mogamulizumab (1 mg/kg for 8 doses at 2-week intervals) was initiated between the start of the third course of CHOP-21 and day 42. The primary endpoint was OS at months 12. Secondary endpoints were proportion of subjects with PFS, OS, overall response rate (ORR), organ-specific response rate, CR rate and adverse events (AEs) at month 12. Results: A total of 24 patients were enrolled and the median age was 75.5 years (range, 64-85). The median follow-up period was 11.0 (3.0-30.6) months. Five subjects discontinued study treatment before mogamulizumab administration attributable to insufficient effect (n=2), continuation deemed inappropriate (n=2), and start of the next course extended (n=1). ORR was 87.5%. Organ-specific response rates for peripheral blood, other than peripheral blood, target lesion, and skin lesion were 83.3%, 87.5%, 79.2%, and 66.7%, respectively. OS and PFS rates in the full analysis set (FAS) at months 12 were 52.6 (30.9-70.4)% and 26.6 (10.9-45.3)%, respectively. The median survival time (MST) and 80% confidence interval (CI) for OS was 12.1 (5.0 -21 .0) months (Figure 1). Since the lower limit of the 80% CI was below the threshold of 6 months, this treatment was not considered to be effective. However, the point estimate of MST was 12.1 months, which was equivalent to the expected value. One possible reason for the failure to reach statistical significance could be attributable to occurrence of events in the early stage of the protocol regimen. In other words, patients who did not respond to the preceding chemotherapy did not benefit from mogamulizumab, and only patients who managed to overcome chemotherapy benefited from the immune effects of mogamulizumab, resulting in long-term survival (Figure 1). In the long-term follow-up, the MST (95% CI) of the FAS was 12.4 (4.9-21.0) months, and the median OS (95% CI) at 24 months was 25.1 (9.6-44.1) %. AEs were observed in 16 subjects, of which serious AEs (grade 4/5) were observed in 5 subjects (acute respiratory distress syndrome, ventricular fibrillation, heart failure, hyponatremia, and pneumonia). Largely, AEs were resolved/recovered in 14 subjects including 3 subjects with serious AE; 2 subjects resulted in death, which were not considered treatment-related. Conclusions: Mogamulizumab as an immunological consolidation therapy after CHOP 21 might be one of the treatment options for transplant-ineligible elderly patients with previously-untreated ATL, despite not clearly showing improved OS. Further studies are warranted to examine the dosing timing of mogamulizumab to obtain its maximum benefit for prolonged survival. Figure 1 Figure 1. Disclosures Kato: Abbvie: Consultancy, Research Funding; AstraZeneca: Consultancy; Bristol-Myers Squibb: Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Chugai: Consultancy, Honoraria, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Dainippon-Sumitomo: Honoraria; Eisai: Consultancy, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Kyowa Kirin: Honoraria, Research Funding; MSD: Honoraria; Mundi: Honoraria; Novartis: Consultancy, Research Funding; Ono: Honoraria, Research Funding. Suzuki: Kyowa-kirin: Honoraria, Research Funding, Speakers Bureau; Chugai: Honoraria, Research Funding, Speakers Bureau; Taiho: Research Funding; Ohtsuka: Honoraria, Research Funding; Takeda: Research Funding, Speakers Bureau; Shionogi: Research Funding; Eisai: Honoraria, Research Funding; Bristol-Meyer Squib: Honoraria; MSD: Honoraria; Janssen: Honoraria; Abbvie: Speakers Bureau; Meiji Seika: Honoraria, Speakers Bureau; Ohtsuka: Honoraria. Akashi: Sumitomo Dainippon Pharma: Consultancy; Kyowa Kirin: Consultancy, Research Funding; Celgene: Research Funding; Astellas Pharma: Research Funding; Shionogi: Research Funding; Asahi Kasei Pharma: Research Funding; Chugai: Research Funding; Bristol-Myers Squibb: Research Funding.

Abstract: Abstract 3703 Poster Board III-639 Background Up to 40% of patients with DLBCL present with extranodal involvement of lymphoma, among which stomach is a common site. Patients with gastric DLBCL are generally treated with chemotherapy with or without radiotherapy similar to other DLBCL, but the disease may carry specific biological features. We herein present our experience with gastric DLBCL, and attempted to identify potential prognostic factors. Furthermore, the value of pretreatment PET scan was analyzed in this population, since CT scan is generally not sensitive in detecting gastrointestinal lesions. Methods We reviewed patients with gastric DLBCL treated with CHOP or R-CHOP based therapy in Aichi Cancer Center Hospital from 1995 to 2008. Multiple characteristics were evaluated for their prognostic values for complete response rate (CRR), overall survival (OS) and progression free survival (PFS). We also calculated the sensitivity of PET scan in detection of gastric involvement of lymphoma. Results Seventy-five patients with gastric DLBCL were identified and analyzed. The median age of patients was 66 (range 21-87). Thirty-five patients (47%) had Lugano stage I or II1, defined here as limited disease. International prognostic index (IPI) was low in 39 patients (52%), low-intermediate in 17 (23%), high-intermediate in 7 (9%) and high in 12 (16%). The CRR after initial treatment was 83%, and 5-year overall survival (OS) rate was 72% (median follow up duration was 32months). In 35 patients with limited disease, 25 patients (71%) underwent three courses of CHOP or R-CHOP followed by involved field radiation. Eight patients (23%) underwent gastrectomy (curative intent [n=6] , control of bleeding [n=1] or obstruction [n=1] ,) followed by CHOP or R-CHOP. Two of those with limited disease (avoided radiation due to large primary lesion [n=2]) and all with advanced stage (Lugano II2 or IV; n=40) were treated with 6 to 8 cycles of CHOP with or without rituximab. Multivariate analysis with logistic regression model for CRR revealed that rituximab (odds ratio [OR] 0.1, p=0.007), Hb 〉 12.0g/dl (OR 0.11, p=0.004) were independently associated with higher CRR. Multivariate analysis with Cox proportional hazard model for OS revealed that treatment without rituximab (hazard ratio [HR] 3.27, p=0.027), Hb 〈 12.0g/dl (HR 4.06, p=0.006), and serum albumin level 〈 lower limit of normal range (HR 3.43, p=0.023) were independently associated with shorter OS. An analysis for PFS revealed that treatment without rituximab (HR 2.73, p=0.03), advanced stage (HR 3.36, p=0.006), Hb 〈 12.0g/dl (HR 3.61, p=0.004), and serum albumin level 〈 lower limit of normal range (HR 2.96, p=0.021) were independently associated with shorter PFS. In the initial work up of patients with newly diagnosed DLBCL in general, upper gastrointestinal endoscopy has been a part of staging studies in our institution. PET scan was introduced as a part of pretreatment staging studies in 2003. Gastric lymphoma was diagnosed by gastroscopy performed for screening purposes or digestive symptoms (i.e. DLBCL was diagnosed by biopsy of gastric tumor, group A) in 52 patients (69%), by gastroscopy performed as a part of staging evaluations for proven lymphoma by biopsies of other site in 17 patients (23%, group B) and the diagnostic process was not well documented in 6 (8%). Twenty-two patients in group A underwent pretreatment PET scans, among which five did not show any abnormalities (sensitivity 77%). All these 5 had small stage I disease originally detected by screening gastroscopy. Eleven patients in group B underwent pretreatment PET scan, which all showed gastric lesions (sensitivity: 100%). Conclusions We showed the survival benefit of rituximab in gastric DLBCL. Furthermore, hemoglobin and albumin levels were determined to be potential prognostic factors in these patients. While PET scan seems reasonably sensitive to detect gastric involvement of lymphoma as a part of staging evaluation, small stage I gastric DLBCL can be missed by PET scan. Larger scale studies are needed to validate the prognostic factors identified here, and more data is needed to determine the value of pretreatment PET scan in this patient group. Disclosures: No relevant conflicts of interest to declare.

Abstract: Background: T-cell acute lymphoblastic leukemia (T-ALL) accounts for approximately 10-15% or 25% of cases of pediatric or adolescent and young adult (AYA) ALL, respectively. The use of pediatric protocols can improve outcomes in AYA T-ALL. Furthermore, nelarabine (NEL) has been shown to be effective for patients with relapsed or refractory T-ALL. This nationwide, multicenter, prospective, phase II trial for T-ALL was conducted to assess the feasibility and efficacy of NEL, intensive L-asparaginase (L-asp), and protracted intrathecal therapy (IT) when incorporated in the AIEOP-BFM-ALL 2000 based pediatric treatment for patients & lt;25 years old at diagnosis. Patients & Methods: From December 2011 to November 2017, 364 patients with newly diagnosed T-ALL, age 0-24 (median 9.6 years), were enrolled in the JPLSG ALL-T11/JALSG T-ALL-211-U (ALL-T11) trial conducted by the Japanese Pediatric Leukemia/Lymphoma Study Group and the Japan Adult Leukemia Study Group. Patients were stratified into three groups according to their prednisone (PSL) response, initial central nervous system (CNS) status, and PCR-based minimal residual disease (MRD) at the end of induction consolidation protocol IB (TP2). Good or poor PSL responses were defined as & lt;1.0 × 10 9/L or ≥1.0 × 10 9/L blasts in peripheral blood at day 8 following a 7-day PSL pre-phase plus one IT dose of methotrexate, respectively. Patients with good PSL response, TP2 MRD & lt; 10 −3 and no CNS involvement, were assigned to the standard risk (SR) group, while patients with TP2 MRD ≥ 10 −3 or no complete remission (CR) after induction therapy IA were assigned to the very high risk (VHR) group. The patients who did not fulfill SR and VHR criteria were assigned to the high risk (HR) group. If TP2 MRD evaluation was not applicable, patients were classified as MRD & lt; 10 −3. ALL-T11 was characterized by dexamethasone in IA, the additional use of E. coli derived L-asp (5000 U/m 2 × 8 in IB, 10,000 U/m 2 × 4 in reinduction protocol IIB for SR and HR groups, and 12,500 U/m 2 × 4 in protocol M for SR), incorporation of NEL (5-day course of 650 mg/m 2/day) in HR or VHR groups (6 or 1-2 courses, respectively), and elimination of prophylactic cranial radiotherapy (CRT). CRT was limited to patients with initial CNS involvement (CNS3), and the other patients received protracted IT during each treatment phase including the maintenance phase. Only VHR patients were scheduled to receive hematopoietic stem cell transplantation (HSCT) after being randomized to receive one of two arms of distinct block therapies. Results: Fifteen patients were excluded having not meeting inclusion criteria. Of 349 evaluable patients, 238 (68.2%) were male, the median white blood cell count was 45 × 10 9/L (range 0.4-1375), and 73.4% were HR by NCI criteria. Twenty-eight patients (8.0%) had CNS3 status. PCR-MRD could be evaluated in 208 patients. Among 310 stratified patients, 168 (54.2%), 103 (33.2%), and 39 (12.6%) were SR, HR, and VHR, respectively. HSCT was performed in 35 patients (10.0%). The composite CR (CR+CR in suppression) rate after IA, and the CR rate after IB were 85.4% and 90.5%, respectively. With a median follow-up of 5 years 2 months, the 3-year event-free survival (EFS) and overall survival (OS) of the whole cohort was 85.6% (95% CI: 81.5-89.9) and 91.4% (87.9-93.9), respectively (Figure 1), and the 3-year cumulative incidence of relapse was 8.9% (5.9-12.1). Induction death was seen in 14 patients (4.0%), and 3-year non-relapse mortality of the whole cohort was 0.6% (0.1-2.1). Three-year EFS and OS for each risk group were 90.4% (84.9-94.0) and 95.8% (91.4-98.0) in SR, 91.3% (83.9-95.4) and 95.1% (88.6-97.9) in HR, and 87.2% (71.9-94.5) and 87.2% (71.9-94.5) in VHR respectively. Three-year EFS and OS were 90.1% (86.1-93.0) and 95.7% (92.7-97.5), and 55.6% (30.5-74.8) and 66.7% (40.4-83.4) in MRD-negative and MRD-positive patients (p & lt; 0.001 and p & lt; 0.001), respectively. Grade 3 or higher peripheral motor and sensory neuropathies were seen in 9 (8.7%) and 6 (5.8%) in HR and 2 (5.1%) and 0 in VHR, respectively. Clinical allergic reaction, anaphylaxis, and pancreatitis were reported in 10 (2.9%), 16 (4.6%), and 31 (8.9%) patients, respectively. Conclusions: The addition of NEL, intensified L-asp, and protracted IT in AIEOP-BFM-ALL 2000 based treatment showed encouraging outcomes with acceptable toxicities despite the limited use of CRT and HSCT. Figure 1 Figure 1. Disclosures Hatta: Bristol-Myers Squibb: Honoraria; Novartis KK: Honoraria; Pfizer Japan Inc.: Honoraria; Otsuka Pharmaceutical.: Honoraria. Imai: Juno Therapeutics: Patents & Royalties: chimeric receptor with 4-1BB signaling domain. Saito: Toshiba corporation: Research Funding. Kiyoi: Astellas: Honoraria; celgene: Honoraria; Daiichi Sankyo: Honoraria; Dainippon Sumitomo: Honoraria; Eisai: Honoraria; Fijifilm: Honoraria; Kyowa Kirin: Honoraria; Otsuka: Honoraria; Perseus Proteomics: Honoraria; Pfizer: Honoraria; Pfizer: Honoraria; Sanofi: Honoraria; Takeda: Honoraria; Zenyaku Kogyo: Honoraria. Matsumura: Nippon Shinyaku: Research Funding; Ono: Research Funding; Bristol-Myers Squibb: Speakers Bureau; Daiichi Sankyo: Research Funding, Speakers Bureau; Pfizer: Research Funding, Speakers Bureau; Novartis: Research Funding, Speakers Bureau; Chugai: Research Funding; Asahi Kasei: Research Funding; Japan Blood Products Organization: Research Funding; Mundipharma: Research Funding; Amgen: Speakers Bureau; AYUMI Pharmaceutical: Research Funding; Eli Lilly Japan: Research Funding; Sumitomo Dainippon: Research Funding; Takeda: Research Funding; Astellas: Speakers Bureau; Kyowa Kirin: Research Funding; Taiho: Research Funding; Nihon Pharmaceutical: Research Funding; Janssen: Speakers Bureau; Mitsubishi Tanabe: Research Funding; Eisai: Research Funding; Otsuka: Consultancy, Research Funding, Speakers Bureau; MSD: Research Funding; Shionogi: Research Funding; Addvie: Research Funding. Miyazaki: Chugai: Honoraria; Kyowa-Kirin: Honoraria; Astellas: Honoraria; Novartis: Honoraria; Abbvie: Honoraria; Sumitomo-Dainippon: Honoraria, Research Funding; Daiichi-Sankyo: Honoraria; Eisai: Honoraria; Janssen: Honoraria; Pfizer: Honoraria; Bristol-Myers Squibb: Honoraria; Nippon-Shinyaku: Honoraria; Takeda: Honoraria; Sanofi: Honoraria.

Abstract: Purpose It is difficult to decide whether children with leukemia who could not achieve complete remission (CR) after relapse or primary induction failure should undergo transplantation. Nonetheless, allogeneic hematopoietic stem cell transplantation (HSCT) is a possible approach for refractory acute myeloid leukemia (AML). Despite being refractory to conventional chemotherapy, a graft versus leukemia (GVL) effect could be expected to some extent. This approach is considered to be experimental because the mortality rate of HSCT is extremely high. A previously conducted large-scale study demonstrated that age less than 10 years was a factor of good prognosis; however, the details in children remain unclear. The purpose of this retrospective analysis was to describe the outcomes and risk factors of HSCT for children with refractory AML. Patients and Methods The data was collected through the Transplant Registry Unified Management Program (TRUMP) system, the registry of The Japan Society for Hematopoietic Cell Transplantation. A total of 417 patients with AML younger than 21 years old at the time of HSCT between January 2001 and December 2015 who had blasts in peripheral blood and/or bone marrow were analyzed. Both myeloablative and reduced-intensity conditioning regimens were analyzed. Patients with AML were classified according to a previous report, which was based on the Eastern Cooperative Oncology Group/Southwest Oncology Group classification as good (inv16, t[8;21], t[15;17] ), poor (5/del[5q], 7/del[7q] , inv[3q], abn11q, 20q or 21q, del[9q] , t[6;9], t[9;22] , abn17p, and complex karyotype defined as 3 or more abnormalities), or intermediate (other and normal karyotypes) risk. Myeloablative conditioning was defined as total body irradiation (TBI) of 〉 8 Gy and the administration of 8 mg/kg of busulfan (BU), 〉 140 mg/m2 of melphalan, or 〉 10 mg/kg of thiotepa. All other regimens were analyzed as reduced-intensity conditioning HSCT, including low-dose TBI (≤8 Gy) and low-dose BU (≤8 mg/kg). The graft included bone marrow, peripheral blood stem cells, or cord blood. Overall survival (OS) was used as a primary outcome because for HSCT during relapse, post-HSCT CR was not always achieved or reliably documented. Results The median follow-up time of survivors was 1052 days (range 60-4399). The median age was 13 years. Twenty-three percent of patients had a pre-HSCT performance status (PS) of 0, which corresponds to a Karnofsky PS ≥90. The rate of pre-HSCT fungal infection was 12%. Fifty-two percent of patients had more than 25% marrow blasts at the time of HSCT. At the time of HSCT, 36%, 47%, and 17% of patients exhibited primary induction failure, first relapse, and second or additional relapse, respectively. Eighty-nine percent of patients had neutrophils and 70% exhibited platelet recovery by day 100. Three hundred and fourteen patients died. The causes of death were leukemia progression (58%), followed by graft-versus-host disease (GVHD) (11%) and graft failure (10%). The 3-year OS rate was 23% (95% confidence interval (CI) 19-28). Grade ≥2 acute GVHD did not affect OS. Patients with chronic GVHD had better 3-year OS (47%, 95% CI 36-57%) compared to that in patients without chronic GVHD (22%, 95% CI 16-28%) (p = 0.001) (Figure 1). Low PS, greater than 25% marrow blasts, the presence of blasts in blood at the time of transplantation, French-American-British subgroup other than M1 or M2, transplant from a male donor, and a history of transplantation were adverse pre-HSCT variables (Table 1). Patients with 0 (n = 24), 1-2 (n = 175), 3-4 (n = 188), and 5-6 (n = 30) variables had 52% (95% CI 30-71%), 30% (95% CI 23-37%), 17% (95% CI 12-23%), and 0% 3-year OS, respectively (p 〈 0.001) (Figure 2). Discussion Some patients with refractory pediatric AML achieved relatively long survival following HSCT in the relapsed period, especially when a GVL effect was obtained. A scoring system using pre-HSCT variables should help decide whether HSCT should be performed or not. HSCT is worth considering for children who have undergone ≤2 pre-HSCTs. Disclosures No relevant conflicts of interest to declare.

Abstract: Spleen tyrosine kinase (Syk) is essential for downstream pathways in signaling from B-cell receptor (BCR) in B cells and Fc-gamma receptors in macrophages. Because of the essential roles it plays in signaling, Syk has been targeted in drug development for autoimmune and allergic diseases, in which B cells and macrophages have pivotal roles in the pathophysiology. In addition, accumulated data suggest that aberrant BCR signaling is deeply involved in the pathogenesis of B-cell malignancies. Here we report the pharmacological profile of a novel and highly selective Syk inhibitor, FF-10102-01 (FF-10102 hydrochloride). FF-10102-01 was evaluated in the following in vitro assays: Kinase inhibitory activities were performed with ProfilerPro Kit (PerkinElmer, USA). The effects on cell signaling and functions were studied using THP-1, a human monocyte-derived cell line, after differentiation with human recombinant interferon gamma (IFNγ). The effects on CD69, an activated B-cell marker, expression on B cells were evaluated using whole blood samples from healthy volunteers and mice, and on lymphoma cell growth using SU-DHL-6, a human diffuse large B-cell lymphoma-derived cell line. FF-10102-01 was also evaluated in vivo in animal models of antigen-induced antibody production, anti-platelet antibody-induced thrombocytopenia, and collagen-induced arthritis (CIA). FF-10102-01 showed high potency against recombinant human Syk enzyme activity, with a 50% inhibitory concentration (IC50) value of 1.2 nmol/L. Kinase profiling assay in a panel of 216 kinases revealed that FF-10102-01 is highly selective for Syk, with an IC50 value more than 25 times lower than those of the other kinases. FF-10102-01 exhibited suppressive effects on phosphorylation of downstream molecules of Syk, SLP76, and ERK1/2 in THP-1 cells. FF-10102-01 inhibited tumor necrosis factor α secretion under stimulation by immunoglobulin (Ig) G and phagocytosis of IgG-opsonized beads in IFNγ-induced differentiated THP-1 cells. CD69 expression under stimulation with anti-BCR antibodies in human and mouse blood was also inhibited by FF-10102-01, with IC50 values of 314 nmol/L and 307 nmol/L, respectively. FF-10102-01 was the most potent inhibitor of the growth of SU-DHL-6 cells among other known Syk, JAK, and Bruton's tyrosine kinase inhibitors compared, with an IC50 value of 318 nmol/L. FF-10102-01 is orally available with a good PK profile, and showed inhibitory effect at daily doses 50 mg/kg (as free base) on specific antibody production in ovalbumin-immunized mouse model. Orally administered FF-10102-01 showed significant effects in a mouse model of thrombocytopenia and a rat model of rheumatoid arthritis (CIA) at 25 mg/kg and 10 mg/kg (as free base), respectively. In the thrombocytopenia model, the prevention of platelet decrease by FF-10102-01 was well correlated with suppressions of platelet-phagocytotic macrophages in spleen and CD69-positive B cells in blood. These data indicate that FF-10102-01 is a potent and highly selective orally available Syk inhibitor, with pharmacological effects through inhibition of both B-cell and macrophage activities represented in inhibitions of cell signaling and functions in vitro, and in animal models of autoimmune diseases in vivo. The results suggest that FF-10102-01 is a promising agent for treatment of autoimmune diseases such as immune thrombocytopenia, rheumatoid arthritis, and B-cell malignancies. A clinical trial of FF-10102-01 is planned to commence in 2017. Disclosures Kinouchi: FUJIFILM Corporation: Employment. Taguchi:FUJIFILM Corporation: Employment. Shimoyama:FUJIFILM Corporation: Employment. Ioroi:FUJIFILM Corporation: Employment. Ogura:FUJIFILM Corporation: Employment. Yamamoto:Toyama Chemical Co., Ltd.: Employment. Iino:Toyama Chemical Co., Ltd.: Employment. Maeda:Toyama Chemical Co., Ltd.: Employment. Kato:Toyama Chemical Co., Ltd.: Employment. Fujiwara:FUJIFILM Corporation: Employment. Hagiwara:FUJIFILM Corporation: Employment. Iwamura:FUJIFILM Corporation: Employment. Kuter:Rigel: Consultancy, Research Funding; Genzyme: Consultancy; Bristol-Myers Squibb: Research Funding; GlaxoSmithKline: Consultancy; ONO: Consultancy; Amgen: Consultancy, Paid expert testimony; Protalex: Research Funding; MedImmune: Consultancy; Pfizer: Consultancy; Syntimmune: Consultancy; Shire: Consultancy; Eisai: Consultancy; 3SBios: Consultancy; CRICO: Other: Paid expert testimony; Shionogi: Consultancy. Nakamura:Toyama Chemical Co., Ltd.: Employment. Shimada:FUJIFILM Corporation: Employment.