ALBERT

Description: Background Renal dysfunction is a common complication of allogeneic hematopoietic cell transplantation (Allo-HCT) with proven negative impact on early and long-term mortality. The cumulative incidence of chronic kidney disease(CKD) after Allo- HCT varies from 13~60% in adult studies to as high as 62% in children. So far, most knowledge on chronic renal impairment in the context of Allo-HCT is based on clinical and laboratory findings. Causes of CKD are diverse, usually overlapping, and poorly understood. Kidney biopsies are performed in less than 5% patients with CKD, the pathophysiology of idiopathic CKD remains obscure. We conducted a multi-center clinicopathologic study of Allo-HCT patients with CKD to described the histopathologic spectrum of renal manifestations. Methods and Results Between 2005 and 2018, 24 recipients(17 males and 7 females) of Allo-HCT underwent kidney biopsy for either proteinuria or deterioration of kidney function at four centers. The median age was 43.8 (7.2~54.3) years, and the median time from Allo-HCT to kidney biopsy was 17.2(2.0~74.6)months. Evidence for GVHD was found in 20 (83.3%) patients. Among the 24 patients, 10 patients had a large amount of proteinuria (24-hour urine protein 〉 3.5 g/L), and 12 patients had elevated serum creatinine (Scr 〉110μmol/l). The most common pathological findings of kidney biopsy were GVHD (n=8), membranous nephropathy (MN, n=5), thrombotic microangiopathy (TMA, n=4), BK virus nephropathy (n=2), and we also found ischemic nephropathy, chronic interstitial nephritis, minimal change disease (MCD), GVHD with TMA, MN with focal segmental glomerular sclerosis (FSGS), MCD with acute tubular injury, BK virus nephropathy combined with calcineurin inhibitor nephrotoxicity in one case. The follow-up data showed 3 died of recurrent malignancy, 6 loss to follow-up , the median follow-up time was 18.3(12.3~120.2)months. Of the 18 patients, 8 (44.4%) had an estimated glomerular filtration rate (eGFR) of less than 60 ml/(min1.73m2), 5 (27.8%) still had moderate proteinuria. Conclusions A wide spectrum of renal pathologic findings can be observed in Allo-HCT patients. Either severe proteinuria or elevated serum creatinine were common presentations in this unique setting, which can be due to GVHD , MN, TMA, BK virus nephropathy , MCD, FSGS, and overlapping lesions. Kidney biopsies are necessary to establish the underlying cause of CKD in Allo-HCT patients. Disclosures No relevant conflicts of interest to declare.

Description: DUSP3 (also called VHR) is a member of the dual-specificity protein phosphatase family which can dephosphorylate target proteins at phosphoserine/threonine and phosphotyrosine residuals. There are evidences that DUSP3 is highly expressed in cervical and prostate cancers, and may exert its function in inhibiting apoptosis. By analyzing publicly available data on diffuse large B-cell lymphoma (DLBCL), we found that the expression levels of DUSP3 mRNA were inversely associated with overall survival (OS) in DLBCL. Patients with low levels of DUSP3 mRNA had significant longer OS than did those with high levels of DUSP3 (P=0.0002) (Figure 1). The association between the levels of DUSP3 mRNA and clinical outcome was confirmed using an independent DLBCL cohort. To decipher the role of DUSP3 in DLBCL, we used lentiviral system to stably express shRNA against DUSP3 in the DLBCL cell line, OCI-Ly01. Reduced expression of DUSP3 was associated with significantly decreased proliferation of cells as compared to the control group (P

Description: Chromosomal translocations juxtaposing immunoglobulin (Ig) and MYC genes are the hallmarks of human Burkitt lymphoma (BL), with deregulated MYC expression being a critical factor in pathogenesis. By inserting an intact mouse Myc gene into the mouse genome, proximal to the Ig enhancer Eμ, the effect of a precise mimic of the major t(8;14) translocation of human endemic BL (eBL) could be investigated. Knock-in mice developed IgM-positive B-cell tumors, with most being typical of eBL by histology and immunophenotype, including expression of the germinal center (GC)–associated protein, BCL6. Unlike eBL, however, analysis of Ig VH sequences revealed no significant level of somatic mutation. Thus, constitutive expression of Myc in the knock-in mice is apparently able to induce “Burkitt-like” lymphomas before antigen stimulation and formation of a GC. In contrast, human eBL development occurs in a GC or post-GC site with a likely contribution to pathogenesis from Epstein-Barr virus (EBV) and other epigenetic factors.

Description: Consistent with the role of activation induced cytidine deaminase (AID) as a major “catalyst” of aberrant translocations between the Ig switch regions and c-myc, AID-sufficient Bcl-xL transgenic mice rapidly develop transplantable plasmacytomas with classical T(12;15) translocations. Unexpectedly, we found that Bcl-xL transgenic BALB/cAn mice deficient for AID (designated pBxAicda−/− mice) also developed plasma cell tumors but with a lower frequency (24% vs. 62%) and with a longer mean latency (108 d vs. 36 d) than AID-sufficient controls. Six out of nine of primary tumors were shown by interphase FISH to contain a T(12;15) translocation and one other had a T(6;15). pBxAicda−/− tumors did not transplant well because they were presumably in early stages of neoplastic development or had not progressed to full malignancy including association with ascites. Nevertheless, two tumors (4885 and 4961) were successfully transplanted and established as stable cell lines. They exhibited mature plasma cell phenotype (CD45−, CD138+, PC-1+, CD19−, CD23−) and secreted IgM. Gene expression profiling showed no significant difference from control plasma cell tumors of AID-sufficient mice. Detailed molecular and cytogenetic analysis of 4885 uncovered an unusual unbalanced T(12;15) translocation with IgH Cμ and Pvt-1 in a head to tail orientation at the breakpoint, resulting in elevated c-myc expression as detected by qPCR. In contrast, 4961, a T(12;15) negative cell line, had elevated N-myc expression as a result of paracentric inversion of Chr. 12. These rearrangements had no direct association with RAG activity. We conclude that rapid development of malignant plasma cell tumors with reciprocal T(12;15) does require AID, and that in AID deficiency a novel less efficient mechanism can be utilized to bring c-myc and Ig genes into juxtaposition.

Description: Introduction EBV reactivation and associated diseases have been well recognized as one of the life threatening complications after SCT, which leads to the establishment of prophylactic and preemptive treatment for EBV viremia. However since then, few epidemic data was shown in SCT recipients, especially in China. Patients and Methods An observational data base study was conducted in patients with hematological disorders who received allo-SCT from Jun 2011 through Jun 2014. EBV-negative status was confirmed before transplant for both donors and recipients. EBV-DNA was screened weekly until Day 100 post SCT by qPCR, and then every 2-4 weeks until 1 year. Additional tests were carried out when clinically indicated. All patients received ganciclovir during conditioning regimen, and then switched to acyclovir or valaciclovir after stem cell infusion until 1 year post SCT. Ganciclovir and/or foscarnet were used when DNAemia developed, as well as rituximab for high risk patients such as high viral load or persistent DNAemia. Results This study recruited 892 evaluable cases, including 91 cases of benign diseases and 801 cases of malignancies. Until Jun 2015, EBV-DNA was detected in 178 cases with a median duration of 55 days (16-990days) post SCT, and the long-term cumulative incidence of DNAemia was 22.8¡À1.6%(Fig 1A). Log-rank test showed the onset of EBV-DNAemia had impact on neither OS nor NRM. However, For patients with late-onset EBV viremia (later than 100 days post-SCT), superiority of 3 year-OS (75.6¡À7.9% vs 65.2¡À1.8%, P=0.013) and 3 year-NRM (19.2¡À8.0% vs 25.4¡À1.7%, P=0.028) were observed(Fig 1B and Fig 1C). Furthermore, late-onset of EBV viremia was confirmed as independent protective factor for both OS£¨RR 0.466 [95%CI 0.253-0.859], P=0.014) and NRM (RR 2.271 [95%CI 1.056-4.882], P=0.036) in multivariate analysis. Cox model analysis revealed that the haploidentical donor£¨RR 4.745 [95%CI 1.624-13.866], P=0.004) and the use of ATG/ALG were independent risk factors for late-onset of EBV viremia, as well as the graft of bone marrow (RR 2.188 [95%CI 0.991-4.835], P=0.053) with a marginal significance(Figure 2). Conclusion This work showed the cumulative incidence of EBV viremia after allogeneic SCT was around 22.8% based on virus prophylaxis. As shown in multivariate analysis, late-onset of EBV viremia had independent impact on OS and NRM. Haploidentical donors, the use of ATG/ALG and graft type were independent risk factors for late-onset EBV viremia.. This work was funded by grants of Jiangsu Provincial Special Program of Medical Science (BL2012005), Jiangsu Province¡¯s Key Medical Center (ZX201102) and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD). Figure 1. A. Cumulative incidence of EBV DNAemia; B. Comparison of OS between early-onset and late-onset of EBV viremia; C. Comparison of NRM between early-onset and late-onset of EBV viremia; Figure 1. A. Cumulative incidence of EBV DNAemia; B. Comparison of OS between early-onset and late-onset of EBV viremia; C. Comparison of NRM between early-onset and late-onset of EBV viremia; Figure 2. Independent risk factors for late-onset of EBV viremia: A. the impact of donor types; B. the impact of conditioning regimens with and without ATG/ALG; C. the impact of graft types. Figure 2. Independent risk factors for late-onset of EBV viremia: A. the impact of donor types; B. the impact of conditioning regimens with and without ATG/ALG; C. the impact of graft types. Disclosures No relevant conflicts of interest to declare.

Description: The time in cellular differentiation at which the expression of an oncogene is dysregulated is thought to determine the phenotype of the resulting neoplasia. We tested this assumption in C57BL6/J transgenic mice expressing an HA-tagged c-myc oncogene in B cells under the control of kappa light chain regulatory elements. Two transgenes were engineered that differed by only one nucleotide. The first set of mice carries a wild type HA-MYC transgene, develops pro-B cell tumors, and succumbs rapidly to pronounced lymphosplenomegaly. In the second set of mice, a point mutation in the HA-tag portion of the transgene creates a stop codon that abrogates HA-MYC translation. This stop codon was engineered to be a hotspot for somatic hypermutation. Thus sporadically, in a germinal center B cell, somatic hypermutation may revert the stop codon, allowing translation of HA-MYC. In two independently derived lines, mice spontaneously develop monoclonal gammopathies (50% incidence at 30 weeks (n=35), 80% at 40 weeks (n=35)). Serum protein electrophoresis detects M-spikes that increase in intensity over time, and 6 out of 7 cases tested so far were of IgG1 isotype. Unlike other mouse models of plasma cell neoplasia, no lymphosplenomegaly nor ascites were detected. In analogy to human multiple myeloma, that is a disease of isotype-switched and hypermutated cells homing to the bone, large populations of plasma cells were found in the bone marrow. Bone marrow (but not spleen) lysates reacted for HA and human MYC proteins by western blot and immunohistochemistry, thus indicating that reversion of the stop codon occurred. Remarkably, in two young mice, monoclonal spikes appeared 2 weeks after vaccination with NP-CGG. These spikes were sustained and the monoclonal protein was reactive to the NP antigen. Together, comparison of the two sets of mice demonstrates that activation of the same transgene at distinct B cell developmental stages results in dramatically different tumor phenotypes. In addition, and opposite to most engineered mice, we have created a system where the oncogene is turned on sporadically, as occurs in the human disease. Furthermore, we have developed a model that faithfully reproduces important clinical aspects of monoclonal gammopathy of undetermined significance (MGUS) and its progression to multiple myeloma. This model will be useful to develop immunologic and chemoterapeutic approaches.

Description: Abstract 4536 Objective To evaluate the safety profile and efficacy of umbilical cord-derived mesenchymal stem cell infusion in patients with steroid-resistant, severe, acute graft-versus-host disease (aGVHD). Methods A total of 19 patients with steroid-resistant severe aGVHD received mesenchymal stem cell infusion treatment. We analyzed the treatment response, transplantation-related mortality, events associated with infusion and relapse rate. Results Two patients with grade II, 5 patients with grade III and 12 patients with grade ‡W aGVHD received a total of 58 infusions of mesenchymal stem cell. The mean total dose of mesenchymal stem cell was 2.13×106 (range 0.6–7.2×106) cells per kg bodyweight. 7 patients received one infusion, 2 patients received two infusions, and 10 patients received three or more infusions. 11 patients had a complete response and 4 had a partial response and 4 had no response. No patients had side-effects during or immediately after infusions of mesenchymal stem cell and no ectopic tissue was detected to date. 11 patients survived and 8 died, 4 for aGVHD, 1 for infection and 2 for aGVHD with concomitant infection and 1 for underlying leukemia relapse. The cell viability of freshly prepared mesenchymal stem cell is 93% (92%-95%) by trypan blue staining. The cell viability of controlled-rate freezed and thawed cells mesenchymal stem cell is 72% (70%-74%). Conclusion Infusion of umbilical cord-derived mesenchymal stem cell expanded in vitro is an effective therapy for patients with steroid-resistant, severe aGVHD without negative impact on relapse. Freshly prepared mesenchymal stem cells are superior to freezed and thawed cells in terms of cell viability. Disclosures: No relevant conflicts of interest to declare.

Description: Background Reactivation of Epstein-Barr Virus (EBV) frequentlyoccurs after allogeneic stem cell transplantation(allo-SCT) andEBV-induced posttransplant lymphoproliferative disease(PTLD) is a potentially fatalcomplication. Our previous study showed that the cumulative incidence of EBV viremia after allo-SCT was 21.3±1.5% ( data based on 892 evaluable patients received allo-SCT from Jun 2011 through Jun 2014 at our institution). As the preemptive treatment for EBV reactivation after allo-SCT, rituximab (anti-CD20) is commonly used, but is associated with the prolonged immunedefect. The question of over-treatment of systematic rituximab has been raised and further studies investigating the minimal doses of rituximab to resolve EBV reactivation and avoid its prolonged B cell impairment are needed. The aimof this single-center study was to evaluate the strategy of weekly low-dose rituximab as the preemptive management of EBV reactivation. Methods 52 patients received allo-SCT from Mar 2014 through Mar 2015 at our institution were enrolled in a prospective study. 38 males and 14 females, median age 25 years (range, 7-57). Patients underwent transplantation for acute leukemia (n=33), CML (n=2), NHL (n=4), MDS (n=5), or SAA(n=8). The type of donors included HLA-haploidentical donors (n=41), HLA-matched unrelated donors (n=8) and HLA-identical siblings (n=3). EBV viral loads of patients were monitored by quantitative PCR for EBV DNA performed on whole-blood samples once a week after allo-SCT. EBV reactivation was defined as a single positive EBV PCR result according to institutional thresholds (above 100 copies per millitre). Eligibility included EBV reactivation and negative hepatitis B surface antigen. Rituximabwas administered weekly at the fixed dose of 100mg after a positive PCR result (〉100Cop/mL) and discontinued as soon as a negative PCR result was available. The numbers of circulating CD20+ B cellsand serum gammaglobulin levels were assessed weekly during the study. Results Weekly low-dose rituximab was well tolerated without anyserious adverse event. 52 patients receiving preemptive rituximab treatment showed an 100% cumulative complete remission (CR) rate of EBV reactivation, which resulted in cessation of treatmentas per protocol after the 1st (n=25, 48.1%), 2nd (n=24, 46.1%), or 3rd (n=3, 5.8%) dose. To date, none of the patients have developedan EBV-PTLD.There was no significant persistent B cell dysfunction following weekly low-dose rituximab treatment by assessment of the numbers of circulating CD20+ B cellsand serum gammaglobulin levels. Conclusions Our weekly low-dose rituximab-based approach is a high-efficient and safe preemptive therapy for EBV reactivation after allo-SCT. Furthermore, the use of low-dose rituximab for EBV reactivation may avoid its prolonged B cell impairment due to the over-treatment of 375mg/m2 rituxima. Disclosures No relevant conflicts of interest to declare.

Description: The splenic marginal zone (MZ) is comprised of specialized populations of B cells, dendritic cells, and macrophages that are uniquely arrayed outside the white pulp follicles to screen the blood for bacterial and other particulate Ags. Mechanisms responsible for MZ B-cell formation, localization, retention, and function are understood to include antigenic specificity, transcription factors, integrins, and surface receptors for soluble ligands such as S1P. Here, we add to this repertoire by demonstrating that the receptor for CXCL12, CXCR7, is expressed on MZ but not on follicular B cells. Treatment of mice with CXCR7 inhibitors led to disruption of MZ architecture, reduced numbers of MZ B cells, and altered granulocyte homeostasis associated with increasing serum levels of CXCL12. CXCR7 thus appears to function as a scavenger receptor for CXCL12 on MZ B cells.

Description: Abstract 4555 Objective To compare the effect of the hematopoietic stem cell transplantation with and without imatinib to treat adult patients sufferred from Philadelphia chromosome-positive acute lymphocytic leukemia by evaluating the survival post-transplantation and the quality of life. Method 35 acute lymphocytic leukemia patients with Philadelphia chromosome-positive have taken hematopoietic stem cell transplantation between 2003 and 2011, in which 23 cases who were treated combined with imatinib were conducted in imatinib group, and the rest cases who haven't utilized imatinib were conducted in the control group. The incidence of relapse, incidence of graft-versus-host disease (GVHD), overall survival (OS) and disease-free survival (DFS) of the groups were compared so as to identify the advantage of combining treatment. Results The age, gender, cytogenetic classification, doner type, preparative regimen and counts of stem cells were comparative between the two groups. The proportion of patients who were in the first remission (CR1) in the imatinib group was higher than that in control group, however, the single factor analysis showed that it didn't affect the survival significantly. The incidences of relapse were 17.4% in the imatinib group and 16.7% in the control group (P = 0.9569), and the incidences of acute GVHD of Grade II to Grade IV were 35.3% and 41.7% (P = 0.4506), respectively. The 2-year-OS of two groups showed statistical difference of 62.6% versus 41.7% (P = 0.028), and 2-year-DFS were 53.7% and 33.3% (P = 0.054), respectively. Patients who survived more than 2 years post-transplantation would have a favorable prognosis. Conclusion Patients of imatinib group had a better survival, but the incidences of relapses and severe GVHD between the two groups had no significant difference. Thus, patients of Philadelphia chromosome-positive acute lymphocytic leukemia may benefit from the combination of hematopoietic stem cell transplantation and imatinib. Disclosures: No relevant conflicts of interest to declare.