bluuebunny/crossref_metadata_2025_split huggingface dataset:
PKC zeta-mTOR Pathway: A New Target for Rituximab Therapy in Follicular Lymphoma.
Authors: Laurent Guy , Leseux Ludivine , Laurent Camille , Bezombes Christine 
Published: October 2019

Abstract
Previous studies have documented that, in malignant B-cells, Rituximab elicits a complex and not yet totally understood signalling network contributing to its anti-tumour effect. In this context, we investigated the role of protein kinase C zeta, an atypical PKC isoform, in the cellular response to Rituximab. We found that follicular lymphoma cells displayed an increase in PKC zeta expression and activity levels, compared to non malignant B cells, and that this enzyme was a critical regulator of the classical MAPK module by stimulating Raf-1 kinase activity. PKC zeta appeared to be a significant contributor of abnormal mTOR regulation in follicular lymphoma cells through a MAPK-dependent mechanism. Rituximab was found to inhibit the PKC zeta/MAPK/mTOR module in these cells but not in other B-cell lymphomas. Importantly, the expression of a constitutively active form of PKC zeta resulted in an efficient protection of these cells towards Rituximab. Altogether, our study describes a new regulatory component of mTOR pathway in follicular cell lymphoma, and demonstrates that PKC zeta is a target for Rituximab. Therefore, PKC zeta could represent an important parameter for Rituximab efficacy and a promising target for future targeted therapy in follicular lymphoma.
Targeting CD22 in Childhood B-Precursor Acute Lymphoblastic Leukemia (Pre-B ALL): Pre-Clinical Studies and Phase I Trial of the Anti-CD22 Immunotoxin CAT-3888 (BL22).
Authors: Wayne Alan S. , Findley Harry W. , Lew Glen , Ahuja Yachna , Gu Lubing , Stetler-Stevenson Maryalice , Kreitman Robert J. , Pastan Ira 
Published: October 2019

Abstract
Although most children with pre-B ALL are cured, treatment is associated with multiple toxicities and outcome after relapse is poor. New therapies are needed to overcome drug resistance and reduce non-specific toxicities of chemotherapy. We evaluated the B-lineage differentiation antigen CD22 and the anti-CD22 immunotoxin RFB4(dsFv)-PE38 (CAT-3888 or BL22) in childhood ALL.
Methods: Blasts were obtained from children with pre-B ALL. Flow cytometry was used to determine CD22 expression and anti-CD22 antibody binding using the BD Quantibrite System. 72 hour in vitro protein synthesis cytotoxicity assays were conducted. Murine xenografts (human ALL cell line EU-1 into CB17 SCID mice) were treated with varying doses of CAT-3888. A pediatric Phase I trial of CAT-3888 was initiated.
Results: All cases (n=69) were CD22 positive. Median CD22 site density (studied in 28 cases) was 4,099 sites/cell (range, 451 – 9,380). In vitro cytotoxicity to CAT-3888 was assessed in 43 cases and the median IC50 was 10 ng/ml. Murine xenografts treated with CAT-3888 had significant prolongation of leukemia free survival in a dose responsive fashion (p<0.05). 21 subjects (18 ALL, 3 lymphoma; 3–22 years of age) were treated on a Phase I trial of CAT-3888 at doses of 10–40 mcg/kg QOD for 3–6 doses with cycles repeated every 21–28 days. Treatment was well tolerated and adverse events attributed to CAT-3888 were reversible. Pharmacokinetic parameters appeared to be influenced by disease burden consistent with rapid drug binding by CD22 positive blasts. All subjects were heavily pre-treated and had progressive high burden disease at the time of treatment. Transient clinical activity was observed in 17 of 21 subjects as evidenced by decreased peripheral blood blast count (8), decreased marrow infiltration (6), decreased extramedullary infiltration (3), increased platelet count (2), increased neutrophil count (1), increased reticulocyte count (1), improved PET scan (1), decreased tumor-associated pain (2), and/or peripheral blast count stabilization (5). A dose response was apparent with 6 of 12 (50%) achieving disease stabilization at or above 30 mcg/kg (vs. 0/9 at lower doses). Three subjects developed high-titer neutralizing antibodies, 1 of which had pre-existing low titer antibodies from prior pseudomonas infection.
Conclusions: CD22 represents a relevant target for childhood pre-B ALL. All cases tested were CD22+ and most blasts were highly sensitive to CAT-3888 in vitro at concentrations below clinically achievable levels. CAT-3888 showed a dose response effect and prolonged leukemia free survival in murine ALL xenografts. CAT-3888 is well tolerated in children and activity has been seen in most subjects treated on the Phase I trial. A new higher affinity anti-CD22 immunotoxin (CAT-8015 or HA22) is in development.
Prospective Study of Oral Valganciclovir for Pre-Emptive Therapy of Cytomegalovirus After Allogeneic Stem Cell Transplantation.
Authors: De La Camara Rafael , Vazquez Lourdes , Lopez Javier , Solano Carlos , Serrano David , Gracia-Noblejas Ana , Ribera Josep-Maria , Ferra Christelle 
Published: October 2019

Abstract
Abstract 1168
Poster Board I-190
Intravenous ganciclovir (iv-Gcv) is the standard drug for pre-emptive therapy of citomegalovirus (CMV) infection in allogeneic stem cell (allo-SCT) patients. Valganciclovir (Vgcv), an oral prodrug of ganciclovir, is used very often in practice although there is no approved indication for this specific use.

Methods:
We performed a prospective phase II multicentric study with Vgcv in adult patients to evaluate its efficacy and safety in the pre-emptive treatment of CMV-Ag or DNAemia within the first 180 days after SCT (ClinicalTrials.gov Identifier: NCT00386412). The results were compared with those obtained with iv-GCV in a retrospective control group. The primary study endpoint (success) was the achievement of negative CMV-AG/PCR on day 14 of treatment without changing the protocol antiviral (Vgcv or iv-gcv). Secondary end-points were negative CMV-AG/PCR, rate of neutropenia (<500 neutrophils/mm3) and nephrotoxicity, until 35 days after the beginning of treatment. A minimum patient weight of 50 kg was required. Vgcv was given at 900 mg/12h for 14 days (induction therapy) followed by 900 mg/day for another 14 days (maintenance treatment), in both cases adjusted according to renal function. If CMV was positive at day +21, the treatment was considered a failure and Vgcv was stopped.

Patients:
Here we presented the final results on 90 patients (60 prospective treated with Vgcv and 30 treated with iv-Gcv). There were no differences between Vgcv and iv-Gcv groups in median age (47 vs 49 years), median weight (72,5 vs 62kg), type of donor (55% vs 37% HLA identical siblings, 43% vs 56% unrelated and 2% vs 7% related mismatch), and conditioning regimen (mieloablative 42% vs 57%; reduced intensity in 58% vs 43%). More iv-Gcv patients had acute GVHD II-IV at CMV viremia presentation (12% vs 42%). The majority of the patients where receiving immunosuppression at CMV viremia presentation (97% vs 97%). Median time for CMV-Ag/PCR positivity was 46 days after SCT for both groups.

Results:
Two patients developed CMV disease during antiviral therapy: one in the Vgcv group (a proved gastric on day +9 of therapy) and one in the iv-gcv group. At 2 months of follow-up no more cases of CMV disease were diagnosed.
Nuetropenia (<500/mm3): 8 cases in Vgcv group (13.3%) vs 1 case in iv-gcv group (3.3%) (P ns). Only one patient in the iv-gcv group developed nephrotoxicity.

Comments:
Oral valganciclovir therapy given at a fixed dose in patients over 50 kg for the pre-emptive therapy of CMV in allogeneic patients was effective and with similar toxicity compared with iv-gcv.

Disclosures:
No relevant conflicts of interest to declare.
Defective Inhibitory Signaling in CLL B Cells and Increased Recruitment of PI3K by c-Cbl in Zap-70+ CLL.
Authors: Kai Xin , Chellappa Vasant , Moya Jesse , Taylor Kendra N. , Hochberg Ephraim P. , Amrein Philip C. , Pillai Shiv 
Published: October 2019

Abstract
Abstract 1258
Poster Board I-280

Background
An inhibitory signaling pathway involving sialic acid 9-O-acetyl esterase (SIAE), sialic acid binding lectins (Siglecs) particularly Siglec-2/CD22, the Lyn tyrosine kinase, and the SH2 domain containing tyrosine phosphatase, SHP-1, attenuates B cell receptor signaling and sets a threshold for B cell activation. A key step in the process is the requirement that SIAE access N-glycans on Siglec ligands and remove 9-O-acetyl groups from terminal αa2,6 linked sialic acid moieties. Siglec-ligand interaction is followed by phosphorylation of ITIM tyrosines on CD22 by Lyn, and the recruitment of SHP-1 by CD22 resulting in signal attenuation (Cariappa et al., J.Exp.Med.2009, 206, 125). While Lyn has both positive and negative signaling functions, knockout mice studies suggest that inhibitory functions are dominant. Previous studies have shown that CLL cells overexpress active Lyn at the protein level and that Lyn is localized to sites beyond the plasma membrane. Although cell surface expression of CD22 is reduced in CLL, it is not known if CD22 can be accessed in CLL cells by promiscuously active Lyn. We sought to ask if cancer progression in CLL involves the evolution of mechanisms to evade inhibitory signaling, thus tipping the balance towards positive, pro-proliferative signaling by Lyn.

Methods
CLL B cells from patient and control subjects were isolated. Immunoprecipitation and Western blot approaches were used to quantitate the total cellular levels of Lyn and CD22αa and β proteins at the protein level, the ratio of CD22 phosphorylated on an inhibitory tyrosine to total CD22, recruitment of SHP-1 by CD22, the activation of Syk, the expression of c-Cbl and the recruitment of PI3K by c-Cbl in CLL and control B cells.

Results
A modest decrease in total CD22αa and β proteins was observed in CLL but a dramatic reduction in the proportion of ITIM-phosphorylated CD22, and a reduction in the recruitment of SHP-1 by CD22 in CLL B cells. Decreased inhibitory signaling in CLL correlates with an increase in active Syk. An increase in c-Cbl protein levels was observed and an increased recruitment of p85PI3K was observed specifically in Zap-70 positive CLL.

Conclusions
Defective inhibitory signaling may contribute to disease progression in CLL. This defect probably results from the inability of CD22 to access 9-O-deacetylated ligands even in the presence of active Lyn. Enhanced constitutive BCR signaling prevails in all CLL patients but in Zap70+ CLL patients p85PI3K is more readily recruited by c-Cbl.

Disclosures
Hochberg: Biogen-Idec: Speakers Bureau; Genentech: Speakers Bureau; Amgen: Speakers Bureau; Enzon: Speakers Bureau.
Copy Number Alterations at Polymorphic Loci May Be Acquired Somatically in Patients with Myelodysplastic Syndromes.
Authors: Starczynowski Daniel T. , Vercauteren Suzanne , Sung Sandy , Brooks-Wilson Angela , Lam Wan L , Karsan Aly 
Published: October 2019

Abstract
Abstract 2782
Poster Board II-758
Myelodysplastic (MDS) clones are thought to arise from a primitive CD34+ hematopoietic cell as a result of disrupted genomic integrity. Although approximately 50% of low-risk MDS patients do not exhibit karyotypic alterations, recent studies have identified submegabase copy number alterations in a proportion (18–68%) of cytogenetically normal cases using genomic array platforms. Recently, we observed disease-associated copy number alterations in low-risk MDS patients that overlapped common loci known to be sites of copy number variants (CNV). These CNV or copy number polymorphisms are a source of structural variation in the genome of a normal population, and widely assumed to be constitutional and not relevant findings in malignant tissue. Here we show by whole genome array comparative genomic hybridization that copy number changes in the CD34+ MDS clone that occur at polymorphic loci are frequently somatic alterations rather than constitutional variants. Further, the extent of copy number variation is increased in CD34+ cells of MDS patients compared to CD34+ cells of age-matched controls. This increase in disease-associated copy number alterations at polymorphic loci shows a trend toward association with poorer overall survival. Our findings demonstrate that copy number alterations at known polymorphic loci in CD34+ cells from lower-risk MDS patients are frequently due to somatic changes rather than constitutional polymorphisms. Further, alterations in copy number at these sites are likely not benign, regardless of whether they represent constitutional or somatic alterations, and may contribute to disease progression.

Disclosures:
No relevant conflicts of interest to declare.
Combination of ATRA with a COX2 Inhibitor Induces Synergistic Effects On RARalpha2-Expressing Multiple Myeloma (MM) Cells.
Authors: Wang Siqing , Shi Lei , Xu Hongwei , Xu Chunjiao , Zangari Maurizio , Tricot Guido J. , Zhan Fenghuang 
Published: October 2019

Abstract
Abstract 2809
Poster Board II-785
We recently observed that ATRA treatment selectively kills RARalpha2-expressing, while sparing RARalpha2-deficient MM cells. Previous investigations in the colon cancer cells have shown that ATRA inhibits WNT signaling through down-regulation of COX-2. Therefore, we wanted to evaluate the role of WNT signaling in ATRA-induced cell death and growth inhibition of RARalpha2-expressing myeloma cells. To our surprise, we found that ATRA treatment activated but not inhibited WNT signaling in RARalpha2-expressing myeloma cells, based on increased β-catenin levels in ATRA-treated cells. ATRA exerted minimal effects on activation of WNT signaling pathway in RARalpha2-deficient MM cells, and forced expression of RARalpha2 in RARalpha2-deficient cells restored the stimulatory activities of ATRA on the WNT signaling pathway, demonstrating that RARalpha2 expression is required for the ATRA-induced stimulation of WNT signaling in MM cells. Lithium chloride (LiCl) treatment, which activates WNT signaling, partially abrogated ATRA-induced cell death and growth inhibition in RARalpha2-expressing cells, indicating that ATRA-induced activation of WNT signaling resulted in ATRA-resistance and decreased killing of MM cells, suggesting that a combination of targeting WNT signaling pathway and ATRA treatment is necessary for ATRA-based therapy of RARalpha2-expressing myeloma. COX-2 inhibition blocks WNT signaling in colon cancer. Similarly, we found that a COX-2 inhibitor CAY10404 also blocked WNT signaling in RARalpha2-expressing cells as well as in ATRA-treated cells. Interestingly, CAY10404 activated MEK/ERK signaling pathway, while ATRA abrogated CAY10404-induced activation of MEK/ERK signaling pathway. These results demonstrate that the combination of ATRA and COX-2 inhibitor exerts synergistic inhibitory effects on both WNT and MEK/ERK signaling pathways. A combination of ATRA and the COX-2 inhibitor resulted in synergistic cytotoxicity of RARalpha2-expressing MM cells in-vitro. More importantly, the combination of ATRA and CAY10404 also resulted in a synergistic growth inhibition of established MM tumors in SCID mice. Our study demonstrates the importance of targeting WNT signaling in ATRA-based therapy in RARalpha2-expressing myeloma and provides a rationale for the combinational use of ATRA and COX-2 inhibitors.

Disclosures:
No relevant conflicts of interest to declare.
Factor XII Stimulates ERK1/2 and Akt through uPAR, Integrins, and the EGFR to Initiate Angiogenesis.
Authors: Larusch Gretchen , Mahdi Fakhri , Shariat-Madar Zia , Adams Gregory N , Sitrin Robert , Zhang Wanming , McCrae Keith R. , Schmaier Alvin H. 
Published: October 2019

Abstract
Abstract 3040
Poster Board II-1016
The physiologic function of factor XII (XII) is not known. New interest in XII has occurred because XII KO mice are protected from thrombosis. Exposed arterial collagen, aggregated protein, RNA, and platelet polysomes are recently recognized entities in developing thrombus that promote XII autoactivation to XIIa increasing thrombus formation, independent of a role in hemostasis. However, these observations do not indicate a constitutive, physiologic function for XII. We sought a physiologic function for zymogen XII. XII has been recognized to stimulate MAP kinase. Cleaved high molecular weight kininogen (HKa) is known to be antiangiogenic. Further, XII and HK mutually block each others binding to endothelial cells. Both XII and HKa bind urokinase plasminogen activator receptor (uPAR) at an overlapping site. We investigated if XII stimulates cells by interacting with uPAR and if this activity influences angiogenesis. XII (3-200 nM) with 0.05 mM Zn ion induces ERK1/2 (MAPK44 and 42) and Akt (Ser473) phosphorylation in endothelial cells. XII-induced phosphorylation of ERK1/2 or Akt is a zymogen activity, not an enzymatic event. ERK1/2 or Akt phosphorylation is blocked upstream by PD98059 or Wortmannin or LY294002, respectively. The uPAR signaling region for XII is on domain 2 adjacent to uPAR's integrin binding site. HKa or peptides from HKa's domain 5 inhibit XII-induced ERK1/2 and Akt phosphorylation. A beta-1-integrin peptide that binds uPAR, antibody 6S6 to beta-1-integrin, or the EGFR inhibitor AG1478 blocks XII-induced phosphorylation of ERK1/2 and Akt. XII induces endothelial cell proliferation and 5-bromo-2'deoxy-uridine incorporation. XII stimulates aortic sprouting in normal but not uPAR deficient mouse aorta and this mechanism is blocked by PD98059, LY294002, AG1478, or HKa. XII also induces angiogenesis in matrigel plugs. Finally, XII knockout mice have reduced constitutive and wound-induced blood vessel number on initial biopsy and 9 days after wound healing, respectively. In sum, XII initiates outside-in signaling mediated by uPAR, beta-1-integrin, and the EGFR leading to HUVEC proliferation, growth, and angiogenesis. XII is a constitutive proangiogenic protein.

Disclosures
No relevant conflicts of interest to declare.
Interferon Alpha Alone Is Able to Cure Chronic Myeloid Leukemia In a Small Subset of Patients Despite the Persistence of Leukemic Cells: Experience of Long Follow up After Treatment Discontinuation
Authors: Mahon Francois-Xavier , Fort Marie-Pierre , Etienne Gabriel , Marit Gerald , Milpied Noel , Pigneux Arnaud , Cony-Makhoul Pascale , Reiffers Josy 
Published: October 2019

Abstract
Abstract 2299
Before the imatinib era and besides allogeneic hematopoietic stem cell transplantation (HSCT), interferon alpha (IFN) was an alternative therapeutic option to treat chronic myeloid leukemia (CML). In very rare situations, some patients achieved a complete molecular remission (CMR) defined as the absence of detectable BCR-ABL transcript using qualitative PCR available at that time.We previously reported the outcome of patients with CML in complete cytogenetic remission after cessation of IFN (J Clin Oncol., 2002, 20:214-220.). Here, we update this experience with a long outcome after discontinuation of IFN. The main criteria for IFN discontinuation was the achievement of a sustained CMR lasting for at least two years. Twenty-one patients (9 males, 12 females; median age 39 years) were eligible for this study. One, 2 and 18 pts belonged to respectively high, intermediate and low risk group according to the Sokal score.All patients were treated with IFN (median dose 56ui/week) during a median time of 7.5 years (2.4-14) and 4 of them received an autologous HSCT. The median time to achieve CMR was 54 month (5-140). The median follow up after discontinuation of IFN treatment was 8 years (mean 9, range 5–18). Quantitative PCR was used to quantify BCR-ABL and evaluate residual disease. We distinguished two groups of patient according to the molecular pattern: group 1 (n=12) regards patients with sustained CMR confirmed by quantitative PCR. One patient belonging to this group relapsed and progressed suddenly after 5 years of IFN discontinuation and was treated with allogeneic HSCT. Group 2 (n=9) regards patients who are not in CMR with leukemic cells detectable by RQ-PCR. Six of them exhibit a fluctuation of BCR-ABL detection assessed by RQ-PCR. For the 3 other patients with a median follow up of 6 years after discontinuation, RQ-PCR became clearly positive after a median time of 2 years with a level of residual disease that corresponds to the definition of major molecular response (3 log reduction of BCR-ABL). No progression was observed in this group.
So we conclude that the persistence of leukemic cells at low level after discontinuation of IFN treatment does not automatically lead to CML relapse. This long term follow up after IFN discontinuation raises the question of the need of a complete eradication of residual leukemic cells to cure the disease

Disclosures:
No relevant conflicts of interest to declare.
Comparative Analysis of Outcomes of Allogeneic Peripheral Blood Stem Cell Transplantation From Related and Unrelated Donors for Adults with Hematologic Malignancies
Authors: Gao Chunji , Li Xiaohong , Li Honghua , Huang Wenrong , Wu Xiaoxiong , Ma Jian , Bo Jian , Wang Zhihong , Cao Yongbin , Zhao Yu , Yu Li , Da Wanming 
Published: October 2019

Abstract
Abstract 2302
Although allogeneic peripheral blood stem cell transplantation from a matched related donor (RD-PBSCT) presents the best curable opportunity for many patients with hematologic malignancies, only about one third of individuals have HLA matched sibling donors. Fortunately, from unrelated donor peripheral blood stem cell transplantation has been acceptable and expanded recently. In order to evaluate the effect of allogeneic peripheral blood stem cell transplantation from unrelated donor (URD-PBSCT), we compare results of URD-PBSCT and RD-PBSCT that were done for 172 consecutive adult patients with hematologic maligancies from Jan 2002 to Dec 2008 at a single-center. Among these patients, 62 cases underwent URD-PBSCT and 110 cases underwent RD-PBSCT. Myeloablative conditioning was adopted for all patients. In graft versus host disease (GVHD) prophylaxis, 49 URD-PBSCT recipients received CSA, MTX, MMF and ATG (URD-ATG group), 13 recipients were given simulect more in base of URD-ATG group (URD-ATG+CD25 group) while RD-PBSCT recipients (RD group) received CSA, MTX and MMF. Engraftment was achieved in 98.4% of URD-PBSCT patients and 98.2% of RD-PBSCT patients (100% for patients surviving beyond 28 days after transplant). The cumulative incidence of acute GVHD (grade II-IV) was 15.4%, 36.7% and 29.1% respectively in the URD-ATG+CD25, URD-ATG and RD groups (P = 0.275). The cumulative incidence of chronic GVHD was 0%, 45.6%, 39.6% respectively and significant lower in URD-ATG+CD25 group than the other two groups (P = 0.0134). Relapse incidence was 53.8%, 12.2%, 14.5% respectively and significant higher in URD-ATG+CD25 group than the other s (P = 0.0059), while there was no different between the URD-ATG and RD groups (P = 0.610). Estimated overall survival (OS) at 5 years was 30.8%, 69.4% and 67.3% respectively and no significant difference between URD-ATG group and RD group (p=0.898). Adverse prognosis factors for relapse and OS included transplant not in remission and GVHD prophylaxis with simulect. Our results indicate PBSCT from unrelated donor may be considered comparable to those from related donor.

Disclosures:
No relevant conflicts of interest to declare.