Chemotherapy at the wheel of ALL relapse

In this issue of Blood, Li et al(1) present an extensive in-depth genetic characterization of diagnostic, relapse, and remission samples from a cohort of 103 pediatric patients with acute lymphoblastic leukemia (ALL) treated according to the Shanghai Children's Medical Center ALL-2005 frontline protocol. Together with data obtained from 208 serial bone marrow samples collected during ALL therapy, their work suggests that relapse in a fraction of childhood ALL patients is driven by chemotherapy-induced mutations, which impact therapy response

Molecular pathogenesis of B-cell Post-Transplant Lymphoproliferative Disorder: what do we know so far?

Posttransplant lymphoproliferative disorder (PTLD) is a potentially fatal disease that arises in 2%-10% of solid organ and hematopoietic stem cell transplants and is most frequently of B-cell origin. This very heterogeneous disorder ranges from benign lymphoproliferations to malignant lymphomas, and despite the clear association with Epstein-Barr Virus (EBV) infection, its etiology is still obscure. Although a number of risk factors have been identified (EBV serostatus, graft type, and immunosuppressive regimen), it is currently not possible to predict which transplant patient will eventually develop PTLD. Genetic studies have linked translocations (involving C-MYC, IGH, BCL-2), various copy number variations, DNA mutations (PIM1, PAX5, C-MYC, RhoH/TTF), and polymorphisms in both the host (IFN-gamma, IL-10, TGF-beta, HLA) and the EBV genome to B-cell PTLD development. Furthermore, the tumor microenvironment seems to play an important role in the course of disease representing a local niche that can allow antitumor immune responses even in an immunocompromised host. Taken together, B-cell PTLD pathogenesis is very complex due to the interplay of many different (patient-dependent) factors and requires thorough molecular analysis for the development of novel tailored therapies. This review aims at giving a global overview of the currently known parameters that contribute to the development of B-cell PTLD.status: publishe

Posttransplant molecular Burkitt lymphomas are frequently MYC-negative and characterized by the 11q-gain/loss pattern

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Clinicopathological comparison of plasmablastic lymphoma in HIV-positive, immunocompetent and post-transplant patients: single center series of 25 cases and meta-analysis of 277 reported cases

Plasmablastic lymphoma (PBL) is a rare B-cell non-Hodgkin lymphoma often associated with Epstein-Barr virus (EBV) infection. To gain insight in this aggressive lymphoma subtype, the clinicopathologic characteristics of 25 unpublished single-center PBLs (2 in acquired immunodeficiency syndrome patients, 11 in immunocompetent individuals [IC-PBL], 12 in transplant recipients [PT-PBL]) and of 277 reported PBLs were summarized. In the reported series, PBL patients were predominantly male (77%) with a median age at diagnosis of 46 years (range, 1.2 to 87 y). The majority of the biopsies (66%) was EBV positive. Extranodal presentation was most frequent (88%, of which 35% were oral, 18% gastrointestinal, 12% cutaneous). PBL was diagnosed in acquired immunodeficiency syndrome patients (50%), immunocompetent individuals (35%), and transplant recipients (14%). These subgroups differed in age at diagnosis (median: 41, 64, 47 y, respectively), primary localization (oral, oral, cutaneous, respectively), EBV positivity (75%, 50%, 67%, respectively), CD45 expression (31%, 33%, 70%, respectively), and C-MYC aberrations (78%, 44%, 38%, respectively). Ann Arbor stage I, EBV positivity, CD45 expression, and lack of C-MYC aberrations were associated with better outcome (P<0.05). Our series of IC-PBL and PT-PBL cases revealed differential expression of CD10 (0% vs. 42%, respectively), CD56 (22% vs. 42%, respectively), TP53 (67% vs. 8%, respectively), and BCL2 (88% vs. 25%, respectively). Gene expression analysis of 5 of our PT-PBLs revealed upregulation of DNMT3B, PTP4A3, and CD320 in EBV-positive PT-PBL and suggested a role for cancer/testis antigens. The results of this retrospective study suggest different pathogenic mechanisms of PBL in different immunologic settings and a potentially important impact of EBV and CD45 on prognosis.status: publishe

Identification of distinct subgroups of EBV-positive post-transplant diffuse large B-cell lymphoma

Post-transplantation lymphoproliferative disorder is an aggressive complication of transplantation, most frequently of diffuse large B-cell lymphoma morphology and associated with Epstein-Barr virus (EBV) infection/reactivation. In this study the microenvironment of EBV(+) (n=23) and EBV(-) (n=9) post-transplant non-germinal center B-cell diffuse large B-cell lymphoma was characterized. Of EBV(+) cases somatic hypermutation analysis, gene expression profiling, and extensive phenotyping were performed. Our results demonstrated variable cytotoxic T-cell infiltration and significantly increased CD163(+) M2 macrophage infiltration in EBV(+) compared with EBV(-) post-transplant diffuse large B-cell lymphoma. On the basis of IgM staining and hypermutation analysis, two EBV(+) post-transplant diffuse large B-cell lymphoma subgroups were identified: IgM(+) tumors lacking somatic hypermutations and IgM(-) tumors harboring somatic hypermutations. IgM(-) tumors arose late following transplantation (median interval: 16 months), mainly in kidney recipients. IgM(+) tumors on the other hand arose early (median interval: 3 months, P-value=0.0032), almost exclusively following stem cell transplantation and were associated with worse outcome (median survival 1 month for IgM(+) versus 41 months for IgM(-) tumors, log-rank/Wilcoxon P-value 0.07/0.04). Notably, IgM(+) tumors were characterized by plasma cell features (monotypic kappa/lambda expression, high MUM1 expression, and partial CD138 expression) and a high proliferation index. Consistent with the plasma cell phenotype, unfolded protein response signaling was upregulated. In contrast, IgM(-) EBV(+) post-transplant diffuse large B-cell lymphoma did not express kappa, lambda, IgD, or CD138 and expressed limited MUM1. In these tumors T-cell signaling was enhanced associated with increased T-cell infiltration compared with IgM(+) cases. Overall, our results allow further molecular classification of EBV(+) post-transplant diffuse large B-cell lymphoma and provide a rationale for the use of subtype-specific-targeted therapies (eg, bortezomib in IgM(+) tumors). Our findings also provide a biological basis for the clinical differences between post-transplant lymphoproliferative disorder following solid organ and stem cell transplantation, which are regarded as different disorders.Modern Pathology advance online publication, 6 January 2017; doi:10.1038/modpathol.2016.199.status: publishe

Detection of bone marrow involvement in newly diagnosed post-transplant lymphoproliferative disorder: (18)F-fluorodeoxyglucose positron emission tomography/computed tomography versus bone marrow biopsy

Detecting bone marrow involvement (BMI) in lymphoma is important as it adversely affects stage. Bone marrow biopsy (BMB) remains the standard to detect BMI but is prone to sampling error. We retrospectively investigated whether (18)F-fluorodeoxyglucose positron emission tomography with computed tomography ((18)F-FDG-PET/CT) could identify BMI in patients with post-transplant lymphoproliferative disorder (PTLD) with sufficient accuracy in comparison with staging BMB. Twenty-five patients diagnosed with PTLD who underwent (18)F-FDG-PET/CT and BMB within one month were evaluated. Based on our criteria, six patients (24%) were considered positive for BMI on (18)F-FDG-PET/CT compared to one by BMB. Although we cannot completely exclude false positive results on (18)F-FDG-PET/CT, our data indicate a significantly higher sensitivity of (18)F-FDG-PET/CT compared to BMB (100% vs 17%) but similar specificity. These data confirm the high diagnostic performance of (18)F-FDG-PET/CT for detecting BMI, but prospective studies are needed to determine whether (18)F-FDG-PET/CT could indeed replace staging BMB in PTLD.peerreview_statement: The publishing and review policy for this title is described in its Aims & Scope. aims_and_scope_url: http://www.tandfonline.com/action/journalInformation?show=aimsScope&journalCode=ilal20status: publishe