Study of the RET receptor dysfunctions caused by mutations associated with human neoplastic disorders and developmental diseases

The ret proto-oncogene encodes a membrane spanning glycoprotein which is a member of the receptor tyrosine kinase family (Hanks et al. 1988). RET is the signaling component of multi-subunit receptor complexes for the GDNF of family ligands, including GDNF, neurturin, artemin and persephin. The binding components of these receptor complexes are glycosyl-phosphatidylinositol (GPI)-membrane anchored molecules, known as GDNF family receptor α (GFRαs). Four different GFRαs (GFRα1–4) dictate ligand specificity. Germline point mutations of RET are responsible for the inheritance of MEN2 (Multiple Endocrine Neoplasia type 2) cancer syndromes which are usually divided into three different clinical subtypes: MEN2A, MEN2B and FMTC (familial medullary thyroid carcinoma), which are all autosomal dominant cancer syndromes. Inactivating mutations of RET cause an impaired development of the enteric nervous system which is responsible for the Congenital megacolon or Hirschprung's disease (HSCR). The aim of my work was to study the expression of different RET mutants in order to highlight their biological role in diverse cellular context. In particular, we focused on gain of function cysteine mutations that are responsible for medullary thyroid carcinoma (MTC) by causing covalent RET dimerisation, leading to ligand-independent activation of its tyrosine kinase. In this context, the association of Cys609 and Cys620 activating mutations with HSCR is still an unresolved paradox. To address this issue, we have developed a transgenic model for human diseases (specifically, Multiple Endocrine Neoplasia type 2 and Hirschsprung disease) through the insertion of a gain and loss of function RET mutation, the RETC620R in the mouse genome. We have also studied the in vitro effects of a tyrosine kinase inhibitor PP1, which we propose could represent a potential treatment strategy and merits further testing, using in vivo models such as the one we have generated

Graft monocytic myeloid-derived suppressor cell content predicts the risk of acute graft-versus-host disease after allogeneic transplantation of granulocyte colony-stimulating factor-mobilized peripheral blood stem cells.

Abstract Myeloid-derived suppressor cells (MDSCs) are powerful immunomodulatory cells that in mice play a role in infectious and inflammatory disorders, including acute graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation. Their relevance in clinical acute GVHD is poorly known. We analyzed whether granulocyte colony-stimulating factor (G-CSF) administration, used to mobilize hematopoietic stem cells, affected the frequency of MDSCs in the peripheral blood stem cell grafts of 60 unrelated donors. In addition, we evaluated whether the MDSC content in the peripheral blood stem cell grafts affected the occurrence of acute GVHD in patients undergoing unrelated donor allogeneic stem cell transplantation. Systemic treatment with G-CSF induces an expansion of myeloid cells displaying the phenotype of monocytic MDSCs (Lin low/neg HLA-DR − CD11b + CD33 + CD14 + ) with the ability to suppress alloreactive T cells in vitro, therefore meeting the definition of MDSCs. Monocytic MDSC dose was the only graft parameter to predict acute GVHD. The cumulative incidence of acute GVHD at 180 days after transplantation for recipients receiving monocytic MDSC doses below and above the median was 63% and 22%, respectively ( P = .02). The number of monocytic MDSCs infused did not impact the relapse rate or the transplant-related mortality rate ( P > .05). Although further prospective studies involving larger sample size are needed to validate the exact monocytic MDSC graft dose that protects from acute GVHD, our results strongly suggest the modulation of G-CSF might be used to affect monocytic MDSCs graft cell doses for prevention of acute GVHD

Circulating miRNA panel for prediction of acute graft-versus-host disease in lymphoma patients undergoing matched unrelated hematopoietic stem cell transplantation

Acute graft-versus-host disease (aGVHD) results in significant morbidity and mortality after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Noninvasive diagnostic and prognostic tests for aGVHD are currently lacking, but would be beneficial in predicting aGVHD and improving the safety of allo-HSCT. Circulating microRNAs exhibit marked stability and may serve as biomarkers in several clinical settings. Here, we evaluated the use of circulating microRNAs as predictive biomarkers of aGVHD in lymphoma patients after allo-HSCT from matched unrelated donors (MUDs). After receiving informed consent, we prospectively collected plasma samples from 24 lymphoma patients before and after unmanipulated MUD allo-HSCT; microRNAs were then isolated. Fourteen patients developed aGVHD symptoms at a median of 48 days (range: 32–90) post-transplantation. Two patients developed intestinal GVHD, eight cutaneous GVHD, and four multiorgan GVHD. The microRNA expression profile was examined using quantitative real-time polymerase chain reaction (qRT-PCR). MicroRNAs 194 and 518f were significantly upregulated in aGVHD samples compared with samples taken from non-aGVHD patients. Remarkably, these upregulated microRNAs could be detected before the onset of aGVHD. Pathway prediction analysis indicated that these microRNAs may regulate critical pathways involved in aGVHD pathogenesis. Considering the noninvasive characteristics of plasma sampling and the feasibility of detecting miRNAs after allo-HSCT using real-time polymerase chain reaction, our results indicate that circulating microRNAs have the potential to enable an earlier aGVHD diagnosis and might assist in individualizing therapeutic strategies after MUD allo-HSCT. Nevertheless, standardization of blood sampling and analysis protocols is mandatory for the introduction of miRNA profiling into routine clinical use

cd3 graft cell count predicts chronic gvhd incidence in haploidentical allogeneic transplantation using post transplant cyclophosphamide

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Impact of Cytomegalovirus Replication and Cytomegalovirus Serostatus on the Outcome of Patients with B Cell Lymphoma after Allogeneic Stem Cell Transplantation

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Biology of peripheral T cell lymphomas – Not otherwise specified: Is something finally happening?

Introduction: Peripheral T-cell lymphomas represent a rare, heterogeneous group of nodal and extra-nodal mature T-cell lymphomas. Among those, the subtype of PTCL not otherwise specified (PTCL-NOS) account for about 25% of all PTCL. While other PTCL subtypes are increasingly recognized as discrete entities based on specific genotypic and phenotypic alterations, the diagnosis of PTCL-NOS is currently performed on an “exclusion criteria” model, since PTCL-NOS lack pathognomonic features. Methods: In this review, we describe the classical pathological features of PTCL-NOS and integrate them with the most recent molecular findings. Results: Thanks to gene expression profiling and next generation sequencing approaches, we have recently improved our knowledge of PTCL in general and PTCL-NOS in particular. Indeed, specific patterns of gene expression were reported to segregate PTCL into more homogeneous subtypes associated with distinct clinical outcome. Furthermore, we describe how immunophenotypic, expression and mutational data helped to better define a new subgroup of PTCL-NOS displaying a global profile close to T Follicular Helper cell elements. Finally, we review how these new acquisitions are changing the current diagnostic approach to PTCL-NOS, and how phenotypic features and oncogenic pathways operative in these lymphomas are becoming targets of novel treatments. Conclusion: Although no recurrent and specific biological aberrations have been discovered yet, novel integrated genomic and transcriptomics approaches are significantly improving our knowledge of PTCL biology and support the development of new powerful diagnostic and prognostic markers, as well as targets of future therapies

Targeting the DNA Damage Response to Increase Anthracycline-Based Chemotherapy Cytotoxicity in T-Cell Lymphoma

Mature T-cell lymphomas (MTCLs) represent a heterogeneous group of aggressive non-Hodgkin lymphomas comprising different entities. Anthracycline-based regimens are considered the standard of care in the front-line treatment. However, responses to these approaches have been neither adequate nor durable, and new treatment strategies are urgently needed to improve survival. Genomic instability is a common feature of cancer cells and can be caused by aberrations in the DNA damage response (DDR) and DNA repair mechanisms. Consistently, molecules involved in DDR are being targeted to successfully sensitize cancer cells to chemotherapy. Recent studies showed that some hematological malignancies display constitutive DNA damage and intrinsic DDR activation, but these features have not been investigated yet in MTCLs. In this study, we employed a panel of malignant T cell lines, and we report for the first time the characterization of intrinsic DNA damage and basal DDR activation in preclinical models in T-cell lymphoma. Moreover, we report the efficacy of targeting the apical kinase ATM using the inhibitor AZD0156, in combination with standard chemotherapy to promote apoptotic cell death. These findings suggest that DDR is an attractive pathway to be pharmacologically targeted when developing novel therapies and improving MTCL patients’ outcomes