The involvement of microRNA in the pathogenesis of Richter syndrome.

Richter syndrome is the name given to the transformation of the most frequent type of leukemia, chronic lymphocytic leukemia, into an aggressive lymphoma. Patients with Richter syndrome have limited response to therapies and dismal survival. The underlying mechanisms of transformation are insufficiently understood and there is a major lack of knowledge regarding the roles of microRNA that have already proven to be causative for most cases of chronic lymphocytic leukemia. Here, by using four types of genomic platforms and independent sets of patients from three institutions, we identified microRNA involved in the transformation of chronic lymphocytic leukemia to Richter syndrome. The expression signature is composed of miR-21, miR-150, miR-146b and miR-181b, with confirmed targets significantly enriched in pathways involved in cancer, immunity and inflammation. In addition, we demonstrated that genomic alterations may account for microRNA deregulation in a subset of cases of Richter syndrome. Furthermore, network analysis showed that Richter transformation leads to a complete rearrangement, resulting in a highly connected microRNA network. Functionally, ectopic overexpression of miR-21 increased proliferation of malignant B cells in multiple assays, while miR-150 and miR-26a were downregulated in a chronic lymphocytic leukemia xenogeneic mouse transplantation model. Together, our results suggest that Richter transformation is associated with significant expression and genomic loci alterations of microRNA involved in both malignancy and immunity.

Case report: lenvatinib in neoadjuvant setting in a patient affected by invasive poorly differentiated thyroid carcinoma.

We report a case of an elderly woman presenting with a huge cervical mass invading the tracheal lumen. Diagnosed as invasive poorly differentiated thyroid cancer, after an endotracheal biopsy, stenting and radiotherapy, it was judged eligible for total thyroidectomy, but surgery was delayed due to pulmonary thromboembolism. The patient was therefore treated with lenvatinib with a neoadjuvant intent until hemodynamic stability was obtained. Thyroidectomy and radioiodine therapy were then performed and the postdose scan revealed an area of modest uptake in the anterior part of the neck. The patient is now in a good clinical status and she continues her follow-up program without any adjuvant therapy.

Efficacy of bendamustine and rituximab in splenic marginal zone lymphoma: results from the phase II BRISMA/IELSG36 study.

Splenectomy in addition to immunotherapy with rituximab can provide quick and sometimes durable disease control in patients with splenic marginal zone lymphoma (SMZL). However, systemic chemotherapy is ultimately required in many cases. The BRISMA (Bendamustine-rituximab as first-line treatment of splenic marginal zone lymphoma)/IELSG (International Extranodal Lymphoma Study Group)36 trial is an open-label, single arm phase II study designed by the IELSG in cooperation with the Fondazione Italiana Linfomi and the lymphoma Study Association according to Simon's two-stage method. The primary endpoint was complete response rate. Fifty-six patients with SMZL diagnosis confirmed on central revision were treated with bendamustine (90 mg/m2  days 1, 2) and rituximab (375 mg/m2  day 1) every 28 days for six cycles (B-R). The overall response and CR rates were 91% and 73%, respectively. Duration of response, progression-free survival and overall survival at 3 years were 93% (95% confidence interval [CI] 81-98), 90% (95% CI 77-96) and 96% (95% CI 84-98), respectively. Toxicity was mostly haematological. Neutropenia grade ≥3 was recorded in 43% of patients; infections and febrile neutropenia in 5·4% and 3·6%. Overall, 14 patients (25%) experienced serious adverse events. Five patients (9%) went off-study because of toxicity and one patient died from infection. In conclusion, B-R resulted in a very effective first-line regimen for SMZL. Based on the results achieved in the BRISMA trial, B-R should be considered when a chemotherapy combination with rituximab is deemed necessary for symptomatic SMZL patients.

Impaired response to influenza vaccine associated with persistent memory B cell depletion in non-Hodgkin's lymphoma patients treated with rituximab-containing regimens.

Influenza vaccination is generally recommended for non-Hodgkin's lymphoma (NHL) patients, but no data are available about the activity of this vaccine after treatment with rituximab-containing regimens. We evaluated the humoral response to the trivalent seasonal influenza vaccine in a group of NHL patients in complete remission for ≥6 mo (median, 29 mo) after treatment with rituximab-containing regimens (n = 31) compared with age-matched healthy subjects (n = 34). B cell populations and incidence of influenza-like illness were also evaluated. For each viral strain, the response was significantly lower in patients compared with controls and was particularly poor in patients treated with fludarabine-based regimens. In the patient group, the response to vaccination did not fulfill the immunogenic criteria based on the European Committee for Medicinal Products for Human Use requirements. Among the patients, CD27(+) memory B cells were significantly reduced, and their reduction correlated with serum IgM levels and vaccine response. Episodes of influenza-like illness were recorded only in patients. These results showed that NHL patients treated with rituximab-containing regimens have persisting perturbations of B cell compartments and Ig synthesis and may be at particular risk for infection, even in long-standing complete remission.

Multiorgan infiltration by CD8+ T cells and 1p;16p translocation in a patient with hypogammaglobulinemia and a reduced number of B cells.

Common variable immunodeficiency (CVID) disorders are the most common form of clinically significant primary immunodeficiencies found in adults. There is now clear evidence that CVID includes a group of clinically and genetically heterogeneous conditions. In addition to recurrent infections, some patients are highly prone to granulomatous lesions. Rarely, CVID may be characterized by an increased number of circulating CD8+ T cells with tissue infiltration. We report a unique case of CVID associated with a sarcoidosis-like disease and polyclonal CD8+ T cell expansion with multiple tissue infiltration occurring in a subject with the chromosome translocation t(1;16). No sequence variant in TACI, APRIL, BAFF, ICOS or BTK genes was discovered. Cytometric analysis showed that the chemokine receptors expressed on peripheral and tissue CD8+ T cells are responsible for the tissue homing of the cells. Moreover, CD8+ T cells produced high amounts of IFN-γ, but not IL-4 and IL-17, with regular expression of the transcription factor Vav1. Genes coding for IL-32 and FRAP1, both involved in the regulation of memory T cell differentiation, are located in the translocation breakpoint. This suggests that a chromosomal abnormality plays a role in the clinical features of this phenotypic variant of CVID.

PIK3CA Mutations as a Molecular Target for Hormone Receptor-Positive, HER2-Negative Metastatic Breast Cancer.

Despite the significant achievements in the diagnosis and treatment of metastatic breast cancer (MBC), this condition remains substantially an incurable disease. In recent years, several clinical studies have aimed to identify novel molecular targets, therapeutic strategies, and predictive biomarkers to improve the outcome of women with MBC. Overall, ~40% of hormone receptor (HR)+/HER2- MBC cases harbor alterations affecting the (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway. This pathway is a major target in oncogenesis, as it regulates growth, proliferation, cell survival, and angiogenesis. Lately, the pharmacologic targeting of PIK3CA in HR+/HER2- MBC has shown significant benefits after the occurrence of endocrine therapy resistance. The orally available α-selective PIK3CA inhibitor, alpelisib, has been approved in this setting. To perform an optimal patients' selection for this drug, it is crucial to adopt a tailored methodology. Clinically relevant PIK3CA alterations may be detected in several biospecimens (e.g. tissue samples and liquid biopsy) using different techniques (e.g. real-time PCR and next-generation sequencing). In this study, we provide an overview of the role of PIK3CA in breast cancer and of the characterization of its mutational status for appropriate clinical management.

Gene expression analysis of peripheral T cell lymphoma, unspecified, reveals distinct profiles and new potential therapeutic targets.

Peripheral T cell lymphoma, unspecified (PTCL/U), the most common form of PTCL, displays heterogeneous morphology and phenotype, poor response to treatment, and poor prognosis. We demonstrate that PTCL/U shows a gene expression profile clearly distinct from that of normal T cells. Comparison with the profiles of purified T cell subpopulations (CD4+, CD8+, resting [HLA-DR-], and activated [HLA-DR+]) reveals that PTCLs/U are most closely related to activated peripheral T lymphocytes, either CD4+ or CD8+. Interestingly, the global gene expression profile cannot be surrogated by routine CD4/CD8 immunohistochemistry. When compared with normal T cells, PTCLs/U display deregulation of functional programs often involved in tumorigenesis (e.g., apoptosis, proliferation, cell adhesion, and matrix remodeling). Products of deregulated genes can be detected in PTCLs/U by immunohistochemistry with an ectopic, paraphysiologic, or stromal location. PTCLs/U aberrantly express, among others, PDGFRalpha, a tyrosine-kinase receptor, whose deregulation is often related to a malignant phenotype. Notably, both phosphorylation of PDGFRalpha and sensitivity of cultured PTCL cells to imatinib (as well as to an inhibitor of histone deacetylase) were found. These results, which might be extended to other more rare PTCL categories, provide insight into tumor pathogenesis and clinical management of PTCL/U.

Follicular mucinosis: a clinicopathologic, histochemical, immunohistochemical and molecular study comparing the primary benign form and the mycosis fungoides-associated follicular mucinosis.

OBJECTIVES: To determine (i) whether primary (idiopathic) follicular mucinosis (PFM) and lymphoma-associated follicular mucinosis (LAFM) are distinct or related entities and whether there are reliable criteria that allow the two forms to be distinguished, (ii) the histochemical properties and consequently the type of mucin that accumulates in the follicle in PFM and LAFM, and (iii) whether there is any difference between the staining properties of mucin in patients with PFM and LAFM. METHODS: Thirty-one patients were divided into two groups. Group 1 comprised 20 patients with no associated mycosis fungoides or Sézary syndrome (PFM) and group 2 was made up of the other 11 patients who had clinicopathological evidence of cutaneous T-cell lymphoma (LAFM). The biopsy specimens of the patients were studied with histopathological, histochemical and immunohistochemical methods. Molecular biology studies were also performed. RESULTS: Patients with PFM were more frequently younger (mean age 39 years), women (F:M=3:1), and presented with a solitary lesion involving the head/neck area more often than patients with LAFM who were older (mean age 54 years), men (M:F=2:1), and presented with multiple lesions on areas of the body other than the head/neck area. As for histopathological findings, large cystic spaces filled with mucin and a slight perivascular and periadnexal polyclonal infiltrate of mostly non-atypical lymphocytes without epidermotropism and with an equivalent CD4+/CD8+ cell rate were more suggestive of PFM. On the contrary, patients with LAFM were more probably to present with a dense band-like infiltrate with some atypical lymphocytes and sign of epidermotropism, a prominent CD4+ immunophenotype and a monoclonal rearrangement of the infiltrate. Mucin proved to be a dermal-type mucin, composed of both hyaluronic acid and sulfated glycosaminoglycans. No differences were found in the composition of the follicular mucin in the PFM compared with LAFM. CONCLUSIONS: Although no single, indisputable feature can reliably differentiate PFM from LAFM and a considerable overlapping among the two groups exists, the use of multiple clinical, histological and immunopathological criteria associated with gene rearrangement analysis can be useful in evaluation of those patients.

Time to first treatment and P53 dysfunction in chronic lymphocytic leukaemia: results of the O-CLL1 study in early stage patients.

Chronic lymphocytic leukaemia (CLL) is characterised by a heterogeneous clinical course. Such heterogeneity is associated with a number of markers, including TP53 gene inactivation. While TP53 gene alterations determine resistance to chemotherapy, it is not clear whether they can influence early disease progression. To clarify this issue, TP53 mutations and deletions of the corresponding locus [del(17p)] were evaluated in 469 cases from the O-CLL1 observational study that recruited a cohort of clinically and molecularly characterised Binet stage A patients. Twenty-four cases harboured somatic TP53 mutations [accompanied by del(17p) in 9 cases], 2 patients had del(17p) only, and 5 patients had TP53 germ-line variants. While del(17p) with or without TP53 mutations was capable of significantly predicting the time to first treatment, a reliable measure of disease progression, TP53 mutations were not. This was true for cases with high or low variant allele frequency. The lack of predictive ability was independent of the functional features of the mutant P53 protein in terms of transactivation and dominant negative potential. TP53 mutations alone were more frequent in patients with mutated IGHV genes, whereas del(17p) was associated with the presence of adverse prognostic factors, including CD38 positivity, unmutated-IGHV gene status, and NOTCH1 mutations.

Evaluation of Glycosylated PTGS2 in Colorectal Cancer for NSAIDS-Based Adjuvant Therapy.

Observational/retrospective studies indicate that prostaglandin-endoperoxide synthase-2 (PTGS2) inhibitors could positively affect colorectal cancer (CRC) patients' survival after diagnosis. To obtain an acceptable cost/benefit balance, the inclusion of PTGS2 inhibitors in the adjuvant setting needs a selective criterion. We quantified the 72 kDa, CRC-associated, glycosylated form of PTGS2 in 100 frozen CRC specimens and evaluated PTGS2 localization by IHC in the same tumors, scoring tumor epithelial-derived and stroma-derived fractions. We also investigated the involvement of interleukin-1 beta (IL1ß) in PTGS2 induction, both in vitro and in CRC lysates. Finally, we used overall survival (OS) as a criterion for patient selection. Glycosylated PTGS2 can be quantified with high sensibility in tissue lysates, but the expression in both tumor and stromal cells limits its use for predictive purposes. Immunohistochemistry (IHC) analysis indicates that stromal PTGS2 expression could exert a protective role on patient OS. Stromal PTGS2 was prevalently expressed by cancer-associated fibroblasts exerting a barrier function near the gut lumen, and it apparently favored the antitumor M1 macrophage population. IL1ß was directly linked to gPTGS2 expression both in vitro and in tumors, but its activity was apparently prevalent on the stromal cell population. We suggest that stromal PTGS2 could exert a positive effect on patients OS when expressed in the luminal area of the tumor.

Definition of progression risk based on combinations of cellular and molecular markers in patients with Binet stage A chronic lymphocytic leukaemia.

IGHV mutational status and ZAP-70 or CD38 expression correlate with clinical course in B-cell chronic lymphocytic leukaemia (CLL). The three markers may be discordant in the single case and there is no consensus on their combined use in clinical practise. This multicenter study investigated this issue. Two-hundred and sixty-two Binet stage A patients were studied for the three markers. Sixty patients were profiled with HG-U133A gene expression chips. Disease progression was determined by time from diagnosis to treatment (TTT). The probability of being treatment-free at 3 years was significantly shorter in patients with unmutated IGHV genes (IGHVunmut 66% vs. 93%, chi square of log-rank = 30, P < 0.0001), ZAP-70 positive (ZAP-70pos 73% vs. 96%, chi square of log-rank = 8.2, P = 0.004) or CD38-positive cells (CD38pos 68% vs. 91%, chi square of log-rank = 21, P < 0.0001). Cox multivariate regression analysis showed that the three markers had an independent predictive value for TTT of similar power. A prognostic system based on presence of none (low-risk), one (intermediate-risk) or two or three (high-risk) markers was generated. Based on such criteria, 56%, 23% and 21% of cases were clustered in low (HR = 1), intermediate [HR = 2.8, 95% confidence interval (CI) 2.4-5.8] and high-risk group (HR = 8.0, 95% CI 3.9-16.2). Specific transcriptional patterns were significantly associated with risk groups.

Clonal heterogeneity in chronic lymphocytic leukemia cells: superior response to surface IgM cross-linking in CD38, ZAP-70-positive cells.

BACKGROUND: Patients with chronic lymphocytic leukemia whose cells express CD38 and ZAP-70 and utilize unmutated Ig VH region genes have a very poor prognosis. We studied whether cells expressing CD38 and ZAP-70 are more susceptible to stimulation through B-cell receptors than are cells that do not express CD38 and ZAP-70. DESIGN AND METHODS: CD38-positive and CD38-negative leukemic cells were separated from single cases and compared for their response to B-cell receptor cross-linking and ZAP-70 expression. Cohort studies were also carried out by measuring the apoptotic response to surface immunoglobulin M (IgM) cross-linking in 82 patients with chronic lymphocytic leukemia and the protein tyrosine phosphorylation induced by surface IgM in 21 patients. RESULTS: CD38-positive cells, isolated from cases of chronic lymphocytic leukemia classified as CD38-positive or CD38-negative, expressed more ZAP-70 than the corresponding CD38-negative cells, exhibited more robust protein tyrosine phosphorylation and had a greater tendency to apoptosis upon B-cell receptor cross-linking. In the cohort studies, surface IgM-induced protein tyrosine phosphorylation correlated significantly with CD38 and ZAP-70 expression and with the absence of Ig VH gene mutations. Apoptosis induced by surface IgM cross-linking correlated significantly only with the proportion of CD38-positive cells. Difficulties in finding more definitive correlations were probably related to imprecision in the in vitro test system and in the definition of cases as positive or negative. CONCLUSIONS: Collectively, these data indicate that CD38-positive, ZAP-70-positive cells have a greater capacity for signaling through the B-cell receptor and suggest a function for B-cell receptor signaling in promoting chronic lymphocytic leukemia cell expansion, especially within the CD38-positive fraction of the leukemic clone.

MicroRNA signatures and Foxp3+ cell count correlate with relapse occurrence in follicular lymphoma.

First line drug treatment of follicular lymphoma (FL) patients is followed by a highly variable disease-free time before relapse in about one third of patients. No molecular marker is able to predict efficiently the risk of relapse. We investigated the expression profile of microRNAs (miRNAs) by microarrays and of the tumor microenvironment by immunohistochemistry in 26 FLs and 12 reactive lymph nodes (rLN) as reference. Twenty-nine miRNAs were differentially expressed in FLs compared to rLNs and some of them discriminated grade 1 from 3a FLs. Both FLs and rLNs displayed molecular heterogeneity. FLs grouped into two clusters mostly driven by the tumor T-cell content. Among 21 drug-treated FL patients with an average follow-up of 13.5 years, eight cases relapsed. Twenty-six miRNAs discriminated between relapsed and non-relapsed FLs. Ten miRNAs also correlated with Foxp3+ cells number. Notably, Foxp3+ cells were significantly less in relapsed patients and lower Foxp3+ cell number associated with shorter time-to-relapse. Foxp3+ cells did not co-expressed follicular helper T-cell markers and were therefore classified as regulatory T cells rather than follicular regulatory T-cells. These findings introduce new knowledge about the relationship between miRNA alterations and infiltrating immune cells and show that Foxp3+ cells might be predictive of disease relapse.

MYC-related microRNAs signatures in non-Hodgkin B-cell lymphomas and their relationships with core cellular pathways.

In order to investigate the role of microRNAs in the pathogenesis of different B-cell lymhoma subtypes, we have applied an array-based assay to a series of 76 mixed non-Hodgkin B-cell lymphomas, including Burkitt's lymphoma (BL), diffuse large B-cell lymphoma, primary mediastinal B-cell lymphoma, mantle cell lymphoma (MCL) and follicular lymphoma. Lymphomas clustered according to histological subtypes, driven by two miRNA clusters (the miR-29 family and the miR-17-92 cluster). Since the two miRNA clusters are known to be MYC-regulated, we investigated whether this would be supported in MYC-driven experimental models, and found that this signature separated BL cell lines and a MYC-translocated MCL cell lines from normal germinal center B-cells and other B-cell populations. Similar results were also reproduced in tissue samples comparing BL and reactive lymph node samples. The same series was then quantitatively analyzed for MYC expression by immunohistochemistry and MYC protein levels were compared with corresponding miRNA signatures. A specific metric was developed to summarize the levels of MYC-related microRNAs and the corresponding protein levels. We found that MYC-related signatures are directly related to MYC protein expression across the whole spectrum of B-cells and B-cell lymphoma, suggesting that the MYC-responsive machinery shows predominantly quantitative, rather than qualitative, modifications in B-cell lymphoma. Novel MYC-related miRNAs were also discovered by this approach. Finally, network analysis found that in BL MYC-related differentially expressed miRNAs could control, either positively or negatively, a limited number of hub proteins, including BCL2, CDK6, MYB, ZEB1, CTNNB1, BAX and XBP1.

Microenvironmental regulation of the IL-23R/IL-23 axis overrides chronic lymphocytic leukemia indolence.

Although the progression of chronic lymphocytic leukemia (CLL) requires the cooperation of the microenvironment, the exact cellular and molecular mechanisms involved are still unclear. We investigated the interleukin (IL)-23 receptor (IL-23R)/IL-23 axis and found that circulating cells from early-stage CLL patients with shorter time-to-treatment, but not of those with a more benign course, expressed a defective form of the IL-23R complex lacking the IL-12Rß1 chain. However, cells from both patient groups expressed the complete IL-23R complex in tissue infiltrates and could be induced to express the IL-12Rß1 chain when cocultured with activated T cells or CD40L+ cells. CLL cells activated in vitro in this context produced IL-23, a finding that, together with the presence of IL-23 in CLL lymphoid tissues, suggests the existence of an autocrine/paracrine loop inducing CLL cell proliferation. Interference with the IL-23R/IL-23 axis using an anti-IL-23p19 antibody proved effective in controlling disease onset and expansion in xenografted mice, suggesting potential therapeutic strategies.

Complementation of the oxidatively damaged DNA repair defect in Cockayne syndrome A and B cells by Escherichia coli formamidopyrimidine DNA glycosylase.

Repair of the oxidized purine 8-oxo-7,8-dihydroguanine (8-oxoGua) is inefficient in cells belonging to the B complementation group of Cockayne syndrome (CS-B), a developmental and neurological disorder characterized by defective transcription-coupled repair. We show here that cells belonging to the A complementation group (CS-A) are also defective in repair of 8-oxoGua and we demonstrate that expression of the Escherichia coli formamidopyrimidine DNA glycosylase (FPG) completely corrects the repair deficiency in both CS-A and CS-B cells. Phenotypically, CS-A cells are normally sensitive to toxicity and micronuclei induced by the oxidizing agent potassium bromate. CS-B cells display sensitivity to elevated concentrations of potassium bromate but this is not compensated by FPG expression, suggesting toxicity of lesions that are not FPG substrates. The data indicate that 8-oxoGua is not a major toxic and clastogenic lesion in CS cells.

Retrospective cytological evaluation of indeterminate thyroid nodules according to the British Thyroid Association 2014 classification and comparison of clinical evaluation and outcomes.

The cytology of 130 indeterminate nodules (Thy 3) was retrospectively reviewed according to the British Thyroid Association 2014 classification. Nodules were divided into Thy 3a (atypical features) and Thy 3f (follicular lesion) categories. Histology was available as a reference for 97 nodules. Pre-surgical evaluations comprised biochemical tests, color-Doppler ultrasonography (US), semi-quantitative elastography-US (USE), contrast-enhanced US (CEUS), and mutation analysis from cytological slides. Thyroid malignancy was the final diagnosis for 19% of surgically-treated nodules. No statistically significant difference in the risk of malignancy was found between Thy 3a (26%) and Thy 3f (14%) nodules. Histology of the Thy 3a and Thy 3f nodules showed a higher incidence of Hurtle cell adenomas in Thy 3f (29%) than in Thy 3a (3%) nodules (P=0.01). The only pre-surgical difference concerned the BRAF V600E mutation, which was positive in some Thy 3a but not in any Thy 3f nodules (P=0.04). Receiver-operating characteristic (ROC) analysis was used to obtain cut-off values from US (score), USE (ELX 2/1 strain index), and CEUS (time-to-peak index and peak index) data. The cut-off values were similar for Thy 3a and Thy 3f nodules. Data showed that malignancy can be suspected if the US score is >2, ELX 1/2 strain index >1, time-to-peak index >1, and peak index <1. In a sub-group of 24 revised nodules (12 Thy 3a and 12 Thy 3f) with histology as a reference, the diagnostic power of cumulative pre-surgical analysis by means of US, USE, and CEUS showed high positive and negative predictive values (83% and 100%, respectively) for the presence of malignancy in Thy 3a and Thy 3f nodules. In conclusion, in our series of revised Thy 3 nodules, malignancy was low and displayed no significant differences between Thy 3a and Thy 3f categories. The use of cut-offs based on histology as a reference could reduce surgery. Our data support the conviction that, in mutation-negative Thy 3a and Thy 3f nodules, observation should be the first choice when not all instrumental results are suspect.

Identification of microRNAs implicated in the late differentiation stages of normal B cells suggests a central role for miRNA targets ZEB1 and TP53.

In the late B cell differentiation stages, miRNAs expression modifications promoting or inhibiting key pathways are only partially defined. We isolated 29 CD19+ human B cell samples at different stages of differentiation: B cells from peripheral blood; naïve, germinal center (GC) and subepithelial (SE) B cells from tonsils. SE cells were further split in activated and resting B cell. The miRNA expression profile of these B cells was assessed by microarray analysis and selected miRNAs were validated by quantitative RT-PCR and in situ hybridization on normal tonsils. The comparison of all samples showed changes in 107 miRNAs in total. Among 48 miRNAs differentially expressed in naïve, GC and SE cells, we identified 8 miRNAs: mir-323, mir-138, mir-9*, mir-211, mir-149, mir-373, mir-135a and mir-184, strictly specific to follicular cells that had never been implicated before in late stages of B cell development. Moreover, we unveiled 34 miRNAs able to discriminate between CD5- activated B cells and resting B cells. The miRNAs profile of CD5- resting B cells showed a higher similarity to naïve CD5+ than CD5- activated B cells. Finally, network analysis on shortest paths connecting gene targets suggested ZEB1 and TP53 as key miRNA targets during the follicular differentiation pathway. These data confirm and extend our knowledge on the miRNAs-related regulatory pathways involved in the late B cell maturation.

Small cell lung cancer transformation and the T790M mutation: A case report of two acquired mechanisms of TKI resistance detected in a tumor rebiopsy and plasma sample of EGFR-mutant lung adenocarcinoma.

The present study describes the case of a 45-year-old man diagnosed with metastatic lung adenocarcinoma, which harbored a deletion within exon 19 of the epidermal growth factor receptor (EGFR) gene. The patient was subsequently treated with gefitinib (250 mg/day orally from May 2013 to March 2014), but developed acquired resistance to the drug following 11 months of treatment. Tumor burden molecular analysis was performed on a tumor rebiopsy and plasma sample, and histological analysis was also performed on the tumor rebiopsy. A small cell transformation retaining the original EGFR mutation was detected in the tumor rebiopsy, while the T790M mutation together with the activating ex19del mutation were identified only in the plasma sample. The patient was treated with cytotoxic chemotherapy (off-label schedule with epirubicin 80 mg/mq and paclitaxel 160 mg/mq every 21 days for 6 cycles) and radiation (50.4 Gy administered in 28 fractions of 1.8 Gy once daily for 5.5 weeks) specific for small cell lung cancer, and may also have benefitted from treatment with a third generation T790M-specific EGFR-TKI. To better describe the mechanisms of resistance to TKI inhibitors and to optimize therapeutic regimens, the simultaneous analysis of tumor biopsies and circulating tumor DNA should be considered.