Anaplastic large-cell lymphoma (ALCL) is a clinical and biological heterogeneous disease that includes systemic anaplastic lymphoma kinase (ALK)-positive and ALK-negative entities. To discover biomarkers and/or genes involved in ALK-negative ALCL pathogenesis, we applied the cancer outlier profile analysis algorithm to a gene expression profiling data set including 249 cases of T-cell non-Hodgkin lymphoma and normal T cells. Ectopic coexpression of ERBB4 and COL29A1 genes was detected in 24% of ALK-negative ALCL patients. RNA sequencing and 5' RNA ligase-mediated rapid amplification of complementary DNA ends identified 2 novel ERBB4-truncated transcripts displaying intronic transcription start sites. By luciferase assays, we defined that the expression of ERBB4-aberrant transcripts is promoted by endogenous intronic long terminal repeats. ERBB4 expression was confirmed at the protein level by western blot analysis and immunohistochemistry. Lastly, we demonstrated that ERBB4-truncated forms show oncogenic potentials and that ERBB4 pharmacologic inhibition partially controls ALCL cell growth and disease progression in an ERBB4-positive patient-derived tumorgraft model. In conclusion, we identified a new subclass of ALK-negative ALCL characterized by aberrant expression of ERBB4-truncated transcripts carrying intronic 5' untranslated regions.

Maintaining cellular redox balance is vital for cell survival and tissue homoeostasis because imbalanced production of reactive oxygen species (ROS) may lead to oxidative stress and cell death. The antioxidant enzyme glutathione peroxidase 4 (Gpx4) is a key regulator of oxidative stress-induced cell death. We show that mice with deletion of Gpx4 in hematopoietic cells develop anemia and that Gpx4 is essential for preventing receptor-interacting protein 3 (RIP3)-dependent necroptosis in erythroid precursor cells. Absence of Gpx4 leads to functional inactivation of caspase 8 by glutathionylation, resulting in necroptosis, which occurs independently of tumor necrosis factor α activation. Although genetic ablation of Rip3 normalizes reticulocyte maturation and prevents anemia, ROS accumulation and lipid peroxidation in Gpx4-deficient cells remain high. Our results demonstrate that ROS and lipid hydroperoxides function as not-yet-recognized unconventional upstream signaling activators of RIP3-dependent necroptosis.

Bacteria can induce human lymphomas, whereas lymphoproliferative disorders have been described in patients with Q fever. We observed a lymphoma in a patient with Q fever that prompted us to investigate the association between the 2 diseases. We screened 1468 consecutive patients of the 2004 to 2014 French National Referral Center for Q fever database. The standardized incidence ratios (SIRs) of diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL) were calculated comparatively to the 2012 Francim Registry. The presence of Coxiella burnetii was tested using immunofluorescence and fluorescence in situ hybridization using a specific 16S ribosomal RNA probe and genomic DNA probe. Seven patients (0.48%) presented mature B-cell lymphoma consisting of 6 DLBCL and 1 FL. An excess risk of DLBCL and FL was found in Q fever patients compared with the general population (SIR [95% confidence interval], 25.4 [11.4-56.4] and 6.7 [0.9-47.9], respectively). C burnetii was detected in CD68(+) macrophages within both lymphoma and lymphadenitis tissues but localization in CD123(+) plasmacytoid dendritic cells (pDCs) was found only in lymphoma tissues. Q fever patients with persistent focalized infection were found more at risk of lymphoma (hazard ratio, 9.35 [1.10-79.4]). Interleukin-10 (IL10) overproduction (P = .0003) was found in patients developing lymphoma. These results suggest that C burnetii should be added to the list of bacteria that promote human B-cell non-Hodgkin lymphoma, possibly by the infection of pDCs and IL10 overproduction. Screening for early lymphoma diagnosis should be considered in the management of patients with Q fever, especially those with persistent focalized infections.

Mutations in signaling molecules of the cytokine receptor axis play a central role in myeloproliferative neoplasm (MPN) pathogenesis. Polycythemia vera is mainly related to JAK2 mutations, whereas a wider mutational spectrum is detected in essential thrombocythemia (ET) with mutations in JAK2, the thrombopoietin (TPO) receptor (MPL), and the calreticulin (CALR) genes. Here, we studied the mutational profile of 17 ET patients negative for JAK2V617F, MPLW515K/L, and CALR mutations, using whole-exome sequencing and next-generation sequencing (NGS) targeted on JAK2 and MPL. We found several signaling mutations including JAK2V617F at very low allele frequency, 1 homozygous SH2B3 mutation, 1 MPLS505N, 1 MPLW515R, and 2 MPLS204P mutations. In the remaining patients, 4 presented a clonal and 7 a polyclonal hematopoiesis, suggesting that certain triple-negative ETs are not MPNs. NGS on 26 additional triple-negative ETs detected only 1 MPLY591N mutation. Functional studies on MPLS204P and MPLY591N revealed that they are weak gain-of-function mutants increasing MPL signaling and conferring either TPO hypersensitivity or independence to expressing cells, but with a low efficiency. Further studies should be performed to precisely determine the frequency of MPLS204 and MPLY591 mutants in a bigger cohort of MPN.

Our understanding of the pathogenesis and heterogeneity of diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL) has been dramatically enhanced by recent attempts to profile molecular features of these lymphomas. In this article, we discuss ways in which testing for molecular features may impact DLBCL and FL management if clinical trials are designed to incorporate such tests. Specifically, we discuss how distinguishing lymphomas on the basis of cell-of-origin subtypes or the presence of other molecular features is prognostically and therapeutically significant. Conversely, we discuss how the molecular similarities of DLBCL and FL have provided insight into the potential of both DLBCL and FL cases to respond to agents targeting alterations they have in common. Through these examples, we demonstrate how the translation of our understanding of cancer biology into improvements in patient outcomes depends on analyzing the molecular correlates of treatment outcomes in clinical trials and in routinely treated patients.

In patients with hypogammaglobulinemia secondary to chronic lymphocytic leukemia (CLL) or multiple myeloma (MM), intravenous immune globulin (IVIg) may be administered to reduce the risk of infection. Since 2013, IVIg products have carried a boxed safety warning about the risk of thromboembolic events (TEEs), with TEEs reported in 0.5% to 15% of patients treated with IVIg. In this retrospective cohort study of older patients with CLL or MM identified from the Surveillance, Epidemiology, and End Results-Medicare Linked Database, we assessed rates of clinically serious TEEs in 2724 new users of IVIg and a propensity-matched comparison group of 8035 nonusers. For the primary end point, arterial TEE, we observed a transient increased risk of TEE during the day of an IVIg infusion and the day afterward (hazard ration = 3.40; 95% confidence interval [CI]: 1.25, 9.25); this risk declined over the remainder of the 30-day treatment cycle. When considered in terms of absolute risk averaged over a 1-year treatment period, the increase in risk attributable to IVIg was estimated to be 0.7% (95% CI: -0.2%, 2.0%) compared with a baseline risk of 1.8% for the arterial TEE end point. A statistically nonsignificant risk increase of 0.3% (95% CI: -0.4%, 1.5%) compared with a baseline risk of 1.1% was observed for the venous TEE end point. Further research is needed to establish the generalizability of these results to patients receiving higher doses of IVIg for other indications.

Essential thrombocythemia (ET) and primary myelofibrosis (PMF) are chronic diseases characterized by clonal hematopoiesis and hyperproliferation of terminally differentiated myeloid cells. The disease is driven by somatic mutations in exon 9 of CALR or exon 10 of MPL or JAK2-V617F in >90% of the cases, whereas the remaining cases are termed "triple negative." We aimed to identify the disease-causing mutations in the triple-negative cases of ET and PMF by applying whole-exome sequencing (WES) on paired tumor and control samples from 8 patients. We found evidence of clonal hematopoiesis in 5 of 8 studied cases based on clonality analysis and presence of somatic genetic aberrations. WES identified somatic mutations in 3 of 8 cases. We did not detect any novel recurrent somatic mutations. In 3 patients with clonal hematopoiesis analyzed by WES, we identified a somatic MPL-S204P, a germline MPL-V285E mutation, and a germline JAK2-G571S variant. We performed Sanger sequencing of the entire coding region of MPL in 62, and of JAK2 in 49 additional triple-negative cases of ET or PMF. New somatic (T119I, S204F, E230G, Y591D) and 1 germline (R321W) MPL mutation were detected. All of the identified MPL mutations were gain-of-function when analyzed in functional assays. JAK2 variants were identified in 5 of 57 triple-negative cases analyzed by WES and Sanger sequencing combined. We could demonstrate that JAK2-V625F and JAK2-F556V are gain-of-function mutations. Our results suggest that triple-negative cases of ET and PMF do not represent a homogenous disease entity. Cases with polyclonal hematopoiesis might represent hereditary disorders.

Somatic hypermutation and class-switch recombination of the immunoglobulin (Ig) genes occur in germinal center (GC) B cells and are initiated through deamination of cytidine to uracil by activation-induced cytidine deaminase (AID). Resulting uracil-guanine mismatches are processed by uracil DNA glycosylase (UNG)-mediated base-excision repair and MSH2-mediated mismatch repair (MMR) to yield mutations and DNA strand lesions. Although off-target AID activity also contributes to oncogenic point mutations and chromosome translocations associated with GC and post-GC B-cell lymphomas, the role of downstream AID-associated DNA repair pathways in the pathogenesis of lymphoma is unknown. Here, we show that simultaneous deficiency of UNG and MSH2 or MSH2 alone causes genomic instability and a shorter latency to the development of BCL6-driven diffuse large B-cell lymphoma (DLBCL) in a murine model. The additional development of several BCL6-independent malignancies in these mice underscores the critical role of MMR in maintaining general genomic stability. In contrast, absence of UNG alone is highly protective and prevents the development of BCL6-driven DLBCL. We further demonstrate that clonal and nonclonal mutations arise within non-Ig AID target genes in the combined absence of UNG and MSH2 and that DNA strand lesions arise in an UNG-dependent manner but are offset by MSH2. These findings lend insight into a complex interplay whereby potentially deleterious UNG activity and general genomic instability are opposed by the protective influence of MSH2, producing a net protective effect that promotes immune diversification while simultaneously attenuating malignant transformation of GC B cells.

Internal tandem duplication of the Fms-like tyrosine kinase-3 receptor (FLT3) internal tandem duplication (ITD) is found in 30% of acute myeloid leukemia (AML) and is associated with a poor outcome. In addition to tyrosine kinase inhibitors, therapeutic strategies that modulate the expression of FLT3-ITD are also promising. We show that AML samples bearing FLT3-ITD mutations are more sensitive to proteasome inhibitors than wild-type samples and this sensitivity is strongly correlated with a higher FLT3-ITD allelic burden. Using pharmacologic inhibitors of autophagy, specific downregulation of key autophagy proteins including Vps34, autophagy gene (Atg)5, Atg12, Atg13, biochemical, and microscopy studies, we demonstrated that proteasome inhibitors induced cytotoxic autophagy in AML cells. FLT3-ITD molecules were detectable within autophagosomes after bortezomib treatment indicating that autophagy induction was responsible for the early degradation of FLT3-ITD, which preceded the inhibition of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK), PI3K/AKT, and STAT5 pathways, and subsequent activation of cell death. Moreover, proteasome inhibitors overcome resistance to quizartinib induced by mutations in the kinase domain of FLT3, suggesting that these compounds may prevent the emergence of mutant clones arising from tyrosine kinase inhibitor treatments. In xenograft mice models, bortezomib stimulated the conversion of LC3-I to LC3-II, indicating induction of autophagy in vivo, downregulated FLT3-ITD protein expression and improved overall survival. Therefore, selecting patients according to FLT3-ITD mutations could be a new way to detect a significant clinical activity of proteasome inhibitors in AML patients.