Inhibition of spleen tyrosine kinase (SYK) in tonic B-cell receptor (BCR) signal-dependent diffuse large B-cell lymphomas (DLBCLs) inhibits cellular proliferation, decreases cholesterol biosynthesis, and triggers apoptosis, at least in part via a mechanism involving decreased activity of phosphatidylinositol 3-kinase/AKT axis. Because forkhead box O1 (FOXO1) is a major effector of this pathway, we investigated the role of FOXO1 in toxicity of BCR pathway inhibition. Inhibition of SYK in DLBCL cells with tonic BCR signaling decreased phospho-AKT and phospho-FOXO1 levels and triggered FOXO1-driven gene expression. Introduction of constitutively active FOXO1 mutant triggered cell cycle arrest and apoptosis, indicating that increased FOXO1 activity is toxic to these DLBCL cells. Depletion of FOXO1 with short hairpin RNA led to almost complete resistance to chemical SYK inhibitor R406, demonstrating that FOXO1 is also required for R406-induced cell death. FOXO1 in these cells is also involved in regulation of expression of the critical master regulator of cholesterol biosynthesis, SREBP1. Because HRK is the key effector of SYK inhibition, we characterized a mechanism linking FOXO1 activation and HRK induction that involves caspase-dependent cleavage of HRK's transcriptional repressor DREAM. Because AKT in lymphoma cells can be regulated by other signals than BCR, we assessed the combined effects of the AKT inhibitor MK-2206 with R406 and found markedly synergistic FOXO1-dependent toxicity. In primary DLBCLs, FOXO1 expression was present in 80% of tumors, correlated with SYK activity, and was associated with longer overall survival. These results demonstrate that FOXO1 is required for SYK and AKT inhibitor-induced toxicity.

Thrombin-induced cellular response in platelets not only requires protease-activated receptors (PARs), but also involves another thrombin receptor, the glycoprotein Ib-IX complex (GPIb-IX). It remains controversial how thrombin binding to GPIb-IX stimulates platelet responses. It was proposed that GPIb-IX serves as a dock that facilitates thrombin cleavage of protease-activated receptors, but there are also reports suggesting that thrombin binding to GPIb-IX induces platelet activation independent of PARs. Here we show that GPIb is neither a passive thrombin dock nor a PAR-independent signaling receptor. We demonstrate a novel signaling-mediated cooperativity between PARs and GPIb-IX. Low-dose thrombin-induced PAR-dependent cell responses require the cooperativity of GPIb-IX signaling, and conversely, thrombin-induced GPIb-IX signaling requires cooperativity of PARs. This mutually dependent cooperativity requires a GPIb-IX-specific 14-3-3-Rac1-LIMK1 signaling pathway, and activation of this pathway also requires PAR signaling. The cooperativity between GPIb-IX signaling and PAR signaling thus drives platelet activation at low concentrations of thrombin, which are important for in vivo thrombosis.

Determination of defined roles for endogenous homeobox (Hox) genes in adult hematopoietic stem and progenitor cell (HSPC) activity has been hampered by a combination of embryonic defects and functional redundancy. Here we show that conditional homozygous deletion of the Hoxa cluster (Hoxa(-/-)) results in a marked reduction of adult HSPC activity, both in vitro and in vivo. Specifically, proliferation of Hoxa(-/-) HSPCs is reduced compared with wild-type (WT) cells in vitro and they are less competitive in vivo. Notably, the loss of Hoxa genes had little impact on HSPC differentiation. Comparative RNA sequencing analyses of Hoxa(-/-) and WT hematopoietic stem cells (CD150(+)/CD48(-)/Lineage(-)/c-kit(+)/Sca-1(+)) identified a large number of differentially expressed genes, three of which (Nr4a3, Col1a1, and Hnf4a) showed >10-fold reduced levels. Engineered overexpression of Hoxa9 in Hoxa(-/-) HSPCs resulted in partial phenotypic rescue in vivo with associated recovery in expression of a large proportion of deregulated genes. Together, these results provide definitive evidence linking Hoxa gene expression to proliferation of adult HSPCs.

Because the clinical diagnosis of deep-vein thrombosis and pulmonary embolism is nonspecific, integrated diagnostic approaches for patients with suspected venous thromboembolism have been developed over the years, involving both non-invasive bedside tools (clinical decision rules and D-dimer blood tests) for patients with low pretest probability and diagnostic techniques (compression ultrasound for deep-vein thrombosis and computed tomography pulmonary angiography for pulmonary embolism) for those with a high pretest probability. This combination has led to standardized diagnostic algorithms with proven safety for excluding venous thrombotic disease. At the same time, it has become apparent that, as a result of the natural history of venous thrombosis, there are special patient populations in which the current standard diagnostic algorithms are not sufficient. In this review, we present 3 evidence-based patient cases to underline recent developments in the imaging diagnosis of venous thromboembolism.

The development of BCR/ABL1 tyrosine kinase inhibitors (TKIs) over the past 20 years has dramatically improved the outcomes for patients with every stage of Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia (CML). Clinicians now have access to 5 oral, generally well-tolerated, and highly effective TKIs. How should these agents be used for an individual patient to ensure the best possible duration and quality-of-life, to avoid treatment-related complications, and potentially to achieve a cure at an affordable cost? Because CML patients may need to continue TKI therapy indefinitely, the long-term safety of each treatment option must be considered. Evidence-based care requires an understanding of the optimal use of these drugs, their specific early and late toxicities, the prognostic significance of achieving treatment milestones, and the critical importance of molecular monitoring. Efficacy is important, but treatment choice does not depend only on efficacy. Choosing among various treatment options is informed by understanding the distinct benefits and risks of each agent, along with careful consideration of patient-specific factors, such as risk status, age, and comorbidities.

Enhanced expression of ecotropic viral integration site 1 (EVI-1) occurs in ∼10% of acute myeloid leukemia (AML) patients and is associated with a very poor disease outcome. Patients with EVI-1-positive AML have poor initial responses to chemotherapy and high relapse rates, indicating an urgent need for alternative treatment strategies improving clinical outcome for these patients. Because treatment of acute promyelocytic patients with all-trans retinoic acid (ATRA) has improved the survival of these patients substantially, we investigated whether ATRA might also be effective for the subgroup of AML patients with EVI-1 overexpression. Here, we show that a substantial part of the EVI-1-positive AML cases respond to ATRA by induction of differentiation and decreased clonogenic capacity of myeloid blasts. Most importantly, we demonstrate that in vivo treatment of primary EVI-1-positive AML with ATRA leads to a significant reduction in leukemic engraftment. Altogether, our results show that a considerable part of the EVI-1-positive primary AML cases are sensitive to ATRA, suggesting that combining ATRA with the currently used conventional chemotherapy might be a promising treatment strategy decreasing relapse rates and enhancing complete remissions in this poor prognostic subgroup of AML patients.

Complement is increasingly being recognized as an important driver of human disease, including many hemolytic anemias. Paroxysmal nocturnal hemoglobinuria (PNH) cells are susceptible to hemolysis because of a loss of the complement regulatory proteins CD59 and CD55. Patients with atypical hemolytic uremic syndrome (aHUS) develop a thrombotic microangiopathy (TMA) that in most cases is attributable to mutations that lead to activation of the alternative pathway of complement. For optimal therapy, it is critical, but often difficult, to distinguish aHUS from other TMAs, such as thrombotic thrombocytopenic purpura; however, novel bioassays are being developed. In cold agglutinin disease (CAD), immunoglobulin M autoantibodies fix complement on the surface of red cells, resulting in extravascular hemolysis by the reticuloendothelial system. Drugs that inhibit complement activation are increasingly being used to treat these diseases. This article discusses the pathophysiology, diagnosis, and therapy for PNH, aHUS, and CAD.

Hodgkin lymphoma (HL) is a highly curable form of childhood cancer, with estimated 5 year survival rates exceeding 98%. However, the establishment of a "standard of care" approach to its management is complicated by the recognition that long-term overall survival declines in part from delayed effects of therapy and that there continue to be subgroups of patients at risk for relapse for which prognostic criteria cannot adequately define. This challenge has resulted in the development of various strategies aimed at identifying the optimal balance between maintaining overall survival and avoidance of long-term morbidity of therapy, often representing strategies quite different from those used for adults with HL. More precise risk stratification and methods for assessing the chemosensitivity of HL through imaging studies and biomarkers are in evolution. Recent advances in the understanding of the biology of HL have led to the introduction of targeted therapies in both the frontline and relapsed settings. However, significant barriers exist in the development of new combination therapies, necessitating collaborative studies across pediatric HL research consortia and in conjunction with adult groups for the adolescent and young adult (AYA) population with HL.

Deep remission and prolonged disease-free survival can be achieved with first-line chemoimmunotherapy (CIT), such as combined fludarabine, cyclophosphamide, and rituximab, in the majority of patients with chronic lymphocytic leukemia (CLL). More modest results are reported with less intense regimens like obinutuzumab plus chlorambucil. Clinical assessment has limited sensitivity in detecting residual disease responsible for subsequent relapse, even including morphologic bone marrow (BM) evaluation. Multicolor flow cytometry and polymerase chain reaction (PCR)-based methods can detect minimal residual disease (MRD) to a sensitivity of ≥1:10,000 (10(-4)). Achieving BM MRD-negative complete remission (CR) is associated with superior progression-free survival (PFS) and overall survival; MRD status is the single best posttreatment predictor of long-term outcomes after CIT. Newer oral B-cell receptor signaling pathway inhibitors are highly effective at controlling disease, but best monotherapy responses are typically partial remission, and patients must remain on treatment to maintain disease control. Therapeutic progress is still needed for CLL. We propose that targeting MRD provides opportunity to realize this progress. Achieving BM MRD-negative CR is a prerequisite for long-term unmaintained disease-free survival and potential for cure. We review available methodologies for detecting MRD and correlations with posttreatment outcomes. We discuss the potential utility of MRD to direct individualized therapy. Finally, we discuss the importance of MRD-negative status as a surrogate marker for longer PFS in clinical studies to allow more rapid determination of clinical benefit.

Many patients with hematologic malignancies cannot tolerate hematopoietic cell transplantation (HCT), whereas others may not have a compatible human leukocyte antigen-matched donor. To overcome these limitations, we optimized a conditioning regimen employing anti-CD45 radioimmunotherapy (RIT) replacing total body irradiation (TBI) before haploidentical HCT in a murine model. Mice received 200 to 400 μCi (90)Y-anti-CD45 antibody (30F11), with or without fludarabine (5 days starting day -8), with cyclophosphamide (CY; days -2 and +2) for graft-versus-host disease prophylaxis, and 1.5 × 10(7) haploidentical donor bone marrow cells (day 0). Haploidentical bone marrow transplantation (BMT) with 300 μCi (90)Y-anti-CD45 RIT and CY, without TBI or fludarabine, led to mixed chimeras with 81.3 ± 10.6% mean donor origin CD8(+) cells detected 1 month after BMT, and remained stable (85.5 ± 11% mean donor origin CD8(+) cells) 6 months after haploidentical BMT. High chimerism levels were induced across multiple hematopoietic lineages 28 days after haploidentical BMT with 69.3 ± 14.1%, 75.6 ± 20.2%, and 88.5 ± 11.8% CD3(+) T cells, B220(+) B cells, and CD11b(+) myeloid cells, respectively. Fifty percent of SJL leukemia-bearing mice treated with 400 μCi (90)Y-DOTA-30F11, CY, and haploidentical BMT were cured and lived >200 days. Mice treated with 200 μCi (90)Y-DOTA-30F11 had a median overall survival of 73 days, while untreated leukemic mice had a median overall survival of 34 days (P < .001, Mantel-Cox test). RIT-mediated haploidentical BMT without TBI may increase treatment options for aggressive hematologic malignancies.

Despite the success of standard front-line chemotherapy for classical Hodgkin lymphoma (cHL), a subset of these patients, particularly those with poor prognostic factors at diagnosis (including the presence of B symptoms, bulky disease, advanced stage, or extranodal disease), relapse. For those patients who relapse following autologous stem cell transplant (SCT), multiple treatment options are available, including single-agent chemotherapy, combination chemotherapy strategies, radiotherapy, the immunoconjugate brentuximab, checkpoint inhibitors nivolumab and pembrolizumab, lenalidomide, everolimus, or observation in selected patients. In patients with an available donor, allogeneic SCT may also be considered. With numerous treatment options available, we advocate for a tailored therapeutic approach for patients with relapsed cHL guided by patient-specific characteristics including age, comorbidities, sites of disease (nodal or organ), previous chemosensitivity, and goals of treatment (long-term disease control vs allogeneic SCT).

Adult T-cell leukemia/lymphoma (ATLL) is a distinct form of peripheral T-cell lymphoma with poor prognosis, which is caused by the human T-lymphotropic virus type 1 (HTLV-1). In contrast to the unequivocal importance of HTLV-1 infection in the pathogenesis of ATLL, the role of acquired mutations in HTLV-1 infected T cells has not been fully elucidated, with a handful of genes known to be recurrently mutated. In this study, we identified unique RHOA mutations in ATLL through whole genome sequencing of an index case, followed by deep sequencing of 203 ATLL samples. RHOA mutations showed distinct distribution and function from those found in other cancers. Involving 15% (30/203) of ATLL cases, RHOA mutations were widely distributed across the entire coding sequence but almost invariably located at the guanosine triphosphate (GTP)-binding pocket, with Cys16Arg being most frequently observed. Unexpectedly, depending on mutation types and positions, these RHOA mutants showed different or even opposite functional consequences in terms of GTP/guanosine diphosphate (GDP)-binding kinetics, regulation of actin fibers, and transcriptional activation. The Gly17Val mutant did not bind GTP/GDP and act as a dominant negative molecule, whereas other mutants (Cys16Arg and Ala161Pro) showed fast GTP/GDP cycling with enhanced transcriptional activation. These findings suggest that both loss- and gain-of-RHOA functions could be involved in ATLL leukemogenesis. In summary, our study not only provides a novel insight into the molecular pathogenesis of ATLL but also highlights a unique role of variegation of heterologous RHOA mutations in human cancers.

Patients with breast cancer are at increased risk of venous thromboembolism (VTE), particularly in the peridiagnosis period. However, no previous epidemiologic studies have investigated the relative impact of breast cancer treatments in a time-dependent manner. We aimed to determine the impact of breast cancer stage, biology, and treatment on the absolute and relative risks of VTE by using several recently linked data sources from England. Our cohort comprised 13,202 patients with breast cancer from the Clinical Practice Research Datalink (linked to Hospital Episode Statistics and Cancer Registry data) diagnosed between 1997 and 2006 with follow-up continuing to the end of 2010. Cox regression analysis was performed to determine which demographic, treatment-related, and biological factors independently affected VTE risk. Women had an annual VTE incidence of 6% while receiving chemotherapy which was 10.8-fold higher (95% confidence interval [CI], 8.2-14.4; absolute rate [AR], 59.6 per 1000 person-years) than that in women who did not receive chemotherapy. After surgery, the risk was significantly increased in the first month (hazard ratio [HR], 2.2; 95% CI, 1.4-3.4; AR, 23.5; reference group, no surgery), but the risk was not increased after the first month. Risk of VTE was noticeably higher in the 3 months after initiation of tamoxifen compared with the risk before therapy (HR, 5.5; 95% CI, 2.3-12.7; AR, 24.1); however, initiating therapy with aromatase inhibitors was not associated with VTE (HR, 0.8; 95% CI, 0.5-1.4; AR, 28.3). In conclusion, women receiving chemotherapy for breast cancer have a clinically important risk of VTE, whereas an increased risk of VTE immediately after endocrine therapy is restricted to tamoxifen.