Current Cancer Drug Targets - Volume 16, Issue 8, 2016

Chronic lymphocytic leukemia (CLL), a clonal expansion of B CD5+ cells, is the most common type of adult leukemia in western countries. The accumulation of neoplastic B-cells is primarily caused by prolonged life-span of these cells due to deregulation of apoptosis, and only marginally due to a higher proliferation rate. In spite of numerous reports characterizing particular mechanisms of B-CLL cell apoptosis, still relatively little is known about the complex regulation of this process. Therefore, more detailed research is required to understand the complicated mechanisms and regulatory processes of apoptosis in neoplastic Blymphocytes.

Chronic lymphocytic leukemia (CLL) is a clinically heterogeneous disease characterized by the accumulation/expansion of a clonal population of neoplastic cells with the morphological appearance of small mature B lymphocytes in blood, bone marrow, and lymphoid organs. CD49d, the α chain of the α4β1 integrin heterodimer, is one of the main interactors between CLL cells and accessory cells in the microenvironmental sites and one of the main predictors of overall survival. In particular, CD49d is known to play a pivotal role in mediating both cell-cell and cell-matrix interactions in CLL-involved tissues eventually delivering prosurvival signals and protecting CLL cells from drug-induced damages. Treatment strategies targeting the α4β1 integrin could represent an interesting option in CLL. In this context, the recombinant anti-CD49d antibody natalizumab demonstrated the potential to overcome stromal cell-induced resistance of B cell lymphoma cells against cytotoxic drugs and rituximab in vitro. Moreover, a specific interest for the CD49d molecule raises from the clinical activity of the recently proposed inhibitors of kinases downstream the BCR that has been recently related with the inside-out activation of the α4β1 integrin. In the review, we addressed in detail the role of CD49d in CLL cells, including clinical impact, relationship with specific cytogenetic features, and CD49d-dependent interactions in lymph node and bone marrow microenvironment responsible for growth- and survival- supporting signals, eventually influencing CLL prognosis and therapeutic options.

Various signal transduction pathways have been implicated in the pathogenesis of chronic lymphocytic leukemia (CLL), which is characterized by the progressive accumulation of monoclonal CD5+ B cells in the blood. B cell receptor (BCR) signaling appears to have a crucial role in disease onset and is thought to be induced by self or non-self-antigen recognition leading to chronic stimulation. Several of the kinases functioning downstream of the BCR are aberrantly expressed or constitutively activated in CLL. Yet, these kinases have additional roles, particularly in chemokine receptor signaling, which is essential for homing and survival of CLL cells in lymphoid organs, or in toll-like receptor signaling. Recently, small molecule inhibitors of kinases in the BCR signaling pathway have shown impressive anti-tumor activity in clinical trials. Remarkably, the observed durable responses in CLL patients were accompanied by transient increases in blood lymphocyte numbers, indicating the importance of these kinases in chemokine receptor signaling. In this review, we therefore highlight the role of BCR signaling and the important other associated signal transduction cascades for CLL cells and give an overview of novel agents that target these specific pathways and were shown to be successful for CLL treatment in clinical trials.

There have been significant advances in our understanding of the pathogenesis of chronic lymphocytic leukemia (CLL) over the last decade, which has been accompanied by a rapid increase in treatment options. Inhibitors of BCRsignaling such as ibrutinib and idelalisib, and pro-apoptotic agents such as ABT- 199 have shown great promise in initial clinical trials and have been at the forefront of recent developments. However, despite the encouraging early data, these agents do not appear to represent a “cure” for CLL and mechanisms of resistance to these agents have already been identified. In light of these considerations there remains a need for alternative treatment strategies. Lenalidomide, a second-generation derivative of thalidomide, has been demonstrated to have significant clinical activity in CLL. Its effect appears to be mediated by reduction of CLL-cell proliferation, improvement of anti-tumor immune responses and reduction of pro-tumoral factors in the CLL microenvironment. This review discusses our current understanding of the mechanism of action of lenalidomide on both healthy cells and in CLL. It also summarises the published clinical trial experience with this drug, and proposes an ongoing role for this agent in the CLL armamentarium.

Despite impressive therapeutic progress represented by the advent of chemoimmunotherapy, chronic lymphocytic leukemia (CLL) remains incurable by conventional modalities. Refractory CLL defined by non-response to treatment or relapse/progression within 6 months is associated with multiple unfavourable prognostic factors such as p53 pathway disruption, deteriorating patient condition, increased risk of severe infections, and poor response to treatment, resulting in a very short overall survival. Therefore, refractory CLL represents a highly challenging situation for the hematologist as well as the patient. The amount and quality of data on refractory CLL are rather limited as clinical trials usually combine patients with relapsed and refractory disease. Therapeutic options for refractory CLL include alemtuzumab, ofatumumab, fludarabine- and bendamustine-based regimens, platinum-based aggressive protocols and high-dose corticosteroids combined with monoclonal antibodies. The recent introduction of ibrutinib and idelalisib, small molecules interfering with B-cell receptor pathways, revolutionized the treatment of refractory CLL by the novel concept of long-term, oral treatment leading to impressive progression-free and overall survival improvement. Allogeneic stem cell transplantation is still considered the only option with curative potential. This review focuses on the currently available therapeutic strategies for refractory CLL.

Clinical trials in chronic lymphocytic leukemia (CLL) have focused mainly on younger fit patients until recently. However, CLL is a disease of elderly and many patients have significant comorbid conditions which together with advanced age preclude the use of aggressive regimens like FCR (fludarabine, cyclophosphamide, rituximab). Therefore, parameters such as performance status, renal function and number/severity of comorbidities together with clinical judgment should be used to guide the decision-making process regarding intensity of treatment. Two large randomized trials recently demonstrated that addition of monoclonal anti-CD20 antibodies (obinutuzumab, rituximab, and ofatumumab) to chlorambucil in untreated comorbid patients lead to improvement in complete remission rate, progression-free survival and even overall survival (obinutuzumab-chlorambucil and rituximab-chlorambucil), with acceptable toxicity profile. Thus, chemoimmunotherapy combining chlorambucil with an anti-CD20 antibody is the new standard approach for elderly/comorbid CLL patients in the first line. Treatment of relapsed/refractory disease in this patient population is very challenging and data regarding this subpopulation are rather limited. Impressive efficacy of novel targeted small molecules interfering with B-cell receptor signaling, namely Bruton tyrosine kinase inhibitor ibrutinib and phosphatidylinositol-3 kinase delta inhibitor idelalisib, radically changed the treatment paradigms for relapsed/refractory CLL; relatively mild toxicity of these agents make them very good candidates for elderly/comorbid patients. Other options for relapsed/refractory disease include alemtuzumab, ofatumumab, high-dose glucocorticoids+rituximab and bendamustine+rituximab. This review summarizes the current knowledge on prognostication and therapy of elderly and comorbid patients with CLL.

Esophageal squamous cell carcinoma (ESCC), which is the most common subtype of esophageal cancers, is the sixth leading cause of cancer deaths worldwide with a five-year survival rate of 19%. Identification of efficient biomarkers for early detection and better understanding of the molecular mechanisms of ESCC may offer reduced mortality. However, proper biomarkers for clinical diagnosis and prognosis have not been defined yet. In the presented study, we employed a systematic and integrative ‘omics’ strategy to reconstruct networks of transcriptional regulation and protein-protein interaction to identify novel biomarkers, potential molecular targets, and mechanisms of transcriptional control in ESCC. Towards this end, we revealed 30 down-regulated and 21 upregulated genes as ESCC specific biomarkers since these were differentially expressed between 91 ESCC tumor samples compared to normal tissues in five different datasets. We report the association of ACPP, C2orf54, DYNLT3, ENDOU, FMO2, and KANK1 (down-regulated genes) and COL10A1, FNDC3B, HOMER3, MARCKSL1, and RFC4 (up-regulated genes) to ESCC for the first time. Further, the ESCC driven molecular pathways were also constructed to elucidate the molecular mechanism of the disease; specifically several metabolic pathways were down-regulated while the signaling pathways were up-regulated. Additionally, reporter metabolites for ESCC were analyzed and metabolic dysfunction was ascertained in arachidonic acid metabolism and steroid hormone biosynthesis pathways. The multi-omics network strategy presented here may enable discovery of novel biomarkers and targets for personalized medicine in ESCC patients.