Complete remission in a patient with relapsed angioimmunoblastic T-cell lymphoma following treatment with bevacizumab

Biological Therapy of Hematologic Malignancies: Toward a Chemotherapy- free Era

Less than 70 years ago, the vast majority of hematologic malignancies were untreatable diseases with fatal prognoses. The development of modern chemotherapy agents, which had begun after the Second World War, was markedly accelerated by the discovery of the structure of DNA and its role in cancer biology and tumor cell division. The path travelled from the first temporary remissions observed in children with acute lymphoblastic leukemia treated with single-agent antimetabolites until the first cures achieved by multi-agent chemotherapy regimens was incredibly short. Despite great successes, however, conventional genotoxic cytostatics suffered from an inherently narrow therapeutic index and extensive toxicity, which in many instances limited their clinical utilization. In the last decade of the 20th century, increasing knowledge on the biology of certain malignancies resulted in the conception and development of first molecularly targeted agents designed to inhibit specific druggable molecules involved in the survival of cancer cells. Advances in technology and genetic engineering enabled the production of structurally complex anticancer macromolecules called biologicals, including therapeutic monoclonal antibodies, antibody-drug conjugates and antibody fragments. The development of drug delivery systems (DDSs), in which conventional drugs were attached to various types of carriers including nanoparticles, liposomes or biodegradable polymers, represented an alternative approach to the development of new anticancer agents. Despite the fact that the antitumor activity of drugs attached to DDSs was not fundamentally different, the improved pharmacokinetic profiles, decreased toxic side effects and significantly increased therapeutic indexes resulted in their enhanced antitumor efficacy compared to conventional (unbound) drugs. Approval of the first immune checkpoint inhibitor for the treatment of cancer in 2011 initiated the era of cancer immunotherapy. Checkpoint inhibitors, bispecific T-cell engagers, adoptive T-cell approaches and cancer vaccines have joined the platform so far, represented mainly by recombinant cytokines, therapeutic monoclonal antibodies and immunomodulatory agents. In specific clinical indications, conventional drugs have already been supplanted by multi-agent, chemotherapy-free regimens comprising diverse immunotherapy and/or targeted agents. The very distinct mechanisms of the anticancer activity of new immunotherapy approaches not only call for novel response criteria, but might also change fundamental treatment paradigms of certain types of hematologic malignancies in the near future.

Immunologic Milieu of Mature T-Cell and NK-Cell Lymphomas-Implications for Therapy

PURPOSE OF THE REVIEW

T-cells and natural killer (NK) cells share the same ontogeny, and lymphomas derived from them are clinically diverse, occurring in nodal and extranodal sites. In addition to inherent properties of these lymphomas, their microenvironment also impacts on pathogenesis and response to therapy. An understanding of the milieu of T-cell and NK cell lymphomas has important implications on treatment.

RECENT FINDINGS

Components of the microenvironment include tumour-associated macrophages (TAM), non-neoplastic T-cells and B-cells, eosinophils, dendritic cells, endothelial cells and blood vessels. TAM typically undergoes M2 polarization, promoting angiogenesis and inhibiting anti-tumour cellular immunity. In lymphomas of follicular helper T-cell derivation, increased B-cell proliferation occurs, which may in turn enhance neoplastic T-cell growth. The expression of immune checkpoint ligands on TAM, dendritic cells or lymphoma cells induces an immunosuppressive environment conducive to neoplastic proliferation. Strategies against this complex cellular and immunologic microenvironment have shown promises. These include the use of signal transduction inhibitors, monoclonal antibodies against chemokines or non-neoplastic microenvironmental cells, immunomodulatory drugs and immune checkpoint blockade. As T-cell and NK cell lymphomas are highly heterogeneous, clinical trials to demonstrate efficacy of a given therapeutic approach requires careful design aiming at enriching patient populations who will best respond. Targeting of the immunologic milieu in T-cell and NK-cell lymphomas offers exciting challenges and opportunities.

The aggressive peripheral T-cell lymphomas: 2017

BACKGROUND

T-cell lymphomas make up approximately 10%-15% of lymphoid malignancies. The frequency of these lymphomas varies geographically, with the highest incidence in parts of Asia.

DIAGNOSIS

The diagnosis of aggressive peripheral T-cell lymphoma (PTCL) is usually made using the World Health Organization classification. The ability of hematopathologists to reproducibly diagnose aggressive PTCL is lower than that for aggressive B-cell lymphomas, with a range of 72%-97% for the aggressive PTCLs. Risk Stratification: Patients with aggressive PTCL are staged using the Ann Arbor Classification. Although somewhat controversial, positron emission tomography scans seem to be useful as they are in aggressive B-cell lymphomas. The specific subtype of aggressive PTCL is an important risk factor with the best survival seen in anaplastic large-cell lymphoma-particularly young patients with the anaplastic lymphoma kinase positive subtype.

RISK-ADAPTED THERAPY

Anaplastic large-cell lymphoma is the only subgroup to have a good response to a CHOP-like regimen. Angioimmunoblastic T-cell lymphoma has a prolonged disease-free survival in only ∼20% of patients, but younger patients who have an autotransplant in remission seem to do better. PTCL-not otherwise specified is not one disease. Anthracycline-containing regimens have disappointing results, and a new approach is needed. Natural killer/T-cell lymphoma localized to the nose and nasal sinuses seems to be best treated with radiotherapy-containing regimens and the majority of patients are cured. Enteropathy-associated PTCL and hepatosplenic PTCL are rare disorders with a generally poor response to therapy although selected patients with enteropathy- associated PTCL seem to benefit from intensive therapy.

The aggressive peripheral T-cell lymphomas: 2015

BACKGROUND

T-cell lymphomas make up approximately 10%-15% of lymphoid malignancies. The frequency of these lymphomas varies geographically, with the highest incidence in parts of Asia.

DIAGNOSIS

The diagnosis of aggressive peripheral T-cell lymphoma (PTCL) is usually made using the World Health Organization classification. The ability of hematopathologists to reproducibly diagnosis aggressive PTCL is lower than that for aggressive B-cell lymphomas, with a range of 72%-97% for the aggressive PTCLs.

RISK STRATIFICATION

Patients with aggressive PTCL are staged using the Ann Arbor Classification. Although somewhat controversial, positron emission tomography scans seem to be useful as they are in aggressive B-cell lymphomas. The most commonly used prognostic index is the International Prognostic Index. The specific subtype of aggressive PTCL is an important risk factor, with the best survival seen in anaplastic large-cell lymphoma-particularly young patients with the anaplastic lymphoma kinase positive subtype.

RISK-ADAPTED THERAPY

Anaplastic large-cell lymphoma is the only subgroup to have a good response to a CHOP-like regimen. Angioimmunoblastic T-cell lymphoma has a prolonged disease-free survival in only ~20% of patients, but younger patients who have an autotransplant in remission seem to do better. PTCL-not otherwise specified is not one disease. Anthracycline-containing regimens have disappointing results, and a new approach is needed. Natural killer/T-cell lymphoma localized to the nose and nasal sinuses seems to be best treated with radiotherapy-containing regimens. Enteropathy-associated PTCL and hepatosplenic PTCL are rare disorders with a generally poor response to therapy, although selected patients with enteropathy-associated PTCL seem to benefit from intensive therapy.

Past, present and future treatment strategies in peripheral T-cell lymphomas

SUMMARY 

Nodal peripheral T-cell lymphomas (PTCLs) are very aggressive tumors characterized by poor response to conventional chemotherapy and dismal prognosis. Recent evidence has indicated that, at least for patients aged less than 60 years, frontline high-dose chemotherapy followed by autologous stem cell transplantation can be an effective strategy. Unfortunately, however, a significant fraction of patients cannot benefit from this approach, due to age, poor performance status or early relapse. In addition, a percentage of transplanted patients eventually relapse. In this article, based on their experience and on the most recent literature, the authors review the current concept on PTCL treatment, focusing on the most common PTCL nodal subtypes.

Molecular genetics of peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCL) are rare neoplasms that in most instances respond poorly to conventional chemotherapies. Four varieties--PTCL not otherwise specified (NOS), angioimmunoblastic T-cell lymphoma (AITL), ALK+ anaplastic T-cell lymphoma (ALCL), and ALK- ALCL--account for about 60 % of them. Their classification is difficult because of the wide spectrum of morphologic features and the lack of robust immunohistochemical markers. Thus, high-throughput technologies can importantly contribute to their better understanding. In particular, gene expression profiling has cleared the borders among PTCL/NOS, ALK- ALCL and AITL. In fact, gene signatures have been developed even from formalin-fixed paraffin-embedded tissue samples that definitely distinguish one tumor from the other(s). This has important practical implications: for instance on routine diagnostics PTCL/NOS expressing CD30 can be easily confused with ALK- ALCL, but has a much worse prognosis. Therefore, the clear-cut distinction between the two conditions is pivotal to understand the results of ongoing trials with Brentuximab Vedotin, targeting the CD30 molecule. Besides improving the diagnosis, molecular studies have provided the rationale for the usage of novel drugs in the setting of PTCLs, such as ALK inhibitors in ALK+ ALCL, anti-angiogenetic drugs in AITL, and tyrosine kinase inhibitors in PTCL/NOS and ALK+ and ALK- ALCLs.

The aggressive peripheral T-cell lymphomas: 2013

BACKGROUND

T-cell lymphomas make up approximately 10-15% of lymphoid malignancies. The frequency of these lymphomas varies geographically, with the highest incidence in parts of Asia.

DIAGNOSIS

The diagnosis of aggressive peripheral T-cell lymphoma (PTCL) is usually made using the WHO classification. The ability of hematopathologists to reproducibly diagnosis aggressive PTCL is lower than for aggressive B-cell lymphomas, with a range of 72-97% for the aggressive PTCLs.

RISK STRATIFICATION

Patients with aggressive PTCL are staged using the Ann Arbor Classification. Although somewhat controversial, PET scans appear to be useful as they are in aggressive B-cell lymphomas. The most commonly used prognostic index is the International Prognostic Index. The specific subtype of aggressive PTCL is an important risk factor, with the best survival seen in anaplastic large cell lymphoma-particularly young patients with the anaplastic lymphoma kinase positive subtype.

RISK ADAPTED THERAPY

Anaplastic large cell lymphoma is the only subgroup to have a good response to a CHOP-like regimen. Angioimmunoblastic T-cell lymphoma has a prolonged disease-free survival in only ~20% of patients, but younger patients who have an autotransplant in remission seem to do better. PTCL-NOS (not otherwise specified) is not one disease. Anthracycline containing regimens have disappointing results and a new approach is needed. NK/T-cell lymphoma localized to the nose and nasal sinuses seems to be best treated with radiotherapy containing regimens. Enteropathy associated PTCL and hepatosplenic PTCL are rare disorders with a generally poor response to therapy, although selected patients with enteropathy associated PTCL seem to benefit from intensive therapy.

Treatment strategies for peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCL) are a heterogeneous group of clinically aggressive diseases historically associated with inferior outcomes using conventional lymphoma therapies. Aggressive first line therapy and consolidation with autologous stem cell transplantation has led to improved survival, but the majority of patients either fails to respond to therapy or are not transplant candidates. Novel approaches have included new classes of drug and biological agents, including antifolates, immunoconjugates, histone deacetylase (HDAC) inhibitors, monoclonal antibodies, and signal transduction inhibitors. Molecular profiling has led to identification of relevant pathways for future novel approaches.

New molecular insights into peripheral T cell lymphomas

Peripheral T cell lymphomas (PTCLs) are heterogeneous neoplasms and represent about 12% of all lymphoid malignancies. They are often regarded as "orphan diseases," a designation that does not reflect their real incidence but rather signifies the difficulties encountered in their classification, diagnosis, and treatment. Here we revise the current understanding of the pathobiological characteristics of the most common nodal PTCLs by focusing on the contribution given by high-throughput technologies and the identification of potential therapeutic targets proposed by translational studies.

BCL2 expression in CD105 positive neoangiogenic cells and tumor progression in angioimmunoblastic T-cell lymphoma

The angiogenic microenvironment has been known to be a component of angioimmunoblastic T-cell lymphoma since its initial characterization. We have shown that angioimmunoblastic T-cell lymphoma endothelial cells produce vascular endothelial growth factor-A (VEGFA), and participate in lymphoma progression. In squamous cell carcinoma, endothelial BCL2 expression induces a crosstalk with tumor cells through VEGFA, a major mediator of tumoral angiogenesis. In the present study, we analyzed BCL2 and VEGFA in 30 angioimmunoblastic T-cell lymphomas, using triple immunofluorescence to identify protein coexpression in well-characterized lymphoma cells and microenvironment neoangiogenic endothelial cells. Using quantitative real-time PCR, we assessed mRNA expression levels in laser-microdissected endothelial and lymphoma cells. In lymphoma cells, as in endothelial cells, BCL2 and VEGFA proteins were coexpressed. BCL2 was expressed only in neoangiogenic CD34(+)CD105(+) endothelial cells. In laser-microdissected cells, mRNA studies showed a significant relationship between BCL2 and VEGFA levels in CD34(+) endothelial cells, but not in CD3(+)CD10(+)lymphoma cells, or in CD34(+) endothelial cells from lymph node hyperplasia. Further study showed that, in AITL, BCL2 mRNA levels in CD34(+)CD105(+) neoangiogenic endothelial cells also correlated with microvessel density, International Prognostic Index, Ann Arbor stage, bone marrow involvement and elevated LDH. BCL2 expression by CD105(+) neoangiogenic endothelial cells is related to tumor progression in angioimmunoblastic T-cell lymphoma.

The aggressive peripheral T-cell lymphomas: 2012 update on diagnosis, risk stratification, and management

BACKGROUND

T-cell lymphomas make up approximately 10-15% of lymphoid malignancies. The frequency of these lymphomas varies geographically, with the highest incidence in parts of Asia.

DIAGNOSIS

The diagnosis of aggressive peripheral T-cell lymphoma (PTCL) is usually made using the WHO classification. The ability of hematopathologists to reproducibly diagnose aggressive PTCL is lower than for aggressive B-cell lymphomas, with a range of 72-97% for the aggressive PTCLs.

RISK STRATIFICATION

Patients with aggressive PTCL are staged using the Ann Arbor Classification. Although somewhat controversial, positron emission tomography (PET) scans appear to be useful as they are in aggressive B-cell lymphomas. The most commonly used prognostic index is the International Prognostic Index. The specific subtype of aggressive PTCL is an important risk factor, with the best survival seen in anaplastic large-cell lymphoma-particularly young patients with the anaplastic lymphoma kinase positive subtype.

RISK ADAPTED THERAPY

Anaplastic large-cell lymphoma is the only subgroup to have a good response to a cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP)-like regimen. Angioimmunoblastic T-cell lymphoma has a prolonged disease-free survival in only ∼20% of patients, but younger patients who have an autotransplant in remission seem to do better. PTCL-not otherwise specified (NOS) is not one disease. Anthracycline containing regimens have disappointing results and a new approach is needed. NK/T-cell lymphoma localized to the nose and nasal sinuses seems to be best treated with radiotherapy containing regimens. Enteropathy associated PTCL and hepatosplenic PTCL are rare disorders with a generally poor response to therapy, although selected patients with enteropathy associated PTCL seem to benefit from intensive therapy.

Pediatric T- and NK-cell lymphomas: new biologic insights and treatment strategies

T- and natural killer (NK)-cell lymphomas are challenging childhood neoplasms. These cancers have varying presentations, vast molecular heterogeneity, and several are quite unusual in the West, creating diagnostic challenges. Over 20 distinct T- and NK-cell neoplasms are recognized by the 2008 World Health Organization classification, demonstrating the diversity and potential complexity of these cases. In pediatric populations, selection of optimal therapy poses an additional quandary, as most of these malignancies have not been studied in large randomized clinical trials. Despite their rarity, exciting molecular discoveries are yielding insights into these clinicopathologic entities, improving the accuracy of our diagnoses of these cancers, and expanding our ability to effectively treat them, including the use of new targeted therapies. Here, we summarize this fascinating group of lymphomas, with particular attention to the three most common subtypes: T-lymphoblastic lymphoma, anaplastic large cell lymphoma, and peripheral T-cell lymphoma-not otherwise specified. We highlight recent findings regarding their molecular etiologies, new biologic markers, and cutting-edge therapeutic strategies applied to this intriguing class of neoplasms.

Angioimmunoblastic T-cell lymphoma: the effect of initial treatment and microvascular density in 31 patients

The objectives of this study are to explore the clinical features and treatment outcomes and to investigate the correlation between microvessel density (MVD) and survival in patients with angioimmunoblastic T-cell lymphoma (AITL). We retrospectively analyzed clinical and follow-up data of 31 patients treated in two hospitals during 1995-2009 histologically proven AITL. We also assessed MVD in the lump of 31 previously untreated patients using α-CD34 immunohistochemical staining. The median age of the 31 patients was 48 years, eighty percent of the patients were in an advanced stage. 67.7% of them had B symptoms, with the follow-up of 2-13 years, the 5-year overall survival rate was 25.8%. The response rates (RR) of CHOP group and COP (cyclophosphamide, vincristine and prednisolone) group are 76.5 and 75%, respectively, which is no significant difference (P=0.894). RR did not differ whether chemotherapy regimens contained anthracycline or not. The 3-year PFS rate for patients who received COP and CHOP regimen was 25.4 and 35.3% (P=0.562), while 5-year OS rates were 25.0 and 29.4%, respectively (P=0.667). The median PFS for patients with high MVD and low MVD were 15.1 and 30.0 months (P=0.048), while the median OS were 20 and 45 months, respectively (P=0.038). Patients who were sensitive to initial chemotherapy COP regimen have the similar therapeutic effect to CHOP regimen. Patients with high MVD measured in the microenvironment had worse PFS and OS than AITL patients with low expression.

Targeted molecular therapy in peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCLs) are rare neoplasms constituting a heterogeneous group of diseases. At present, available chemotherapy regimens that have improved outcomes in B-cell lymphomas appear to be less efficacious in the context of PTCLs and, thus, alternative strategies are warranted. In the last few years, based on the recent, deeper understanding of PTCL biology, several molecules and/or pathways have been proposed for targeted therapy in this setting, including surface antigens, tyrosine kinases, the NF-κB pathway, folate metabolism, histone modification and others. Of particular interest, histone deacetylase and proteasome inhibitors, as well as novel chemotherapeutic agents such as pralatrexate, have already demonstrated efficacy in PTCL therapy. In addition, a strong biological rationale and early clinical evidence supports the future study of tyrosine kinase inhibitors in this setting. In this article, the authors review the available literature on targeted therapy in PTCLs and also, based on their own experience, discuss potential opportunities in this intriguing area.

New drug therapies in peripheral T-cell lymphoma

Peripheral T-cell lymphomas (PTCLs) are a heterogeneous collection of lymphomas that are associated with very poor prognosis. Conventional therapies, historically based on protocols for aggressive B-cell lymphomas, deliver less than adequate outcomes; the majority of patients experience early relapse after front-line treatment and current 5-year overall survival is only 10-30%. Clearly, new approaches are needed. In recent years there has been a plethora of novel agents showing activity in PTCL, often in patients with advanced relapsed or refractory disease. These agents include antifolate drugs (pralatrexate), histone deacetylase inhibitors (vorinostat, romidepsin, panobinostat and belinostat), nucleoside analogues (gemcitabine, forodesine and clofarabine), monoclonal antibodies (anti-CD52, anti-CD4 and anti-CD2), fusion toxins (denileukin diftitox), immunomodulatory agents (lenalidomide) and proteasome inhibitors (bortezomib). This is an exciting time in the treatment of PTCL, as our ever improving understanding of the distinguishing features, pathogenesis, molecular biology and progression of PTCL, and the knowledge of the mechanism and efficacy of novel therapies, may see a real improvement in outcomes for patients. The purpose of this article is to focus on these novel therapies and the results of recent clinical trials in PTCL.

Peripheral T-cell lymphoma

Peripheral T-cell lymphomas (PTCLs) are a heterogeneous group of clinically aggressive diseases associated with poor outcome. Studies that focus specifically on PTCL are emerging, with the ultimate goal of improved understanding of disease biology and the development of more effective therapies. However, one of the difficulties in classifying and studying treatment options in clinical trials is the rarity of these subtypes. Various groups have developed lymphoma classifications over the years, including the World Health Organization, which updated its classification in 2008. This article briefly reviews the major lymphoma classification schema, highlights contributions made by the collaborative International PTCL Project, discusses prognostic issues and gene expression profiling, and outlines therapeutic approaches to PTCL. These include the standard chemotherapeutic regimens and other modalities incorporating antifolates, conjugates, histone deacetylase inhibitors, monoclonal antibodies, nucleoside analogs, proteasome inhibitors, and signaling inhibitors. As this review emphasizes, the problem has now evolved into an abundance of drugs and too few patients available to test them. Collaborative groups will aid in future efforts to find the best treatment strategies to improve the outcome for patients with PTCL.

Evolving Therapy of Peripheral T-cell Lymphoma: 2010 and beyond

The peripheral T-cell lymphomas are a rare, heterogeneous group of non-Hodgkin's lymphomas which have an aggressive clinical course. Treatment approaches have traditionally been similar to those of diffuse large B-cell lymphomas, but outcomes have been inferior. Novel approaches involving agents and pathways developed from a better understanding of the biology of the diseases have led to therapeutic advances. The introduction of new agents, including antifolates, immunoconjugates, histone deacetylase inhibitors, monoclonal antibodies, nucleoside analogs, proteasome inhibitors, and signaling inhibitors have improved outcomes for patients with relapsed and refractory disease and are being incorporated into strategies for first-line therapy. Stem cell transplantation remains a potentially curative option for a subset of patients.

Guidelines for the management of mature T-cell and NK-cell neoplasms (excluding cutaneous T-cell lymphoma)

The peripheral T-cell neoplasms are a biologically and clinically heterogeneous group of rare disorders that result from clonal proliferation of mature post-thymic lymphocytes. Natural killer (NK) cell neoplasms are included in this group. The World Health Organization classification of haemopoietic malignancies has divided this group of disorders into those with predominantly leukaemic (disseminated), nodal, extra-nodal or cutaneous presentation. They usually affect adults and are more commonly reported in males than in females. The median age at diagnosis is 61 years with a range of 17-90 years. Although some subtypes may follow a relatively benign protracted course most have an aggressive clinical behaviour and poor prognosis. Excluding anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma (ALCL), which has a good outcome, 5-year survival for other nodal and extranodal T-cell lymphomas is about 30%. Most patients present with unfavourable international prognostic index scores (>3) and poor performance status. The rarity of these diseases and the lack of randomized trials mean that there is no consensus about optimal therapy for T- and NK-cell neoplasms and recommendations in this guideline are therefore based on small case series, phase II trials and expert opinion.

Clinical features and prognostic factors of angioimmunoblastic T-cell lymphoma in Taiwan: a single-institution experience

Angioimmunoblastic T-cell lymphoma (AITL) is a rare subtype of peripheral T-cell lymphoma that carries a poor prognosis. This study retrospectively analyzed patients with AITL from a single institution in Taiwan, aiming to define the clinical features and prognostic factors. Patients with AITL treated at our institution from February 1988 through January 2010 were enrolled. Factors associated with overall survival (OS) were determined by statistical methods. A total of 31 Taiwanese patients (21 males) were identified. The median age was 74 years (range, 27-90). Among all patients, 67.7% were Ann Arbor stage III or IV, 58.1% presented with B symptoms, 48.4% had hypoalbuminenia (<35 g/L), and 63.3% had elevated lactate dehydrogenase (LDH) at diagnosis. First-line chemotherapy was mostly CHOP (cyclophosphamide, vincristine, doxorubicin, and prednisolone)-based and complete response (CR) was achieved in 25% of patients. The actuarial 2-year survival rate was 38.7%, and the median OS was 14.9 months. In multivariate analysis, initial presentation with fever (p = 0.035), advanced stage (p = 0.024), and failure to achieve CR (p = 0.029) were independent adverse factors associated with poorer OS. Interestingly, OS did not differ whether chemotherapy regimens contained anthracycline or not. Taiwanese patients with AITL were usually elderly. Despite the prognosis being generally poor, patients with AITL should be treated with the goal of achieving CR, regardless of anthracycline- or non-anthracycline-based chemotherapy.

Vascular endothelial growth factor-related pathways in hemato-lymphoid malignancies

Angiogenesis is essential for malignant tumor growth. This has been documented for solid tumors, and there is an emerging evidence suggesting that tumor progression of hematolymphoid malignancies also depends on the induction of new blood vessel formation. The most important proangiogenic agent is vascular endothelial growth factor (VEGF), activating VEGF receptors 1 and 2. The available data on angiogenesis in hemato-lymphoid malignancies, such as acute leukemias, myelodysplastic syndromes, myeloproliferative neoplasms, multiple myeloma, and lymphomas, point towards the significance of autocrine and paracrine VEGF-mediated effects for proliferation and survival of leukemia/lymphoma cells in addition to tumor vascularization. Antiangiogenic strategies have become an important therapeutic modality for solid tumors. Several antiangiogenic agents targeting VEGF-related pathways are also being utilized in clinical trials for the treatment of hemato-lymphoid malignancies, and in some instances these pathways have emerged as promising therapeutic targets. This review summarizes recent advances in the basic understanding of the role of angiogenesis in hemato-lymphoid malignancies and the translation of such basic findings into clinical studies.

Targeted therapies in cancer

Recent advances in understanding the biologic mechanisms underlying cancer development have driven the design of new therapeutic approaches, termed 'targeted therapies', that selectively interfere with molecules or pathways involved in tumor growth and progression. Inactivation of growth factors and their receptors on tumor cells as well as the inhibition of oncogenic tyrosine kinase pathways and the inhibition of molecules that control specific functions in cancer cells constitute the main rational bases of new cancer treatments tailored for individual patients. Small-molecule inhibitors and monoclonal antibodies are major components of these targeted approaches for a number of human malignancies. As the studies of the bio-molecular features of cancer progress, new exciting strategies have arisen, such as targeting cancer stem cells that drive tumor relapses or the selective induction of apoptosis in malignant cells. This article primarily focuses on the biologic bases of the new cancer drugs and summarizes their mechanisms of action, the clinical evidence of their anti-cancer effectiveness as well as the rationale for their use in clinical practice.

Lymphoma endothelium preferentially expresses Tim-3 and facilitates the progression of lymphoma by mediating immune evasion

Angiogenesis is increasingly recognized as an important prognosticator associated with the progression of lymphoma and as an attractive target for novel modalities. We report a previously unrecognized mechanism by which lymphoma endothelium facilitates the growth and dissemination of lymphoma by interacting with circulated T cells and suppresses the activation of CD4⁺ T cells. Global gene expression profiles of microdissected endothelium from lymphoma and reactive lymph nodes revealed that T cell immunoglobulin and mucin domain–containing molecule 3 (Tim-3) was preferentially expressed in lymphoma-derived endothelial cells (ECs). Clinically, the level of Tim-3 in B cell lymphoma endothelium was closely correlated to both dissemination and poor prognosis. In vitro, Tim-3⁺ ECs modulated T cell response to lymphoma surrogate antigens by suppressing activation of CD4⁺ T lymphocytes through the activation of the interleukin-6–STAT3 pathway, inhibiting Th1 polarization, and providing protective immunity. In a lymphoma mouse model, Tim-3–expressing ECs promoted the onset, growth, and dissemination of lymphoma by inhibiting activation of CD4⁺ T cells and Th1 polarization. Our findings strongly argue that the lymphoma endothelium is not only a vessel system but also a functional barrier facilitating the establishment of lymphoma immune tolerance. These findings highlight a novel molecular mechanism that is a potential target for enhancing the efficacy of tumor immunotherapy and controlling metastatic diseases.

Peripheral T-cell lymphomas, unspecified (or not otherwise specified): a review

Peripheral T-cell lymphomas (PTCL) comprises a heterogeneous group of haematological tumours, which originate from mature T-cells, and constitute less than 15% of all non-Hodgkin's lymphomas (NHLs) in adults. The current WHO classification recognizes nine distinct clinicopathologic peripheral T-cell NHLs, being the 'unspecified variant' (PTCL-U) the most common subtype. These neoplasms often present in advanced stage at diagnosis, and most commonly have an aggressive clinical course requiring prompt treatment. The rarity of these tumours requires additional studies to better understand their biology and search for new therapies which may hopefully improve the dismal outcome of most patients. This review aims to describe the pathobiological aspects as well the clinical characteristics and current therapeutic strategies of the PTCLs, with special attention to the group of PTCL-U.

Antibody-based cancer therapy

BACKGROUND

The clinical efficacy of mAbs is generally ascribed to interference with signaling pathways leading to arrest of cell-cycle progression and inhibition of tumor growth. Furthermore, mAbs also have the capacity to activate effector functions of the innate immune system and facilitate the destruction of malignant cells.

OBJECTIVES

The induction of tumor-specific immunity is a desired outcome in cancer immunotherapy. The prevailing situation raises one major question that has to be addressed. This is the clear need for the induction of tumor-specific immunity by combining mAb treatment with other modalities of cancer immunotherapy.

METHODS

Through mAb treatment, recent efforts focus at initiating or enhancing active antitumor immune responses by i) potentiating co-stimulation and blocking co-inhibition; and ii) rendering tumors more immunogenic through increased tumor peptide expression.

RESULTS/CONCLUSIONS

In this review, the functional characteristics of mAbs, together with their mechanisms of action and clinical application, is summarized as is the potential of combination immunotherapies using mAbs for the augmentation of adaptive antitumor immunity. The results from preclinical and clinical studies demonstrate that mAbs can also promote tumor-specific active immunity.

Novel Therapies and Role of Transplant in the Treatment of Peripheral T-Cell Lymphomas

Peripheral T-cell lymphomas (PTCL) are an uncommon, heterogeneous group of non-Hodgkin lymphomas that carry a much poorer prognosis than their more common B-cell counterparts. The most commonly used treatment is CHOP or its variations. However, while the results with CHOP are inadequate, there is little compelling data to suggest a preferred alternate strategy. Many of these alternate strategies have been assembled from retrospective data, small case series, subset analyses, phase II studies and individual experience. The greatest experience with alternative treatments has been with the use of high-dose therapy as consolidation. These approaches are promising, but most of the studies are retrospective and include patients with diverse prognoses, making interpretation difficult. Preliminary results of prospective trials in PTCL are only recently being reported. Perhaps more exciting have been the increasing numbers of new therapies being studied for patients with PTCL. The activities of new drugs are being described in studies specifically for PTCL, and attempts at novel combinations are beginning.

Gene expression analysis of angioimmunoblastic lymphoma indicates derivation from T follicular helper cells and vascular endothelial growth factor deregulation

Angioimmunoblastic lymphoma (AILT) is the second most common subtype of peripheral T-cell lymphoma (PTCL) and is characterized by dismal prognosis. Thus far, only a few studies have dealt with its molecular pathogenesis. We performed gene expression profile (GEP) analysis of six AILT, six anaplastic large cell lymphomas (ALCL), 28 PTCL-unspecified (PTCL/U), and 20 samples of normal T lymphocytes (including CD4(+), CD8(+), and activated and resting subpopulations), aiming to (a) assess the relationship of AILT with other PTCLs, (b) establish the relationship between AILT and normal T-cell subsets, and (c) recognize the cellular programs deregulated in AILT possibly looking for novel potential therapeutic targets. First, we found that AILT and other PTCLs have rather similar GEP, possibly sharing common oncogenic pathways. Second, we found that AILTs are closer to activated CD4(+), rather than to resting or CD8(+) lymphocytes. Furthermore, we found that the molecular signature of follicular T helper cells was significantly overexpressed in AILT, reinforcing the idea that AILT may arise from such cellular counterpart. Finally, we identified several genes deregulated in AILT, including PDGFRA, REL, and VEGF. The expression of several molecules was then studied by immunohistochemistry on tissue microarrays containing 45 independent AILT cases. Notably, we found that the vascular endothelial growth factor (VEGF) was expressed not only by reactive cells, but also by neoplastic cells, and that nuclear factor-kappaB (NF-kappaB) activation is uncommon in AILT, as suggested by frequent exclusively cytoplasmic c-REL localization. Our study provides new relevant information on AILT biology and new candidates for possible therapeutic targets such as PDGFRA (platelet-derived growth factor alpha) and VEGF.

Lymphomes T angio-immunoblastiques

Angioimmunoblastic T-cell lymphoma most often affects the elderly. Patients present with generalized lymphadenopathy and systemic symptoms; half also have hepatomegaly, splenomegaly and a rash. Polyclonal hypergammaglobulinemia, elevated lactate dehydrogenase, and anemia are the main laboratory abnormalities. Autoimmune phenomena (including autoimmune hemolytic anemia, immunologic thrombocytopenia, and autoantibodies) are common. Lymph node biopsy is needed to confirm this diagnosis. Genetic analysis that reveals a monoclonal T-cell population is also relevant. The underlying immune deficiency explains the frequency of infections. Most patients are treated with combination chemotherapy. Autologous stem cell transplantation is proposed to the youngest. Immunosuppressive drugs may be appropriate for elderly or relapsing patients. The overall 5-year survival rate is 30%.

Novel therapeutic targets in mantle cell lymphoma

Mantle cell lymphoma (MCL) is characterised by cell cycle dysregulation and a defective DNA damage response pathway. An evolving understanding of these processes has provided the rationale for development of novel agents targeting various steps that appear to be involved in lymphomagenesis and disease progression. Cyclin D1, overexpressed in nearly 100% of MCL, and the cyclin-dependent kinases were among the first rational targets identified. Therapies focusing on the PI3K/Akt pathway, the tumour microenvironment, and cell surface markers are also in various stages of exploration. Here, the authors discuss the rationale for developing targeted therapies and discuss future challenges in combining some of these agents.

Angioimmunoblastic T cell lymphoma: pathobiological insights and clinical implications

PURPOSE OF REVIEW

Angioimmunoblastic T cell lymphoma is a complex lymphoproliferative disorder. While recent evidence suggests that the Epstein-Barr virus and B cell disregulation are implicated in the disease's pathogenesis, their mechanistic roles remain largely unknown. The prognosis with traditional chemotherapy has been poor, but improved understanding of the disease's pathobiology has led to several promising novel therapeutic strategies.

RECENT FINDINGS

The recent finding of overexpression of the chemokine CXCL13 by the neoplastic cells of angioimmunoblastic T cell lymphoma suggests that it is derived from follicular helper T cells. In addition, gene-expression profiling has demonstrated overexpression of several genes characteristic of follicular helper T cells. Vascular endothelial growth factor-A is also highly expressed. Novel therapeutic strategies including immunomodulation with agents like cyclosporine and angiogenesis inhibition with drugs such as bevacizumab are being investigated, and show early promise in this disease.

SUMMARY

Diseases such as angioimmunoblastic T cell lymphoma can help illuminate the biology of the normal immune system. Significant progress has been made in understanding the biology of angioimmunoblastic T cell lymphoma. This has paved the way for the development of new therapeutic strategies and these have shown interesting results.