Lenalidomide inhibits lymphangiogenesis in preclinical models of mantle cell lymphoma

Empowering macrophages: the cancer fighters within the tumour microenvironment in mantle cell lymphoma

In Mantle Cell Lymphoma (MCL), the role of macrophages within the tumour microenvironment (TME) has recently gained attention due to their impact on prognosis and response to therapy. Despite their low absolute number in MCL tumour tissue, recent findings reveal an association between the levels of macrophages and prognosis, consistent with trends observed in other lymphoma subtypes. M2-like macrophages, identified by markers such as CD163, contribute to angiogenesis and suppression of the immune response. Clinical trials with MCL patients treated with chemoimmunotherapy and targeted treatments underscore the adverse impact of high levels of M2-like macrophages. Immunomodulatory drugs like lenalidomide reduce the levels of MCL-associated CD163+ macrophages and enhance macrophage phagocytic activity. Similarly, clinical approaches targeting the CD47 "don't eat me" signalling, in combination with the anti-CD20-antibody rituximab, demonstrate increased macrophage activity and phagocytosis of MCL tumour cells. Cell-based therapies such as chimeric antigen receptor (CAR) T-cell have shown promise but various challenges persist, leading to a potential interest in CAR-macrophages (CAR-M). When macrophages are recruited to the TME, they offer advantages including phagocytic function and responsiveness to microenvironment alterations, suggesting their potential as a manipulable and inducible alternative when CAR T-cell therapies fails in the complex landscape of MCL treatment.

Macrophages and angiogenesis in human lymphomas

A link exists between chronic inflammation and cancer and immune cells, angiogenesis, and tumor progression. In hematologic malignancies, tumor-associated macrophages (TAMs) are a significant part of the tumor microenvironment. Macrophages are classified into M1/classically activated and M2/alternatively activated. In tumors, TAMs are mainly constituted by M2 subtype, which promotes angiogenesis, lymphangiogenesis, repair, and remodeling, suppressing adaptive immunity, increasing tumor cell proliferation, drug resistance, histological malignancy, and poor clinical prognosis. The aim of our review article is to define the role of TAMs and their relationship with the angiogenesis in patients with lymphoma reporting both an analysis of main published data and those emerging from our studies. Finally, we have discussed the anti-angiogenic approach in the treatment of lymphomas.

Nine-year follow-up of lenalidomide plus rituximab as initial treatment for mantle cell lymphoma

Although chemoimmunotherapy is the current standard of care for initial treatment of mantle cell lymphoma (MCL), newer data suggest that there may be a role for a chemotherapy-free approach. We report the 9-year follow-up results of a multicenter, phase 2 study of lenalidomide plus rituximab (LR) as the initial treatment of MCL. The LR doublet is used as induction and maintenance until progression, with optional discontinuation after 3 years. We previously reported an overall response rate of 92% in evaluable patients, with 64% achieving a complete response. At a median follow-up of 103 months, 17 of 36 evaluable patients (47%) remain in remission. The 9-year progression-free survival and overall survival were 51% and 66%, respectively. During maintenance, hematologic adverse events included asymptomatic grade 3 or 4 cytopenia (42% neutropenia, 5% thrombocytopenia, and 3% anemia) and mostly grade 1 to 2 infections managed in the outpatient setting (50% upper respiratory infections, 21% urinary tract infections, 16% sinusitis, 16% cellulitis, and 13% pneumonia, with 5% requiring hospitalization). More patients developed grade 1 and 2 neuropathy during maintenance therapy (29%) than during induction therapy (8%). Twenty-one percent of patients developed secondary malignancies, including 5% with invasive malignancies, whereas the remainder were noninvasive skin cancers treated with local skin-directed therapy. Two patients permanently discontinued therapy because of concerns of immunosuppression during the COVID-19 pandemic. With long-term follow-up, LR continues to demonstrate prolonged, durable responses with manageable safety as initial induction therapy. This trial was registered at www.clinicaltrials.gov as #NCT01472562.

Soluble CD163 predicts outcome in both chemoimmunotherapy and targeted therapy-treated mantle cell lymphoma

The outcome for patients with mantle cell lymphoma (MCL) has drastically improved with new treatments directed toward the tumor immune microenvironment, where macrophages play an important role. In MCL, the presence of M2 macrophages defined by CD163 expression in diagnostic biopsies has been associated with a worse prognosis. An alternative way to assess the abundance of M2 macrophages is by measuring the level of soluble CD163 in serum (sCD163). We aimed to investigate the prognostic value of sCD163 in 131 patients with MCL. We found that high sCD163 at diagnosis was associated with shorter progression-free survival (PFS) and shorter overall survival (OS) in 81 patients who were newly diagnosed and subsequently treated with chemoimmunotherapy. The same was seen in a cohort of 50 patients with relapsed MCL that were mainly treated within the phase 2 Philemon-trial with rituximab, ibrutinib, and lenalidomide. In patients who were newly diagnosed and had low levels of sCD163, 5-year survival was 97%. There was a moderate correlation between sCD163 and tissue CD163. The association with a poor prognosis was independent of MCL international prognostic index, Ki67, p53 status, and blastoid morphology, as assessed in a multivariable Cox proportional hazards model. In this study, high sCD163 was associated with both shorter PFS and shorter OS, showing that high levels of the M2 macrophage marker sCD163 is an independent negative prognostic factor in MCL, both in the chemoimmunotherapy and ibrutinib/lenalidomide era. In addition, low sCD163 levels identify patients with MCL with a very good prognosis.

Blockade of CCR1 induces a phenotypic shift in macrophages and triggers a favorable antilymphoma activity

Tumor-associated macrophages (TAMs) within the tumor microenvironment (TME) play an important role in tumor growth and progression. TAMs have been involved in producing immunosuppressive TME via various factors; however, the underlying mechanisms remain unclear in B-cell lymphoma, including mantle cell lymphoma (MCL). We identified that chemokine receptor-1 (CCR1) is highly expressed on monocytes (Mo) and macrophages (MΦ), and CCR1 pharmacological inhibition or CCR1 siRNA abolished lymphoma-mediated Mo/MΦ migration in a chemotaxis assay. The deficiency of host CCR1 (CCR1 KO) was associated with decreased infiltration of peritoneal-MΦ compared with WT-CCR1. Functional studies indicated that the genetic depletion of CCR1 or treatment inhibited protumor MΦ (M2-like) phenotype by decreasing CD206 and IL-10 expression. Moreover, CCR1 depletion reprogrammed MΦ toward an MHCII+/TNFα+ immunogenic phenotype. Mechanistically, protumor MΦ driven-IL-10 provides a positive feedback loop to tumor-CCL3 by regulating the CCL3 promoter via STAT1 signaling. Therapeutic in vivo targeting of CCR1 with CCR1 antagonist BX-471 significantly reduced FC-muMCL1 mouse tumors in the syngeneic MCL model by the depletion of M2-TAMs and increased infiltration of cytotoxic CD8+ T cells. Our study established that CCR1 exerts a pivotal role in macrophage programming, thus shaping protumor TME and lymphoma progression. CCR1 inhibition through CCR1 antagonists may be a promising therapeutic strategy to reprogram macrophages in lymphoma-TME and achieve better clinical outcomes in patients.

Lenalidomide overcomes the resistance to third-generation CD19-CAR-T cell therapy in preclinical models of diffuse large B-cell lymphoma

PURPOSE

Chimeric antigen receptor (CAR)-T cells against CD19 have been proven to be effective in treating B-cell hematological malignancies. However, the efficacy of this promising therapy is limited by many factors.

METHODS

In this study, the germinal center B-cell-like diffuse large B-cell lymphoma (GCB-DLBCL) cell line OCI-Ly1, and patient-derived xenografted (PDX) mice (CY-DLBCL) were used as the CAR-T cell-resistant model. Meanwhile, the activated B-cell-like (ABC) DLBCL cell line OCI-Ly3 and PDX mice (ZML-DLBCL) were defined as the CAR-T sensitive model. The enhancement of CAR-T cell function by lenalidomide (LEN) was examined in vitro and in vivo.

RESULTS

Lenalidomide effectively enhanced the function of third-generation CD19-CAR-T cells by polarizing CD8⁺ CAR-T cells to CD8 early-differentiated stage and Th1 type, reducing CAR-T cell exhaustion and improving cell expansion. It was further demonstrated that CAR-T cells combined with LEN substantially reduce the tumor burden and prolong the survival time in various DLBCL mouse models. LEN was also found to promote the infiltration of CD19-CAR-T cells into the tumor site by modulating the tumor microenvironment.

CONCLUSION

In summary, the results of the present study suggest that LEN can improve the function of CD19-CAR-T cells, providing a basis for clinical trials using this combination therapy against DLBCL.

The IL32/BAFF axis supports prosurvival dialogs in the lymphoma ecosystem and is disrupted by NIK inhibition

Aggressive B-cell malignancies, such as mantle cell lymphoma (MCL), are microenvironment-dependent tumors and a better understanding of the dialogs occurring in lymphoma-protective ecosystems will provide new perspectives to increase treatment efficiency. To identify novel molecular regulations, we performed a transcriptomic analysis based on the comparison of circulating MCL cells (n=77) versus MCL lymph nodes (n=107) together with RNA sequencing of malignant (n=8) versus normal B-cell (n=6) samples. This integrated analysis led to the discovery of microenvironment-dependent and tumor-specific secretion of interleukin-32 beta (IL32β), whose expression was confirmed in situ within MCL lymph nodes by multiplex immunohistochemistry. Using ex vivo models of primary MCL cells (n=23), we demonstrated that, through the secretion of IL32β, the tumor was able to polarize monocytes into specific MCL-associated macrophages, which in turn favor tumor survival. We highlighted that while IL32β-stimulated macrophages secreted several protumoral factors, they supported tumor survival through a soluble dialog, mostly driven by BAFF. Finally, we demonstrated the efficacy of selective NIK/alternative-NFkB inhibition to counteract microenvironment-dependent induction of IL32β and BAFF-dependent survival of MCL cells. These data uncovered the IL32β/BAFF axis as a previously undescribed pathway involved in lymphoma-associated macrophage polarization and tumor survival, which could be counteracted through selective NIK inhibition.

Reshaping the tumor microenvironment: The versatility of immunomodulatory drugs in B-cell neoplasms

Immunomodulatory drugs (IMiDs) such as thalidomide, lenalidomide and pomalidomide are antitumor compounds that have direct tumoricidal activity and indirect effects mediated by multiple types of immune cells in the tumor microenvironment (TME). IMiDs have shown remarkable therapeutic efficacy in a set of B-cell neoplasms including multiple myeloma, B-cell lymphomas and chronic lymphocytic leukemia. More recently, the advent of immunotherapy has revolutionized the treatment of these B-cell neoplasms. However, the success of immunotherapy is restrained by immunosuppressive signals and dysfunctional immune cells in the TME. Due to the pleiotropic immunobiological properties, IMiDs have shown to generate synergetic effects in preclinical models when combined with monoclonal antibodies, immune checkpoint inhibitors or CAR-T cell therapy, some of which were successfully translated to the clinic and lead to improved responses for both first-line and relapsed/refractory settings. Mechanistically, despite cereblon (CRBN), an E3 ubiquitin ligase, is considered as considered as the major molecular target responsible for the antineoplastic activities of IMiDs, the exact mechanisms of action for IMiDs-based TME re-education remain largely unknown. This review presents an overview of IMiDs in regulation of immune cell function and their utilization in potentiating efficacy of immunotherapies across multiple types of B-cell neoplasms.

Ibrutinib, rituximab, and lenalidomide in unfit or frail patients aged 75 years or older with de novo diffuse large B-cell lymphoma: a phase 2, single-arm study

BACKGROUND

The optimal treatment for older adults with diffuse large B-cell lymphoma (DLBCL) needs to be further explored due to patient comorbidities, standard immunochemotherapy intolerance, and unfavourable genetic features. We did a phase 2 trial of ibrutinib, rituximab, and lenalidomide (iR2) to evaluate the efficacy and safety in older adult patients with de novo DLBCL.

METHODS

In this phase 2, single-arm study, unfit or frail patients with de novo DLBCL aged 75 years or older were enrolled at Shanghai Ruijin Hospital, Shanghai, China. During the induction phase from cycle 1 to 6, 560 mg ibrutinib was given orally daily throughout each 21-day treatment cycle, 375 mg/m² rituximab was given intravenously on day 1, and 25 mg lenalidomide was given orally daily from day 1 to 10 in each cycle. Patients who had a complete response after induction were given another 6 cycles of lenalidomide maintenance (25 mg orally daily from day 1 to 10 every 21 days from cycle 7 to 12). The primary endpoint was complete response rate after 6 cycles or at the end of the induction treatment. This trial is registered with ClinicalTrials.gov, NCT03949062.

FINDINGS

Between May 15, 2019, and May 8, 2020, a total of 30 patients were enrolled. The end of induction complete response rate was 56·7% (95% CI 37·4-74·5), and overall response rate was 66·7% (95% CI 47·2-82·7). With a median follow-up of 27·6 months (IQR 23·9-29·6), the 2-year progression-free survival rate was 53·3% (95% CI 34·3-69·1) and the 2-year overall survival rate was 66·7% (95% CI 46·9-80·5). The main grade 3-4 haematological adverse events were neutropenia (seven patients [23%]), thrombocytopenia (three patients [10%]), and anaemia (two patients [7%]). The most common grade 3-4 non-haematological adverse event was pulmonary infection (seven patients [23%]). Atrial fibrillation was observed in three (10%) patients, including one grade 2 and two grade 3.

INTERPRETATION

A chemotherapy-free iR2 regimen is clinically effective and safe and warrants further investigation in phase 3 trials as first-line treatment in older adult patients with DLBCL.

FUNDING

National Natural Science Foundation of China, Shanghai Municipal Education Commission Gaofeng Clinical Medicine Grant Support, Clinical Research Plan of Shanghai Hospital Development Center, and Multicenter Clinical Research Project by Shanghai Jiao Tong University School of Medicine.

Targeted Agents in the Treatment of Indolent B-Cell Non-Hodgkin Lymphomas

Targeted therapies continue to change the landscape of lymphoma treatment, resulting in improved therapy options and patient outcomes. Numerous agents are now approved for use in the indolent lymphomas and many others under development demonstrate significant promise. In this article, we review the landscape of targeted agents that apply to the indolent lymphomas, predominantly follicular lymphoma, lymphoplasmacytic lymphoma/Waldenstrom macroglobulinaemia and marginal zone lymphoma. The review covers small molecule inhibitors, immunomodulators and targeted immunotherapies, as well as presenting emerging and promising combination therapies.

Approaches of the Innate Immune System to Ameliorate Adaptive Immunotherapy for B-Cell Non-Hodgkin Lymphoma in Their Microenvironment

A dominant paradigm being developed in immunotherapy for hematologic malignancies is of adaptive immunotherapy that involves chimeric antigen receptor (CAR) T cells and bispecific T-cell engagers. CAR T-cell therapy has yielded results that surpass those of the existing salvage immunochemotherapy for patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL) after first-line immunochemotherapy, while offering a therapeutic option for patients with follicular lymphoma (FL) and mantle cell lymphoma (MCL). However, the role of the innate immune system has been shown to prolong CAR T-cell persistence. Cluster of differentiation (CD) 47-blocking antibodies, which are a promising therapeutic armamentarium for DLBCL, are novel innate immune checkpoint inhibitors that allow macrophages to phagocytose tumor cells. Intratumoral Toll-like receptor 9 agonist CpG oligodeoxynucleotide plays a pivotal role in FL, and vaccination may be required in MCL. Additionally, local stimulator of interferon gene agonists, which induce a systemic anti-lymphoma CD8⁺ T-cell response, and the costimulatory molecule 4-1BB/CD137 or OX40/CD134 agonistic antibodies represent attractive agents for dendritic cell activations, which subsequently, facilitates initiation of productive T-cell priming and NK cells. This review describes the exploitation of approaches that trigger innate immune activation for adaptive immune cells to operate maximally in the tumor microenvironment of these lymphomas.

Sequencing of Novel Therapies for Mantle Cell Lymphoma

OPINION STATEMENT

There is no standard approach to sequencing novel therapies in mantle cell lymphoma (MCL). For initial treatment, intensive induction chemotherapy followed by autologous stem cell transplant and rituximab maintenance remains our preferred approach in young, fit patients. We consider bendamustine plus rituximab or lenalidomide plus rituximab in patients who are ineligible for intensive chemotherapy-based approaches. Bruton's tyrosine kinase inhibitors are our preferred class of agents to use in the second-line setting. When patients inevitably relapse on one of these agents, we proceed with chimeric antigen receptor T-cell (CAR T) therapy in eligible patients, often with the use of bridging therapy with corticosteroids, lenalidomide, or venetoclax. We treat patients who are ineligible for CAR T or clinic trial with venetoclax, lenalidomide, or proteosome inhibitor-based regimens, although efficacy is expected to be limited in this setting with a shortened duration of response to each subsequent line of therapy. Allogeneic stem cell transplant remains an option for carefully selected patients who progress after autologous stem cell transplant and CAR T. Clinical trials involving combinations of novel agents in early lines of therapy are ongoing, and new compounds with unique mechanisms of action are in development. The results of ongoing clinical trials with novel agents will further change the treatment landscape for patients with MCL in the coming years.

Role of lenalidomide in the treatment of peripheral T-cell non-Hodgkin lymphomas

T-cell lymphomas (TCLs) represent a group of lymphoid neoplasms characterized by an aggressive clinical course, even after an anthracycline-containing regimen. Novel agents for patients with relapsed/refractory TCL are urgently needed. Lenalidomide is an oral drug with immunomodulatory, antiangiogenic and direct antineoplastic effects. These peculiar mechanisms of action make TCL an attractive target for lenalidomide. We have identified five clinical trials in which lenalidomide monotherapy was investigated to treat TCL, including cutaneous TCL (CTCL) and adult T-cell lymphoma/leukemia (ATLL). In the ATLL-002 study, the overall response rate (ORR) was 42% and median progression-free survival (PFS) and overall survival were 3.8 mo and 20.3 mo, respectively. In a phase II trial for CTCL, ORR was 28% and median PFS and overall survival were 8 mo and 43 mo, respectively. For nodal peripheral TCL, ORR was between 10% and 43% in three clinical trials, with a median PFS of about 4 mo, even if some patients had a durable response. Overall toxicity is manageable and grade 3-4 events are mainly hematological and reversible. Combination strategies did not improve PFS. In conclusion, lenalidomide could represent a suitable treatment option for relapsed/refractory TCL, especially for neoplasms with a T-follicular helper origin, such as angioimmunoblastic TCL.

Non-chemotherapy Options for Newly Diagnosed Mantle Cell Lymphoma

OPINION STATEMENT

Mantle cell lymphoma is a rare and incurable non-Hodgkin lymphoma with a heterogenous clinical presentation. Typically, treatment consists of frontline chemoimmunotherapy induction with or without autologous stem cell transplant (ASCT) as consolidation. However, this approach has the propensity to increase short- and long-term toxicities, such as secondary malignancies, without being curative. Genomic profiling of MCL will allow for greater impact of new targeted therapies in the future and may become a helpful tool to guide treatment. Based on the data discussed, use of non-chemotherapy options may become the preferred approach for frontline therapy as opposed to conventional chemotherapy and hematopoietic stem cell transplants.

Immunomodulatory Drugs for the Treatment of B Cell Malignancies

Accumulating evidence suggests that the tumor microenvironment (TME) is involved in disease progression and drug resistance in B cell malignancies, by supporting tumor growth and facilitating the ability of malignant cells to avoid immune recognition. Immunomodulatory drugs (IMiDs) such as lenalidomide have some direct anti-tumor activity, but critically also target various cellular compartments of the TME including T cells, NK cells, and stromal cells, which interfere with pro-tumor signaling while activating anti-tumor immune responses. Lenalidomide has delivered favorable clinical outcomes as a single-agent, and in combination therapy leads to durable responses in chronic lymphocytic leukemia (CLL) and several non-Hodgkin lymphomas (NHLs) including follicular lymphoma (FL), diffuse large B cell lymphoma (DLBCL), and mantle cell lymphoma (MCL). Recently, avadomide, a next generation cereblon E3 ligase modulator (CELMoD), has shown potent anti-tumor and TME immunomodulatory effects, as well as promising clinical efficacy in DLBCL. This review describes how the pleiotropic effects of IMiDs and CELMoDs could make them excellent candidates for combination therapy in the immuno-oncology era-a concept supported by preclinical data, as well as the recent approval of lenalidomide in combination with rituximab for the treatment of relapsed/refractory (R/R) FL.

Angiogenesis in Lymph Nodes Is a Critical Regulator of Immune Response and Lymphoma Growth

Tumor-induced remodeling of the microenvironment in lymph nodes (LNs) includes the formation of blood vessels, which goes beyond the regulation of metabolism, and shaping a survival niche for tumor cells. In contrast to solid tumors, which primarily rely on neo-angiogenesis, hematopoietic malignancies usually grow within pre-vascularized autochthonous niches in secondary lymphatic organs or the bone marrow. The mechanisms of vascular remodeling in expanding LNs during infection-induced responses have been studied in more detail; in contrast, insights into the conditions of lymphoma growth and lodging remain enigmatic. Based on previous murine studies and clinical trials in human, we conclude that there is not a universal LN-specific angiogenic program applicable. Instead, signaling pathways that are tightly connected to autochthonous and infiltrating cell types contribute variably to LN vascular expansion. Inflammation related angiogenesis within LNs relies on dendritic cell derived pro-inflammatory cytokines stimulating vascular endothelial growth factor-A (VEGF-A) expression in fibroblastic reticular cells, which in turn triggers vessel growth. In high-grade B cell lymphoma, angiogenesis correlates with poor prognosis. Lymphoma cells immigrate and grow in LNs and provide pro-angiogenic growth factors themselves. In contrast to infectious stimuli that impact on LN vasculature, they do not trigger the typical inflammatory and hypoxia-related stroma-remodeling cascade. Blood vessels in LNs are unique in selective recruitment of lymphocytes via high endothelial venules (HEVs). The dissemination routes of neoplastic lymphocytes are usually disease stage dependent. Early seeding via the blood stream requires the expression of the homeostatic chemokine receptor CCR7 and of L-selectin, both cooperate to facilitate transmigration of tumor and also of protective tumor-reactive lymphocytes via HEV structures. In this view, the HEV route is not only relevant for lymphoma cell homing, but also for a continuous immunosurveillance. We envision that HEV functional and structural alterations during lymphomagenesis are not only key to vascular remodeling, but also impact on tumor cell accessibility when targeted by T cell-mediated immunotherapies.

Mechanisms of lenalidomide sensitivity and resistance

The discovery that the immunomodulatory imide drugs (IMiDs) possess antitumor properties revolutionized the treatment of specific types of hematological cancers. Since then, much progress has been made in understanding why the IMiDs are so efficient in targeting the malignant clones in difficult-to-treat diseases. Despite their efficacy, IMiD resistance arises eventually. Herein we summarize the mechanisms of sensitivity and resistance to lenalidomide in del(5q) myelodysplastic syndrome and multiple myeloma, two diseases in which these drugs are at the therapeutic frontline. Understanding the molecular and cellular mechanisms underlying IMiD efficacy and resistance may allow development of specific strategies to eliminate the malignant clone in otherwise incurable diseases.

IMiDs New and Old

PURPOSE OF REVIEW

IMiDs are a class of biologic agents with immunomodulatory, anti-angiogenic, and direct anti-cancer activities. This review summarizes current data on clinical development and application of IMiDs in non-Hodgkin lymphoma (NHL) subtypes, focusing primarily on lenalidomide, with additional discussion on managing common side effects.

RECENT FINDINGS

Improved upon the prototype thalidomide, the second-generation compound lenalidomide has enhanced immunological and anti-cancer properties with fewer side effects, while next-generation small molecule cereblon/E3 ubiquitin ligase modulator CC-122 is in early clinical studies. Lenalidomide is FDA-approved for treatment of relapsed/refractory mantle cell lymphoma as a single agent, as well as in combination with rituximab for R/R follicular lymphoma and marginal zone lymphoma. In addition, numerous clinical trials of lenalidomide, as single agent, in combination with anti-CD20 antibodies, or in combination with chemoimmunotherapy regimens, have shown promise in aggressive and indolent NHL in both the upfront and relapsed/refractory setting. As clinical trials with lenalidomide continue to find success in both indolent and aggressive lymphomas, IMiDs are poised to be important building blocks for combinatorial strategies with antibodies, chemotherapy, novel target agents, and emerging immunotherapy involving immune checkpoint inhibitors and chimeric antigen receptor T cell (CAR-T) therapy. Delineation of treatment-specific and disease-specific biomarkers is an important research objective to gain insight into potential mechanisms of action, and to guide future clinical development.

Emerging therapies in mantle cell lymphoma

Mantle cell lymphoma (MCL) is a rare, B cell non-Hodgkin's lymphoma with highly heterogeneous clinical presentation and aggressiveness. First-line treatment consists of intensive chemotherapy with autologous stem cell transplant for the fit, transplant eligible patients, or less intensive chemotherapy for the less fit (and transplant-ineligible) patients. Patients eventually relapse with a progressive clinical course. Numerous therapeutic approaches have emerged over the last few years which have significantly changed the treatment landscape of MCL. These therapies consist of targeted approaches such as BTK and BCL2 inhibitors that provide durable therapeutic responses. However, the optimum combination and sequencing of these therapies is unclear and is currently investigated in several ongoing studies. Furthermore, cellular therapies such as chimeric antigen receptor (CAR) T cells and bispecific T cell engager (BiTe) antibodies have shown impressive results and will likely shape treatment approaches in relapsed MCL, especially after failure with BTK inhibitors. Herein, we provide a comprehensive review of past and ongoing studies that will likely significantly impact our approach to MCL treatment in both the frontline (for transplant eligible and ineligible patients) as well as in the relapsed setting. We present the most up to date results from these studies as well as perspectives on future studies in MCL.

B-cell non-Hodgkin lymphoma: importance of angiogenesis and antiangiogenic therapy

Angiogenesis is critical for the initiation and progression of solid tumors, as well as hematological malignancies. While angiogenesis in solid tumors has been well characterized, a large body of investigation is devoted to clarify the impact of angiogenesis on lymphoma development. B-cell non-Hodgkin lymphoma (B-NHL) is the most common lymphoid malignancy with a highly heterogeneity. The malignancy remains incurable despite that the addition of rituximab to conventional chemotherapies provides substantial improvements. Several angiogenesis-related parameters, such as proangiogenic factors, circulating endothelial cells, microvessel density, and tumor microenvironment, have been identified as prognostic indicators in different types of B-NHL. A better understanding of how these factors work together to facilitate lymphoma-specific angiogenesis will help to design better antiangiogenic strategies. So far, VEGF-A monoclonal antibodies, receptor tyrosine kinase inhibitors targeting VEGF receptors, and immunomodulatory drugs with antiangiogenic activities are being tested in preclinical and clinical studies. This review summarizes recent advances in the understanding of the role of angiogenesis in B-NHL, and discusses the applications of antiangiogenic therapies.

Lymphoma Angiogenesis Is Orchestrated by Noncanonical Signaling Pathways

Tumor-induced remodeling of the microenvironment relies on the formation of blood vessels, which go beyond the regulation of metabolism, shaping a maladapted survival niche for tumor cells. In high-grade B-cell lymphoma, angiogenesis correlates with poor prognosis, but attempts to target established proangiogenic pathways within the vascular niche have been inefficient. Here, we analyzed Myc-driven B-cell lymphoma-induced angiogenesis in mice. A few lymphoma cells were sufficient to activate the angiogenic switch in lymph nodes. A unique morphology of dense microvessels emerged without obvious tip cell guidance and reliance on blood endothelial cell (BEC) proliferation. The transcriptional response of BECs was inflammation independent. Conventional HIF1α or Notch signaling routes prevalent in solid tumors were not activated. Instead, a nonconventional hypersprouting morphology was orchestrated by lymphoma-provided VEGFC and lymphotoxin (LT). Interference with VEGF receptor-3 and LTβ receptor signaling pathways abrogated lymphoma angiogenesis, thus revealing targets to block lymphomagenesis. SIGNIFICANCE: In lymphoma, transcriptomes and morphogenic patterns of the vasculature are distinct from processes in inflammation and solid tumors. Instead, LTβR and VEGFR3 signaling gain leading roles and are targets for lymphomagenesis blockade.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/80/6/1316/F1.large.jpg.

Lenalidomide improves the therapeutic effect of an interferon-α-dendritic cell-based lymphoma vaccine

The perspective of combining cancer vaccines with immunomodulatory drugs is currently regarded as a highly promising approach for boosting tumor-specific T cell immunity and eradicating residual malignant cells. The efficacy of dendritic cell (DC) vaccination in combination with lenalidomide, an anticancer drug effective in several hematologic malignancies, was investigated in a follicular lymphoma (FL) model. First, we evaluated the in vitro activity of lenalidomide in modulating the immune responses of lymphocytes co-cultured with a new DC subset differentiated with IFN-α (IFN-DC) and loaded with apoptotic lymphoma cells. We next evaluated the efficacy of lenalidomide and IFN-DC-based vaccination, either alone or in combination, in hu-PBL-NOD/SCID mice bearing established human lymphoma. We found that lenalidomide reduced Treg frequency and IL-10 production in vitro, improved the formation of immune synapses of CD8 + lymphocytes with lymphoma cells and enhanced anti-lymphoma cytotoxicity. Treatment of lymphoma-bearing mice with either IFN-DC vaccination or lenalidomide led to a significant decrease in tumor growth and lymphoma cell spread. Lenalidomide treatment was shown to substantially inhibit tumor-induced neo-angiogenesis rather than to exert a direct cytotoxic effect on lymphoma cells. Notably, the combined treatment with the vaccine plus lenalidomide was more effective than either single treatment, resulting in the significant regression of established tumors and delayed tumor regrowth upon treatment discontinuation. In conclusion, our data demonstrate that IFN-DC-based vaccination plus lenalidomide exert an additive therapeutic effect in xenochimeric mice bearing established lymphoma. These results may pave the way to evaluate this combination in the clinical ground.

Targeting the Immune Microenvironment in Lymphomas of B-Cell Origin: From Biology to Clinical Application

In lymphomas of B-cell origin, cancer cells orchestrate an inflammatory microenvironment of immune and stromal cells that sustain the tumor cell survival and growth, known as a tumor microenvironment (TME). The features of the TME differ between the different lymphoma types, ranging from extremely inflammatory, such as in Hodgkin lymphoma, to anergic, leading to immune deficiency and susceptibility to infections, such as in chronic lymphocytic leukemia. Understanding the characteristic features of the TME as well as the interactions between cancer and TME cells has given insight into the pathogenesis of most lymphomas and contributed to identify novel therapeutic targets. Here, we summarize the preclinical data that contributed to clarifying the role of the immune cells in the TME of different types of lymphomas of B-cell origin, and explain how the understanding of the biological background has led to new clinical applications. Moreover, we provide an overview of the clinical results of trials that assessed the safety and efficacy of drugs directly targeting TME immune cells in lymphoma patients.

[Changes of lymphatic vessel density in lung adenocarcinoma in situ, minimally invasive adenocarcinoma, and invasive adenocarcinoma and the regulatory factors]

OBJECTIVE

To analyze the changes in tumor lymphatic vessel density (LVD) in patients with lung adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA), and invasive adenocarcinoma (IA) and explore the regulatory factors of LVD.

METHODS

Complete clinicopathological data were collected form a total of 301 patients with lung adenocarcinoma, including 28 (9.3%) with AIS, 86 (28.6%) with MIA, and 187 (62.1%) with IA. The LVD of all the adenocarcinomas were calculated after D2-40 immunohistochemical staining, and MT1-MMP and VEGF-C expression levels were also evaluated. The differences in LVD among the groups and the correlations of tumor LVD with the expressions of MT1-MMP and VEGF-C and the clinicopathological factors were analyzed.

RESULTS

The LVD differed significantly among AIS, MIA, and IA groups (P= 0.000). The LVDs was significantly correlated with the level of VEGF-C protein expression (r=0.917, P=0.009), tumor size (r= 0.686, P=0.017), lymph node metastasis (r=0.739, P=0.000), and clinical stage (r=0.874, P=0.012) of the patients.

CONCLUSIONS

Tumor lymphangiogenesis plays an important role in lung adenocarcinoma progression, and VEGF-C may promote this process.

Five-year follow-up of lenalidomide plus rituximab as initial treatment of mantle cell lymphoma

We report 5-year follow-up of a multicenter phase 2 study of lenalidomide plus rituximab (LR) as initial treatment of mantle cell lymphoma (MCL). The regimen includes induction and maintenance with the LR doublet. Treatment was continuous until progression, with optional discontinuation after 3 years. The median age of the 38 participants was 65 years, with MCL international prognostic index scores balanced among low, intermediate, and high risk (34%, 34%, and 32%, respectively). Twenty-seven (75%) of the 36 evaluable patients completed ≥3 years of study treatment. At a median follow-up of 64 months (range, 21-78), the 3-year progression-free survival (PFS) and overall survival (OS) were 80% and 90%, respectively, with 5-year estimated PFS and OS of 64% and 77%, respectively. During maintenance, hematologic adverse events (AEs) included asymptomatic grade 3 or 4 cytopenias (42% neutropenia, 5% thrombocytopenia, 3% anemia) and mostly grade 1 or 2 infections managed in the outpatient setting (45% upper respiratory infection, 21% urinary tract infection, 13% sinusitis, 11% cellulitis, 8% pneumonia). Nonhematologic AEs, such as constitutional and inflammatory symptoms, occurred at reduced frequency and intensity compared with induction. A peripheral blood minimal residual disease (MRD) assay (clonoSEQ) showed MRD-negative complete remission in 8 of 10 subjects who had completed ≥3 years of treatment and with available samples for analysis. With longer follow-up, LR continues to demonstrate durable responses and manageable safety as initial induction and maintenance therapy for MCL (ClinicalTrials.gov NCT01472562).

Observational study of lenalidomide in patients with mantle cell lymphoma who relapsed/progressed after or were refractory/intolerant to ibrutinib (MCL-004)

BACKGROUND

The observational MCL-004 study evaluated outcomes in patients with relapsed/refractory mantle cell lymphoma who received lenalidomide-based therapy after ibrutinib failure or intolerance.

METHODS

The primary endpoint was investigator-assessed overall response rate based on the 2007 International Working Group criteria.

RESULTS

Of 58 enrolled patients (median age, 71 years; range, 50-89), 13 received lenalidomide monotherapy, 11 lenalidomide plus rituximab, and 34 lenalidomide plus other treatment. Most patients (88%) had received ≥ 3 prior therapies (median 4; range, 1-13). Median time from last dose of ibrutinib to the start of lenalidomide was 1.3 weeks (range, 0.1-21.7); 45% of patients had partial responses or better to prior ibrutinib. Primary reasons for ibrutinib discontinuation were lack of efficacy (88%) and ibrutinib toxicity (9%). After a median of two cycles (range, 0-11) of lenalidomide-based treatment, 17 patients responded (8 complete responses, 9 partial responses), for a 29% overall response rate (95% confidence interval, 18-43%) and a median duration of response of 20 weeks (95% confidence interval, 2.9 to not available). Overall response rate to lenalidomide-based therapy was similar for patients with relapsed/progressive disease after previous response to ibrutinib (i.e., ≥PR) versus ibrutinib-refractory (i.e., ≤SD) patients (30 versus 32%, respectively). The most common all-grade treatment-emergent adverse events after lenalidomide-containing therapy (n = 58) were fatigue (38%) and cough, dizziness, dyspnea, nausea, and peripheral edema (19% each). At data cutoff, 28 patients have died, primarily due to mantle cell lymphoma.

CONCLUSION

Lenalidomide-based treatment showed clinical activity, with no unexpected toxicities, in patients with relapsed/refractory mantle cell lymphoma who previously failed ibrutinib therapy.

TRIAL REGISTRATION

Clinicaltrials.gov identifier NCT02341781 . Date of registration: January 14, 2015.

S1P Provokes Tumor Lymphangiogenesis via Macrophage-Derived Mediators Such as IL-1β or Lipocalin-2

A pleiotropic signaling lipid, sphingosine-1-phosphate (S1P), has been implicated in various pathophysiological processes supporting tumor growth and metastasis. However, there are only a few descriptive studies suggesting a role of S1P in tumor lymphangiogenesis, which is critical for tumor growth and dissemination. Corroborating own data, the literature suggests that apoptotic tumor cell-derived S1P alters the phenotype of tumor-associated macrophages (TAMs) to gain protumor functions. However, mechanistically, the role of TAM-induced lymphangiogenesis has only been poorly described, mostly linked to the production of lymphangiogenic factors such as vascular endothelial growth factor C (VEGF-C) and VEGF-D, or transdifferentiation into lymphatic endothelial cells. Recent findings highlight a rather underappreciated role of S1P in tumor lymphangiogenesis, referring to the production of interleukin-1β (IL-1β) and lipocalin-2 (LCN2) by a tumor-promoting macrophage phenotype. In this review, we aim to provide to the readers with the current understanding of the molecular mechanism how apoptotic cell-derived S1P triggers TAMs to promote lymphangiogenesis.

A comprehensive review of lenalidomide in B-cell non-Hodgkin lymphoma

Lenalidomide, an immunomodulatory drug that the US Food and Drug Administration (FDA) approved for the treatment of multiple myeloma, 5q- myelodysplasia and mantle-cell lymphoma (MCL), has encouraging efficacy in other B-cell malignancies. Its unique mechanism of action is in part due to altering the tumor microenvironment and potentiating the activity of T and natural-killer (NK) cells. Impressive clinical activity and excellent tolerability allows broad applicability. Lenalidomide has been used in a wide range of B-cell malignancies for years, but in 2013, the FDA marked its approval as a single agent only in relapsed/refractory mantle-cell lymphoma. Perhaps most impressive is the efficacy of lenalidomide when combined with monoclonal antibodies. Impressive efficacy and toxicity profiles with the combination of lenalidomide and rituximab in B-cell lymphomas in both the upfront and relapsed/refractory setting may allow a shift in our current treatment paradigm in both indolent and aggressive non-Hodgkin lymphoma (NHL). This review will summarize the current data in the relapsed/refractory and front-line setting of NHL with single-agent lenalidomide as well as its use in combination with other agents.

Lenalidomide for the treatment of B-cell lymphoma

INTRODUCTION

Although the combination of an anti-CD20 monoclonal antibody and chemotherapy has widely improved survival of patients with B-cell lymphoma, the disease still relapses. A better understanding of the biology of lymphomas has highlighted the role of the cell of origin in response to treatment and outcome. Lenalidomide represents an attractive therapeutic option due to its original mechanism of action.

AREAS COVERED

In this review, the authors describe the pharmacological properties of lenalidomide, and the rational for its use in B-cell lymphomas; focusing on diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), and mantle cell lymphoma (MCL). They discuss the mechanism of action of the drug and its current and future clinical development. They also review the current data in relapsed/refractory situations as well as in first-line treatment.

EXPERT OPINION

Lenalidomide is an oral non-chemotherapy immunomodulatory agent with an acceptable toxicity profile and manageable side-effects. Efficacy has widely been demonstrated, especially in MCL, FL and non-Germinal Center DLBCL patients. Further studies are now warranted to better define the strategy for the use of lenalidomide in B-NHL patients, and clarify which subgroup of patients will really benefit of lenalidomide as part of first-line treatment or in a relapsed/refractory setting.

Lymphangiogenesis: Origin, Specification, and Cell Fate Determination

The two vascular systems of our body are the blood and the lymphatic vasculature. Our understanding of the genes and molecular mechanisms controlling the development of the lymphatic vasculature network has significantly improved. The availability of novel animal models and better imaging tools led to the identification of lymphatics in tissues and organs previously thought to be devoid of them. Similarly, the classical textbook list of established functional roles of the lymphatic system has been expanded by the addition of novel findings. In this review we provide a historical perspective of some of the important landmarks that opened the doors to researchers working in this field. We also summarize some of the current views about embryonic lymphangiogenesis, particularly about the source(s), commitment, and differentiation of lymphatic endothelial cells.

The dual role of tumor lymphatic vessels in dissemination of metastases and immune response development

Lymphatic vasculature plays a crucial role in the immune response, enabling transport of dendritic cells (DCs) and antigens (Ags) into the lymph nodes. Unfortunately, the lymphatic system has also a negative role in the progression of cancer diseases, by facilitating the metastatic spread of many carcinomas to the draining lymph nodes. The lymphatics can promote antitumor immune response as well as tumor tolerance. Here, we review the role of lymphatic endothelial cells (LECs) in tumor progression and immunity and mechanism of action in the newest anti-lymphatic therapies, including photodynamic therapy (PDT).

Mantle Cell Lymphoma

Mantle cell lymphoma (MCL) is an uncommon subtype of non-Hodgkin lymphoma previously considered to have a poor prognosis. Large gains were made in the first decade of the new century when clinical trials established the importance of high-dose therapy and autologous stem-cell rescue and high-dose cytarabine in younger patients and the benefits of maintenance rituximab and bendamustine in older patients. In particular, greater depth of understanding of the molecular pathophysiology of MCL has resulted in an explosion of specifically targeted new efficacious agents. In particular, agents recently approved by the Food and Drug Administration include the proteasome inhibitor bortezomib, immunomodulator lenalidomide, and Bruton's tyrosine kinase inhibitor ibrutinib. We review recent advances in the understanding of MCL biology and outline our recommended approach to therapy, including choice of chemoimmunotherapy, the role of stem-cell transplantation, and mechanism-based targeted therapies, on the basis of a synthesis of the data from published clinical trials.

Lenalidomide plus Rituximab as Initial Treatment for Mantle-Cell Lymphoma

BACKGROUND

Mantle-cell lymphoma is generally incurable. Initial treatment is not standardized but usually includes cytotoxic chemotherapy. Lenalidomide, an immunomodulatory compound, and rituximab, an anti-CD20 antibody, are active in patients with recurrent mantle-cell lymphoma. We evaluated lenalidomide plus rituximab as a first-line therapy.

METHODS

We conducted a single-group, multicenter, phase 2 study with induction and maintenance phases. During the induction phase, lenalidomide was administered at a dose of 20 mg daily on days 1 through 21 of every 28-day cycle for 12 cycles; the dose was escalated to 25 mg daily after the first cycle if no dose-limiting adverse events occurred during the first cycle and was reduced to 15 mg daily during the maintenance phase. Rituximab was administered once weekly for the first 4 weeks and then once every other cycle until disease progression. The primary end point was the overall response rate. Secondary end points included outcomes related to safety, survival, and quality of life.

RESULTS

A total of 38 participants were enrolled at four centers from July 2011 through April 2014. The median age was 65 years. On the basis of the Mantle Cell Lymphoma International Prognostic Index scores, the proportions of participants with low-risk, intermediate-risk, and high-risk disease at baseline were similar (34%, 34%, and 32%, respectively). The most common grade 3 or 4 adverse events were neutropenia (in 50% of the patients), rash (in 29%), thrombocytopenia (in 13%), an inflammatory syndrome ("tumor flare") (in 11%), anemia (in 11%), serum sickness (in 8%), and fatigue (in 8%). At the median follow-up of 30 months (through February 2015), the overall response rate among the participants who could be evaluated was 92% (95% confidence interval [CI], 78 to 98), and the complete response rate was 64% (95% CI, 46 to 79); median progression-free survival had not been reached. The 2-year progression-free survival was estimated to be 85% (95% CI, 67 to 94), and the 2-year overall survival 97% (95% CI, 79 to 99). A response to treatment was associated with improvement in quality of life.

CONCLUSIONS

Combination biologic therapy consisting of lenalidomide plus rituximab was active as initial therapy for mantle-cell lymphoma. (Funded by Celgene and Weill Cornell Medical College; ClinicalTrials.gov number, NCT01472562.).

Depletion of CLL-associated patrolling monocytes and macrophages controls disease development and repairs immune dysfunction in vivo

Chronic lymphocytic leukemia (CLL) is characterized by apoptosis resistance and a dysfunctional immune system. Previous reports suggested a potential role of myeloid cells in mediating these defects. However, the composition and function of CLL-associated myeloid cells have not been thoroughly investigated in vivo. Using the Eμ-TCL1 mouse model, we observed severe skewing of myeloid cell populations with CLL development. Monocytes and M2-like macrophages infiltrated the peritoneal cavity of leukemic mice. Monocytes also accumulated in the spleen in a CCR2-dependent manner, and were severely skewed toward Ly6C(low) patrolling or nonclassical phenotype. In addition, the percentage of MHC-II(hi) dendritic cells and macrophages significantly dropped in the spleen. Gene expression profiling of CLL-associated monocytes revealed aberrantly high PD-L1 expression and secretion of multiple inflammatory and immunosuppressive cytokines like interleukin-10, tumor necrosis factor-α and CXCL9. In vivo myeloid cell depletion using liposomal Clodronate resulted in a significant control of CLL development accompanied by a pronounced repair of innate immune cell phenotypes and a partial resolution of systemic inflammation. In addition, CLL-associated skewing of T cells toward antigen-experienced phenotypes was repaired. The presented data suggest that targeting nonmalignant myeloid cells might serve as a novel immunotherapeutical strategy for CLL.

CD68+, but not stabilin-1+ tumor associated macrophages in gaps of ductal tumor structures negatively correlate with the lymphatic metastasis in human breast cancer

Tumor associated macrophages (TAM) support tumor growth and metastasis in several animal models of breast cancer, and TAM amount is predictive for efficient tumor growth and metastatic spread via blood circulation. However, limited information is available about intratumoral TAM heterogeneity and functional role of TAM subpopulations in tumor progression. The aim of our study was to examine correlation of TAM presence in various morphological segments of human breast cancer with clinical parameters. Thirty six female patients with nonspecific invasive breast cancer T1-4N0-3M0 were included in the study. Morphological examination was performed using Carl Zeiss Axio Lab.A1 and MiraxMidiZeiss. Immunohistochemical and immunofluorescence/confocal microcopy analysis was used to detect CD68 and stabilin-1 in 5 different tumor segments: (1) areas with soft fibrous stroma; (2) areas with coarse fibrous stroma; (3) areas of maximum stromal-and-parenchymal relationship; (4) parenchymal elements; (5) gaps of ductal tumor structures. The highest expression of CD68 was in areas with soft fibrous stroma or areas of maximum stromal-and-parenchymal relationship (79%). The lowest expression of CD68 was in areas with coarse fiber stroma (23%). Inverse correlation of tumor size and expression of CD68 in gaps of tubular tumor structures was found (R=-0.67; p=0.02). In case of the lymph node metastases the average score of CD68 expression in ductal gaps tumor structures was lower (1.4±0.5) compared to negative lymph nodes case (3.1±1.0; F=10.9; p=0.007). Confocal microscopy identified 3 phenotypes of TAM: CD68⁺/stabilin-1^-; CD68⁺/stabilin-1⁺ (over 50%); and CD68^-/stabilin-1⁺. However, expression of stabilin-1 did not correlate with lymph node metastasis. We concluded, that increased amount of CD68+TAM in gaps of ductal tumor structures is protective against metastatic spread in regional lymph nodes.

ROR1-targeted delivery of OSU-2S, a nonimmunosuppressive FTY720 derivative, exerts potent cytotoxicity in mantle-cell lymphoma in vitro and in vivo

Mantle-cell lymphoma (MCL) remains incurable despite numerous therapeutic advances. OSU-2S, a novel nonimmunosuppressive FTY720 (Fingolimod) derivative, exhibits potent cytotoxicity in MCL cell lines and primary cells. OSU-2S increased the surface expression of CD74, a therapeutic antibody target in MCL cells. OSU-2S, in combination with anti-CD74 antibody milatuzumab, enhanced cytotoxicity in MCL. Moreover, MCL tumor antigen receptor tyrosine kinase-like orphan receptor 1 (ROR1) targeted immunonanoparticle-carrying OSU-2S (2A2-OSU-2S-ILP)-mediated selective cytotoxicity of MCL in vitro, as well as activity in a xenografted mouse model of MCL in vivo. The newly developed OSU-2S delivery using ROR1-directed immunonanoparticles provide selective targeting of OSU-2S to MCL and other ROR1(+) malignancies, sparing normal B cells.

Lenalidomide in non-Hodgkin lymphoma: biological perspectives and therapeutic opportunities

Lenalidomide is an immunomodulatory drug (IMiD) with activity in lymphoid malignancies occurring primarily through immune modulation (eg, T-cell immune synapse enhancement and NK-cell/T-cell effector augmentation) and antiproliferative effects. Food and Drug Administration-approved for bortezomib-resistant, relapsed/refractory mantle-cell lymphoma, lenalidomide has demonstrated efficacy in several additional lymphoma subtypes. There are many ongoing clinical trials examining the use of lenalidomide alone or in combinatorial therapy. It will be important in these studies to delineate reliable, predictive biomarkers to optimally integrate lenalidomide into lymphoma treatment paradigms.

Novel and emerging targeted-based cancer therapy agents and methods

After several decades of uncovering the cancer features and following the improvement of therapeutic agents, however cancer remains as one of the major reasons of mortality. Chemotherapy is one of the main treatment options and has significantly improved the overall survival of cancer patients, but chemotherapeutic agents are highly toxic for normal cells. Therefore, there is a great unmet medical need to develop new therapeutic principles and agents. Targeted-based cancer therapy (TBCT) agents and methods have revolutionized the cancer treatment efficacy. Monoclonal antibodies (mAbs) and small molecule inhibitors (SMIs) are among the most effective agents of TBCT. These drugs have improved the prognosis and survival of cancer patients; however, the therapeutic resistance has subdued the effects. Several mechanisms lead to drug resistance such as mutations in the drug targets, activation of compensatory pathways, and intrinsic or acquired resistance of cancer stem cells. Therefore, new modalities, improving current generation of inhibitors and mAbs, and optimizing the combinational therapy regimens are necessary to decrease the current obstacles in front of TBCT. Moreover, the success of new TBCT agents such as mAbs, SMIs, and immunomodulatory agents has sparked further therapeutic modalities with novel targets to inhibit. Due to the lack of cumulative information describing different agents and methods of TBCT, this review focuses on the most important agents and methods of TBCT that are currently under investigation.

SOX11 promotes tumor angiogenesis through transcriptional regulation of PDGFA in mantle cell lymphoma

SOX11 mediates regulation of angiogenesis via the PDGFA signaling pathway in MCL. SOX11-dependent increased angiogenesis contributes to a more aggressive MCL phenotype.

Mantle cell lymphoma: taking therapeutic advantage of new insights into the biology

Mantle cell lymphoma (MCL) is an uncommon, incurable B-cell non-Hodgkin's lymphoma that afflicts the elderly. There is no standard course of treatment, with options varying from observation in asymptomatic patients to aggressive induction/consolidation regimens in younger patients with rapidly progressive disease. Emerging data regarding the role of the ubiquitin-proteasome system, B-cell receptor and mTOR signaling pathways, cell cycle regulation, and epigenetic and immune-modulation in the pathogenesis of MCL have resulted in the development of novel therapies, with a shift away from conventional cytotoxic chemotherapy to relatively less toxic, more targeted treatment. The challenge now is to determine the optimal sequence and combination of the various available and emerging therapies for use in patients with MCL.

Molecular and cellular mechanisms of lymphatic vascular maturation

Lymphatic vasculature is necessary for maintaining fluid homeostasis in vertebrates. During embryogenesis lymphatic endothelial cells originate from the veins as a homogeneous population. These cells undergo a series of changes at the morphological and molecular levels to become mature lymphatic vasculature that consists of lymphatic capillaries, collecting lymphatic vessels and valves. In this article we summarize our current knowledge about these steps and highlight some black boxes that require further clarification.

Lenalidomide in relapsed or refractory mantle cell lymphoma: overview and perspective

Lenalidomide, a novel immunomodulatory agent, was approved by the US Food and Drug Administration for the treatment of myelodysplastic syndrome and relapsed multiple myeloma. Data from preclinical studies paved the way for clinical trials of lenalidomide in mantle cell lymphoma (MCL). Initial phase I and II clinical trials of lenalidomide alone and as part of combination regimens in patients with relapsed/refractory MCL have shown promising results. Its immunomodulatory, T cell costimulatory, anti-inflammatory and anti-angiogenic actions working together in the tumor cell microenvironment seem to be responsible for its enhanced antitumor efficacy. Lenalidomide's nature of action and safety profile favor it over other agents studied in relapsed/refractory MCL. This review summarizes the data from preclinical and clinical studies of lenalidomide in relapsed/refractory MCL and compares the results with those of other novel agents being used for relapsed/refractory MCL.

Role of tumor associated macrophages in tumor angiogenesis and lymphangiogenesis

Tumor angiogenesis is an essential process for supplying rapidly growing malignant tissues with essential nutrients and oxygen. An angiogenic switch allows tumor cells to survive and grow, and provides them access to vasculature resulting in metastatic disease. Monocyte-derived macrophages recruited and reprogrammed by tumor cells serve as a major source of angiogenic factors boosting the angiogenic switch. Tumor endothelium releases angiopoietin-2 and further facilitates recruitment of TIE2 receptor expressing monocytes (TEM) into tumor sites. Tumor-associated macrophages (TAM) sense hypoxia in avascular areas of tumors, and react by production of angiogenic factors such as VEGFA. VEGFA stimulates chemotaxis of endothelial cells (EC) and macrophages. In some tumors, TAM appeared to be a major source of MMP9. Elevated expression of MMP9 by TAM mediates extracellular matrix (ECM) degradation and the release of bioactive VEGFA. Other angiogenic factors released by TAM include basic fibroblast growth factor (bFGF), thymidine phosphorylase (TP), urokinase-type plasminogen activator (uPA), and adrenomedullin (ADM). The same factors used by macrophages for the induction of angiogenesis [like vascular endothelial growth factor A (VEGF-A) and MMP9] support lymphangiogenesis. TAM can express LYVE-1, one of the established markers of lymphatic endothelium. TAM support tumor lymphangiogenesis not only by secretion of pro-lymphangiogenic factors but also by trans-differentiation into lymphatic EC. New pro-angiogenic factor YKL-40 belongs to a family of mammalian chitinase-like proteins (CLP) that act as cytokines or growth factors. Human CLP family comprises YKL-40, YKL-39, and SI-CLP. Production of all three CLP in macrophages is antagonistically regulated by cytokines. It was recently established that YKL-40 induces angiogenesis in vitro and in animal tumor models. YKL-40-neutralizing monoclonal antibody blocks tumor angiogenesis and progression. The role of YKL-39 and SI-CLP in tumor angiogenesis and lymphangiogenesis remains to be investigated.