INTERIM REPORT FROM A PHASE 2 MULTICENTER STUDY OF TAZEMETOSTAT, AN EZH2 INHIBITOR, IN PATIENTS WITH RELAPSED OR REFRACTORY B-CELL NON-HODGKIN LYMPHOMAS

Second-line treatment of diffuse large B-cell lymphoma: Evolution of options

In the era of immunochemotherapy, approximately 60%-70% of diffuse large B-cell lymphoma (DLBCL) patients achieve remission with first-line rituximab-based chemoimmunotherapy. However, 30%-40% relapse after initial response to first-line therapy and, out of them, 20%-50% are refractory or experience early relapse. The second-line therapy algorithm for DLBCL has recently evolved, thanks to the recent approval of new therapeutic agents or their combinations. The new guidelines suggest a stratification of relapsed/refractory (R/R) DLBCL based on the time to relapse. For transplant-eligible patients, autologous stem cell transplant remains the preferred option when the patient relapses after 12 months from diagnosis, while anti-CD19 CART-cell therapy is the current preferred choice for high-risk DLBCL, defined as primary refractory or relapse ≤12 months. For transplant-ineligible or CAR T-cell therapy-ineligible patients, the therapeutic arsenal historically lacked effective options. However, new therapeutic options, including polatuzumab vedotin combined with bendamustine-rituximab and tafasitamab with lenalidomide, have been recently approved, and novel agents such as loncastuximab tesirine, selinexor, anti-CD19 CAR T-cell therapy, and bispecific antibodies have shown promising efficacy and manageable safety in this setting offering new hope to patients in this challenging scenario.

The progress of novel strategies on immune-based therapy in relapsed or refractory diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) can be cured with standard front-line immunochemotherapy, whereas nearly 30-40% of patients experience refractory or relapse. For several decades, the standard treatment strategy for fit relapsed/refractory (R/R) DLBCL patients has been high-dose chemotherapy followed by autologous hematopoietic stem cell transplant (auto-SCT). However, the patients who failed in salvage treatment or those ineligible for subsequent auto-SCT have dismal outcomes. Several immune-based therapies have been developed, including monoclonal antibodies, antibody-drug conjugates, bispecific T-cell engaging antibodies, chimeric antigen receptor T-cells, immune checkpoint inhibitors, and novel small molecules. Meanwhile, allogeneic SCT and radiotherapy are still necessary for disease control for fit patients with certain conditions. In this review, to expand clinical treatment options, we summarize the recent progress of immune-related therapies and prospect the future indirections in patients with R/R DLBCL.

Novel agents in relapsed/refractory diffuse large B-cell lymphoma

Patients with relapsed or refractory (R/R) diffuse large B-cell lymphoma (DLBCL), ineligible for or relapsing after autologous stem-cell transplant or chimeric antigen-receptor T-cell therapies have poor outcomes. Several novel agents, polatuzumab vedotin, tafasitamab, loncastuximab tesirine, and selinexor, have been approved and offer new opportunities for this difficult to treat population. Studies are evaluating combination of these agents with chemotherapy and other emerging therapies. Additionally, advances in our understanding of DLBCL biology, genetics, and immune microenvironment have allowed for the identification of new therapeutic targets like Ikaros and Aiolos, IRAK4, MALT1, and CD47 with several agents in ongoing clinical trials. In this chapter we review updated data supporting the use of the approved agents and discuss other emerging novel therapies for patients with R/R DLBCL.

Clinical relevance of molecular characteristics in Burkitt lymphoma differs according to age

While survival has improved for Burkitt lymphoma patients, potential differences in outcome between pediatric and adult patients remain unclear. In both age groups, survival remains poor at relapse. Therefore, we conducted a comparative study in a large pediatric cohort, including 191 cases and 97 samples from adults. While TP53 and CCND3 mutation frequencies are not age related, samples from pediatric patients showed a higher frequency of mutations in ID3, DDX3X, ARID1A and SMARCA4, while several genes such as BCL2 and YY1AP1 are almost exclusively mutated in adult patients. An unbiased analysis reveals a transition of the mutational profile between 25 and 40 years of age. Survival analysis in the pediatric cohort confirms that TP53 mutations are significantly associated with higher incidence of relapse (25 ± 4% versus 6 ± 2%, p-value 0.0002). This identifies a promising molecular marker for relapse incidence in pediatric BL which will be used in future clinical trials.

Combination of Atezolizumab and Tazemetostat in Patients With Relapsed/Refractory Diffuse Large B-Cell Lymphoma: Results From a Phase Ib Study

BACKGROUND

The combination of atezolizumab, a monoclonal antibody that targets programmed death-ligand 1 (PD-L1) and inhibits the interaction between PD-L1 and its receptors, and tazemetostat, an EZH2 inhibitor, may lead to selective epigenetic reprogramming, alter the tumor microenvironment, and provide additive or synergistic response to patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL).

MATERIALS AND METHODS

This was an open-label, phase Ib study assessing the safety, tolerability, and preliminary efficacy of atezolizumab plustazemetostat in patients with R/R DLBCL. Atezolizumab (1200 mg) was administered via intravenous (IV) infusion on day 1 of each cycle and tazemetostat (800 mg) was given orally twice daily (BID) on days 1 to 21. Primary endpoints were safety and tolerability, and to identify a recommended phase II dose (RP2D) for atezolizumab. Secondary efficacy endpoints included response rate and duration of response.

RESULTS

A total of 43 patients were enrolled, receiving a median of 3 prior lines of treatment (range: 1-9). The RP2D for atezolizumab was 1200 mg IV infusion every 3 weeks in combination with tazemetostat 800 mg BID. At the RP2D, adverse events reported in ≥20% patients were anemia(11 patients [26%]), fatigue (10 patients [23%]), and nausea (10 patients [23%]). Overall response rate was 16% (complete response rate: 7%). Median progression-free survival was 2 months (range: 0-24) and median overall survival was 13 months (range: 1-29).

CONCLUSIONS

The combination of atezolizumab and tazemetostat was determined to be safe and tolerable. However, anti-tumor activity of the combination was modest.

Prognostic Value of Histone Modifying Enzyme EZH2 in RCHOP-Treated Diffuse Large B-Cell Lymphoma and High Grade B-Cell Lymphoma

Background: DLBCL represent a heterogeneous group of aggressive diseases. High grade B-cell lymphomas (HGBCL) were recently individualized from DLBCL as a discrete diagnostic entity due to their worse prognosis. Currently, although most patients are successfully treated with RCHOP regimens, 1/3 will either not respond or ultimately relapse. Alterations in histone modifying enzymes have emerged as the most common alterations in DLBCL, but their role as prognostic biomarkers is controversial. We aimed to ascertain the prognostic value of EZH2 immunoexpression in RCHOP-treated DLBCL and HGBCL. Results: We performed a retrospective cohort study including 125 patients with RCHOP-treated DLBCL or HGBCL. EZH2 expression levels did not differ between diagnostic groups or between DLBCL-NOS molecular groups. We found no associations between EZH2 expression levels and outcome, including in the subgroup analysis (GC versus non-GC). Nonetheless, EZH2/BCL2 co-expression was significantly associated with worse outcome (event free survival and overall survival). Conclusion: Although EZH2 mutations are almost exclusively found in GC-DLBCL, we found similar EZH2 expression levels in both DLBCL-NOS molecular groups, suggesting non-mutational mechanisms of EZH2 deregulation. These findings suggest that the use of EZH2 antagonists might be extended to non-GC DLBCL patients with clinical benefit. EZH2/BCL2 co-expression was associated with a worse outcome.

Treatment resistance in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is a highly heterogeneous disease and represents the most common subtype of lymphoma. Although 60-70% of all patients can be cured by the current standard of care in the frontline setting, the majority of the remaining patients will experience treatment resistance and have a poor clinical outcome. Numerous efforts have been made to improve the efficacy of the standard regimen by, for example, dose intensification or adding novel agents. However, these results generally failed to demonstrate significant clinical benefits. Hence, understanding treatment resistance is a pressing need to optimize the outcome of those patients. In this Review, we first describe the conceptual sources of treatment resistance in DLBCL and then provide detailed and up-to-date molecular insight into the mechanisms of resistance to the current treatment options in DLBCL. We lastly highlight the potential strategies for rationally managing treatment resistance from both the preventive and interventional perspectives.

Combined EZH2 Inhibition and IKAROS Degradation Leads to Enhanced Antitumor Activity in Diffuse Large B-cell Lymphoma

PURPOSE

The efficacy of EZH2 inhibition has been modest in the initial clinical exploration of diffuse large B-cell lymphoma (DLBCL), yet EZH2 inhibitors are well tolerated. Herein, we aimed to uncover genetic and pharmacologic opportunities to enhance the clinical efficacy of EZH2 inhibitors in DLBCL.

EXPERIMENTAL DESIGN

We conducted a genome-wide sensitizing CRISPR/Cas9 screen with tazemetostat, a catalytic inhibitor of EZH2. The sensitizing effect of IKZF1 loss of function was then validated and leveraged for combination treatment with lenalidomide. RNA sequencing (RNA-seq) and chromatin immunoprecipitation sequencing analyses were performed to elucidate transcriptomic and epigenetic changes underlying synergy.

RESULTS

We identified IKZF1 knockout as the top candidate for sensitizing DLBCL cells to tazemetostat. Treating cells with tazemetostat and lenalidomide, an immunomodulatory drug that selectively degrades IKAROS and AIOLOS, phenocopied the effects of the CRISPR/Cas9 screen. The combined drug treatment triggered either cell-cycle arrest or apoptosis in a broad range of DLBCL cell lines, regardless of EZH2 mutational status. Cell-line-based xenografts also showed slower tumor growth and prolonged survival in the combination treatment group. RNA-seq analysis revealed strong upregulation of interferon signaling and antiviral immune response signatures. Gene expression of key immune response factors such as IRF7 and DDX58 were induced in cells treated with lenalidomide and tazemetostat, with a concomitant increase of H3K27 acetylation at their promoters. Furthermore, transcriptome analysis demonstrated derepression of endogenous retroviruses after combination treatment.

CONCLUSIONS

Our data underscore the synergistic interplay between IKAROS degradation and EZH2 inhibition on modulating epigenetic changes and ultimately enhancing antitumor effects in DLBCL.

Prognostic molecular biomarkers in diffuse large B-cell lymphoma in the rituximab era and their therapeutic implications

Diffuse large B-cell lymphoma (DLBCL) represents a group of tumors characterized by substantial heterogeneity in terms of their pathological and biological features, a causal factor of their varied clinical outcome. This variation has persisted despite the implementation of rituximab in treatment regimens over the last 20 years. In this context, prognostic biomarkers are of great importance in order to identify high-risk patients that might benefit from treatment intensification or the introduction of novel therapeutic agents. Herein, we review current knowledge on specific immunohistochemical or genetic biomarkers that might be useful in clinical practice. Gene-expression profiling is a tool of special consideration in this effort, as it has enriched our understanding of DLBCL biology and has allowed for the classification of DLBCL by cell-of-origin as well as by more elaborate molecular signatures based on distinct gene-expression profiles. These subgroups might outperform individual biomarkers in terms of prognostication; however, their use in clinical practice is still limited. Moreover, the underappreciated role of the tumor microenvironment in DLBCL prognosis is discussed in terms of prognostic gene-expression signatures, as well as in terms of individual biomarkers of prognostic significance. Finally, the efficacy of novel therapeutic agents for the treatment of DLBCL patients are discussed and an evidence-based therapeutic approach by specific genetic subgroup is suggested.

Combined EZH2 and Bcl-2 inhibitors as precision therapy for genetically defined DLBCL subtypes

Molecular alterations in the histone methyltransferase EZH2 and the antiapoptotic protein Bcl-2 frequently co-occur in diffuse large B-cell lymphoma (DLBCL). Because DLBCL tumors with these characteristics are likely dependent on both oncogenes, dual targeting of EZH2 and Bcl-2 is a rational therapeutic approach. We hypothesized that EZH2 and Bcl-2 inhibition would be synergistic in DLBCL. To test this, we evaluated the EZH2 inhibitor tazemetostat and the Bcl-2 inhibitor venetoclax in DLBCL cells, 3-dimensional lymphoma organoids, and patient-derived xenografts (PDXs). We found that tazemetostat and venetoclax are synergistic in DLBCL cells and 3-dimensional lymphoma organoids that harbor an EZH2 mutation and an IGH/BCL2 translocation but not in wild-type cells. Tazemetostat treatment results in upregulation of proapoptotic Bcl-2 family members and priming of mitochondria to BH3-mediated apoptosis, which may sensitize cells to venetoclax. The combination of tazemetostat and venetoclax was also synergistic in vivo. In DLBCL PDXs, short-course combination therapy resulted in complete remissions that were durable over time and associated with superior overall survival compared with either drug alone.

Advances in Treatment of Follicular Lymphoma

Follicular lymphoma (FL) is a heterogeneous disease with varying prognosis owing to differences in clinical, laboratory, and disease parameters. Although generally considered incurable, prognosis for early and advanced stage disease has improved because of therapeutic advances, several of which have resulted from elucidation of the biologic and molecular basis of the disease. The choice of treatment for FL is highly dependent on patient and disease characteristics. Several tools are available for risk stratification, although limitations in their routine clinical use exist. For limited disease, treatment options include radiotherapy, rituximab monotherapy or combination regimens, and surveillance. Treatment of advanced disease is often determined by tumor burden, with surveillance or rituximab considered for low tumor burden and chemoimmunotherapy for high tumor burden disease. Treatment for relapsed or refractory disease is influenced by initial first-line therapy and the duration and quality of the response. At present, there is no consensus for treatment of patients with early or multiply-relapsed disease; however, numerous agents, combination regimens, and transplant options have demonstrated efficacy. While the number of therapies available to treat FL has increased together with an improved understanding of the underlying biologic basis of disease, the best approach to select the most appropriate treatment strategy for an individual patient at a particular time continues to be elucidated. This chapter considers prognostic factors and the evolving treatment landscape of FL, including recent and emerging therapies, as well as remaining unmet needs.

Recent developments in epigenetic cancer therapeutics: clinical advancement and emerging trends

Epigenetic drug discovery field has evidenced significant advancement in the recent times. A plethora of small molecule inhibitors have progressed to clinical stage investigations and are being explored exhaustively to ascertain conclusive benefits in diverse malignancies. Literature precedents indicates that substantial amount of efforts were directed towards the use of epigenetic tools in monotherapy as well as in combination regimens at the clinical level, however, the preclinical/preliminary explorations were inclined towards the identification of prudent approaches that can leverage the anticancer potential of small molecule epigenetic inhibitors as single agents only. This review article presents an update of FDA approved epigenetic drugs along with the epigenetic inhibitors undergoing clinical stage investigations in different cancer types. A detailed discussion of the pragmatic strategies that are expected to steer the progress of the epigenetic therapy through the implementation of emerging approaches such as PROTACS and CRISPR/Cas9 along with logical ways for scaffold fabrication to selectively approach the enzyme isoforms in pursuit of garnering amplified antitumor effects has been covered. In addition, the compilation also presents the rational strategies for the construction of multi-targeting scaffold assemblages employing previously identified pharmacophores as potential alternatives to the combination therapy.

Treatment of Aggressive B Cell Lymphomas: Updates in 2019

PURPOSE OF REVIEW

Recent years have seen the development of gene expression profiling and next-generation sequencing in diffuse large B cell lymphoma (DLBCL), leading to a more defined characterization of this disease into distinct subentities. The genomic era has ushered in the possibility of using precision guided therapy, in part based on targeting genes with somatic mutations. Such precision-targeted therapies will ultimately reduce the need for chemotherapy, induce fewer adverse events, and likely enhance the cure rate for these patients. Here, we discuss emerging therapeutic strategies that have been recently developed for the upfront and relapse setting of DLBCL.

RECENT FINDINGS

Clinical trials exploring precision medicine have showed promising results; however, attempts to enhance frontline immunochemotherapy by adding targeted agents to the R-CHOP backbone did not confirm the expected benefit. The last decade has also seen a revolutionary development of immunotherapy in B cell lymphomas. While cellular immunotherapy demonstrated a striking success of CAR T cells in DLBCL, checkpoint inhibitors have lacked success in B cell lymphomas. A parallel therapeutic expansion has involved bispecific monoclonal antibodies as a powerful tool for redirected T cell therapy independently from costimulatory molecules and major-histocompatibility complex. The landscape of drugs for the treatment of DLBCL has become overwhelmed by the increasing number of targeted and immunological therapies; however, none have enhanced efficacy of frontline therapy. Future direction should focus to redefine therapeutic paradigm and develop mechanism-based combinatorial regimens specifically tailored for DLBCL genetic subgroups.

New agents and regimens for diffuse large B cell lymphoma

As a widely recognized standard regimen, R-CHOP (rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone) is able to cure two-thirds patients with diffuse large B cell lymphoma (DLBCL), and the remaining patients suffer from refractory or relapsed disease due to resistance to R-CHOP and fare poorly. Unsatisfied outcomes for those relapsed/refractory patients prompted efforts to discover new treatment approaches for DLBCL, including chimeric antigen receptor T cells, bispecific T cell engagers, immunomodulatory drugs, immune checkpoint inhibitors, monoclonal antibodies, antibody-drug conjugates, molecular pathway inhibitors, and epigenetic-modifying drugs. Herein, up-to-date data about the most promising treatment approaches for DLBCL are recapitulated, and novel genetic classification systems are introduced to guide individualized treatment for DLBCL.

R-CHOP resistance in diffuse large B-cell lymphoma: biological and molecular mechanisms

Although the first-line rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone regimen (R-CHOP) substantially improved outcomes for patients with diffuse large B-cell lymphoma (DLBCL), 40% of the patients suffered from relapsed/refractory disease and had poor survival outcomes. The detailed mechanism underlying R-CHOP resistance has not been well defined. For this review, we conducted a thorough search for literature and clinical trials involving DLBCL resistance. We discussed DLBCL biology, epigenetics, and aberrant signaling of the B-cell receptor (BCR), phosphatidylinositol 3-kinase (PI3K)/Akt, nuclear factor kappa light chain enhancer of activated B-cells (NF-κB), and the Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) pathways as defining mechanisms of DLBCL heterogeneity and R-CHOP resistance. The cell of origin, double- or triple-hit lymphoma and double-protein-expression, clonal evolution, tumor microenvironment, and multi-drug resistance help to contextualize DLBCL resistance in an (epi)genetically and biologically comparative manner. With better understanding of the biological and molecular landscape of DLBCL, a more detailed classification system and tailored treatments will ideally become available to further improve the prognosis of DLBCL patients.

Diagnosis and treatment of lymphomas in the era of epigenetics

Lymphomas represent a heterogeneous group of cancers characterized by clonal lymphoproliferation. Over the past decades, frequent epigenetic dysregulations have been identified in hematologic malignancies including lymphomas. Many of these impairments occur in genes with established roles and well-known functions in the regulation and maintenance of the epigenome. In hematopoietic cells, these dysfunctions can result in abnormal DNA methylation, erroneous chromatin state and/or altered miRNA expression, affecting many different cellular functions. Nowadays, it is evident that epigenetic dysregulations in lymphoid neoplasms are mainly caused by genetic alterations in genes encoding for enzymes responsible for histone or chromatin modifications. We summarize herein the recent epigenetic modifiers findings in lymphomas. We focus also on the most commonly mutated epigenetic regulators and emphasize on actual epigenetic therapies.

Design, Synthesis, and Pharmacological Evaluation of Second Generation EZH2 Inhibitors with Long Residence Time

Histone methyltransferase EZH2, which is the catalytic subunit of the PRC2 complex, catalyzes the methylation of histone H3K27-a transcriptionally repressive post-translational modification (PTM). EZH2 is commonly mutated in hematologic malignancies and frequently overexpressed in solid tumors, where its expression level often correlates with poor prognosis. First generation EZH2 inhibitors are beginning to show clinical benefit, and we believe that a second generation EZH2 inhibitor could further build upon this foundation to fully realize the therapeutic potential of EZH2 inhibition. During our medicinal chemistry campaign, we identified 4-thiomethyl pyridone as a key modification that led to significantly increased potency and prolonged residence time. Leveraging this finding, we optimized a series of EZH2 inhibitors, with enhanced antitumor activity and improved physiochemical properties, which have the potential to expand the clinical use of EZH2 inhibition.

The Targeted Therapies Era Beyond the Surgical Point of View: What Spine Surgeons Should Know Before Approaching Spinal Metastases

In the last few years, the treatment of spinal metastases has significantly changed. This is due to the advancements in surgical technique, radiotherapy, and chemotherapy which have enriched the multidisciplinary management. Above all, the field of molecular biology of tumors is in continuous and prosperous evolution. In this review, the molecular markers and new approaches that have radically modified the chemotherapeutic strategy of the most common metastatic neoplasms will be examined together with clinical and surgical implications. The experience and skills of several different medical professionals are mandatory: an interdisciplinary oncology team represents the winning strategy in the treatment of patients with spinal metastases

Follicular lymphoma

Follicular lymphoma (FL) is a systemic neoplasm of the lymphoid tissue displaying germinal centre (GC) B cell differentiation. FL represents ~5% of all haematological neoplasms and ~20-25% of all new non-Hodgkin lymphoma diagnoses in western countries. Tumorigenesis starts in precursor B cells and becomes full-blown tumour when the cells reach the GC maturation step. FL is preceded by an asymptomatic preclinical phase in which premalignant B cells carrying a t(14;18) chromosomal translocation accumulate additional genetic alterations, although not all of these cells progress to the tumour phase. FL is an indolent lymphoma with largely favourable outcomes, although a fraction of patients is at risk of disease progression and adverse outcomes. Outcomes for FL in the rituximab era are encouraging, with ~80% of patients having an overall survival of >10 years. Patients with relapsed FL have a wide range of treatment options, including several chemoimmunotherapy regimens, phosphoinositide 3-kinase inhibitors, and lenalidomide plus rituximab. Promising new treatment approaches include epigenetic therapeutics and immune approaches such as chimeric antigen receptor T cell therapy. The identification of patients at high risk who require alternative therapies to the current standard of care is a growing need that will help direct clinical trial research. This Primer discusses the epidemiology of FL, its molecular and cellular pathogenesis and its diagnosis, classification and treatment.

Emerging epigenetic-modulating therapies in lymphoma

Despite considerable advances in the treatment of lymphoma, the prognosis of patients with relapsed and/or refractory disease continues to be poor; thus, a continued need exists for the development of novel approaches and therapies. Epigenetic dysregulation might drive and/or promote tumorigenesis in various types of malignancies and is prevalent in both B cell and T cell lymphomas. Over the past decade, a large number of epigenetic-modifying agents have been developed and introduced into the clinical management of patients with haematological malignancies. In this Review, we provide a concise overview of the most promising epigenetic therapies for the treatment of lymphomas, including inhibitors of histone deacetylases (HDACs), DNA methyltransferases (DNMTs), enhancer of zeste homologue 2 (EZH2), bromodomain and extra-terminal domain proteins (BETs), protein arginine N-methyltransferases (PRMTs) and isocitrate dehydrogenases (IDHs), and highlight the most promising future directions of research in this area.

Epigenetic modifiers as new immunomodulatory therapies in solid tumours

Background

Immune therapies have revolutionized cancer treatment over the last few years by allowing improvements in overall survival. However, the majority of patients is still primary or secondary resistant to such therapies, and enhancing sensitivity to immune therapies is therefore crucial to improve patient outcome. Several recent lines of evidence suggest that epigenetic modifiers have intrinsic immunomodulatory properties, which could be of therapeutic interest.

Material and methods

We reviewed preclinical evidence and clinical studies which describe or exploit immunomodulatory properties of epigenetic agents. Experimental approaches, clinical applicability and corresponding ongoing clinical trials are described.

Results

Several epigenetic modifiers, such as histone deacetylase inhibitors, DNA methyl transferase inhibitors, bromodomain inhibitors, lysine-specific histone demethylase 1 inhibitors and enhancer of zeste homolog 2 inhibitors, display intrinsic immunomodulatory properties. The latter can be achieved through the action of these drugs either on cancer cells (e.g. presentation and generation of neoantigens, induction of immunogenic cell death, modulation of cytokine secretion), on immune cells (e.g. linage, differentiation, activation status and antitumor capability), or on components of the microenvironment (e.g. regulatory T cells and macrophages). Several promising combinations, notably with immune checkpoint blockers or adoptive T-cell therapy, can be envisioned. Dedicated clinically relevant approaches for patient selection and trial design will be required to optimally develop such combinations.

Conclusion

In an era where immune therapies are becoming a treatment backbone in many tumour types, epigenetic modifiers could play a crucial role in modulating tumours' immunogenicity and sensitivity to immune agents. Optimal trial design, including window of opportunity trials, will be key in the success of this approach, and clinical evaluation is ongoing.

Hitting back at lymphoma: How do modern diagnostics identify high-risk diffuse large B-cell lymphoma subsets and alter treatment?

Diffuse large B-cell lymphoma (DLBCL) is a clinically and biologically heterogeneous disease. Diagnostic tools in the clinic can now identify distinct subsets characterized by unique molecular features, which are increasingly transforming how these patients are managed. Activated B-cell-like DLBCL is characterized by NF-κB activation and chronic B-cell receptor signaling and may be targeted with lenalidomide or ibrutinib in the relapsed setting. Germinal center-like DLBCL is enriched for activating EZH2 mutations, and encouraging activity has been observed for the EZH2 inhibitor tazemetostat, which now has a fast-track US Food and Drug Administration designation. Double-hit lymphoma is a high-grade B-cell lymphoma characterized by translocations of MYC and BCL2 and/or BCL6 and carries a poor prognosis. Intensive chemoimmunotherapy strategies appear to be superior to standard R-CHOP (rituximab combined with cyclophosphamide, doxorubicin, vincristine, and prednisone) as initial therapy, and anti-CD19 chimeric antigen receptor T cells are inducing remission in patients with relapsed/refractory disease who previously had few available options. Primary mediastinal (thymic) large B-cell lymphoma is a molecularly distinct large-cell lymphoma with clinical and molecular features that overlap with those of classical Hodgkin lymphoma. R-CHOP has been associated with an unacceptably high rate of primary treatment failure in this young population, whereas dose-adjusted EPOCH-R (etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin plus rituximab) produces durable remissions without the need for radiotherapy in most patients. For relapsed/refractory disease, immune checkpoint inhibitors targeting PD-1 have shown promising activity in chemotherapy-refractory disease, as have anti-CD19 chimeric antigen receptor T cells. Additional therapeutic targets, including JAK2, continue to be evaluated. The identification of discrete biological subsets is steadily moving us away from a "one-size-fits-all" approach in DLBCL.

Pathogenesis and biomarkers of natural killer T cell lymphoma (NKTL)

Natural killer T cell lymphoma (NKTL) is an aggressive disease with very poor treatment outcomes in the advanced stages. With chemotherapy, initial response rates to treatment are high but responses are short lived. A better understanding of the complex molecular pathogenesis of this disease is essential in order to design and develop better therapeutics with improved efficacy. This review aims to summarise the key pathogenic mechanisms in NKTL which may have significant prognostic and therapeutic implications.

Targeting epigenetic modifications in cancer therapy: erasing the roadmap to cancer. Nat Med. 2019;25:403-418. [PMID: 30842676 DOI: 10.1038/s41591-019-0376-8]

Epigenetic dysregulation is a common feature of most cancers, often occurring directly through alteration of epigenetic machinery. Over the last several years, a new generation of drugs directed at epigenetic modulators have entered clinical development, and results from these trials are now being disclosed. Unlike first-generation epigenetic therapies, these new agents are selective, and many are targeted to proteins which are mutated or translocated in cancer. This review will provide a summary of the epigenetic modulatory agents currently in clinical development and discuss the opportunities and challenges in their development. As these drugs advance in the clinic, drug discovery has continued with a focus on both novel and existing epigenetic targets. We will provide an overview of these efforts and the strategies being employed.

The Need for a Consensus Next-generation Sequencing Panel for Mature Lymphoid Malignancies

Supplemental Digital Content is available in the text

EZH2 as a therapeutic target for multiple myeloma and other haematological malignancies

Enhancer of zeste homolog 2 (EZH2) is a histone methyltransferase that is of great interest in human cancer. It has been shown to have a dual nature, as it can act as a gene repressor or activator. Studies have highlighted the various roles of EZH2 in the pathophysiology of multiple myeloma (MM). It was also shown to have a role in the development of drug resistance in MM. There are several ongoing clinical trials of EZH2 inhibitors in haematological malignancies. Pre-clinical studies have provided a rationale for the therapeutic relevance of EZH2 inhibitors in MM. This paper reviews the evidence supporting the role of EZH2 in MM pathophysiology and drug resistance, with an emphasis on interactions between EZH2 and microRNAs, as well as the prognostic significance of EZH2 expression in MM. Furthermore, results from the pre-clinical studies of EZH2 inhibition in MM and currently available interim results from clinical trials of EZH2 inhibitors in haematological malignancies are presented. Preliminary data exploring anticipated mechanisms of resistance to EZH2 inhibitors are also reviewed. There is therefore strong evidence to support the relevance of targeting EZH2 for the treatment of MM.

Optimizing initial therapy in DLBCL

Diffuse large B-cell lymphoma (DLBCL) is a group of lymphomas comprising heterogeneous molecular and biological subtypes, reflected in a broad range of clinical outcomes. With the standard R-CHOP regimen of cyclophosphamide, doxorubicin, vincristine, and prednisone plus rituximab administered every 21 days, the treatment failure rate remains unacceptably high in certain DLBCL subsets. Here we review possible avenues for optimizing initial therapy. The role of functional imaging and biological features, such as double-hit lymphomas, defined by the dual translocation of MYC and BCL2, and dual protein-expresser lymphomas, defined by the overexpression of MYC and BCL2, activated B-cell (ABC)-like DLBCL, to better define these high-risk patient subsets, and their use to guide and personalize treatment decisions are discussed. Secondly, the implications of varying dose-intensification of the various agents administered, and the link to imaging are reviewed. Thirdly, the results of the addition of novel drugs to standard R-CHOP will be analyzed, when added at induction or in maintenance. Finally, with CNS relapse in DLBCL representing a major and devastating unmet medical need, an overview and future directions for CNS prophylaxis is presented.

Report of the 14th International Conference on Malignant Lymphoma (ICML) Closed Workshop on Future Design of Clinical Trials in Lymphomas

The 14th ICML held in Lugano in June 2017 was preceded by a closed workshop (organized in collaboration with the American Association for Cancer Research and the European School of Oncology) where experts in preclinical and clinical research in lymphomas met to discuss the current drug development landscape focusing on critical open questions that need to be addressed in the future to permit a more efficient drug development paradigm in lymphoma. Topics discussed included both preclinical models that can be used to test new drugs and drug combinations, as well as the optimal design of clinical trials and the endpoints that should be used to facilitate accelerated progress. This report represents a summary of the workshop. Clin Cancer Res; 24(13); 2993-8. ©2018 AACR.

Follicular Lymphoma: Past, Present, and Future

OPINION STATEMENT

Even in the modern era, follicular lymphoma (FL) remains largely an incurable but treatable disease with both standard and novel treatment modalities. Despite the abundance of efficacious treatment modalities currently available, there is no universally agreed upon standard approach to treatment for patients with FL, particularly in the relapsed/refractory (R/R) setting. There is an increasing need for better tools to risk-stratify patients and to identify those likely to experience relapse early. Additionally, the use of gene expression profiling and next-generation sequencing techniques in recent years has led to a wealth of knowledge regarding the molecular drivers of lymphomagenesis; however, much of this knowledge is not currently applicable on a day to day basis in the clinic setting. Further studies are needed to determine a validated, clinically relevant predictive model that incorporates patient factors and molecular factors that will guide clinicians on the most effective treatment strategy. With many questions left unanswered, it is our opinion that the treatment of FL and sequencing of therapy in the R/R setting should be a personalized approach that balances patient-specific factors such as preferences and comorbidities with treatment-related factors such as known response rates and toxicity profiles.

What Does This Mutation Mean? The Tools and Pitfalls of Variant Interpretation in Lymphoid Malignancies

High throughput sequencing (HTS) is increasingly important in determining cancer diagnoses, with subsequent prognostic and therapeutic implications. The biology of cancer is becoming increasingly deciphered and it is clear that therapy needs to be individually tailored. Whilst translational research plays an important role in lymphoid malignancies, few guidelines exist to guide biologists and routine laboratories through this constantly evolving field. In this article, we review the challenges of interpreting HTS in lymphoid malignancies and provide a toolkit to interpret single nucleotide variants obtained from HTS. We define the pre-analytical issues such as sequencing DNA obtained from formalin-fixed and paraffin-embedded tissue (FFPE), the acquisition of germline DNA, or the bioinformatic pitfalls, the analytical issues encountered and how to manage them. We describe the main constitutional and cancer databases, their characteristics and limitations, with an emphasis on variant interpretation in lymphoid malignancies. Finally, we discuss the challenges of predictions that one can make using in silico or in vitro modelling, pharmacogenomic screening, and the limits of those prediction tools. This description of the current status in genomic interpretation highlights the need for new large databases and international collaboration in the lymphoma field.

From genetics to the clinic: a translational perspective on follicular lymphoma

Follicular lymphoma (FL) is the most frequent indolent B cell lymphoma and is still considered to be incurable. In recent years, whole-exome sequencing studies of large cohorts of patients have greatly improved our knowledge of the FL mutational landscape. Moreover, the prolonged evolution of this disease has enabled some insights regarding the early pre-lymphoma lesions as well as the clonal evolution after treatment, allowing an evolutionary perspective on lymphomagenesis. Deciphering the earliest initiating lesions and identifying the molecular alterations leading to disease progression currently represent important goals; accomplishing these could help identify the most relevant targets for precision therapy.

Novel acquisitions on biology and management of transformed follicular lymphoma

Follicular lymphoma (FL) generally has an indolent clinical course, but in some patients, a histological transformation (HT) into aggressive entities may take place and often lead to a poorer survival. The rituximab era has seen an improved outcome of FL, including those with HT. The current treatment strategies for transformed FL are based on immunochemotherapy for the cases with HT at the time of diagnosis or as the first event after watchful waiting. Patients transforming after prior treatment of FL usually benefit from autologous stem cell transplant. Unfortunately, early assessment of the transformation risk remains elusive. Recent studies delved the mechanisms of HT, showing that this is a complex process, resulting from a number of epigenetic and genetic lesions occurring in the tumour cell population as well as progressive changes in the tumour microenvironment. This novel knowledge has prompted clinical investigations on a variety of new therapeutic strategies.

Mechanisms of resistance to EZH2 inhibitors in diffuse large B-cell lymphomas

Resistance to targeted therapies has become increasingly prevalent. We noted that resistance to different targeted therapies occurs by largely common mechanisms. In this study, we used this information for identifying the mechanisms of resistance to enhancer of zeste homolog 2 (EZH2) inhibitors in diffuse large B-cell lymphoma (DLBCL) harboring EZH2 mutations. We discovered that EZH2 inhibitor-resistant DLBCL cells showed activation of the insulin-like growth factor 1 receptor (IGF-1R), MEK, and phosphoinositide-3-kinase (PI3K) pathways. Constitutive activation of IGF-1R, MEK, or PI3K pathways was sufficient to confer resistance to EZH2 inhibitors in DLBCL. The activation of the PI3K/AKT and MAPK pathways decreased TNFSF10 and BAD expression through a FOXO3-dependent mechanism, which was required for the antitumor effects of EZH2i GSK126. We also identified multiple acquired mutations in EZH2 inhibitor-resistant DLBCL cell lines. These mutations independently conferred resistance to EZH2 inhibitors. Mechanistically, cellular thermal shift assays revealed that the acquired EZH2 mutations that confer resistance to EZH2 inhibitors prevent EZH2 inhibitor binding to the EZH2 mutants. Notably, EZH2 inhibitor GSK126- and EPZ-6438-resistant DLBCL cells remained sensitive to the EZH2 inhibitor UNC1999 and embryonic ectoderm development protein inhibitor EED226, which provides an opportunity to treat DLBCLs that are resistant to these drugs. Collectively, our results underpin the importance for developing a unified approach for forestalling drug resistance by prospectively considering lessons learned from the use of different targeted therapeutic agents.

Enhancer of zeste homolog 2 (EZH2) inhibitors

Dysregulation of the histone methyltransferase EZH2 plays a critical role in the development of a variety of malignancies including B-cell lymphomas. As a result, a series of small molecule inhibitors of EZH2 have been developed and studied in the pre-clinical setting. Three EZH2 inhibitors: tazemetostat (EPZ-6438), GSK2816126 and CPI-1205 have moved into phase I/phase II clinical trials in patients with non-Hodgkin lymphoma and genetically defined solid tumors. Early data from the tazemetostat trials indicate an acceptable safety profile and early signs of activity in diffuse large B-cell lymphoma and follicular lymphoma, including patients with EZH2 wild-type and mutant tumors. In this review, we present the rationale, key pre-clinical and early clinical findings of small molecule EZH2 inhibitors for use in lymphoma as well as future challenges and potential opportunities for combination therapies.

Follicular lymphoma: are we ready for a risk-adapted approach?

Follicular lymphoma is the most common indolent non-Hodgkin lymphoma in the Western hemisphere. The natural history of FL appears to have been favorably impacted by the introduction of rituximab after randomized clinical trials demonstrated that the addition of rituximab to standard chemotherapy induction has improved the overall survival. Yet, the disease is biologically and clinically heterogeneous with wide variations in outcomes for individual patients. The ability to accurately risk-stratify patients and then tailor therapy to the individual is an area of ongoing research. Historically, tumor grade, tumor burden, and the FL international prognostic index (version 1 and version 2) have been used to distinguish low-risk from high-risk patients. Biologic factors such as mutations in key genes can identify patients at high risk for poor outcomes to first-line therapy (mutational status of 7 genes [EZH2, ARID1A, MEF2B, EP300, FOX01, CREBBP, and CARD11] with Follicular Lymphoma International Prognostic Index). More recently, the quality of the response to initial therapy, as measured by either PET imaging or by remission duration, has been show to identify individuals at high risk. However, several unmet needs remain, including a better ability to identify high-risk patients at diagnosis, the development of predictive biomarkers for targeted agents, and strategies to reduce the risk of transformation.

Tailoring front-line therapy in diffuse large B-cell lymphoma: who should we treat differently?

Although there have been significant insights into the biology of diffuse large B-cell lymphoma (DLBCL) over recent years, progress in our therapeutic approach has been disappointing over the same timeframe. This is not for want of trying. In 2017, R-CHOP (rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone) remains the "gold standard," despite all of our insights into cell-of-origin and other subgroups. We have traditionally used clinical risk factors to tailor our therapies and have tested intensification of chemotherapy with little success. We are now in an era of testing therapies according to the molecular phenotype of the individual's tumor. Many phase 1/2 studies have looked at adding targeted agents to conventional R-CHOP with some promise. The phase 3 data are now starting to emerge. Are we ready yet to modify our standard of care and have we reached an era of precision medicine in DLBCL? The answer to this is "not yet." The exception is perhaps patients with the newly defined World Health Organization category of high-grade B-cell lymphoma with rearrangements of MYC and BCL2 and/or BCL6, the so-called double- and triple-hit lymphomas. In these tumors there has been a move away from R-CHOP to more intensified regimens, however, has not been based upon rigorous prospective evaluation but review of retrospective datasets. This article will review the molecular subgroups of DLBCL, interventional strategies, and the outcomes of these interventions to date.

Chromatin modifying gene mutations in follicular lymphoma

Follicular lymphoma (FL) is an indolent malignancy of germinal center B cells. Although the overall survival of FL patients has recently improved with the introduction of novel therapies, there is significant heterogeneity in patient outcome and a need for rationally designed therapeutic strategies that target disease biology. Next-generation sequencing studies have identified chromatin modifying gene (CMG) mutations as a hallmark of FL, highlighting epigenetic modifiers as an attractive therapeutic target in this disease. Understanding the complex roles of these mutations will be central to identifying and adaptively targeting associated vulnerabilities. Recent studies have provided insight into the functional consequences of the most frequently mutated CMGs (KMT2D, CREBBP, and EZH2) and point to a role for these events in modifying normal B-cell differentiation programs and impeding germinal center exit. However, the majority of FL tumors serially acquire multiple CMG mutations, suggesting that there is a level of cross talk or cooperation between these events that has not yet been defined. Here, I review the current state of knowledge on CMG mutations in FL, discuss their potential as therapeutic targets, and offer my perspective on unexplored areas that should be considered in the future.

Current prognostic and predictive factors in follicular lymphoma

Follicular lymphoma (FL) is generally considered an indolent disorder. With modern day treatments, long remissions are often achieved both in the front-line and relapsed setting. However, a subset of patients has a more aggressive course and a worse outcome. Their identification is the main purpose of modern day prognostic tools. In this review, we attempt to summarize the evidence concerning prognostic and predictive factors in FL, including (1) pre-treatment factors, from baseline clinical characteristics and imaging tests to histological grade, the microenvironment and genomic abnormalities; (2) post-treatment factors, i.e., depth of response, measured both by imaging tests and minimal residual disease; (3) factors at relapse and duration of response; and (4) prognostic factors in histological transformation. We conclude that, despite the existence of numerous tools, the availability of some of them is still limited; they generally suffer from notable downsides, and most have unproven predictive value, thus having scarce bearing on the choice of regimen at present. However, with the technological and scientific developments of the last few years, the potential for these prognostic factors is promising, particularly in combination, which will probably, in time, help guide therapeutic decisions.

The promises and challenges of using gene mutations for patient stratification in follicular lymphoma

Follicular lymphoma (FL) is a clinically and molecularly highly heterogeneous disease. Most patients achieve long-lasting remissions and have excellent overall survival (OS) with current treatment. However, ∼20% of patients have early progression of disease and short OS. At present, therapies are not guided by individual risk or disease biology. Reliable tools for patient stratification are urgently needed to avoid overtreatment of low-risk patients and to prioritize alternative approaches in high-risk patients. A rapidly expanding repertoire of promising therapeutic options is available for clinical evaluation; however, the numbers of patients with FL and the resources to conduct adequately powered trials are limited. Recent studies have shown that gene mutations can serve as prognostic and/or predictive biomarkers, in particular when integrated into composite risk models. Before translating these findings into routine clinical practice, however, several challenges loom. We review aspects of “clinicogenetic” risk model development and validation that apply to FL and more generally to other cancers. Finally, we propose a crowdsourcing effort that could expedite the development, validation, refinement, and selection of risk models. A new era of collaboration and harmonization is required if we hope to transition from empiric selection of therapeutics to risk-based, biology-guided treatment of patients with FL.