Gene targeted and immune therapies for nodal and gastrointestinal follicular lymphomas

Follicular lymphoma (FL) is the most common indolent B-cell lymphoma (BCL) globally. Recently, its incidence has increased in Europe, the United States, and Asia, with the number of gastrointestinal FL cases expected to increase. Genetic abnormalities related to t(14;18) translocation, BCL2 overexpression, NF-κB pathway-related factors, histone acetylases, and histone methyltransferases cause FL and enhance its proliferation. Meanwhile, microRNAs are commonly used in diagnosing FL and predicting patient prognosis. Many clinical trials on novel therapeutics targeting these genetic abnormalities and immunomodulatory mechanisms have been conducted, resulting in a marked improvement in therapeutic outcomes for FL. Although developing these innovative therapeutic agents targeting specific genetic mutations and immune pathways has provided hope for curative options, FL treatment has become more complex, requiring combinatorial therapeutic regimens. However, optimal treatment combinations have not yet been achieved, highlighting the importance of a complete under-standing regarding the pathogenesis of gastrointestinal FL. Accordingly, this article reviews key research on the molecular pathogenesis of nodal FL and novel therapies targeting the causative genetic mutations. Moreover, the results of clinical trials are summarized, with a particular focus on treating nodal and gastrointestinal FLs.

Recent advances in treatment of nodal and gastrointestinal follicular lymphoma

Follicular lymphoma (FL) is the most common low-grade lymphoma, and although nodal FL is highly responsive to treatment, the majority of patients relapse repeatedly, and the disease has been incurable with a poor prognosis. However, primary FL of the gastrointestinal tract has been increasingly detected in Japan, especially due to recent advances in small bowel endoscopy and increased opportunities for endoscopic examinations and endoscopic diagnosis. However, many cases are detected at an early stage, and the prognosis is good in many cases. In contrast, in Europe and the United States, gastrointestinal FL has long been considered to be present in 12%-24% of Stage-IV patients, and the number of advanced gastrointestinal cases is expected to increase. This editorial provides an overview of the recent therapeutic advances in nodal FL, including antibody-targeted therapy, bispecific antibody therapy, epigenetic modulation, and chimeric antigen receptor T-cell therapy, and reviews the latest therapeutic manuscripts published in the past year. Based on an understanding of the therapeutic advances in nodal FL, we also discuss future possibilities for gastroenterologists to treat gastrointestinal FL, especially in advanced cases.

Multispecific CAR T Cells Deprive Lymphomas of Escape via Antigen Loss

Chimeric antigen receptor (CAR) modified T cell therapy has transformed the management of relapsed/refractory B cell malignancies. Despite high overall response rates, relapse post CAR T treatment remains a clinical challenge. Loss of target antigen, specifically CD19, is one well-defined mechanism of disease relapse. The mechanism of CD19 loss and which patients are at higher risk of CD19 loss remain poorly understood. To overcome CD19 loss, CARs targeting multiple antigens are being tested in clinical trials. CD19/20 and CD19/22 bispecific CARs demonstrate cytotoxicity against CD19-negative cells in preclinical studies. These CARs have also shown efficacy, safety, and a relatively low rate of CD19-negative relapse in phase I trials. These small studies suggest that multispecific CAR T cells can deprive lymphomas of escape via antigen loss. However, the selection of an ideal target, the right CAR construct, and whether these multispecific CARs can induce long-term remissions are still under investigation.

Follicular lymphoma: The long and winding road leading to your cure?

Follicular lymphoma, the most common indolent lymphoma, though highly responsive to therapy is coupled with multiple relapses for the majority of patients. Advances in biologic understanding of molecular events in lymphoma cells and the tumor microenvironment, along with novel cellular and targeted therapies, suggest this may soon change. Here we first review the development of the molecular concepts and classification of follicular lymphoma, along with therapeutic development of treatments based on chemotherapy plus monoclonal antibodies targeting CD20. We then focus on developments over the last decade in further defining follicular lymphoma pathophysiology, leading to targeted therapeutics, as well as novel immunotherapeutic strategies effective against B cell lymphomas including follicular, particularly patients with advanced stage disease. Additional alterations beyond the hallmark t(14;18) translocation are necessary for development of follicular lymphoma. Epigenetic mutations are almost universally identified in follicular lymphoma, most commonly involving histone-lysine N-methyltransferase 2D (KMT2D, the histone acetyltransferases, cAMP response element-binding protein binding protein (CREBBP) and E1A binding protein P300 (EP300) and the histone methyltransferase enhancer of zeste homologue 2 (EZH2). Mutations are also commonly identified in other proliferation/survival pathways such as B-cell receptor, RAS, mTOR and JAK-STAT pathways, as well as immune escape mutations. The host immune response plays a key role as well, based on studies correlating various immune cell subsets and gene expression signatures with outcomes. Over the last decade, many therapeutic options beyond the commonly used bendamustine-rituximab induction regimen have become available or are being investigated. We focus on these newer agents in the relapsed setting. New antibody-based agents include the naked CD19 directed antibody tafasitamab, the CD79b directed antibody drug conjugate (ADC) polatuzumab vedotin and the CD47 directed antibody magrolimab that targets macrophages rather than FL cells directly. Immune modulation by lenalidomide has moved to earlier lines of therapy and in combinations. Several small molecule inhibitors of proliferation signal pathways involving PI3kinase and BTK have activity against FL. Apoptotic pathway modulators also have activity. With increasing recognition of the high rate of epigenetic mutations in FL, HDAC inhibition has a role. More importantly, the EZH2 inhibitor tazemetostat is FDA approved for FL after 2 prior lines of therapy. The most exciting data currently involve immune attack against follicular lymphoma by chimeric antigen receptor T-cells (CART) or bispecific antibody constructs. Given these multiple potentially non-crossreactive mechanisms, studies of rationally designed combination strategies hold the promise of improving outcomes and possibly cure of follicular lymphoma.

Current updates on generations, approvals, and clinical trials of CAR T-cell therapy

Chimeric antigen receptor (CAR) T-cell therapy is a novel, customized immunotherapy that is considered a 'living' and self-replicating drug to treat cancer, sometimes resulting in a complete cure. CAR T-cells are manufactured through genetic engineering of T-cells by equipping them with CARs to detect and target antigen-expressing cancer cells. CAR is designed to have an ectodomain extracellularly, a transmembrane domain spanning the cell membrane, and an endodomain intracellularly. Since its first discovery, the CAR structure has evolved greatly, from the first generation to the fifth generation, to offer new therapeutic alternatives for cancer patients. This treatment has achieved long-term and curative therapeutic efficacy in multiple blood malignancies that nowadays profoundly change the treatment landscape of lymphoma, leukemia, and multiple myeloma. But CART-cell therapy is associated with several hurdles, such as limited therapeutic efficacy, little effect on solid tumors, adverse effects, expensive cost, and feasibility issues, hindering its broader implications.

Prospects in the management of patients with follicular lymphoma beyond first-line therapy

The management of patients with relapsed or refractory follicular lymphoma has evolved markedly in the last decade, with the availability of new classes of agents (phosphoinositide 3-kinase inhibitors, immunomodulators, epigenetic therapies, and chimeric antigen receptor T cells) supplementing the multiple approaches already available (cytotoxic agents, anti-CD20 antibodies, radiation therapy, radioimmunotherapy, and autologous and allogeneic transplants). The diversity of clinical scenarios, the flood of data derived from phase II studies, and the lack of randomized studies comparing treatment strategies preclude firm recommendations and require personalized decisions. Patients with early progression require specific attention given the risk of histological transformation and their lower response to standard therapies. In sequencing therapies, one must consider prior treatment regimens and the potential need for future lines of therapy. Careful evaluation of risks and expected benefits of available options, which vary depending on location and socioeconomics, should be undertaken, and should incorporate the patient's goals. Preserving quality of life for these patients is essential, given the likelihood of years to decades of survival and the possibility of multiple lines of therapy. The current landscape is likely to continue evolving rapidly with other effective agents emerging (notably bispecific antibodies and other targeted therapies), and multiple combinations being evaluated. It is hoped that new treatments under development will achieve longer progression-free intervals and minimize toxicity. A better understanding of disease biology and the mechanisms of these different agents should provide further insights to select the optimal therapy at each stage of disease.

Overview of approved CAR-T therapies, ongoing clinical trials, and its impact on clinical practice

In recent years, we have seen rapid expansion of chimeric antigen receptor T-cell (CAR-T) therapies in multiple malignancies. CAR-T therapy has profoundly altered the treatment landscape of non-Hodgkin lymphoma, B-cell acute lymphoblastic leukemia, and multiple myeloma. Currently available CD19 and B-cell maturation antigen-directed CAR-T therapies have shown high overall response rate and durable remissions in patients who have failed standard therapies. Multiple studies are underway exploring the role of CAR-T-cell therapy as earlier line of treatment. In high-grade B-cell lymphoma, CD19 CAR-T therapy may replace autologous hematopoietic cell transplantation as second line therapy in near future. CAR-T-cell therapy targeting novel tumor-associated antigens will help expand utility of this treatment modality in other hematological malignancies. It may also help overcome limitations of currently approved CAR-T-cell therapies. In this review, we have provided an overview of currently approved CAR-T therapies and upcoming clinical trials which may potentially impact the clinical practice.

[A 2021 inventory in oncology news]

Once again this year, the Editorial Board presents here a summary of the most important advances in treatment and patient care in oncology over the past year. Some of the most important results in breast and gynecological cancers (endometrium and cervix), lung, brain, urologic and digestive cancers. Are also presented progresses in hematological malignancies, pediatric oncology, and of course supportive care essential for our patients.

Tazemetostat: a treatment option for relapsed/refractory follicular lymphoma

INTRODUCTION

Follicular lymphoma (FL) is the second most common form of B cell lymphoma and generally presents as an indolent and relatively slow-growing tumor. However, most FLs are incurable with a shortening of subsequent responses. Therefore, novel and more effective treatments are desperately needed. Tazemetostat is a first-in-class, selective, oral inhibitor of EZH2, a lysine methyltransferase that is mutated in about 25% of FL. Tazemetostat has been recently approved for relapsed/refractory FL after two or more lines of therapy in the presence of an EZH2 mutation or independent of an EZH2 mutation in the absence of other options.

AREAS COVERED

Here, the authors provide a review focusing on the molecular mechanisms of EZH2, clinical development of tazemetostat and other EZH2 inhibitors (EZH2i), as single-agent therapy and in combinatorial regimens. Finally, they provide a futuristic look at therapeutic approaches for this disease.

EXPERT OPINION

Tazemetostat monotherapy showed clinically meaningful and durable responses with a favorable toxicity profile, especially in EZH2 mutant lymphoma. Future studies should explore mechanism-based combinatorial regimens to maximize and prolong the anti-lymphoma effect.