The rules of T-cell engagement: current state of CAR T cells and bispecific antibodies in B-cell lymphomas

ABSTRACT

T-cell engaging-therapies have transformed the treatment landscape of relapsed and refractory B-cell non-Hodgkin lymphomas by offering highly effective treatments for patients with historically limited therapeutic options. This review focuses on the advances in chimeric antigen receptor-modified T cells and bispecific antibodies, first providing an overview of each product type, followed by exploring the primary data for currently available products in large B-cell lymphoma, follicular lymphoma, and mantle cell lymphoma. This review also highlights key logistical and sequencing considerations across diseases and product types that can affect clinical decision-making.

Moving T-Cell Therapies into the Standard of Care for Patients with Relapsed or Refractory Follicular Lymphoma: A Review

Patients with follicular lymphoma, an indolent form of non-Hodgkin lymphoma, typically experience multiple relapses over their disease course. Periods of remission become progressively shorter with worse clinical outcomes after each subsequent line of therapy. Currently, no clear standard of care/preferred treatment approach exists for patients with relapsed or refractory follicular lymphoma. As novel agents continue to emerge for treatment in the third-line setting, guidance is needed for selecting the most appropriate therapy for each patient. Several classes of targeted therapeutic agents, including monoclonal antibodies, phosphoinositide 3-kinase inhibitors, enhancer of zeste homolog 2 inhibitors, chimeric antigen receptor (CAR) T-cell therapies, and bispecific antibodies, have been approved by regulatory authorities based on clinical benefit in patients with relapsed or refractory follicular lymphoma. Additionally, antibody-drug conjugates and other immunocellular therapies are being evaluated in this setting. Effective integration of CAR-T cell therapy into the treatment paradigm after two or more prior therapies requires appropriate patient selection based on transformation status following a rebiopsy; a risk evaluation based on age, fitness, and remission length; and eligibility for CAR-T cell therapy. Consideration of important logistical factors (e.g., proximity to the treatment center and caregiver support during key periods of CAR-T cell therapy) is also critical. Overall, an individualized treatment plan that considers patient-related factors (e.g., age, disease status, tumor burden, comorbidities) and prior treatment types is recommended for patients with relapsed or refractory follicular lymphoma. Future analyses of real-world data and a better understanding of mechanisms of relapse are needed to further refine patient selection and identify optimal sequencing of therapies in this setting.

Allogeneic Chimeric Antigen Receptor Therapy in Lymphoma

The therapeutic armamentarium has significantly expanded since the approval of various CD19-targeting chimeric antigen receptor T cell (CAR-T) therapies in non-Hodgkin lymphoma (NHL). These CAR-Ts are patient-specific and require a complex, resource, and time-consuming process. While this appears promising, autologous CAR-Ts are limited due to the lack of accessibility, manufacturing delays, and variable product quality. To overcome these, allogeneic (allo) CARs from healthy donors appear appealing. These can be immediately available as “off the shelf” ready-to-use products of standardized and superior quality exempt from the effects of an immunosuppressive tumor microenvironment and prior treatments, and potentially with lower healthcare utilization using industrialized scale production. Allogeneic CARs, however, are not devoid of complications and require genomic editing, especially with αβ T cells to avoid graft versus host disease (GvHD) and allo-rejection by the recipient’s immune system. Tools for genomic editing such as TALEN and CRISPR provide promise to develop truly “off the shelf” universal CARs and further advance the field of cellular immunotherapy. Several allogeneic CARs are currently in early phase clinical trials, and preliminary data is encouraging. Longer follow-up is required to truly assess the feasibility and safety of these techniques in the patients. This review focuses on the strategies for developing allogeneic CARs along with cell sources and clinical experience thus far in lymphoma.

New Indications and platforms for CAR-T therapy in lymphomas beyond DLBCL

CD19 directed chimeric antigen receptor T-cell therapy (CAR-T) represents a significant advancement for patients with relapsed/refractory large B-cell lymphoma (LBCL). Long term follow-up confirms durable remissions in nearly half of the patients, a population which was previously estimated to have a median survival of around 6 months with standard salvage therapy. This initial success of CAR-T has led to significant expansion across other lymphoma histologies resulting in the recent regulatory approval of CAR-T in mantle cell lymphoma and follicular lymphoma. Additionally, multiple novel platforms of CAR-T therapy are under development to improve efficacy and limit toxicity such dual antigen targeting, allogeneic and natural killer CAR's. In this review, we focus on the new indications of CAR-T in lymphomas beyond LBCL as well as emerging platforms of CAR-T therapy.

T-cell Redirecting Therapies for the Treatment of B-cell Lymphomas: Recent Advances

Simple Summary

B-cell non-Hodgkin lymphomas (NHL) include many diseases with distincts pathogenic mechanisms, prognoses and management. Most patients benefit generally from efficient therapies allowing cure or prolonged remission. However, when they are refractory or relapse after standard therapy, they harbor a poor prognosis. In last decades, numerous novel immunotherapies have been developed with the aim of redirecting T-cell specificity against tumor antigens. Latest data on CAR T-cells confirm their efficacy and their safety in this setting. In addition, trials with bispecific antibodies are also ongoing for these patients, with encouraging premiminary findings, whether before or after CAR T-cells treatment. Here, we review the main results of CAR T-cells and bispecific T-cell engagers studies in the B-cell non-Hodgkin lymphomas setting. These advances in immunotherapies have transformed diffuse large B-cell lymphomas prognosis and will process indolent NHL’s future. Results with such treatments could lead to a new standard of care for those patients who are often heavily pretreated.

Abstract

T-cell specificity can be redirected against tumor antigens either ex vivo using engineered chimeric antigen receptor (CAR) T-cells or in vivo by bridging natural T-cells and tumor cells with bispecific T-cell engager (TCE) antibodies. Currently, four CAR T-cells have been approved by the FDA for the treatment of B-cell lymphomas, including diffuse large B cell lymphomas (DLBCL), mantle cell lymphoma (MCL), and follicular lymphoma (FL). No TCE have yet been approved for the treatment of B-cell lymphomas. However, at least four of them are in clinical development and show promising activity. Here, we review the most recent advances of CAR T-cells and TCE in the treatment of B-cell lymphomas.