Safety of AFM11 in the treatment of patients with B-cell malignancies: findings from two phase 1 studies

Bispecific and multispecific antibodies in oncology: opportunities and challenges

Research into bispecific antibodies, which are designed to simultaneously bind two antigens or epitopes, has advanced enormously over the past two decades. Owing to advances in protein engineering technologies and considerable preclinical research efforts, bispecific antibodies are constantly being developed and optimized to improve their efficacy and to mitigate toxicity. To date, >200 of these agents, the majority of which are bispecific immune cell engagers, are in either preclinical or clinical evaluation. In this Review, we discuss the role of bispecific antibodies in patients with cancer, including history and development, as well as innovative targeting strategies, clinical applications, and adverse events. We also discuss novel alternative bispecific antibody constructs, such as those targeting two antigens expressed by tumour cells or cells located in the tumour microenvironment. Finally, we consider future research directions in this rapidly evolving field, including innovative antibody engineering strategies, which might enable more effective delivery, overcome resistance, and thus optimize clinical outcomes.

New immune cell engagers for cancer immunotherapy

There have been major advances in the immunotherapy of cancer in recent years, including the development of T cell engagers - antibodies engineered to redirect T cells to recognize and kill cancer cells - for the treatment of haematological malignancies. However, the field still faces several challenges to develop agents that are consistently effective in a majority of patients and cancer types, such as optimizing drug dose, overcoming treatment resistance and improving efficacy in solid tumours. A new generation of T cell-targeted molecules was developed to tackle these issues that are potentially more effective and safer. In addition, agents designed to engage the antitumour activities of other immune cells, including natural killer cells and myeloid cells, are showing promise and have the potential to treat a broader range of cancers.

T-Cell Engagers-The Structure and Functional Principle and Application in Hematological Malignancies

Recent advancements in cancer immunotherapy have made directing the cellular immune response onto cancer cells a promising strategy for the treatment of hematological malignancies. The introduction of monoclonal antibody-based (mAbs) targeted therapy has significantly improved the prognosis for hematological patients. Facing the issues of mAb-based therapies, a novel bispecific antibody (BsAb) format was developed. T-cell engagers (TCEs) are BsAbs, which simultaneously target tumor-associated antigens on tumor cells and CD3 molecules present on T-cells. This mechanism allows for the direct activation of T-cells and their anti-tumor features, ultimately resulting in the lysis of tumor cells. In 2014, the FDA approved blinatumomab, a TCE directed to CD3 and CD19 for treatment of acute lymphoblastic leukemia. Since then, numerous TCEs have been developed, allowing for treating different hematological malignancies such as acute myeloid leukemia, multiple myeloma, and non-Hodgkin lymphoma and Hodgkin lymphoma. As of November 2023, seven clinically approved TCE therapies are on the market. TCE-based therapies still have their limitations; however, improving the properties of TCEs, as well as combining TCE-based therapies with other forms of treatment, give hope to find the cures for currently terminal diseases. In this paper, we summarized the technical basis of the TCE technology, its application in hematology, and its current issues and prospects.

Bispecific Antibodies in Hematological Malignancies: A Scoping Review

Bispecific T-cell engagers (BiTEs) and bispecific antibodies (BiAbs) have revolutionized the treatment landscape of hematological malignancies. By directing T cells towards specific tumor antigens, BiTEs and BiAbs facilitate the T-cell-mediated lysis of neoplastic cells. The success of blinatumomab, a CD19xCD3 BiTE, in acute lymphoblastic leukemia spearheaded the expansive development of BiTEs/BiAbs in the context of hematological neoplasms. Nearly a decade later, numerous BiTEs/BiAbs targeting a range of tumor-associated antigens have transpired in the treatment of multiple myeloma, non-Hodgkin's lymphoma, acute myelogenous leukemia, and acute lymphoblastic leukemia. However, despite their generally favorable safety profiles, particular toxicities such as infections, cytokine release syndrome, myelosuppression, and neurotoxicity after BiAb/BiTE therapy raise valid concerns. Moreover, target antigen loss and the immunosuppressive microenvironment of hematological neoplasms facilitate resistance towards BiTEs/BiAbs. This review aims to highlight the most recent evidence from clinical trials evaluating the safety and efficacy of BiAbs/BiTEs. Additionally, the review will provide mechanistic insights into the limitations of BiAbs whilst outlining practical applications and strategies to overcome these limitations.

Bi- and trispecific immune cell engagers for immunotherapy of hematological malignancies

Immune cell engagers are engineered antibodies with at least one arm binding a tumor-associated antigen and at least another one directed against an activating receptor in immune effector cells: CD3 for recruitment of T cells and CD16a for NK cells. The first T cell engager (the anti-CD19 blinatumomab) was approved by the FDA in 2014, but no other one hit the market until 2022. Now the field is gaining momentum, with three approvals in 2022 and 2023 (as of May): the anti-CD20 × anti-CD3 mosunetuzumab and epcoritamab and the anti-B cell maturation antigen (BCMA) × anti-CD3 teclistamab, and another three molecules in regulatory review. T cell engagers will likely revolutionize the treatment of hematological malignancies in the short term, as they are considerably more potent than conventional monoclonal antibodies recognizing the same tumor antigens. The field is thriving, with a plethora of different formats and targets, and around 100 bispecific T cell engagers more are already in clinical trials. Bispecific NK cell engagers are also in early-stage clinical studies and may offer similar efficacy with milder side effects. Trispecific antibodies (engaging either T cell or NK cell receptors) raise the game even further with a third binding moiety, which allows either the targeting of an additional tumor-associated antigen to increase specificity and avoid immune escape or the targeting of additional costimulatory receptors on the immune cell to improve its effector functions. Altogether, these engineered molecules may change the paradigm of treatment for relapsed or refractory hematological malignancies.