Targeting CD20: teaching an old dog new tricks

Monoclonal antibodies used for the management of haematological disorders

INTRODUCTION

Monoclonal antibodies Ab (MoAb) are increasingly becoming part of therapeutic armamentarium for haematologists and haemato-oncologists. This review brings together commonly used antibodies in one place for brevity and novel understanding.

AREAS COVERED

Pubmed and Scopus databases were explored focusing on MoAb in clinical haematological practice. Emphasis was given to current review articles. The data base was searched from 1997 till present. 24 different antibodies, most of which are in use were discussed. Antibodies are used for diverse conditions i.e. malignant and benign haematological conditions, treatment at various phases of stem cell transplantation. These antibodies were used both alone or in combination with various chemotherapy, targeted small molecules or as immunoconjugates. Some of the side effect profiles of these antibodies were common and some were unique. Unusual infections or organ dysfunctions were noted. Improved function of antibodies by protein engineering is also advancing rapidly. Dosage, frequency and route of administration depended on the convenience and condition for which the antibody is used.

EXPERT OPINION

: MoAbs are increasingly used in haematology practice either alone or in combination with other types of therapy for improved out come in various haematological conditions.

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.

Targeting Bruton's Tyrosine Kinase in CLL

Targeting the B-cell receptor signaling pathway through BTK inhibition proved to be effective for the treatment of chronic lymphocytic leukemia (CLL) and other B-cell lymphomas. Covalent BTK inhibitors (BTKis) led to an unprecedented improvement in outcome in CLL, in particular for high-risk subgroups with TP53 aberration and unmutated immunoglobulin heavy-chain variable-region gene (IGHV). Ibrutinib and acalabrutinib are approved by the US Food and Drug Administration for the treatment of CLL and other B-cell lymphomas, and zanubrutinib, for patients with mantle cell lymphoma. Distinct target selectivity of individual BTKis confer differences in target-mediated as well as off-target adverse effects. Disease progression on covalent BTKis, driven by histologic transformation or selective expansion of BTK and PLCG2 mutated CLL clones, remains a major challenge in the field. Fixed duration combination regimens and reversible BTKis with non-covalent binding chemistry hold promise for the prevention and treatment of BTKi-resistant disease.

Indolent lymphomas: pushing the pace with novel agents

Chemoimmunotherapy has been a hallmark of treatment of indolent B-cell non-Hodgkin lymphomas for the past 2 decades, with high response rates seen but relapses nearly inevitable and patients spending, on average, 20 years on and off treatment. Treatment advances, then, should be aimed at maintaining efficacy while minimizing toxicity or at achieving cure. Improved understanding of the genetic and molecular features of these diseases, as well as of the interaction between the tumor cell and its immune microenvironment, has resulted in an accelerated expansion of tolerable treatment options for patients, with new combinations of therapy holding promise that definitive therapy in these diseases is possible. These drugs include immunomodulating agents such as lenalidomide, small-molecule inhibitors of the B-cell receptor signaling pathway such as ibrutinib and idelalisib, B-cell lymphoma 2 homology 3 mimetics such as venetoclax, and enhancer of zeste homolog 2 inhibitors such as tazemetostat. Therapies that improve the host immune response against the malignant B cell are also of great interest, given the durable remission seen after allogeneic stem cell transplant in these diseases, and immune checkpoint inhibitors, agonist antibodies against immunostimulatory T-cell receptors, antibody-drug conjugates, bispecific antibodies, and finally chimeric antigen receptor T cells are all being investigated, with promising early efficacy signals. These treatments may not necessarily replace chemotherapy but rather augment it in an attempt to improve quality of life and survival for these patients.