BL-01, an Fc-bearing, tetravalent CD20 × CD5 bispecific antibody, redirects multiple immune cells to kill tumors in vitro and in vivo

BACKGROUND AIMS

The authors describe here a novel therapeutic strategy combining a bispecific antibody (bsAb) with cytokine-induced killer (CIK) cells.

METHODS

The authors have designed, produced and purified a novel tetravalent IgG1-like CD20 × CD5 bsAb called BL-01. The bsAb is composed of a fused heavy chain and two free light chains that pair correctly to the heavy chain sequences thanks to complementary mutations in the monoclonal antibody 2 CH1/CL sequences.

RESULTS

The authors show that BL-01 can bind specifically to CD20 and CD5 with an affinity of 4-6 nM, demonstrating correct pairing of two light chains to the fused heavy chain. The CD20 × CD5 BL-01 bsAb has a functional human IgG1 Fc and can induce up to 65% complement-dependent cytotoxicity of a CD20⁺ lymphoma cell line in the presence of human complement, similar to anti-CD20 rituximab. The bsAb also induces significant natural killer cell activation and antibody-dependent cytotoxicity of up to 25% as well as up to 65% phagocytosis by human macrophages in the presence of CD20⁺ tumor cells. The BL-01 bsAb binds to CD20 and CD5 simultaneously and can redirect CIK cells in vitro to kill CD20⁺ targets, increasing the cytotoxicity of CIK cells by about 3-fold. The authors finally show that the CD20 × CD5 BL-01 bsAb synergizes with CIK cells in vivo in controlling tumor growth and prolonging survival of nonobese diabetic/severe combined immunodeficiency mice inoculated with a patient-derived, aggressive diffuse large B-cell lymphoma xenograft.

CONCLUSIONS

The authors suggest that the efficacy of bsAb in vivo is due to the combined activation of innate immunity by Fc and redirection of CIK cells to kill the tumor target.

Ofatumumab treatment for nephrotic syndrome recurrence after pediatric renal transplantation

BACKGROUND

Relapsing nephrotic syndrome (NS) after transplantation can be a challenge to treat. The result of the consequent long-lasting proteinuria is the loss of the graft. Disease recurrence after renal transplantation occurs in around half of cases, and the efficacy of therapeutic strategies is often limited. Recently, ofatumumab, a second-generation and fully human anti-CD20 monoclonal antibody, has been shown to be effective in severe situations.

METHODS

We retrospectively collected data from the medical records of children with recurrence of NS after renal transplantation treated with ofatumumab in France, after failure of previous treatments.

RESULTS

Six patients were included in this study in five centers with a median duration of follow-up of 10.5 months. Two different ofatumumab regimens were administered. The primary outcome was proteinuria at 6 months after the last dose of ofatumumab. No patient achieved a complete remission, 3/6 had a partial remission, and 3/6 had no response to ofatumumab. Four patients exhibited a minor allergic reaction with the first infusion. One patient died of infection, as a consequence of multiple factors. No malignancies were observed; however, the time of follow-up was not sufficient to see such disease.

CONCLUSIONS

Altogether, these results suggest ofatumumab has a poor efficacy in treating recurrence of NS after renal transplantation. However, it could be discussed in multidrug-resistant refractory NS, but infectious complications and overimmunosuppression have to be balanced. There is a need for further studies to confirm these findings and safety and to determine a standardized protocol in this indication.

Clinical application of obinutuzumab for treating chronic lymphocytic leukemia

Alkylators and nucleoside analogs were the main drugs for treatingchronic lymphoblastic leukemia (CLL), which have been replaced by monoclonal antibodies, such as rituximab in the past 10 years for refractory or relapsed CLL. The first-line immunochemotherapy regimen, rituximab combined with nucleoside analogs, significantly increased CLL patients’ first-reaction rate and improved progression-free survival. Despite the long-lasting remissions by the use of chemoimmunotherapy, most CLL patients will relapse eventually. The obinutuzumab (GA101), an updated CD20 antibody, that is thought to achieve a more durable response with unique molecular and functional characteristics. Obinutuzumab is a humanized, monoclonal type II CD20 antibody modified by glycoengineering. The glycoengineered Fc portion enhances the binding affinity to the FcγRIII receptor on immune effector cells, resulting in increased antibody-dependent cellular cytotoxicity and phagocytosis. In addition, the type II antibody binding characteristics of obinutuzumab to CD20 lead to an efficient induction of direct non-apoptotic cell death. This review summarizes the results of clinical studies using obinutuzumab and looks forward to its further application in treating CLL clinically.

The role of obinutuzumab in the management of follicular lymphoma

The outcomes for follicular lymphoma (FL) have improved significantly in recent years. This has been driven by an improved understanding of the pathobiology of FL and the development of therapeutic anti-CD20 antibodies. Combining rituximab with chemotherapy, coupled with its use as maintenance therapy, has contributed to significant improvements in disease control and progression-free survival. However, FL remains incurable and almost all patients invariably relapse. Therefore, there remains a need to develop novel therapeutic options and optimize existing regimens. Obinutuzumab (a first-in-class, glycoengineered, humanized type 2 anti-CD20 antibody) has been evaluated in a number of clinical trials. In this review, we will summarize the evaluable results of clinical trials investigating the efficacy of obinutuzumab in the treatment of FL.

Targeted Drugs as Maintenance Therapy after Autologous Stem Cell Transplantation in Patients with Mantle Cell Lymphoma

The treatment landscape for mantle cell lymphoma (MCL) is rapidly evolving toward the incorporation of novel and biologically targeted pharmaceuticals with improved disease activity and gentler toxicity profiles compared with conventional chemotherapeutics. Upfront intensive treatment of MCL includes autologous stem cell transplantation (SCT) consolidation aimed at deepening and lengthening disease remission, but subsequent relapse occurs. Maintenance therapy after autologous SCT in patients with MCL in remission features lower-intensity treatments given over extended periods to improve disease outcomes. Targeted drugs are a natural fit for this space, and are the focus of considerable clinical investigation. This review summarizes recent advances in the field and their potential impact on treatment practices for MCL.

Obinutuzumab in chronic lymphocytic leukemia: design, development and place in therapy

For decades, treatment of chronic lymphocytic leukemia (CLL) has been based on chemotherapy. This changed when the first CD20 antibody rituximab was introduced. Since 2008, the combination of chemotherapy and CD20 antibodies has become the standard of care for most patients, and a significant fraction of patients had very long-lasting remissions after chemoimmunotherapy. Despite the improvement of response rates and overall survival (OS) by the use of chemoimmunotherapy, most CLL patients will relapse eventually. One approach to achieve more durable responses was the development of obinutuzumab (GA101), a new type of CD20 antibody that has unique molecular and functional characteristics. Obinutuzumab is a type II fully humanized CD20 antibody that binds to a partly different epitope of the CD20 protein than rituximab and due to its glycoengineered design induces greater antibody-dependent cell-mediated cytotoxicity (ADCC). Initial preclinical observations of a more effective B-cell depletion have been successfully reproduced in clinical trials with CLL patients. This review summarizes results of preclinical as well as clinical studies with obinutuzumab and provides an outlook on its future role in the therapy of CLL.

Chronic lymphocytic leukemia (CLL)-Then and now

The field of chronic lymphocytic leukemia (CLL) has witnessed considerable change since the time clinical staging was introduced in clinical practice in 1975. Over the years, the prognostication in CLL has expanded with the addition in late 90s of mutational status of variable region of immunoglobulin heavy chain (IGHV), and chromosomal analyses using fluorescent in situ hybridization (FISH). More recently, stereotypy of BCR (B cell receptor) and whole exome sequencing (WES) based discovery of specific mutations such as NOTCH1, TP53, SF3B1, XPO-1, BIRC3, ATM, and RPS15 further refined the current prognostication system in CLL. In therapy, the field of CLL has seen major changes from oral chlorambucil and steroids prior to 1980s, to chemo-immunotherapy (CIT) with fludarabine, cyclophosphamide, rituximab (FCR) to the orally administered targeted therapeutic agents inhibiting kinases in the B cell receptor (BCR) signaling pathway such as Ibrutinib (BTK inhibitor) and Idelalisib (p110 PI3Kδ inhibitor) and novel anti-CD20 mAb's (monoclonal antibodies) such as obinutuzumab. This progress is continuing and other targeted therapeutics such as Bcl2 antagonists (Venetoclax or ABT-199) and finally chimeric antigen receptor against T cells (CART) are in the process of being developed. This review is an attempt to summarize the major benchmarks in the prognostication and in the therapy of CLL. The topic allocated to us by Dr Ayalew Tefferi and Dr Carlo Brugnara is very appropriate to reminisce what our understanding of chronic lymphocytic leukemia (CLL) was in 1976 and how rapidly have the advances occurring in this field affected the patients with CLL.

Idelalisib for the treatment of non-Hodgkin lymphoma

INTRODUCTION

B-cell Non-Hodgkin lymphomas (B-NHLs) include a number of disease subtypes, each defined by the tempo of disease progression and the identity of the cancerous cell. Idelalisib is a potent, selective inhibitor of the delta isoform of phosphatidylinositol-3-kinase (PI3K), a lipid kinase whose over-activity in B-NHL drives disease progression. Idelalisib has demonstrated activity in indolent B-NHL (iB-NHL) and is approved for use as monotherapy in patients with follicular lymphoma and small lymphocytic lymphoma and in combination with rituximab in patients with chronic lymphocytic leukemia.

AREAS COVERED

Herein we review the development and pharmacology of idelalisib, its safety and efficacy in clinical studies of iB-NHL, and its potential for inclusion in future applications in iB-NHL and in combination with other therapies.

EXPERT OPINION

Idelalisib adds to the growing arsenal of iB-NHL pharmacotherapeutics and to the progression of the field toward precision agents with good efficacy and reduced toxicities. Nevertheless, idelalisib carries important risks that require careful patient counseling and monitoring. The appropriate sequencing of idelalisib with other proven treatment options in addition to its potential for combination with established or novel drugs will be borne out in ongoing and planned investigations.