A phase I study of escalated dose subcutaneous alemtuzumab given weekly with rituximab in relapsed chronic lymphocytic leukemia/small lymphocytic lymphoma

Identification of Peptide Mimotope Ligands for Natalizumab

Mimotope peptides selected from combinatorial peptide libraries can be used as capture reagents for immunoassay detection of therapeutic monoclonal antibodies (mAbs). We report the use of phage display libraries to identify peptide ligands (Veritopes^TM) that bind natalizumab, a therapeutic mAb indicated for use in multiple sclerosis. PKNPSKF is identified as a novel natalizumab-binding motif, and peptides containing this motif demonstrated utility as capture reagents in enzyme-linked immunosorbent assays (ELISAs). A peptide containing the identified motif was shown to be competitive with the natural ligand (α4-integrin) and a neutralizing anti-idiotype antibody for natalizumab binding, indicating that Veritopes^TM act as surrogate ligands that bind the antigen binding site of natalizumab. Affinity maturation further confirmed the motif sequence and yielded peptides with greater apparent affinity by ELISA. Veritopes^TM are promising assay reagents for therapeutic drug level monitoring.

Individualized Dosing of Therapeutic Monoclonal Antibodies-a Changing Treatment Paradigm?

The introduction of monoclonal antibodies (mAbs) to the treatment of inflammatory bowel disease (IBD) was an important medical milestone. MAbs have been demonstrated as safe and efficacious treatments of IBD. However, a large percentage of patients either fail to respond initially or lose response to therapy after a period of treatment. Although there are factors associated with poor treatment outcomes in IBD, one cause for treatment failure may be low mAb exposure. Consequently, gastroenterologists have begun using therapeutic drug monitoring (TDM) to guide dose adjustment. However, while beneficial, TDM does not provide sufficient information to effectively adjust doses. The pharmacokinetics (PK) and pharmacodynamics (PD) of mAbs are complex, with numerous factors impacting on mAb PK and PD. The concept of dashboard-guided dosing based on Bayesian PK models allows physicians to combine TDM with factors influencing mAb PK to individualize therapy more effectively. One issue with TDM has been the slow turnaround of assay results, either necessitating an additional clinic visit for a sample or reacting to TDM results at a subsequent, rather than the current, dose. New point-of-care (POC) assays for mAbs are being developed that would potentially allow physicians to determine drug concentration quickly. However, work remains to understand how to determine what target exposure is needed for an individual patient, and whether the combination of POC assays and dashboards presents a safe approach with substantial outcome benefit over the current standard of care.

Venetoclax in Patients with Previously Treated Chronic Lymphocytic Leukemia

Venetoclax is the first BCL2 inhibitor to enter routine clinical practice. It is an orally bioavailable small molecule that binds BCL2 very specifically. Acting as a pharmacologic mimic of the proteins that initiate apoptosis (a so-called BH3 mimetic), venetoclax rapidly induces apoptosis in chronic lymphocytic leukemia (CLL) cells, which express high levels of BCL2 and rely on it to maintain their survival. As a single agent, daily venetoclax treatment induced durable responses in 79% of patients with relapsed or refractory CLL or small lymphocytic lymphoma in a phase I study, including complete remissions in 20% of patients. Its use was approved by the FDA in April 2016 for patients with previously treated del(17p) CLL on the basis of a single-arm phase II trial demonstrating a 79% response rate and an estimated 1-year progression-free survival of 72% with 400 mg/day continuous therapy. This review focuses on venetoclax, its mechanism of action, pharmacology, and clinical trial data and seeks to place it in the context of rapid advances in therapy for patients with relapsed CLL, especially those with del(17p) CLL. Clin Cancer Res; 23(16); 4527-33. ©2017 AACR.

The use of combinations of monoclonal antibodies in clinical oncology

Treatment with monoclonal antibodies is becoming increasingly important in clinical oncology. These antibodies specifically inhibit signaling pathways in tumor growth and/or induce immunological responses against tumor cells. By combining monoclonal antibodies several pathways may be targeted simultaneously, potentially leading to additive or synergistic effects. Theoretically, antibodies are very suitable for use in combination therapy, because of limited overlapping toxicity and lack of pharmacokinetic interactions. In this article an overview is given of preclinical and clinical data on twenty-five different combinations of antibodies in oncology. Some of these combinations have proven clinical benefit, for example the combination of trastuzumab and pertuzumab in HER2-positive breast cancer, which exemplifies an additive or synergistic effect on antitumor activity in clinical studies and the combination of nivolumab and ipilimumab, which results in significant increases in progression-free and overall survival in patients with advanced melanoma. However, other combinations may lead to unfavorable results, such as bevacizumab with cetuximab or panitumumab in advanced colorectal cancer. These combinations result in shorter progression-free survival and increased toxicity compared to therapy with a single antibody. In summary, the different published studies showed widely varying results, depending on the combination of antibodies, indication and patient population. More preclinical and clinical studies are necessary to unravel the mechanisms behind synergistic or antagonistic effects of combining monoclonal antibodies. Most research on combination therapies is still in an early stage, but it is expected that for several tumor types the use of combination therapy of antibodies will become standard of care in the near future.

Transplantation in chronic lymphocytic leukemia: does it still matter in the era of novel targeted therapies?

Allogeneic stem cell transplantation (HSCT) offers the only potentially curative approach in chronic lymphocytic leukemia (CLL). However, this applies only to a minority of patients, and is associated with significant treatment-related mortality and morbidity. HSCT must therefore always be considered in view of other, potentially less toxic therapies. Several new agents demonstrate impressive and durable responses in high-risk patients who might be candidates for HSCT. Therefore the choice of HSCT versus a novel agent is one that must be gauged on a patient-by-patient basis; this will change as data mature on the use of these novel agents in CLL.

New antibody approaches to lymphoma therapy

The CD20-directed monoclonal antibody rituximab established a new era in lymphoma therapy. Since then other epitopes on the lymphoma surface have been identified as potential targets for monoclonal antibodies (mAb). While most mAbs eliminate lymphoma cells mainly by antibody-dependent cellular cytotoxicity, complement-dependent cytotoxicity or direct cell death, others counter mechanisms utilized by malignant cells to evade immune surveillance. Expression of PD-L1 on malignant or stromal cells in the tumor environment for example leads to T-cell anergy. Targeting either PD-1 or PD-L1 via mAbs can indirectly eliminate cancer cells by unblocking the host intrinsic immune response. Yet another mechanism of targeted therapy with mAbs are bi-specific T-cell engagers (BiTE) such as blinatumomab, which directly engages the host immune cells. These examples highlight the broad spectrum of available therapies targeting the lymphoma surface with mAbs utilizing both passive and active immune pathways. Many of these agents have already demonstrated significant activity in clinical trials. In this review we will focus on novel CD20-directed antibodies as well as mAbs directed against newer targets like CD19, CD22, CD40, CD52 and CCR4. In addition we will review mAbs unblocking immune checkpoints and the BiTE blinatumomab. Given the success of mAbs and the expansion in active and passive immunotherapies, these agents will play an increasing role in the treatment of lymphomas.

Alemtuzumab use in relapsed and refractory chronic lymphocytic leukemia: a history and discussion of future rational use

In this review, we outline the clinical experience with single-agent alemtuzumab as a treatment for relapsed and refractory chronic lymphocytic leukemia (CLL) in both prospective and retrospective trials and describe the multiagent use of the drug with the goal of updating clinicians on recent developments and possible future rational combinations. Alemtuzumab, an antibody targeting the lymphocyte-specific surface marker CD52, is an approved agent for the treatment of CLL. Despite its demonstrated efficacy, likely secondary to concerns regarding infectious complications, it is most commonly used in the relapsed and refractory setting. Given alemtuzumab's unique mechanism of action it has been demonstrated to have activity in disease that is refractory to both alkylating agents and purine analogs. Furthermore, it has activity in TP53-mutated disease, which has the worst prognosis of any subset of CLL. Alemtuzumab has greater efficacy on circulating disease relative to nodal disease. Rational combinations are attempting to use these attributes to increase response rates in patients with relapsed and refractory disease.