Janice Reichert, Author at The Antibody Society

Using bispecific antibodies for T-cell recruitment

June 13, 2016 by Janice Reichert

Post written by Whitney Shatz

T-cell recruitment for the treatment of cancer has garnered substantial interest over the past thirty years [1,2]. In this type of therapy, activated tumor-specific cytotoxic T-cell lymphocytes are directed to malignant tumor, and subsequently destroy them. Activation of this mechanism relies on T cells and tumor cells being in close proximity to one another. One popular strategy for bringing the cells together involves use of a bispecific antibody [3] where the dual-antigen specificity can enable simultaneous binding of a tumor-specific antigen along with an antigen present on a cytotoxic T-cell. In addition to having the advantage of enhanced functionality compared to a monospecific antibody, garnering dual specificity from single-agent therapy can simplify the development process, e.g., only one molecule needs to be approved. Two bispecific antibodies that take advantage of this principle have been approved: catumaxomab (Removab®) for the treatment of malignant ascites secondary to epithelial cancers and blinatumomab (Blincyto®) as second-line treatment for B cell acute lymphocytic leukemia (ALL).

Catumaxomab is a monoclonal IgG-like antibody [4]. It is termed trifunctional because one of the Fab arms binds epithelial tumor cells via the epithelial cell-adhesion molecule (EpCAM) antigen site, the other Fab arm binds cytotoxic T cells via the CD3 receptor, while the Fc acts as the third site of action, selectively engaging Fcγ receptor I-, IIa- or III on accessary cells. Thusly in this strategy, tumor cell destruction relies not only on T-cell lysis, but also on T-cell activation of accessory cells such as macrophages, dendritic cells and natural killer cells, which engage in destruction of tumor cells by various mechanisms such as perforin-mediated lysis, antibody-mediated phagocytosis and cytokine release. In 2009, catumaxomab became the first bispecific antibody to be approved, for use in Europe [4].

Blinatumomab, in contrast, is a bispecific T cell engager (BiTE) [5]. It is composed of two tandem single-chain variable fragments, each with unique specificity, fused together by a short flexible linker. One arm of this bispecific molecule binds CD3 on T cells while the other arm binds CD19, an antigen found on almost all B-lineage ALL cells and in many places throughout B cell differentiation. Bridging of the two antigens enables T-cell activation and exertion of cytotoxic activity by lysis of target B cells. Two advantages of this bispecific molecule are its small size, which results in fast systemic clearance and ensures close proximity of T cells to target cell, and its flexibility, which is thought to lead to efficient induction of T-cell activation by enabling optimal interaction with target epitopes on the two opposing cell membranes. In some cases, bifunctionality is preferred over trifunctionality because of concern that the Fc receptor interactions could potentially lead to dampening of the immune response. In 2014, blinatumomab became the first bispecific antibody approved for use in the United States. It is currently being evaluated in Phase 2 clinical trials for the treatment of other ALL-related diseases [6].

Nonetheless despite very encouraging preclinical results [7-9] and extensive clinical activities [10-13], additional successful outcomes in the clinic have not been forthcoming. Of the twenty novel bispecific antibodies that entered first-in-humans clinical studies in 2014-2015, approximately half invoke a T-cell recruiting mechanism. Despite this abundance, none of these have advanced beyond Phase 1. Thus far, toxicity and lack of significant anti-tumor response appear to be the primary barriers to advancement of these agents. Improving the selectivity of T-cell activation is being examined as a way to address toxicity issues. To increase the effectiveness of the agents, alternate dose administration strategies are being tested. For example, blinatumomab’s dosing was changed to continuous infusion instead of intravenous injection to ensure continuous activation of T cells against target cells [14]. In addition, use of T-cell recruiting bispecific antibodies as first in-line treatment or as a component of combination therapies are also being evaluated to determine whether significant gains in patient response can be achieved. If such gains can be achieved with these approaches, more T-cell activating bispecific antibodies that will successfully meet patient needs may be available in the future.

1. Staerz UD, Kanagawa O, Bevan M. Hybrid antibodies can target sites for attack by T cells. Nature 1985; 314:628–31.

2. Perez P, Hoffman RW, Shaw S, Bluestone JA, Segal DM. Specific targeting of cytotoxic T cells by anti-T3 linked to anti-target cell antibody. Nature 1985; 316:354–6.

3. Weidle UH, Kontermann RE, Brinkmann U. Tumor-antigen–binding bispecific antibodies for cancer treatment. Seminars in Oncology 2014; 41:653–60.

4. Linke R, Klein A, Seimetz D. Catumaxomab: Clinical development and future directions. mAbs 2014; 2:129–36.

5. Wolf E, Hofmeister R, Kufer P, Schlereth B, Baeuerle PA. BiTEs: bispecific antibody constructs with unique anti-tumor activity. Drug Discovery Today 2005; 10:1237–44.

6. Turner J, Schneider S. Blinatumomab: A new treatment for adults with relapsed acute lymphocytic leukemia. Clin J Oncol Nurs. 2016; 20:165–8.

7. Deo YM, Sundarapandiyan K, Keler T, Wallace PK, Graziano RF. Bispecific molecules directed to the Fc receptor for IgA (FcαRI, CD89) and tumor antigens efficiently promote cell-mediated cytotoxicity of tumor targets in whole blood. J Immunol 1998; 160:1677–86.

8. Löffler A, Kufer P, Lutterbüse R, Zettl F, Daniel PT, Schwenkenbecher JM, Riethmüller G, Dörken B, Bargou RC. A recombinant bispecific single-chain antibody, CD19 x CD3, induces rapid and high lymphoma-directed cytotoxicity by unstimulated T lymphocytes. Blood 2000; 95:2098–103.

9. Heiss MM, Ströhlein MA, Jäger M, Kimmig R, Burges A, Schoberth A, Jauch K-W, Schildberg F-W, Lindhofer H. Immunotherapy of malignant ascites with trifunctional antibodies. Int J Cancer 2005; 117:435–43.

10. Begent RH, Verhaar MJ, Chester KA, Casey JL, Green AJ, Napier MP, Hope-Stone LD, Cushen N, Keep PA, Johnson CJ, et al. Clinical evidence of efficient tumor targeting based on single-chain Fv antibody selected from a combinatorial library. Nat Med 1996; 2:979–84.

11. Burges A, Wimberger P, Kümper C, Gorbounova V. Effective relief of malignant ascites in patients with advanced ovarian cancer by a trifunctional anti-EpCAM× anti-CD3 antibody: a phase I/II study. Clin Cancer Res. 2007; 13:3899-905.

12. De Gast GC, Van Houten AA, Haagen IA, Klein S, De Weger RA, Van Dijk A, Phillips J, Clark M, Bast BJ. Clinical experience with CD3 X CD19 bispecific antibodies in patients with B cell malignancies. J Hematother. 1995;4:433-7.

13. Heiss MM, Murawa P, Koralewski P, Kutarska E, Kolesnik OO, Ivanchenko VV, Dudnichenko AS, Aleknaviciene B, Razbadauskas A, Gore M, et al. The trifunctional antibody catumaxomab for the treatment of malignant ascites due to epithelial cancer: Results of a prospective randomized phase II/III trial. Int J Cancer 2010; 127:2209–21.

14. Klinger M, Brandl C, Zugmaier G, Hijazi Y, Bargou RC, Topp MS, Gökbuget N, Neumann S, Goebeler M, Viardot A, et al. Immunopharmacologic response of patients with B-lineage acute lymphoblastic leukemia to continuous infusion of T cell–engaging CD19/CD3-bispecific BiTE antibody blinatumomab. Blood 2012; 119:6226–33.

European Medicines Agency’s antibody PRIority MEdicines

June 6, 2016 by Janice Reichert

On June 1, the European Medicines Agency (EMA) announced that four medicines in development were accepted under their new PRIority MEdicines (PRIME) scheme, which focuses on medicines that may offer a major therapeutic advantage over existing treatments, or benefit patients without treatment options. In this voluntary scheme, EMA offers early, proactive and enhanced support to developers to optimize the generation of robust data on a medicine’s benefits and risks, and enable accelerated assessment of medicine applications. Early clinical data that shows a medicine has the potential to benefit patients with unmet medical needs must be provided for it to be accepted for PRIME access.

Of the four medicines given PRIME access to date, two, aducanumab and NI-0501, are antibody therapeutics. Aducanumab, which targets amyloid beta, has PRIME access as a treatment of Alzheimer’s disease. The antibody is currently being evaluated in two Phase 3 studies of patients with early Alzheimer’s disease. The primary objective of the studies is to evaluate the efficacy of monthly doses of aducanumab in slowing cognitive and functional impairment. An estimated 1350 patients will be enrolled in each study. Both studies were initiated in 2015, and have primary completion dates in February 2020.

NI-0501, a human mAb targeting interferon gamma, has PRIME access as a treatment of primary hemophagocytic lymphohistiocytosis (PHL). A Phase 2, open-label, single arm study to explore the safety, tolerability, pharmacokinetics and efficacy of intravenous multiple administrations of NI-0501 in children with PHL is currently recruiting patients. The study was initiated in 2013 and has an estimated enrollment of 10 patients. The primary completion date of the study is December 2016. NI-0501 has orphan drug designations in the European Union and United States. It also has the US Food and Drug Administration’s Breakthrough Therapy Designation, which, like the PRIME scheme, is intended to expedite the development and review of new therapies for serious or life threatening conditions that have shown encouraging early clinical results over available therapies.

Find information about the four medicines accepted under the PRIME scheme here.

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New antibody therapeutics for multiple sclerosis

June 3, 2016 by Janice Reichert

On May 27, 2016 the Food and Drug Administration (FDA) approved daclizumab (Zinbryta®) for the treatment of adults with relapsing forms of multiple sclerosis (MS). The product, which targets interleukin-2 receptor alpha chain (CD25), is manufactured using a high-yield process. Daclizumab (Zenapax®) was first approved in 1997 for the prevention of organ transplant rejection. While the two products have the same amino acid sequence, Zinbryta has a different glycosylation pattern and reduced antibody-dependent cytotoxicity compared to Zenapax. Zinbryta’s approval was based in part on the results of the Phase 3 DECIDE study (NCT01064401) of Zinbryta versus interferon β 1a (Avonex®) in patients with relapsing-remitting MS. In this study, patients administered Zinbryta experienced fewer clinical relapses than those who received Avonex (annualized relapse rate 0.22 vs. 0.39; 45% lower rate with Zinbryta; P<0.001). Due to serious safety risks, FDA has included a boxed warning on the product label, and it is available only through a restricted distribution program under a Risk Evaluation and Mitigation Strategy.

Another antibody therapeutic, ocrelizumab, has been evaluated in a Phase 3 study of patients with primary progressive multiple sclerosis (PPMS). The antibody targets CD20 on B cells, which are implicated in the inflammatory and neurodegenerative processes of MS. Ocrelizumab was granted FDA’s Breakthrough Therapy Designation for PPMS, which is a debilitating form of MS characterized by steadily worsening symptoms. PPMS patients typically do not experience distinct relapses or periods of remission. Currently, no treatments are approved for treatment of the disease. In the pivotal Phase 3 ORATORIO study, treatment with ocrelizumab significantly reduced disability progression and other markers of disease activity compared with placebo. Ocrelizumab is also undergoing evaluation in Phase 3 studies of patients with relapsing-remitting forms of the disease. Genentech plans to submit a marketing application for ocrelizumab as a treatment for MS in 2016. If an application is submitted to FDA by the end of June and receives a priority review, which is a benefit of the Breakthrough Therapy Designation, then ocrelizumab could be approved for marketing in the US by the end of 2016.

Atezolizumab: 4th mAb granted a first approval in 2016

May 23, 2016 by Janice Reichert

On May 18, 2016, anti-PD-L1 atezolizumab (Tecentriq®) was approved by the Food and Drug Administration (FDA) as a treatment for patients with locally advanced or metastatic urothelial carcinoma. The marketing application for atezolizumab had received breakthrough therapy designation, priority review status and accelerated approval for this indication. A PD-L1 (SP142) assay complementary diagnostic to detect PD-L1 protein expression levels on the tumor-infiltrating immune cells of patients was also approved. An FDA action on a second application for use of atezolizumab as a treatment for patients with non-small cell lung cancer is expected by October 2016. Atezolizumab is the fourth antibody that inhibits an immune checkpoint to be granted a marketing approval. Two anti-PD1 antibodies, nivolumab (Opdivo®) and pembrolizumab (Keytruda®), were approved in 2014 in the US (2015 in the EU), and one anti-CTLA4 antibody, ipilimumab (Yervoy®), was approved in the US and EU in 2011. Atezolizumab is the fourth antibody product to be granted a first marketing approval in 2016.

Six additional antibody therapeutics (bezlotoxumab, sarilumab, brodalumab, Xilonix, begelomab, olaratumab) are now undergoing their first regulatory review in the European Union and the United States. If these antibodies are approved by the end of the year, the number of first approvals for antibody products in 2016 will set a new record (10 products), exceeding by 1 the previous record set in 2015. The Antibody Society maintains a comprehensive table of approved antibody therapeutics and those in regulatory review in the European Union and the Unites States. The antibody’s target, format and year of first approval are included. Please log in to access the table, located in the Members Only section.

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Antibody immune checkpoint modulators in the clinic

May 5, 2016 by Janice Reichert

The possibility of using antibody therapeutics to modulate immune checkpoint pathways has captured the attention of many organizations involved in the research and development of cancer drugs. As of early May 2016, three antibody checkpoint inhibitors (ipilimumab / Yervoy®, pembrolizumab / Keytruda® and nivolumab / Opdivo®) have been approved for marketing, and one (atezolizumab) is undergoing regulatory review. In 2011, ipilimumab, which targets CTLA-4, became the first antibody of this class to be approved. Pembrolizumab and nivolumab, which target PD1, were subsequently granted first approvals in 2014. These drugs are currently marketed as treatments for melanoma and non-small cell lung cancer (NSCLC), but they have also undergone evaluation as treatments for other cancers, e.g., head and neck squamous cell carcinoma. A marketing application for the use of anti-PD-L1 atezolizumab as a treatment for urothelial carcinoma is undergoing a priority review by the Food and Drug Administration (FDA), and a regulatory action is expected in September 2016. An FDA action on a second application for use of atezolizumab as a treatment for NSCLC is expected in October 2016.

The biology of immune checkpoint pathways is complicated, and the use of antibodies to modulate numerous immune checkpoint targets is being explored. At least 45 antibody checkpoint modulators are currently undergoing evaluation in clinical studies of patients with a variety of cancers. In addition to CTLA-4, PD1 and PD-L1, other targets for antibodies in the clinic include B7-H3, CD70, CD40, CD137, GITR, OX40, KIR, LAG-3 and TIM3. Antibodies that modulate immune checkpoints are now ~16% of the entire clinical pipeline of antibodies for cancer, but most (~80%) are in early stage (i.e., Phase 1 or 1/2) clinical studies. First-in-human studies for over 20 antibody checkpoint modulators were initiated in 2015, and given the intense interest in the topic, many more are expected to enter clinical studies in the near future. Much work remains to be done, however, to demonstrate the relevance of some targets, and to determine suitable treatment regimens, especially when the antibody is administered as part of combination therapy. If the potential of this class of molecules is realized, unmet medical need could be reduced, and patients’ choice of antibody therapeutics could substantially increase, in the next 5-10 years.

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