mAbs

The twenty two monoclonal antibodies (mAbs) currently marketed in the U.S. have captured almost half of the top-20 U.S. therapeutic biotechnology sales for 2007. Eight of these products have annual sales each of more than $1 B, were developed in the relatively short average period of six years, qualified for FDA programs designed to accelerate drug approval, and their cost has been reimbursed liberally by payers. With growth of the product class driven primarily by advancements in protein engineering and the low probability of generic threats, mAbs are now the largest class of biological therapies under development. The high cost of these drugs and the lack of generic competition conflict with a financially stressed health system, setting reimbursement by payers as the major limiting factor to growth. Advances in mAb engineering are likely to result in more effective mAb drugs and an expansion of the therapeutic indications covered by the class. The parallel development of biomarkers for identifying the patient subpopulations most likely to respond to treatment may lead to a more cost-effective use of these drugs. To achieve the success of the current top-tier mAbs, companies developing new mAb products must adapt to a significantly more challenging commercial environment.     

New challenges to medicare beneficiary access to mAbs

Precision binding of monoclonal antibodies (mAbs) to biological targets, their relative clinical success, and expansion of indications following initial approval, are distinctive clinical features. The relatively high cost of mAbs, together with the absence of a regulatory pathway to generics, stand out as distinctive economic features. Based on both literature review and primary data collection we enumerated mAb original approvals, supplemental indications and off-label uses, assessed payer formulary management of mAbs, and determined new challenges to Medicare beneficiary access to mAbs. We found that the FDA has approved 22 mAbs and 30 supplemental indications pertaining to the originally approved mAbs. In addition, there are 46 off-label use citations in officially recognized pharmaceutical compendia. Across Part B carriers and Part D plans, we found considerable variation in terms of coverage and conditions of reimbursement related to on- and off-label uses of mAbs. Our results point to four major challenges facing mAb developers, health care providers, Medicare beneficiaries, payers and policymakers. These include administrative price controls, coverage variation, projected shift from physician- to self-administered mAbs, and comparative effectiveness. We suggest more systematic use of “coverage with evidence development” as a means of optimally addressing these challenges.Key words: mAbs, medicare, formulary management, comparative effectiveness, off-label, reimbursement     

New challenges to medicare beneficiary access to mAbs

Precision binding of monoclonal antibodies (mAbs) to biological targets, their relative clinical success, and expansion of indications following initial approval, are distinctive clinical features. The relatively high cost of mAbs, together with the absence of a regulatory pathway to generics, stand out as distinctive economic features. Based on both literature review and primary data collection we enumerated mAb original approvals, supplemental indications, and off-label uses, assessed payer formulary management of mAbs, and determined new challenges to Medicare beneficiary access to mAbs. We found that the FDA has approved 22 mAbs and 30 supplemental indications pertaining to the originally approved mAbs. In addition, there are 46 off-label use citations in officially recognized pharmaceutical compendia. Across Part B carriers and Part D plans, we found considerable variation in terms of coverage and conditions of reimbursement related to on- and off-label uses of mAbs. Our results point to four major challenges facing mAb developers, health care providers, Medicare beneficiaries, payers, and policymakers. These include administrative price controls, coverage variation, projected shift from physician- to self-administered mAbs, and comparative effectiveness. We suggest more systematic use of “coverage with evidence development” as a means of optimally addressing these challenges.     

Arming antibodies: prospects and challenges for immunoconjugates

Immunoconjugates--monoclonal antibodies (mAbs) coupled to highly toxic agents, including radioisotopes and toxic drugs (ineffective when administered systemically alone)--are becoming a significant component of anticancer treatments. By combining the exquisite targeting specificity of mAbs with the enhanced tumor-killing power of toxic effector molecules, immunoconjugates permit sensitive discrimination between target and normal tissue, resulting in fewer toxic side effects than most conventional chemotherapeutic drugs. Two radioimmunoconjugates, ibritumomab tiuxetan (Zevalin) and tositumomab-131I (Bexxar), and one drug conjugate, gemtuzumab ozogamicin (Mylotarg), are now on the market. For the next generation of immunoconjugates, advances in protein engineering will permit greater control of mAb targeting, clearance and pharmacokinetics, resulting in significantly improved delivery to tumors of radioisotopes and potent anticancer drugs. Pre-targeting strategies, which separate the two functions of antibody-based localization and delivery or generation of the toxic agent into two steps, also promise to afford superior tumor targeting and therapeutic efficacy. Several challenges in optimizing immunoconjugates remain, however, including poor intratumoral mAb uptake, normal tissue conjugate exposure and issues surrounding drug potency and conditional release from mAb carriers. Nonetheless, highly promising results from preclinical models will continue to drive the clinical development of this therapeutic class.     

Antibody–drug conjugates (ADCs) for cancer therapy: Strategies,challenges, and successes

Targeted delivery of therapeutic molecules into cancer cells is considered as a promising strategy to tackle cancer. Antibody–drug conjugates (ADCs), in which a monoclonal antibody (mAb) is conjugated to biologically active drugs through chemical linkers, have emerged as a promising class of anticancer treatment agents, being one of the fastest growing fields in cancer therapy. The failure of early ADCs led researchers to explore strategies to develop more effective and improved ADCs with lower levels of unconjugated mAbs and more-stable linkers between the drug and the antibody, which show improved pharmacokinetic properties, therapeutic indexes, and safety profiles. Such improvements resulted in the US Food and Drug Administration approvals of brentuximab vedotin, trastuzumab emtansine, and, more recently, inotuzumab ozogamicin. In addition, recent clinical outcomes have sparked additional interest, which leads to the dramatically increased number of ADCs in clinical development. The present review explores ADCs, their main characteristics, and new research developments, as well as discusses strategies for the selection of the most appropriate target antigens, mAbs, cytotoxic drugs, linkers, and conjugation chemistries.     

Towards the implementation of quality by design to the production of therapeutic monoclonal antibodies with desired glycosylation patterns

Quality by design (QbD) is a scheme for the development, manufacture, and approval of pharmaceutical products. The end goal of QbD is to ensure product quality by building it into the manufacturing process. The main regulatory bodies are encouraging its implementation to the manufacture of all new pharmaceuticals including biological products. Monoclonal antibodies (mAbs) are currently the leading products of the biopharmaceutical industry. It has been widely reported that glycosylation directly influences the therapeutic mechanisms by which mAbs function in vivo. In addition, glycosylation has been identified as one of the main sources of monoclonal antibody heterogeneity, and thus, a critical parameter to follow during mAb manufacture. This article reviews the research on glycosylation of mAbs over the past 2 decades under the QbD scope. The categories presented under this scope are: (a) definition of the desired clinical effects of mAbs, (b) definition of the glycosylation‐associated critical quality attributes (glycCQAs) of mAbs, (c) assessment of process parameters that pose a risk for mAb glycCQAs, and (d) methods for accurately quantifying glycCQAs of mAbs. The information available in all four areas leads us to conclude that implementation of QbD to the manufacture of mAbs with specific glycosylation patterns will be a reality in the near future. We also foresee that the implementation of QbD will lead to the development of more robust and efficient manufacturing processes and to a new generation of mAbs with increased clinical efficacy. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010     

Industrialization of mAb production technology The bioprocessing industry at a crossroads

Manufacturing processes for therapeutic monoclonal antibodies (mAbs) have evolved tremendously since the first licensed mAb product in 1986. The rapid growth in product demand for mAbs triggered parallel efforts to increase production capacity through construction of large bulk manufacturing plants as well as improvements in cell culture processes to raise product titers. This combination has led to an excess of manufacturing capacity, and together with improvements in conventional purification technologies, promises nearly unlimited production capacity in the foreseeable future. The increase in titers has also led to a marked reduction in production costs, which could then become a relatively small fraction of sales price for future products which are sold at prices at or near current levels. The reduction of capacity and cost pressures for current state-of-the-art bulk production processes may shift the focus of process development efforts and have important implications for both plant design and product development strategies for both biopharmaceutical and contract manufacturing companies.Key words: bioprocessing, cell culture, purification, economics, capacity, manufacturing, production, facility, biopharmaceutical     

Guardians at the gate

Product life cycle management, which necessarily utilizes a multi-disciplinary approach, is an essential tool for companies that develop or market therapeutic monoclonal antibodies (mAbs). Too little attention to such a plan, or use of the wrong resources, could substantially curtail a product’s life span. The most difficult part of the therapeutic antibody business is the development of high-quality, safe and effective products. Great care should thus be taken to ensure that products with these characteristics are positioned in a marketplace that is competition-free for as long as possible. In an era of mAbs with billion dollar markets, the loss of even a single day of sales could cost companies millions of dollars in lost revenue.     

Industrialization of mAb production technology: The bioprocessing industry at a crossroads

Manufacturing processes for therapeutic monoclonal antibodies (mAbs) have evolved tremendously since the first licensed mAb product (OKT3) in 1986. The rapid growth in product demand for mAbs triggered parallel efforts to increase production capacity through construction of large bulk manufacturing plants as well as improvements in cell culture processes to raise product titers. This combination has led to an excess of manufacturing capacity, and together with improvements in conventional purification technologies, promises nearly unlimited production capacity in the foreseeable future. The increase in titers has also led to a marked reduction in production costs, which could then become a relatively small fraction of sales price for future products which are sold at prices at or near current levels. The reduction of capacity and cost pressures for current state-of-the-art bulk production processes may shift the focus of process development efforts and have important implications for both plant design and product development strategies for both biopharmaceutical and contract manufacturing companies.     

The therapeutic monoclonal antibody market

Since the commercialization of the first therapeutic monoclonal antibody product in 1986, this class of biopharmaceutical products has grown significantly so that, as of November 10, 2014, forty-seven monoclonal antibody products have been approved in the US or Europe for the treatment of a variety of diseases, and many of these products have also been approved for other global markets. At the current approval rate of ～ four new products per year, ～70 monoclonal antibody products will be on the market by 2020, and combined world-wide sales will be nearly $125 billion.     

Potential of plants to produce recombinant protein products

Plants have great potential as photosynthetic factories to produce pharmaceutically important and commercially valuable biomedicines and industrial proteins at low cost. The U.S. Food and Drug Administration (U.S. FDA) has approved the drug Elelyso (taliglucerase alfa) produced by carrot cells for treatment of type 1 Gaucher’s disease in 2012. The commercial potential of biomedicines produced by molecular farming has dramatically improved due to the success of an experimental drug called ZMapp, which has immunological activity in Ebola patients. A cocktail of three monoclonal antibodies was produced in tobacco (Nicotiana benthamiana) plants (Chen and Davis 2016). At present, very few drugs made by this technology have been approved by worldwide authorities such as the U.S. FDA. However, plants have been proposed as a novel paradigm for commercial production of proteins over the next decade. In recent years, leading researchers on molecular farming have given more priority to the area of animal-free therapeutic proteins such as parenteral and oral vaccines. Although plant-based platforms have considerable advantages over traditional systems such as bacterial and animal systems, there are several obstacles to commercial-scale production, especially with regards to improving the quality and quantity of plant-produced biologics and industrial materials. One of the biggest barriers to commercialization of this technology is the intense scrutiny of these new plant varieties by regulatory agencies and the public as well as the high costs associated with their regulatory approval.     

The therapeutic monoclonal antibody market

Since the commercialization of the first therapeutic monoclonal antibody product in 1986, this class of biopharmaceutical products has grown significantly so that, as of November 10, 2014, forty-seven monoclonal antibody products have been approved in the US or Europe for the treatment of a variety of diseases, and many of these products have also been approved for other global markets. At the current approval rate of ∼ four new products per year, ∼70 monoclonal antibody products will be on the market by 2020, and combined world-wide sales will be nearly $125 billion.     

Worldwide experience with biosimilar development

Limited access for high-quality biologics due to cost of treatment constitutes an unmet medical need in the US and other regions of the world. The term “biosimilar” is used to designate a follow-on biologic that meets extremely high standards for comparability or similarity to the originator biologic drug that is approved for use in the same indications. Use of biosimilar products has already decreased the cost of treatment in many regions of the world and now a regulatory pathway for approval of these products has been established in the US. The Food and Drug Administration (FDA) led the world with the regulatory concept of comparability and the European Medicines Agency (EMA) was the first to apply this to biosimilars. Patents on the more complex biologics, especially monoclonal antibodies, are now beginning to expire and biosimilar versions of these important medicines are in development. The new Biologics Price Competition and Innovation Act (BPCIA) allows the FDA to approve biosimilars and allows the FDA to lead on the formal designation of interchangeability of biosimilars with their reference products. The FDA''s approval of biosimilars is critical to facilitating patient access to high-quality biologic medicines and will allow society to afford the truly innovative molecules currently in the global biopharmaceutical industry''s pipeline.Key words: monoclonal antibodies (mAbs), biosimilars, recombinant biopharmaceuticals     

Monoclonal antibodies and the transformation of blood typing

Today, when monoclonal antibodies (mAbs) have become one of the most important classes of therapeutic drugs, it is easy to forget how much they have transformed our healthcare in other ways. One of the first clinical areas, as this paper shows, where mAbs made their mark was in the field of blood typing. The adoption of mAbs for this purpose was done with little public fanfare or funding. Nonetheless, it radically transformed the accuracy and cost of blood typing and shifted the procedure away from a dependence on reagents made from human blood donated by volunteers. This paper argues that the development of mAbs as reagents for blood typing laid the foundation for the first large-scale production of mAbs thereby paving the way to the advent of mAb diagnostics and therapeutics.     

The interplay of non-specific binding,target-mediated clearance and FcRn interactions on the pharmacokinetics of humanized antibodies

The application of protein engineering technologies toward successfully improving antibody pharmacokinetics has been challenging due to the multiplicity of biochemical factors that influence monoclonal antibody (mAb) disposition in vivo. Physiological factors including interactions with the neonatal Fc receptor (FcRn) and specific antigen binding properties of mAbs, along with biophysical properties of the mAbs themselves play a critical role. It has become evident that applying an integrated approach to understand the relative contribution of these factors is critical to rationally guide and apply engineering strategies to optimize mAb pharmacokinetics. The study presented here evaluated the influence of unintended non-specific interactions on the disposition of mAbs whose clearance rates are governed predominantly by either non-specific (FcRn) or target-mediated processes. The pharmacokinetics of 8 mAbs representing a diverse range of these properties was evaluated in cynomolgus monkeys. Results revealed complementarity-determining region (CDR) charge patch engineering to decrease charge-related non-specific binding can have a significant impact on improving the clearance. In contrast, the influence of enhanced in vitro FcRn binding was mixed, and related to both the strength of charge interaction and the general mechanism predominant in governing the clearance of the particular mAb. Overall, improved pharmacokinetics through enhanced FcRn interactions were apparent for a CDR charge-patch normalized mAb which was affected by non-specific clearance. The findings in this report are an important demonstration that mAb pharmacokinetics requires optimization on a case-by-case basis to improve the design of molecules with increased therapeutic application.     

Monoclonal antibodies and the transformation of blood typing

Today, when monoclonal antibodies (mAbs) have become one of the most important classes of therapeutic drugs, it is easy to forget how much they have transformed our healthcare in other ways. One of the first clinical areas, as this paper shows, where mAbs made their mark was in the field of blood typing. The adoption of mAbs for this purpose was done with little public fanfare or funding. Nonetheless, it radically transformed the accuracy and cost of blood typing and shifted the procedure away from a dependence on reagents made from human blood donated by volunteers. This paper argues that the development of mAbs as reagents for blood typing laid the foundation for the first large-scale production of mAbs thereby paving the way to the advent of mAb diagnostics and therapeutics.     

The interplay of non-specific binding,target-mediated clearance and FcRn interactions on the pharmacokinetics of humanized antibodies

The application of protein engineering technologies toward successfully improving antibody pharmacokinetics has been challenging due to the multiplicity of biochemical factors that influence monoclonal antibody (mAb) disposition in vivo. Physiological factors including interactions with the neonatal Fc receptor (FcRn) and specific antigen binding properties of mAbs, along with biophysical properties of the mAbs themselves play a critical role. It has become evident that applying an integrated approach to understand the relative contribution of these factors is critical to rationally guide and apply engineering strategies to optimize mAb pharmacokinetics. The study presented here evaluated the influence of unintended non-specific interactions on the disposition of mAbs whose clearance rates are governed predominantly by either non-specific (FcRn) or target-mediated processes. The pharmacokinetics of 8 mAbs representing a diverse range of these properties was evaluated in cynomolgus monkeys. Results revealed complementarity-determining region (CDR) charge patch engineering to decrease charge-related non-specific binding can have a significant impact on improving the clearance. In contrast, the influence of enhanced in vitro FcRn binding was mixed, and related to both the strength of charge interaction and the general mechanism predominant in governing the clearance of the particular mAb. Overall, improved pharmacokinetics through enhanced FcRn interactions were apparent for a CDR charge-patch normalized mAb which was affected by non-specific clearance. The findings in this report are an important demonstration that mAb pharmacokinetics requires optimization on a case-by-case basis to improve the design of molecules with increased therapeutic application.     

A novel bicistronic gene design couples stable cell line selection with a fucose switch in a designer CHO host to produce native and afucosylated glycoform antibodies

The conserved glycosylation site Asn²⁹⁷ of a monoclonal antibody (mAb) can be decorated with a variety of sugars that can alter mAb pharmacokinetics and recruitment of effector proteins. Antibodies lacking the core fucose at Asn²⁹⁷ (afucosylated mAbs) show enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) and increased efficacy. Here, we describe the development of a robust platform for the manufacture of afucosylated therapeutic mAbs by engineering a Chinese hamster ovary (CHO) host cell line to co-express a mAb with GDP-6-deoxy-D-lyxo-4-hexulose reductase (RMD), a prokaryotic enzyme that deflects an intermediate in the de novo synthesis of fucose to a dead-end product, resulting in the production of afucosylated mAb (GlymaxX? Technology, ProBioGen). Expression of the mAb and RMD genes was coordinated by co-transfection of separate mAb and RMD vectors or use of an internal ribosome entry site (IRES) element to link the translation of RMD with either the glutamine synthase selection marker or the mAb light chain. The GS-IRES-RMD vector format was more suitable for the rapid generation of high yielding cell lines, secreting afucosylated mAb with titers exceeding 6.0 g/L. These cell lines maintained production of afucosylated mAb over 60 generations, ensuring their suitability for use in large-scale manufacturing. The afucosylated mAbs purified from these RMD-engineered cell lines showed increased binding in a CD16 cellular assay, demonstrating enhancement of ADCC compared to fucosylated control mAb. Furthermore, the afucosylation in these mAbs could be controlled by simple addition of L-fucose in the culture medium, thereby allowing the use of a single cell line for production of the same mAb in fucosylated and afucosylated formats for multiple therapeutic indications.     

Trends in capacity utilization for therapeutic monoclonal antibody production

The administration of high doses of therapeutic antibodies requires large-scale, efficient, cost effective manufacturing processes. An understanding of how the industry is using its available production capacity is important for production planning, and facility expansion analysis. Inaccurate production planning for therapeutic antibodies can have serious financial ramifications. In the recent 5th Annual Report and Survey of Biopharmaceutical Manufacturing Capacity and Production, 434 qualified respondents from 39 countries were asked to indicate, among other manufacturing issues, their current trends and future predictions with respect to the production capacity utilization of monoclonal antibodies in mammalian cell culture systems. While overall production of monoclonals has expanded dramatically since 2003, the average capacity utilization for mammalian cell culture systems, has decreased each year since 2003. Biomanufacturers aggressively attempt to avoid unanticipated high production demands that can create a capacity crunch. We summarize trends associated with capacity utilization and capacity constraints which indicate that biopharmaceutical manufacturers are doing a better job planning for capacity. The results have been a smoothing of capacity use shifts and an improved ability to forecast capacity and outsourcing needs. Despite these data, today, the instability and financial constraints caused by the current global economic crisis are likely to create unforeseen shifts in our capacity utilization and capacity expansion trends. These shifts will need to be measured in subsequent studies.Key words: capacity, production, monoclonal antibody, survey, biopharmaceutical, manufacturing, constraints, facilityBuilding new capacity and improving existing systems to meet the demand for new monoclonal antibody (mAb) therapeutics, whether through in-house manufacturing or out-sourced contract manufacturing, has long-term cost implications for biotechnology firms. Bringing new capacity on line requires accurate market knowledge, lead-time, large capital expenditures and careful planning, and understanding trends in capacity utilization for the manufacture of mAbs can be critical to the planning process.For the first three quarters of the twentieth century, the traditional and most efficient way of producing antibodies was to immunize a large vertebrate, bleed the animal and, from the serum, collect the polyclonal protein. Because of their hardy binding specificity, the value of immunoglobulins, especially as a potential therapeutic tool, was evident from the time of their discovery because scientists envisioned them as probes and transporters of therapeutic tools. Limitations of using polyclonals were also evident from early on. Therapeutic antibodies needed to be delivered in very high concentration, and polyclonals, a heterogeneous group of molecules, directed against many different epitopes of an antigenic source, could only be extracted from serum in tiny quantities.A solution to at least some of the problems seemed to appear in 1984 when Kohler and Milstein¹ described a novel method for producing antibodies from an immortalized cell line capable of continually producing a virtually unlimited amount of a single antibody, directed at a single epitope. The medical and scientific communities realized that this hybridoma technology could produce sufficient quantities of antibodies for therapy, and in 1986, the first mAb for human use (Orthoclone OKT3—Ortho Pharmaceuticals) was approved for the prevention of kidney transplant rejection.As hybridoma technology evolved, it was clear that there were obstacles to overcome. The first mAbs were murine, but therapeutic candidates needed to be less immunogenic in order to avoid transplantation incompatibility. So chimeric antibodies and humanized mAbs (part murine, part human), and fully human mab production technologies were developed. The OKT3 approval was followed by a wave of mostly anti-cancer mAbs through the 1990''s, and since then, these proteins have become a dominant component of the biopharmaceutical market, representing approximately 20% of all biologic products, with combined revenues of over $20 billion in 2006.²Administration of high doses of therapeutic antibodies requires large-scale, efficient, cost effective manufacturing processes. Over the past few years, improvements have been made in cell line generation, expression vectors, transfection technology and large-scale cell culture production, allowing biotech firms to successfully move candidates through the pipeline. Today''s technologies are enabling five times the concentration of antibody produced by technologies just 5 years ago.³ Biotechnology drugs, including mAbs, now make up more than one-quarter of the FDA filings for approval, and over 40% of preclinical trials are now large molecule candidates, and as a result, planning for biologics manufacturing will continue to require strategic approaches to avoid potentially disruptive production bottlenecks. The long lead-time required to successfully launch a mAb requires pre-planning for capacity. This planning demands a new level of partnership between manufacturers and suppliers to develop novel technologies that will keep pace with industry''s need for capacity.