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MONOCLONALS the billion dollar molecules of the future

In 1975, two British scientists thought of creating a mouse antibody that could be replicated or ‘cloned’ to produce identical copies. Identical copies with identical modes of action had the potential to be a drug.They had launched what was to be one of biotechnology’s best ideas. If the pair could mimic the immune system’s ‘seek and destroy’ capability by pre-designing antibodies for all manner of disease targets, it should be possible to block or activate cellular activity to order. It was an elegant concept opening up a raft of therapeutic possibilities, particularly in the area of cancer. Here it might be possible to attach a chemotherapy drug to an antibody.The antibody’s specificity for a particular disease target would guide the chemo drug only to the cancerous cells and not the healthy ones.The concept, therefore, was excellent, but the use of mice monoclonals had drawbacks.The human body did not like antibodies from mice anymore than it liked the flu virus, so the antibodies themselves triggered an immune response and were destroyed.This ‘immunogenicity’ issue was to occupy researchers for another 20 or so years before it became possible to craft a monoclonal antibody (mAb) that would be acceptable to the human immune system.

fter rather a long period in the desert, untreatable diseases. A further six lead drugs are in By Dr Martin Wiles monoclonal antibody drugs are once the final stages of clinical trials and approximately and Patrik A again generating a wave of excitement. 150 new products are in the pipeline with about 60 Andreassen Over the past five years, a stream of successful companies active in the field. Monoclonal anti- products in this new class has reached the market. body drugs are outpacing traditional pharmaceuti- Thanks to several innovations, sophisticated cals both in regulatory approvals and sales. molecular biology and computer modelling, the By 2010, Datamonitor predicts annual sales technology has matured and the immunogenicity worldwide will reach $30 billion. Already we have issue has largely been resolved. The new drugs are seen brands in the first generation of monoclonals inspiring a degree of confidence among clinicians achieve sales of more than a billion dollars. The big and patients, based on their efficacy and minimal new drivers in the market are Herceptin and side effects. Avastin. Both are from Genentech, one of the old- Today there are 17 monoclonal antibody drugs est biotech companies, and now fully owned by on the market bringing new hope in hitherto Roche. Herceptin, for treating advanced HER2

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This ability to select and even discriminate between similar antigens is the ‘specificity’ that earns the accolade of ‘smart bomb’. Because monoclonals can confine their biological activity to specific targets on specific cells, the possibility of side- Murine Chimaeric CDR-grafted UltiMAb antibodies effects is reduced. Reduced side-effects or low tox- 100% mouse protein 33% mouse protein 5-10% mouse protein 100% human protein icity make for successful drugs. The 25 years it took to perfect the technology for making antibodies work as medicines is attrib- Figure 1 breast cancer, had sales of $1.6 billion in 2005; utable in part to positive scientific struggle but also Evolution of monoclonal Avastin, for metastatic colorectal cancer had sales to negative patent complexities. Meanwhile, as the antibody technologies/ of $1.2 billion. technology for making drugs was evolving, mono- Medarex/ABG Sundal Collier Research Report Rituxan, another product from the clonals were useful tools as laboratory reagents Genentech/Roche label, developed for the treat- and diagnostics (Figure 1). ment of leukaemia and non-Hodgkin’s lymphoma There were effectively three stages in the matur- sold $3.1 billion of product in 2005 and Remicade, ing of antibody technology. Kohler and Milstein from Johnson & Johnson (J&J) and Schering- made the first antibody by fusing mouse myeloma Plough for rheumatoid arthritis and Crohn’s dis- cells with antibody-secreting cells from an immu- ease, achieved sales of £3.4 billion. nised mouse. This resulting fusion or hybridoma had two magic ingredients: unlimited growth Scientific struggle potential derived from the cancerous myeloma Interestingly, these first super successful products cells plus the programmed specificity of the anti- are from the earlier phase of monoclonal antibody body (Figure 2). technology. As we have said, the attraction of anti- The second stage was for these test-bed drugs to bodies as therapies is that they can be both target- become less mouse and more man. From the first ed missiles – blocking or activating cellular activity murine stage, researchers developed a part murine- – and drug transporters – eg delivering cytotoxic part human, chimaeric antibody. Remicade drugs directly to tumour cells. (rheumatoid arthritis and Crohn’s disease) belongs The body naturally produces antibodies when a to this chimaeric stage of monoclonals. disease antigen appears in the form of a virus or Then, third, came the ‘humanised’ versions, bacteria or other alien threat, such as transplanted using only the murine amino acids that made the tissue. The antibody will recognise the alien, bind binding site in an otherwise, human antibody. This with a receptor on the alien’s cell surface and elim- technology was developed by US company PDL inate the offending visitor from the body. BioPharma, formerly Protein Design Labs. Humanised antibody drugs include Roche’s Herceptin, Wyeth’s Mylotarg, for acute myeloid Table 1: Top six mAbs on the market (2005 sales $m) leukaemia and bone marrow cancer, and Xolair for Remicade RA, Crohn’s, J&J/Schering- 3,477 persistent allergic asthma (Genentech and Novartis). psoriasis, psoriatic Plough Although predominantly ‘human’ there remains arthritis, ankylosing the risk of these drugs triggering an immune reac- spondylitis, ulcerative colitis tion. Even with fully-human monoclonal antibodies immunogenicity is a much reduced but residual issue, as the body can still respond to any foreign Rituxan (US) Non-Hodgkin’s Genentech/Roche 3,154 MAbThera (Europe) Lymphoma, RA Biogen Idec matter with an immune response. These fully human monoclonals are achieved in two ways, either using Herceptin Breast cancer Genentech/Roche 1,629 transgenic mouse technology or library technology. The transgenic mice used have a ‘human’ Humira RA/psoriatic arthritis CAT/Abbott 1,400 immune system which, when challenged by any antigen, will produce human antibodies which can Avastin Metastatic colorectal Genentech 1,264 then be harvested. Medarex and Abgenix (now cancer Amgen) make use of this approach. The other technology for generating these anti- Synagis RSV lower Abbott/ 1,063 bodies is the type used by BioInvent as well as respiratory tract MedImmune infections Morphosys and Cambridge Antibody Technology (CAT) (now Astra Zeneca). Here a library of

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Figure 2 Monoclonal Antibody: variable domain.Three-dimensional model of the variable domains of a mouse antibody (left) and a humanised antibody (right). The framework regions are shown in white, and the CDRs are indicated in red.To generate the humanised antibody, the CDRs from the mouse antibody were transplanted, along with key framework amino acids (blue) that were identified by analysis of the model, into a human framework. (Molecular models courtesy of Shankar Kumar, antibody fragments is made from shuffling human engineering, extant patents on multiple small PDL BioPharma) genetic material to produce many different varia- molecular manipulations leave the researcher con- tions of antibodies. A target is ‘put on a hook’ and stantly looking for the next piece of the patent jig- thrown into the library pool and antibodies that saw before moving forward. bind are ‘fished out’. The advantage is that there is There are just eight companies that mainly con- no need, as in transgenic models, to obtain an trol the rights to the antibody technology for devel- immune response. oping human and humanised mAbs. Not all the Humira from CAT, an anti-TNF (Tumour holders of these patents in the early days of mAb Necrosis Factor) treatment for rheumatoid arthri- technology were ready to share this expertise. This tis (RA), leads the way as the first commercial, and some of the ensuing patent contests took up a fully-human monoclonal antibody drug. Marketed lot of management time, doubtless slowing the by Abbott, it first appeared in 2003. whole process down and leaving big pharma a lit- Using its patented library technology, tle uneasy about collaborating with companies n-CoDeR®, BioInvent is developing monoclonals embroiled in litigation. from its library of more than 20 billion differenti- “While patents obviously protect intellectual ated antibody fragments (Figure 3). property they can also become barriers to discov- Fully-human monoclonal antibodies are seen as ery,” says Professor Carl Borrebaeck of Lund third generation mAbs, with chimaeric being first University, scientific adviser to BioInvent. He has generation and humanised (PDL), second. Moving been involved in monoclonal antibody research along the third generation pipeline is Vectibix from the early 1980s. (panitumumab) a fully human mAb for metastatic He says: “We are meeting the same problems colorectal cancer. This is expected to be launched now in the mapping of the human proteome, by Amgen by the end of 2006. Just into the clinic which at present is largely a non-profitable aca- is MDX-1106 from Medarex which has potential demic endeavour. Ideally we would use mAbs to in cancer and infectious disease. help identify proteins that are involved in human Meanwhile, first generation mAbs are now mov- disease. We either pay for licences or take longer by ing into new indications adding considerable value to trying to find alternative methods that don’t each brand. From this March, Erbitux was cleared infringe patents. for use in treating head and neck cancer, a first for “Even the National Institutes of Health in the US this disease. Remicade (RA and Crohn’s) now has an concedes that the IP situation for mAb develop- expanded indication for psoriatic arthritis. ment is difficult. With human antibodies as drugs now a reality, “BioInvent’s monoclonal antibody library is used the technological challenge for the industry is not for in-house discovery programmes as well as indus- making antibodies but selecting the best targets or try collaborations. We have to sign up to several disease pathways for them to attack. licences to be able to manipulate our own material. Fortunately we have the key licences in perpetuity.” Patent puzzle PDL BioPharma developed pivotal research that Taking out patents is core to protecting intellectu- pioneered the method for the second stage of devel- al property in the biotechnology and pharmaceuti- opment, the humanised mouse antibodies. cal sectors, but particularly in the field of genetic Licensing out its technology in the past made PDL

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BioPharma’s annual $280 million revenues. The rel- n-CoDeRs uppbyggnad evant technology is, as we’ve said, now being over- taken and PDL BioPharma is moving into developing its own drugs and building up a sales force. 1 The genetic code (DNA) for antibodies is isolated from Whether the IP situation will prove too expen- the human immune system. sive or too difficult for the smaller entrepreneurs to break into the sector is uncertain. As Max Hermann, Head of Life Sciences at ING says: “Patents never stopped a drug getting to market.” Companies have to accept that biotechnology is strewn with patents. However, if the patent pool is in even fewer hands after more pharma acquisitions, it could hamper access and hinder progress in the shorter term. In the longer term monoclonal technology will move on and some of the patents will cease to retain their grip. 2 DNA is divided into smaller parts. Waiting game 3 The parts are copied. The pioneering of monoclonal antibodies has largely been achieved at the hands of the biotechnology industry. To a biologist the antibody-as-drug makes lots of sense. “It was clear that monoclonals were going to have a major impact,” is Hermann’s view. But the rather more conservative pharmaceutical industry mostly waited on the sidelines. “They either disbelieved the concept or didn’t like it,” The copied DNA 4 says Hermann. “They stuck to their view that is combined randomly and small molecules (chemical drugs) always win out.” new antibody gene So rather late in the day the big pharma compa- combinations are nies are buying into the business, through collabo- The new genes are collected obtained in a fixed 5 rations or straight acquisitions. Witness Astra master framework. in bacteria and a collection of more than 15 billion different Zeneca’s takeover this year of the UK’s longest antibody genes makes up the serving antibody company, CAT. The deal valued antibody library. CAT at £702 million ($1,263 million). Amgen, a company that has been around since the early days of biotech, developed the hugely successful recombinant protein products Epogen and Neupogen, and also Enbrel, a hybrid fusion protein made of an antibody and a receptor. The company is now buying up Abgenix, the innovator of the transgenic mice technology for producing human antibodies. There was one earlier, rather costly, foray by big pharma into the sector. In 2001 Bristol Myers Squibb (BMS) paid $1 billion for a 20% stake in ImClone after cetuximab for colorectal cancer was granted fast-track development status by the FDA. Within a year the drug was rejected by the FDA Figure 3 BioPharma something of a gatekeeper on mono- but Erbitux eventually made its first sales last year. BioInvent’s n-CoDeR® clonal development and provided the company Antibody Library Technology with a lucrative revenue stream. TNF success story Seven marketed products have used PDL’s tech- Despite big pharma’s faith in small molecule drugs, nology including Herceptin, Avastin, Xolair, they never gained mastery over biologics in the bat- Raptiva, Synagis, Mylotarg, and Zenapax, with tle with TNF. Finding monoclonals against the TNF royalties providing more than 50% of PDL target responsible for the inflammatory cascade in

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RA has been the sector’s biggest success so far, and As Bjorn Andersson, biotech analyst at RedEye, this sub sector alone is worth about $8 billion puts it: “You will not get exactly the same drug (2005 figures). Already established are J&J’s from another manufacturer. I don’t think we will Remicade, Amgen’s Enbrel and CAT’s Humira. see generics for a long time, if at all. “It is more With only 13% of RA patients currently on one likely that new kinds of technology, such as anti- of these drugs, and no other drugs available that body fragments, will be used to achieve the same actually tackle, rather than mask, the symptoms, effects as monoclonals.” there is obviously huge market potential. Companies such as Ablynx and Domantis are With monoclonal antibodies taking an increas- pursuing this route, which may represent the next ing share of all product approvals, big pharma will generation of antibody technology. be looking at those biotech companies with prom- Another approach is polyclonal antibodies ising lead products. Drug development collabora- which can target more complex diseases such as tions with biotech, in-licensing deals or straight bacterial or fungal infections as they are able to acquisitions are likely to be a continuing pattern as bind to multiple epitopes. Symphogen with its more pharma companies realise that it is time to ‘Symphobodies’ is one of the leaders in the area. get a share of the action. Andersson also sees big pharma approaching mAbs from different perspectives, such as novel Higher success rate methods of delivery. “If they can’t make them into It is widely recognised that monoclonals have a a pill, maybe they will come up with a nasal spray.” higher success rate in their development phases “The two mature sectors of biologic drugs are than conventional drugs. This is another important recombinant protein therapeutics (such as Amgen’s factor in assessing this market. In 2002, 30% of all Neupogen), and monoclonal antibodies. Between newly approved drugs were either monoclonal them they are set to generate more than 90% of antibodies or recombinant proteins, up from 6% in total biotech sales from 2004 to 2010.” (Nature 1999, according to Tufts Center for the Study of Reviews, Vol. 5, July 2006). Drug Development. In the monoclonal antibody market we are look- Steve Projan, VP of biological technologies at ing at a class of drugs where quick generation of Wyeth Research, commented recently in The drug leads and faster early development has been Scientist: “Biologics are the drugs of the future demonstrated, and there is a low attrition or fail- because they are targeted, causing fewer side- ure rate in development. effects than traditional drugs. Moreover most There is a strong safety profile for these drugs due agents are injectable, making it harder for people to their selectivity and specificity, and the dosing to buy them at lower cost over the Internet. It’s eas- regime of once or twice a month is more convenient ier to manage the biopharmaceutical market.” than for, say, the recombinant protein drugs. At the moment mAbs, which are large molecules A last word from Alex Lindstrom, analyst at that do not readily convert to pill form, have to be ABG Sundal Collier AB: “The positives for the sec- injected or infused. Protein-based drugs, the other tor are that monoclonals are fairly easy to develop, strand of successful biologics, require daily dosing. they work and are safe. They are one of the best But the pharmacokinetics and formulation tech- performing areas in the biotech sector.” DDW nology has improved sufficiently that subcuta- neous administration for fully-human antibodies products can be made once or twice a month. Dr Martin Wiles is currently VP Business Development at BioInvent International AB. From Looking into the future 1999-2003 he was Head of Business Development In looking at the future lifespan of a drug, you nor- at KS Biomedix and, prior to that, was Business mally have to consider when the patent will run Development Director and a Technical Director at out and other companies can apply to manufacture Biocompamptiles PLC. He has a PhD in chemistry a generic version of the drug. With monoclonals, and an MBA. the situation is a little different. As Mark J. Belsey put it in Nature Reviews, Vol. 5, July 2006: “Given Patrik Andreassen has an MSc in Industrial that the innovator’s cell line plays a key role in Engineering, Management and Marketing and has determining the mAb’s characteristics, the propri- trained in medicine and research in genetics from etary nature of the cell line makes it difficult to 1992-1999. He is currently Manager in charge of recreate a genuine biosimilar (generic version of a market research and in-licensing at BioInvent biologic drug).” International AB.

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