Small molecules are still not providing cures for many diseases, and this is why biological therapies continue to be developed. They often offer greater convenience to patients, as well as longer lasting therapies,” says William Prather, MD, senior vice president of corporate development at the Israeli stem cell company, Pluristem. The therapeutics area at this year’s BIO International Convention will play host to many interesting technologies for producing and improving protein therapeutics, vaccines, and stem cells.

Protein Therapies Remain Top Dog

With an estimated market value in excess of US$57 billion in 2006 and a growth rate of 12% until 2010 (1), it’s not hard to see why companies are still very active in protein therapeutics. One driver of this market (encompassing monoclonal antibodies, proteins and peptides) is the increasing need to produce safer protein therapies. Jeff Cleland, vice president of therapeutic development at Barofold and a speaker at the BIO convention this year, states: “There is a lot of concern over immunogenicity arising due to repeated administration of protein therapeutics that can lead to the induction of undesirable antidrug antibodies, which interfere with or neutralize the effect of the drug. It is being mentioned much more vigorously by the FDA and EMEA.” One report estimates that failing to predict and monitor levels of immunogenicity can add 18 months to development times and $75 million to costs (2), so it is essential to find methods to reduce immunogenicity.

WWW.BAROFOLD.COM

To overcome that problem, many companies use technologies to (for example) engineer antibodies into smaller, less immunogenic versions including Fab, scFv, and single variable domains or add polymers such as PEG (polyethylene glycol) to mask the immunogenic effects of the molecule (3).

Companies exhibiting this year that are following this type of approach are Dyax, Pieris, and BaroFold, Inc. Dyax (www.dyax.com) is producing antibodies and smaller proteins for therapeutic use. Its portfolio includes Dyax DX-88, a recombinant small protein currently in phase 2 and 3 clinical trials for treatment of hereditary angioedema (HAE) and which has orphan drug status in the United States and the European Union.

Pieris (www.pieris-ag.com), a German biotech, offers an interesting alternative with its Anticalins technology. This genetically engineered version of human lipocalins is a small protein class formed from a single polypeptide chain of only 160–180 amino acids comprising a β-barrel supporting four CDR-like binding loops. Anticalins technology is said to offer excellent target binding specificity conferred by a large target-binding surface comparable in size to that of an antibody. In contrast with antibodies, they are free of Fc-mediated side effects and can address multiple targets by using a so-called Duocalin format (4, 5).

Andreas Hohlbaum PhD, chief technology officer at Pieris states: “In preclinical studies, our lead candidate PRS-050, a novel cancer therapy, has shown a favorable product profile in direct comparison with the humanized VEGF-specific Avastin antibody marketed by Roche. We are now advancing this program to the clinic and expect to be treating first cancer patients with PRS-050 in 2009.”

An interesting method of making protein therapeutics is being presented by US company, BaroFold, Inc. (www.barofold.com). Its proprietary protein refolding PreEMT technology uses high hydrostatic pressure to force water between the protein molecules, causing dissociation of aggregates and forcing the protein into its most compact form (6). Aggregation may occur during protein expression in mammalian cell culture, bacculovirus and Escherichia coli, or as part of routine manufacturing processes. To remove aggregates, manufacturers of protein therapeutics use chaotropic agents, such as guanidine hydrochloride or urea to solubilize hydrophobic proteins and peptides, which must be removed before the protein can be used in the clinic (8). Cleland explains: “We have found when our proteins are correctly folded they look most like the native protein and produce fewer side effects. For example, we have not observed immunogenicity or injection site reactions.” BaroFold uses PreEMT and other technologies to develop its own pipeline of protein therapeutics, including BaroFeron, a recombinant human interferon beta for the treatment of multiple sclerosis, which will enter phase 1 clinical studies later this year.

Vaccines — On the Up

The global vaccine market remains full of promise. At an annual rate of 16%, it is growing faster than the worldwide pharmaceutical market and is expected to reach $21 billion by 2010 (9). Much of the predicted growth of the vaccines market is expected to come from the introduction of new vaccines, either against diseases for which no vaccine currently exists or as second-generation products to replace existing vaccines. Many pharmaceutical and biotech companies want to have a hand in this market, which is still mainly centered on developing vaccines to prevent infectious diseases. However, the success of prophylactic cancer products such as Merck’s Gardasil vaccine to prevent cervical cancer has had a knock-on effect in therapeutic cancer vaccines, for which investment is increasing. For example, in 2007 Transgene’s TG4001, cervical cancer vaccine, was licensed by Roche, and Oxford Biomedica’s TroVax renal cancer therapy was snapped up by Sanofi-Aventis. So what’s behind this surge in vaccine development?

Gerd Zettlmeissl, chief executive officer of Austrian vaccine company Intercell (www.intercell.com), explains: “There is a realization among big pharmas that vaccines are one of those areas where it is still possible to develop a blockbuster, and that makes it attractive.” Zettlmeissl continues: “Vaccine development is mainly being driven by changes in technology. Twenty years ago we could not produce vaccines for many infectious diseases, but with the advances in molecular biology we are able to identify potent antigens. Also, the improvements to adjuvants have helped tremendously because we can now boost the immune response. These two factors have led to better vaccine design.”

To capitalize on those technology possibilities, Intercell has developed its Antigen Identification Program (AIP). This uses antibodies derived from individuals exposed to bacterial infections to screen an E. coli–based peptide display library. Magnetic beads capture the antibody–cell complex and identify those antigens, which are recognized by the immune system of many individuals during an infection.

This and other methods have been used as the basis for Intercell’s prophylactic partnered Staphylococcus aureus vaccine, which is in phase 2 clinical trials. Intercell is also developing a vaccine for Japanese encepha
litis (IC51) (10), which received its manufacturer’s license from the MHRA in January 2008; and a therapeutic hepatitis C vaccine (IC41), showing promising results in phase 2 trials) (11). The company has also produced IC31, a synthetic adjuvant consisting of an antimicrobial peptide and an immunostimulatory oligodeoxynucleotide that stimulates both a strong T-cell and B-cell immune response against antigens. The adjuvant has a good profile in both preclinical and clinical trials (12).

Another technology advance that has helped with vaccine development is the move from egg-based production of influenza vaccines to cell culture using mammalian, insect, and bacterial cell lines. One company presenting this year is New Jersey–based Vaxinnate (www.vaxinnate.com), which uses E. coli cell lines for rapid production of its M2e universal influenza vaccine currently in phase 1 clinical trials.

Vaccines are attracting more and more small start-ups because vaccines take less time to develop than many other types of biological therapies. And much of the technology to develop good vaccines especially for infectious diseases is well established and readily available. Zettlmeissl adds: “The vaccine response is often very similar in animal models to humans, so in general, when you have got a vaccine through phase 1, the chances of getting it through phase 2 are much higher than for a standard biological therapy. This is great if you’re a small company with limited resources, so I think we’ll continue to see smaller biotechs producing vaccines.”

EXHIBITORS IN THE THERAPEUTICS PRODUCT FOCUS ZONE



BD (Booth #1115): www.bd.com



CMS-Carbosynth (Booth #915): www.carbosynth.com



INTEGRIUM Cardiovascular Research (Booth #1322): www.integrium.com



Intercell AG (Booth #921): www.intercell.com



Kirin Pharma USA, Inc. (Booth #1020): http://kirings.com



Mayo Clinic (Booth #1225): www.mayoclinic.com



Nastech Pharmaceutical Company, Inc. (Booth #1125): www.nastech.com



XOMA (Booth #925): www.xoma.com



CONFERENCE SESSIONS OF INTEREST (A SAMPLING)



Aiming for the Bull’s-Eye: The Pursuit of Personalized, Targeted Therapeutics



California’s Stem Cell Initiative, from Research to Therapies



Cell Therapy: The Solution for Chronic Cardiovascular Diseases?



Combination Therapies: Best of Both Worlds



Diabetes Treatment: Cell-Based Therapies



Opportunity Knocks: Cell Therapies in Regenerative Medicine



Orphan Drugs … The Clinical and Regulatory Landscape



The Crucial Role of Translational Medicine in Drug Development



Therapeutic Gene Silencing: The Next Pharmaceutical Revolution



What the Vector Is Happening Here? Myth vs. Reality in Gene Therapy



What’s Ahead: State and Federal Stem Cell Policy and Funding Opportunities

Stem Cells Grow Up

Adult stem cell therapies have been used in some form for two decades for a range of bone and blood replacement applications, but their use has so far been limited. Stem-cell product sales in the United States totaled $36 million in 2007 (13). However, the projected global sales of stem-cell products by 2016 is estimated at $8.5 billion, so how will this be achieved?

The best hope of providing large-scale therapies currently lies with adult-derived stem cells because of the contrasting ethical barriers and technical difficulties of working with embryonic stem cells. One problem is that maintaining human stem cells in an undifferentiated state is one of the key barriers to stem-cell scale-up and is especially difficult with human embryonic stem cells (14, 15). Gene therapy approaches may perhaps offer a future solution (16).

Yet if human stem cells are to be used routinely as therapies, supplying affordable cells of sufficient quality and quantity has to be a priority. One adult stem cell proving to be popular for therapeutic use is the bone-marrow–derived mesenchymal stem cell. It can become muscle, bone, cartilage, or fat and has some ability to modify immune function in some experimental models. It has therefore become a cell of intense interest for treating musculoskeletal abnormalities, cardiac disease, and some abnormalities of immunity such as graft-versus-host disease after bone marrow transplant (17, 18).

In the vanguard of those using mesenchymal cells as therapeutics is Osiris, based in Maryland. It markets OsteoCel, the only FDA-approved stem cell-based product to date. OsteoCel, which stimulates bone growth, is considered an implant rather than a drug. But Osiris also has a another stem-cell product in its pipeline — Prochymal — a potential treatment for acute graft-versus-host disease, which could be approved later this year.

Another company using mesenchymal cells as an allogenic (nonpersonalized) therapy is Pluristem Therapeutics (www.pluristem.com). It is presenting data at the convention this year to explain its solutions to the problem of manufacturing sufficient cells to test in clinical trials. William Prather of Pluristem Therapeutics states: “We are stem-cell farmers and have to provide enough cells to treat people. To do this, we derive our cells ethically from human placental-derived mesenchymal stromal cells, where our biggest competitor for their use is the wastepaper basket. Our key component is growing them in a 3D bioreactor that imitates the natural microstructure of bone marrow and does not require supplementary growth factors, cytokines or other exogenous materials.”

Using that technology, Pluristem has produced PLX-I, a therapy to promote the engraftment of CD34+ human umbilical cord blood cells in patients afflicted with leukemia and other hematological malignancies. This product is soon to enter phase 1 clinical development after promising preclinical results showing that PLX cells are immune-privileged — hence protecting a recipient from immunological reactions that often accompany transplantation. Prather concludes: “The current hope for most stem-cell therapies is adult stem cells. Allogenic therapies are the way forward because big pharma wants a one-size-fits-all approach.”

Another company at the convention that is showing great promise with the use of adult stem cells is Aastrom Biosciences, Inc. (www.aastrom.com) in Ann Arbor, MI. Unlike Pluristem, Aastrom does not have the problems with such massive scale-up because it is manufacturing autologous cell products for repair or regeneration of human tissue. However, obtaining sufficient numbers of stem cells to treat patients still presents challenges, as Elmar Burchardt, vice president of medical affairs at Aastrom, comments: “We obtain a small sample of bone marrow under conscious sedation, and remove only 30–50mL from each patient. By using our Single-Pass Perfusion system, which controls gas and cell culture media exchange, we are able to replicate the patient’s own early-stage stem and progenitor cells while preventing their differentiation i
nto mature stem cells. The result is a cell product containing extremely high numbers of these cells that could otherwise not be obtained or would require bone marrow volumes of over a liter as starting material.”

The company’s most interesting product generated using this technology is the Cardiac Repair Cell therapy to regenerate damaged heart tissue in patients with dilated cardiomyopathy. The company recently treated its first patients in European compassionate-use cases (pictured), and plans to submit a US Investigational New Drug (IND) application and a European Investigational Medicinal Product Dossier (IMPD) in 2008. Burchardt states: “Many say autologous stem cell therapy is expensive, yet when you consider that the only hope many dilative cardiomyopathy patients have is a heart transplant at a cost of around $200,000 dollars, then it is clear that autologous heart repair therapies make economic sense.”

Future Challenges

At the 2008 BIO International Convention, a number of interesting technologies will reflect the therapeutics market today and its future direction. Protein therapies, with monoclonal antibodies as the dominant player, will be well represented. But because many blockbuster protein therapies are set to come off patent in the next five years, and the specter of biosimilars is just around the corner, technologies that make the next generation of protein therapies either more effective or cheaper to manufacture are becoming more important.

The main challenge facing developers of protein therapeutics is that because this is such a large and lucrative market, many companies continue to enter. This means competition for funding and recruiting patients to early stage clinical trials is fierce. Cleland of Barofold comments: “Protein therapeutics is a maturing market where much of the technology is becoming well established and so is less of an issue. But to overcome the problems of funding and patient recruitment, I think we’ll see companies disappear or more likely become part of big pharma, and there will be a lot more trials in countries where fewer patients are prescribed protein-based therapies.”

The number of vaccine technologies being presented at the BIO International Convention is also increasing again mirroring the renewed interested by big pharma in developing vaccines to prevent infectious diseases and vaccines not only to prevent, but also to treat a variety of cancers. The main roadblocks in the vaccine market, like the protein therapy market, are not technical, but in lack of education. Zettlmeissl of Intercell says: “We need to make health authorities more aware of the risk-benefit ratio of immunization with some of the newer vaccines because many can really reduce the disease burden. Now that many of the big pharmas are becoming more active again in vaccine development, I believe that they will help provide the necessary public awareness that vaccines need to become a much larger part of the biological therapeutics market in the next decade.”

The convention will also showcase a number of stem-cell developments, indicating the increasing number of allogenic adult stem-cell therapies coming into clinical trials to treat autoimmune diseases and orthopedic injuries. The greatest challenge facing stem cells is first to prove their efficacy in clinics and then to make manufacturing costs acceptable. Prather warns: “Cost may be a roadblock especially with autologous stem-cell therapies. However, with allogenic therapies, big pharma will soon become more involved and may offer some automated solutions here to address this issue. This will lead in the next decade, to many more adult stem-cell–based products on the market to treat autoimmune disease, as well as orthopedic and cardiac injury.”

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5.) Hohlbaum, AM 2007. Skerra A. Anticalins: The Lipocalin Family As a Novel Protein Scaffold for the Development of Next Generation Immunotherapeutics. Exp. Rev. of Clin. Immunol. 3:491-501.

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11.) Firbas, C. 2006. Immunogenicity and Safety of a Novel Therapeutic Hepatitis C Virus (HCV) Peptide Vaccine: A Randomized, Placebo Controlled Trial for Dose Optimization in 128 Healthy Subjects. Vaccine 24:4343-4353.

12.) Riedl, K, and A. von Gabain. 2007. IC31 and IC30, Novel Types of Vaccine Adjuvant Based on Peptide Delivery Systems. Expert Rev. Vaccines. 6:741-746.

13.) Stem Cell Market Analysis Fact Sheet 2008..

14.) Laslett, AL. 2007. Transcriptional Analysis of Early Lineage Commitment in Human Embryonic Stem Cells. BMC Dev. Biol. 7:12-16.

15.) Skottman, H, S Narkilahti, and O. Hovatta. 2007. Challenges and Approaches to the Culture of Pluripotent Human Embryonic Stem Cells. Regen. Med. 2:265-273.

16.) Strulovici, Y. 2007. Human Embryonic Stem Cells and Gene Therapy. Mol. Ther. 15:850-866.

17.) Le Blanc, K, and O. Ringden. 2005. Immunobiology of Human Mesenchymal Stem Cells and Future Use in Hematopoietic Stem Cell Transplantation. Biol. Blood Marrow Transplant. 1:321-334.

18.) Pittenger, MF, and BJ. Martin. 2004. Mesenchymal Stem Cells and Their Potential As Cardiac Therapeutics. Cir. Res. 95:9-20.