Dr. Sidney Pestka — A Father of Invention

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Kim Ribbink

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Dr. Sidney Pestka — A Father of Invention by Kim Ribbink With a wealth of discoveries and other scientific achievements to his name, Sidney Pestka, Ph.D., has positioned his company — PBL Biomedical Laboratories and its subsidiary PBL Therapeutics — to lead the charge in cutting-edge research. Sidney Pestka, Ph.D., has been called the father of the interferon, but he argues that such labels need to be kept in perspective, since discoveries emerge from the countless efforts of those who have come before. Modesty aside, Dr. Pestka’s discoveries and innovations have led to cures for certain cancers and viral diseases and have opened a world of possibilities for the prevention, diagnosis, and cure of many life-threatening conditions. Over the years, Dr. Pestka has elucidated the work begun by Alick Isaacs and Jean Lindemann, who in 1957 discovered interferon, a biological response modifier that stimulates the growth of certain disease-fighting blood cells in the immune system that help to combat cancer and other diseases. A Voyage of Discovery From experimentations in the kitchen at home as a pre-teen to detailed and highly valuable drug research, Dr. Pestka has always been thrilled by the unlimited possibilities that research offers. “The voyage of discovery is remarkably exciting, whether it’s the discovery of a new area in the world or trying to understand the nature of infectious disease,” he says. “Discovery is about constantly learning, and what could be more exciting. The paradox is that as we learn more and more, we recognize that we know less and less of the total.” As an undergraduate at Princeton University, where he received a B.A. in chemistry, Dr. Pestka worked in the laboratory of Professor Arthur Tobolsky, who was a renowned researcher in the field of polymers. Dr. Pestka’s path of research discovery was established in medical school at the University of Pennsylvania, where he worked in the laboratory of Joel Flaks, investigating the mechanism of action of antibiotics. Throughout his career, Dr. Pestka has been involved in some of the most cutting-edge and exciting areas of research. He worked at the National Institutes of Health (NIH) in the laboratory of Marshall Nirenberg, who won the Nobel Prize in Physiology or Medicine in 1968 when molecular biology was a nascent field. Dr. Pestka was part of the team that broke the genetic code. He went on to make additional significant discoveries during his career — in academia, at his own laboratory at the NIH, at the Roche Institute of Molecular Biology, and later still as founder of PBL Therapeutics. Among his other research achievements are: the discovery of the ribosome subunit responsible for translation; the discovery of ribosomal mechanisms of protein synthesis; the discovery of mechanisms by which some antibiotics produce misreading of the genetic message in cells; purification of interferon alphas from human cells; purification of interferon beta from human cells; discovery of the interferon alpha family of proteins; the development of RP-HPLC for protein analysis and purification; cloning of interferons; expression and production of human IFN-alpha and IFN-beta for therapeutic use; commercial large-scale, economical purification of IFN-alpha with monoclonal antibodies; first crystallization of interferon or any cytokine; medical application of interferons for viral diseases (hepatitis), cancers, and other diseases (multiple sclerosis); identification of interferon and many cytokine receptors; discovery of new interferons; discovery of new cytokines and receptors; discovery of preassembly of receptors on the surface of cells; discovery of a major protein arginine methytransferase necessary for many cellular functions; and examining protein interactions in living cells in real time by fluorescence transfer linked to confocal microscopy. Pushing Science Forward Today, as founder, chairman, and chief scientific officer of PBL Biomedical Laboratories and its subsidiary PBL Therapeutics, Dr. Pestka continues to lead efforts to develop interferons as therapeutic treatment options for cancer. PBL Biomedical Laboratories, which was founded in 1990, is the world’s largest manufacturer of interferons and interferon reagents for research use. All drug discovery and development work is conducted at PBL Therapeutics. PBL’s origins are somewhat unusual. According to Dr. Pestka, The University of Medicine and Dentistry of New Jersey (UMDNJ), the nation’s largest public university of the health sciences, requested that he establish a company to demonstrate that advances in educational institutions could be translated into jobs and advance the economy within the state. “The idea was that by continuing to demonstrate its strong commitment to educational institutions, the state could stimulate the economy,” Dr. Pestka explains. “I set up the company to help prove that point.” Dr. Pestka believes interferons will play a major role in the next generation of novel antitumor and antiviral therapies. PBL produces about 150 products, including human, mouse, rat, monkey, cat, pig, cow, and sheep interferons. In addition to those, PBL carries all of the human interferons — 15 — found in the vast majority of the world’s population. Interferons today are a $6 billion market, but in 1969 when Dr. Pestka began his studies in the field, while at the Roche Institute of Molecular Biology, very little was known about them. “In 1969, the nature of interferons wasn’t known, though there was a lot of speculation,” he says. “At the time I was studying how proteins were synthesized in cells. I decided to focus on interferons to find out if I could synthesize active interferons in the test tube by the same mechanisms that cells use. This had never been accomplished before for any human protein.” Dr. Pestka speculated that because no one had been able to purify and characterize interferon, it was likely a very potent substance present only in extremely small quantities. Furthermore, he believed that if he could synthesize active interferon in the test tube he might be able to make large quantities of the molecules for therapeutic use. “Fortunately we were able to make it in the test tube,” he says. “We rapidly learned a great deal about interferons, proving that there was more than one type of interferon.” Dr. Pestka and his team at the Roche Institute decided to purify the interferons to understand what the structure was. His work revolutionized the way laboratories purify proteins. “I purified human leukocyte interferon, which is now called interferon alpha, as well as human fibroblast interferon, now called interferon beta,” he says. “This purification led to the development of a new technology, called reverse-phase high performance liquid chromatography (RP-HPLC). Today, virtually every laboratory involved in the purification of proteins uses this method for analysis and purification of proteins.” Dr. Pestka says it soon became evident that there was huge medical potential for the substance. He says through the in vitro work he and his colleagues conducted, they were able to produce the first forms of human alpha and beta interferon to be expressed and purified for therapeutic use. The result of their efforts was recombinant interferon alfa-2a, which today is approved for marketing by Roche under the tradename Roferon-A for the treatment of chronic hepatitis C, hairy cell leukemia, and AIDS-related Kaposi’s sarcoma in patients older than 18, as well as chronic phase Philadelphia chromosome (Ph) positive chronic myelogenous leukemia patients who are minimally pretreated. Roferon-A is manufactured by recombinant DNA technology that employs a genetically engineered Escherichia coli bacterium containing DNA that codes for the human protein. “We prepared recombinant interferon alfa-2a in my laboratory on Oct. 6, 1980; three months later it was used in a patient for the first time, on Jan. 15, 1981,” he says. “This was the first time a recombinant biotherapeutic was used in a patient.” The first trials using recombinant human interferon alpha, prepared by genetic engineering, were carried out with interferon prepared in Roche’s laboratories about one year ahead of any other group in the world. Dr. Pestka’s work resulted in several patents for Roche. Roche produces interferon alpha and owns the major patents in the field, which it has licensed to Schering-Plough and Amgen. The company also licensed interferon beta to a number of companies, including Biogen, which markets it as Avonex, and Berlex and Serono, all for the treatment of multiple sclerosis. Interferon has proven to be a powerful agent in the treatment of many diseases. Most recently, data have shown interferon is effective in preventing the SARS virus from replicating. Dr. Pestka says PBL has the technology to prevent SARS with local treatment or to stop the debilitating aspect of the disease by getting interferon into the lungs. While PBL has the technology to do this, the company now needs to obtain FDA approval for this indication. “Navigating the regulatory environment is a challenge for small companies,” he says. “The company has products that are unique and have enormous potential, but at the same time it is an arduous and expensive process to get these new products to patients so they can do some good. I doubt that I could repeat the feat accomplished from Oct. 6, 1980, to Jan. 15, 1981, to obtain an IND in 101 days even if we had unlimited resources.” A Promising Platform Dr. Pestka says his early research to purify human leukocyte interferons showed that interferon alpha consisted of a family of proteins and that the members of the interferon alpha family have unique individual profiles and characteristics. “This discovery is turning out to be very important and one that PBL has been exploring,” he says. Dr. Pestka says because essentially only one of the 12 recombinant alpha species made by human cells has been used clinically, there is a great deal of potential to use the other 11 as well as new interferons for treating diseases. Several other companies, in addition to his, are exploring these options. One of the therapeutic areas with a great deal of potential is cancer. And one way interferon helps combat cancer is by altering the surface of the tumor cells. “The idea is to inject interferon into the tumors and convert the tumors, in situ, into vaccines,” Dr. Pestka says. “For example, interferons are the only proven treatment in double-blind controlled studies that have shown that patients with advanced malignant melanoma can live longer, about 50% longer.” PBL already has developed two innovative solutions to overcome the toxic side effects caused by the systemic delivery of interferon in the quest to bring the company’s first cancer drug to market. The first is PBL’s drug-discovery platform, which enables the company to identify a virtually unlimited number of interferon variants that are produced naturally in cancer cells, some of which are 20 times to 30 times more effective than the most common interferon used in therapy. To date, the company has discovered 50 different interferon variants. While the therapeutic future of the modified versions of interferons that PBL has discovered needs to be developed, Dr. Pestka believes there is a huge potential for human therapy. “Overall, it’s highly likely that interferons will play a major role in the next generation of novel antitumor and antiviral therapies,” he says. “In the future, interferons will be used to prevent many viral diseases.” Second is a sustained-release protein delivery technology called SuRe-PD. PBL prepares the interferon variants — or ultra interferons — and uses SuRe-PD to deliver interferon directly to tumors for release slowly over time. A single injection can deliver interferon into virtually any tumor for 30 days. Local injection of SuRe-PD interferon into a tumor stimulates the immune system to seek out and destroy tumors and stray cancerous cells throughout the body. So far SuRe-PD has been developed in vitro and has begun to be tested in animals. Together, these two technology platforms enable the company to develop the most promising interferon and to maximize the effectiveness of this potent drug through extended-release, localized delivery. The third major aspect of PBL’s platform permits the novel radiolabeling of monoclonal antibodies (MAbs) and other cancer-targeted proteins. Through its Phosphorylation Technology, PBL genetically engineers phosphorylation sites into MAbs that can then be efficiently labeled with radiophosphate. The resulting homogenous antibodies more efficiently kill tumor cells, appear less immunogenic than MAbs radiolabeled through conventional chemical methods, are less destructive of the bone marrow, and confine the radioactive emissions largely to the tumor site and to the patient, nearly eliminating the exposure of healthcare workers and family members to the potentially harmful radioactive emissions inherent in other isotopes. PBL Therapeutics has successfully engineered and radiolabeled several monoclonal antibodies by this means. The company has assessed plasma clearance and biodistribution of these phosphorylated MAbs in small animals and has demonstrated that these MAbs maintain stability and retain radioactivity in vivo. Introducing phosphorylation sites into MAbs represents an opportunity to significantly improve upon the chemical labeling procedures currently used to target radiation to tumors. “There are about 300 monoclonal antibodies being prepared for clinical trials or that have been approved for therapy, but current methods for labeling produce heterogeneous products rather than homogenous products,” Dr. Pestka says. “PBL has been addressing this issue. We have the U.S. and worldwide patents that will provide a new method to label proteins with radioactive isotopes. This will permit the homogeneous production of radiolabeled monoclonal antibodies, with all the associated benefits of radiophosphate, and reduce the destruction of the essential bone marrow cells required for health. The National Cancer Institute, realizing this is a major advance, is supporting our research with a $1.3 million grant.” A Balanced Approach In addition to his roles at PBL, Dr. Pestka is professor and chairman of the Department of Molecular Genetics, Microbiology, and Immunology at the Robert Wood Johnson Medical School-University of Medicine and Dentistry of New Jersey. Dr. Pestka says he devotes the majority of his time to his role at the school, where he has extensive administrative duties, responsibility for several research programs, overseeing staff, teaching, and general service duties necessary in academia. “PBL has an outstanding staff so I am able to concentrate on the science rather than on the business of running the company,” Dr. Pestka says. “I try to give people the freedom to work, and they often move forward in interesting directions when given that freedom. But individuals need to have commitment and intensity in the first place. This is difficult to instill. Many of my students and fellows have reached high levels, but the internal drive has to be there.” Testament to Dr. Pestka’s leadership, recently the Department of Molecular Genetics, Microbiology and Immunology at the Robert Wood Johnson Medical School, was awarded the honor of the best research department at Robert Wood Johnson Medical School-UMDNJ. At PBL, the company continues to press forward with ambitious goals of developing interferons to treat many diseases. In the near term, PBL’s goal is to seek capital so the company can begin clinical trials. PBL Therapeutics is seeking a minimum of $10 million in equity through a private placement sale of preferred shares to fund continued development of its cancer drug clinical trials. Further down the line, the company may consider an IPO. Mid-term goals include developing the company’s three major platforms — the ultra protein technology, the sustained-release delivery of proteins, and the novel labeling of monoclonal antibodies — with potential products expected to stem from each. In addition, the company is exploring options to license its delivery technology to companies that would like to make their existing protein-based drugs more effective and to license its radiolabeling technology to companies interested in circumventing the drawbacks that complicate current radioimmunotherapy strategies. PharmaVoice welcomes comments about this article. E-mail us at feedback@pharmavoice.com. Interferons today are a $6 billion market, but in 1969 when Dr. Pestka began his studies in the field, while at the Roche Institute of Molecular Biology, very little was known about them. Bumps and Obstacles The road to discovery is paved as much with bumps as it is with successes. During his time at the Roche Institute of Molecular Biology, Dr. Sidney Pestka notes that despite his research achievements and contention that interferon would be effective as a general antiviral agent, some in the administrative hierarchy did not believe interferon would have any practical benefits. Ifound out that the head of marketing had prepared a report and came to the conclusion that there would be no interest in an antiviral therapeutic,” Dr. Pestka explains. “This was after the marketing department surveyed 100 physicians, asking them how many antivirals they were using in their practice. The answer, of course, was zero because there were no antiviral agents at that time.” Nevertheless, Dr. Pestka was able to convince others at Roche of the therapeutic value of his research. A wider and potentially more serious obstacle to his research arose in the late 1970s and early 1980s amid worldwide concern over genetic engineering. “At that time, genetic engineering and recombinant DNA technology were called cloning — though it’s not what we call cloning today,” he says. “Many people were frightened by the concept of ‘cloning’ — incorporating human DNA into bacteria to produce new protein biotherapeutics — and thus were vociferously against cloning. There were wild visions of what might happen. Nevertheless, the National Institutes of Health and other organizations provided safety guidelines that allowed researchers to continue to work. I was at Roche Institute at the time, and although companies weren’t strictly required to follow those guidelines, virtually every investigator and every institution decided to do so. Those guidelines made the work possible.” Still today, many obstacles remain for developing interferons into therapies. A major difficulty is producing interferons under GMP specifications and performing the appropriate clinical trials so they can be used in patients, Dr. Pestka says. This is complicated by the fact that there are many different interferons, and each will need to be independently produced and studied in accordance with regulatory rules. “This is an enormous task and no company has made all the interferons for human use,” Dr. Pestka says. “PBL has all the interferons, probably the only company in the world that does, but not for human use.” Further complicating the situation is that interferons are generally species specific, which means testing them in small mammals is not usually useful, and testing in primates is extremely expensive. “Ideally, it would be useful to have the ability to test all interferons in patients,” the researcher says. “Until this is done, humanity is going to be deprived of the opportunity to take advantage of the efficient and effective use of interferons to treat a multitude of diseases.” November 2003 Road to Discovery SIDNEY PESTKA — resume 1990-Present. Chairman and chief scientific officer, PBL Biomedical Laboratories, Piscataway, N.J. 1986-Present. Professor and chairman, Department of Molecular Genetics, Microbiology, and Immunology, University of Medicine & Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, N.J. 1990-Present. Professor of medicine, Department of Medicine, University of Medicine & Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, N.J. 1972-Present. Adjunct professor of pathology, College of Physicians and Surgeons, Columbia University, New York 1969-1986. Full member and head of Laboratory of Molecular Genetics, Department of Biochemistry, Roche Institute of Molecular Biology, Nutley, N.J. 1966-1969. National Cancer Institute, National Institutes of Health, independent group with research program in protein synthesis, Bethesda, Md. 1962-1966. Laboratory of Dr. Marshall W. Nirenberg, National Heart Institute, National Institutes of Health, research in biochemical genetics, the genetic code, protein synthesis, and ribosome function, Bethesda, Md. 1960-1961. Research on streptomycin dependence, Dept. of Biochemistry, University of Pennsylvania, Philadelphia, under Professor Joel G. Flaks 1959 (summer). Research in pulmonary pharmacology, Dept. of Pharmacology, University of Pennsylvania, Philadelphia, under Professor Domingo M. Aviado 1955-1957. Research assistant, Chemistry Dept., Princeton University, Princeton, N.J., under Professor Arthur V. Tobolsky, mechanical and viscoelastic properties of synthetic and natural polymers Education 1953-1957. B.A., Summa Cum Laude, Chemistry, Princeton University, Princeton, N.J. 1957-1961. M.D., University of Pennsylvania, Philadelphia 1961-1962. Internship, Department of Pediatrics and Department of Medicine, Baltimore City Hospitals, Baltimore Honors and Awards 1977 — The Selman A. Waksman Award in Microbiology 1986-1987 — Foundation of Microbology Lecturer, under the auspices of the American Society for Microbiology 1987 — Honorary Doctor of Science, Rider University 1986 — Mayer Lecture in the Life Sciences, Massachusetts Institute of Technology 1993 — Induction into the New Jersey Inventors Hall of Fame 2001 — Milstein Award, International Society for Interferon and Cytokine Research 2002 — Resolution by the Mayor and Council of North Caldwell, N.J., for contributions to research and to public service as member of the North Caldwell Board of Health since 1973 (VP, 1975-1977; president 1977-1979; 1985-1990) 2002 — Fleet Bank Award for Technological Innovation 2002 — National Medal of Technology, Award from President George W. Bush for pioneering achievements that led to the development of the biotechnology industry, to the first recombinant interferons, and for basic scientific discoveries in chemistry, biochemistry, genetic engineering, and molecular biology 2002 — Medical Excellence Award for contributions to the treatment of multiple sclerosis Most recently, data have shown interferon is effective in preventing the SARS virus from replicating. ‘Father’ Knows Best In an exclusive interview with PharmaVOICE, Dr. Sidney Pestka talks about his goals, accomplishments, and motivations as he enters his fifth decade of research. What in the biopharmaceutical world most inspires you? What matters most to me is the opportunity to make a major impact on diseases — their prevention, diagnosis, and therapy. Prevention is the first goal. Through research and development of interferon there is the potential to prevent certain cancers, such as liver cancer. Interferon already is the major treatment for hepatitis B and hepatitis C. More than 500 million people have chronic hepatitis B and a substantial amount of these people go on to develop liver cancer, probably around 3%. By treating hepatitis with interferon, the development of liver cancer can be prevented. After prevention, the next goal would be the diagnostic testing and treatment of diseases. Biotherapeutics will have a major impact on these areas in the next few years. PBL has plans for how it can use interferons in this area and has done quite a bit of work with people at the National Cancer Institute on this. What do you regard as the biggest challenges facing drug development today, particularly in the area of oncology? There are a number of areas that need to be addressed to enable new agents to get into the clinic. One of the major problems relates to institutional review board approvals, which are not standardized from company to company, from academic center to academic center, and from company to academia. There has to be some coordination of clinical agreements between these entities so that years aren’t wasted in paperwork. Another major issue is getting potential new drugs approved by regulatory agencies. For academic institutions and small companies this is an enormous challenge because of the high cost of manufacturing and regulatory requirements. There are lots of molecules that are in academic centers but the investigators can’t get these agents into clinical trials because they don’t have the ability or the resources to fund these efforts. There is no academic center in the United States that has a full cGMP manufacturing facility. I submitted a proposal from the Robert Wood Johnson Medical School-UMDNJ to the state of New Jersey to create the first full cGMP facility at an academic center in the United States. If it’s approved we can get started in about two years. Another challenge with both small and large molecules is proper targeting. If all agents could be targeted to specific tissues to treat a disease, or tumors in the case of cancers, efficacy would be increased, side effects could be substantially reduced, and pharmaceuticals wouldn’t be floating around the body damaging tissues and organs. PBL is working on ways to keep interferon in tumor cells, which would be a dramatic improvement in treatment. Do you have a particular goal in mind with regard to research going forward? One of my goals would be to make a major dent in cancer prevention, therapy, and diagnostics. I’d like to see this happen in the next few years, not decades. And I’d like to see similar achievements in the prevention, treatment, and diagnosis of viral diseases. One of my concerns is that general funding from the federal government for research is not keeping pace with the needs of our society. Finding well-trained students in the areas we need to fill has been difficult. There is not sufficient scientific training of students in elementary and secondary schools. We must get students interested in science and research early on in their lives if the United States is going to be competitive in the future. You have received numerous awards and been recognized for your contributions to biotechnology. what do those accolades mean to you, and how important are they to help PBL achieve its goals? It is rewarding to be recognized for these achievements that were developed from ideas that went against the dogma of the time — ideas that today have essentially become dogmas themselves. It’s particularly gratifying to get letters and calls from individuals who have benefited from new treatments I helped develop that have saved or extended their lives. The attention is beginning to have an impact for PBL in terms of interest from other companies and organizations in what we’re doing, and we look forward to translating this interest into funding so the company can move into clinical trials and develop new therapies. War on Tumors he actions of interferon alpha and interferon beta that contribute to their antitumor activity are shown in this figure. These interferons act on the tumor cells, the tumor stroma, and cells of the immune system that result in destruction of tumor cells and tumors. Interferons help identify cancer cells to the immune system by stimulating production of cell surface molecules such as MHC complex antigens, tumor-associated antigens (TAA), and costimulatory molecules. Interferon also activates cells of the immune system (cytotoxic lymphocytes, natural killer cells, macrophages, monocytes, and dendritic cells) that eliminate tumor cells throughout the body. A summary of these actions is shown in the figure. Interferon’s Anticancer Advantages nterferon alpha has multiple cancer fighting properties. When deployed by the body it activates the immune system to create, in effect, a vaccine against tumor cells. It does this by activating cell surface molecules such as the MHC complex, tumor antigens, and costimulatory molecules so that the immune system recognizes the diseased cell as a cell to be attacked. Simultaneously, interferon activates the immune system cells — cytotoxic lymphocytes, natural killer cells, macrophages, and dendritic cells — to attack these cancer cells. What results is not only a direct attack on the primary tumor, but also the “education” of the immune system, which is now equipped to find and destroy the metastatic cells that have escaped from the primary tumor. Beyond its vaccine-like properties, interferon has other effects that attack the primary cancer. Interferon has a powerful antiproliferative activity that slows the reproduction of tumor cells. As the most powerful anti-angiogenic agent known, interferon also inhibits the growth of blood vessels necessary to feed a tumor. Finally, interferon stimulates apoptosis, the death of tumor cells. Interferon recruits the powerful human immune system to act directly on tumor cells. One of the major problems in treating cancer, however, is relapse or recurrence of the disease. Many patients treated for cancer die from the disease, even after completing a “successful” course of therapy with undetectable disease for years. It is this relapse and recurrence that PBL Therapeutics will address with interferon, which acts by stimulating the immune system to seek out and destroy metastatic cancer cells dispersed throughout the body. Overall it’s highly likely that interferons will play a major role in the next generation of novel antitumor and antiviral therapies.

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