Chapter 1
Early Recombinant Protein Therapeutics

Pierre De Meyts1,2,3

1Department of Cell Signalling, de Duve Institute, Catholic University of Louvain, Avenue Hippocrate 75, 1200, Brussels, Belgium

2De Meyts R&D Consulting, Avenue Reine Astrid 42, 1950, Kraainem, Belgium

3Global Research External Affairs, Novo Nordisk A/S, 2760, Måløv, Denmark

1.1 Introduction

The successful purification of pancreatic insulin by Frederick Banting, Charles Best, and James Collip in the laboratory of John McLeod at the University of Toronto in the summer of 1921 [1-3], as reviewed in the magistral book of Bliss [4], ushered in the era of protein therapeutics. Banting and McLeod received the Nobel Prize in Physiology or Medicine in 1923. The discovery of insulin was truly a miracle for patients with Type 1 diabetes, for whom the only alternative to a quick death from ketoacidosis was the slow death by starvation on the low-calorie diet prescribed by Allen of the Rockefeller Institute [5-7]. Insulin went into immediate industrial production (from bovine or porcine pancreata) from the Connaught laboratories of the University of Toronto and, under license from the University of Toronto by Eli Lilly and Co. in the United States, by the Danish companies Nordisk Insulin Laboratorium and Novo (who merged in 1989 as Novo Nordisk), and by the German company Hoechst (now Sanofi), all of which remain the major players in the insulin business today.

Insulin also turned out to be a blessing for scientists interested in protein structure. It was the first protein to be sequenced [8, 9], earning Fred Sanger his first Nobel Prize in 1958. It was the first protein to be assembled by total peptide synthesis [10-14]. It was the first peptide hormone to have its minute blood levels measured by radioimmunoassay [15], earning Rosalyn Yalow the Nobel Prize in Physiology or Medicine in 1977. The structure of insulin was solved by X-ray crystallography in 1969 by Nobel Laureate Dorothy Hodgkin and her team in Oxford [16], providing a rationale for detailed structure-activity relationships studies [17] and, later, for protein engineering of insulin and insulin analogs.

For about 60 years after the discovery of insulin, major therapeutic advances were in formulation to improve pharmacokinetic and pharmacodynamic (PK/PD) properties and provide longer acting insulins, and in purification (reviewed in Ref. [18]). The introduction of the first insulin injection pen in 1985 (Novopen) made insulin treatment somewhat more bearable for diabetic patients.

In 1982, insulin once again was at the forefront of a therapeutic revolution by becoming the first DNA recombinant protein therapeutics on the market (human insulin, Humulin by Eli Lilly), kickstarting the biotechnology era. By 2008, 130 protein therapeutics (of which 95 were produced by genetic engineering) had been approved by the US Food and Drug Administration (FDA) [19], and in 2016, 206 [20]. These comprise hormones, interferons, interleukins, hematopoietic growth factors, tumor necrosis factors, blood clotting factors, thrombolytic drugs, enzymes, monoclonal antibodies, and vaccines.

In this introductory chapter, I will attempt to retrace the pioneering early steps in the development of recombinant protein therapeutics.

1.2 The Birth of Genetic Engineering

The term "molecular biology" is said to have been coined in 1938 by Warren Weaver, head of the Division of Natural Sciences at the Rockefeller Foundation. While the field developed since the 1930s, it got a major impetus in 1953 with the discovery of the double-helical structure of DNA by Watson and Crick [21, 22], who deduced from it the mechanism of genetic self-duplication. For this achievement, Watson and Crick were awarded the Nobel Prize in Physiology or Medicine in 1962.

While studying the structure, function, and replication of the genes of simian virus 40 (SV40), Paul Berg of Stanford University had the idea in the early 1970s that viral DNA could be used to transduce inserted nonviral genes into mammalian cells. He and his colleagues succeeded in developing a general way to join two DNAs together in vitro, a process called DNA recombination. This involved synthesizing cohesive ends onto the end of DNA segments and covalently joining them in vitro using DNA ligase. They succeeded in inserting both lambda phage genes and the galactose operon of Escherichia coli into circular SV40 DNA [23]. Recombinant DNA technology was born. Paul Berg received the Nobel Prize in Chemistry in 1980 for this work, shared with Walter Gilbert and Fred Sanger (his second Nobel Prize) for their work on sequencing DNA methods. Interestingly, this landmark paper does not report successful expression of the recombinant DNA into mammalian cells (in part due to biohazard concerns), but Berg and colleagues later developed suitable vectors for this purpose (Figure 1.1) [24].

Figure 1.1 Paul Berg's construction of hybrid genome.

(From his speech: The Nobel Prize in Chemistry 1980. Nobelprize.org. Nobel Media AB 2014. Web. 12 Jan 2017. http://www.nobelprize.org/nobel_prizes/chemistry/laureates/1980/ [24].)

Berg's very basic goal was to insert bacterial, viral, and simple eukaryotic genes into mammalian cells, in order to understand better how human genes are organized and function. What triggered the rise and explosive growth of the biotechnological industry was a different postulate: how to transduce mammalian genes encoding proteins of therapeutic importance into bacteria or simple eukaryotes (and eventually mammalian cells). The key experiments toward this end were done by a team of scientists that included Stanlry N. Cohen from Stanford University, as well as Herbert Boyer and Howard Goodman from the University of California, San Francisco (UCSF), who were to become major players in the nascent biotechnology industry [25, 26].

They transferred and expressed frog ribosomal DNA into bacterial cells using a constructed plasmid vector, pSC101. This plasmid contained a single site for the restriction enzyme EcoRI and a gene for tetracycline resistance. EcoRI was used to cut the frog DNA into small fragments, which were combined with the plasmid that had also been cleaved with EcoRI. The aligned sticky ends of the DNA fragments were joined using DNA ligase. The plasmids were then transferred into E. coli and plated onto a growth medium containing tetracycline. The cells that incorporated the plasmid carrying the tetracycline resistance gene grew and formed colonies of bacteria, some of which carried the frog ribosomal RNA gene. The colonies were shown to express frog ribosomal DNA.

This led to the very first biotechnology patent granted to Cohen and Boyer in 1980, to the Wolf Prize in Medicine in 1981 and the National Medal of Science in 1988 to Cohen, and to the Lasker Award in 1980 and National Medal of Science in 1990 to Boyer.

Berg Boyer and Cohen with other leading molecular biologists raised concern in 1974 about the potential biohazards of recombinant DNA [27], and organized the influential Asilomar Conference in February 1975, which resulted in stringent National Institutes of Health (NIH) guidelines for recombinant DNA work in June 1976; however, these were later relaxed when the technology became more familiar.

Herbert Boyer made a bold move in April 1976 by founding the biotechnology company Genentech in South San Francisco with a young venture capitalist Robert A. Swanson. Genentech to this day (acquired by Roche, Switzerland, in 2009) remains one of the most successful biotech companies. Since 1976, more than 2000 such companies have been founded, and major pharmaceutical companies have subsequently strived to become more biotechnologically oriented.

1.3 Recombinant Human Insulin

1.3.1 The Race to Clone the Human Insulin Gene and to Produce Human Recombinant Insulin

The race to produce the first recombinant protein therapeutics has been vividly described in the excellent book of Hall [28]. By 1976, Eli Lilly and Co. became concerned that the supply of animal pancreata would become insufficient at some point in the future to meet the needs of diabetic patients worldwide. This was supported by a report of the National Diabetes Advisory Board published 2 years later [29]. Lilly was aware of the promise of genetic engineering and had established an in-house group of scientists to evaluate its possibilities.

Forty years ago, in May 1976, Lilly convened one of its periodic academia-industry symposia (the 16th since 1922), focused this time on the theme of making insulin by genetic engineering. Leading molecular biologists and insulin researchers from all over the United States were invited: Donald F. Steiner (the discoverer of proinsulin [30]) and Shu Jin Chan from the University of Chicago, Grady Saunders and Peter Lomedico from University of Texas, William J. Rutter, Raymond Pictet, and Howard M. Goodman from UCSF, and William (Bill) Chick, Argiris Efstratiadis, and Walter Gilbert (who would later become a co-winner of the 1980 Nobel Prize in Chemistry) from Harvard University.

Bill Chick presented his results with establishing an insulin-producing cell line from an irradiated rat insulinoma, which became an obvious tool for attempting to isolate the rat insulin gene (rat and mice have two, in fact). The race was on [28].

The following year, Axel Ullrich and colleagues in the UCSF team led by Bill Rutter and Howard Goodman reported the construction of recombinant...