Robert S. Langer
Wolf Prize Laureate in Chemistry 2013
Robert S. Langer
Affiliation at the time of the award:
“for innovations in polymer chemistry that have had profound impact on medicine, particularly in the areas of drug delivery and tissue engineering”.
Robert Langer is primarily responsible for innovations in polymer chemistry that have had profound impact on medicine, particularly in the areas of drug delivery and tissue engineering.
The last 40 years has seen a rapid increase in the availability of sophisticated macromolecular drugs, such as oligopeptides, proteins, polysaccharides, and nucleic acids, with high potency but limited stability, often surviving for only minutes under physiological conditions. The promise of these agents both for biological research and for medical applications – ranging from vaccination to gene therapy to treatment of brain cancer and schizophrenia – was limited by the problem of delivering them intact to the tissues where they were needed, at the proper rate, and over the required period of time, which can range up to many months.
Langer was convinced that it would be possible to design entirely new biodegradable polymers that could meet the simultaneous daunting challenges of protecting a sensitive drug until it was needed, delivering it to the target tissue, and releasing it slowly and steadily over a very long time. It was of course essential that both these new polymers and their degradation products be biocompatible.
After long cycles of fundamental design and experimentation Langer was able to achieve this goal by tailoring new polymers with very low affinity for water that were joined through links that could be cleaved by water, but not by enzymes whose activity would vary from patient to patient and over time in an individual patient. Low water affinity serves both to protect the macromolecular cargo from degradation and to insure surface erosion of the particle at a rate that can be programmed by its degree of water affinity and by its shape. He was successful in creating a new class of polyanhydrides with aromatic heads and aliphatic tails, in developing the first procedures for synthesizing these polymers, and in shaping polymer-drug aggregates to achieve appropriate therapeutic deliveries. For example, Lupron DepotⓇ is injected as a suspension of tiny particles to achieve steady delivery of hormone analogues for up to four months in treating prostate cancer and endometriosis, while GliadelⓇ wafers are surgically implanted at the site of a brain tumor for long-term, short-range delivery of a highly toxic drug.
Langer has built on this success to design and implement polymeric drug delivery systems that effect controlled drug release in response to magnetic, ultrasonic, or biological stimuli.
In addition to his pioneering work on designing polymers for drug delivery Langer has been the leader in designing bioabsorbable polymers to serve as scaffolds for holding mammalian cells in place during tissue reconstruction. This work led to the first “artificial skin” based on synthetic polymers that was approved by the U.S. Food and Drug Administration