EXECUTIVE SUMMARY
This report shows that far from being just a fashionable buzz term,
systems biology is fundamentally changing the practice of biology and has
began transforming the way drugs are discovered and developed.
The report reviews the "4 Ms" of systems biology (measurement, mining,
modeling, and manipulation of data) and the ways in which its
practitioners are seeking to deliver the "3 Ps" of medicine (predictive,
preventive and personalised drugs).
Systems biology has both experimental and computational sides and ideally
involves an iterative process in which both sides constantly inform one
another. In industry as well as academia, discovery science - the
experimental side of systems biology - has already generated vast amounts
of data. The past decade has seen the ascendance of high-throughput
methods for measuring the global expression of different biological
components - genomics, pharmacogenomics, transcriptomics, proteomics,
glycomics, metabolomics. Systems biology has provided the means to
integrate and make sense of the "omics" data, by using it to analyse and
simulate pathways, cells, tissues, organs and disease mechanisms.
Chapter 2 reviews the types of systems biology model that are currently
in use and the software tools used to create and manipulate them.
Because of their predictive power, working models of healthy and diseased
systems should greatly expedite the processes of drug target
identification, drug development, disease therapy, and diagnostics by
focusing attention on particular molecules and pathways, and eliminating
unnecessary tests and other procedures.
Despite the ongoing data explosion in biology, complete information is
seldom available on any system, which means that most models are
stochastic rather than deterministic. The parameters required by most
biological models are not computed directly, but are estimated by means
of repeated simulations called Monte Carlo methods.
The current practice is to build a systems biology model in steps "top
down" based on human intuition, knowledge, and assumptions. There is no
guaranteee that this yields accurate models, but it can yield complex
ones that are expensive to develop. Alternative data-driven approaches
include constrained models (where only a limited range of parameter
values are allowed), the application of pattern recognition-type
technologies to differential displays of microarray data, and other
attempts to "reverse-engineer" models from the observed data (attempts
which mostly need a great deal of computing power).
Database integration is one of the essential prerequisites of successful
model building. More definite knowledge about a particular pathway means
that it will be easier to model, and that the model will be more accurate
to start with. An increasing number of model building tools include
integrated databases of genomic, proteomic, and/or other information, or
provide close links to such data. It is also important that models can
be shared with other investigators. A uniform systems biology markup
language (SBML) has therefore been developed to facilitate data
interchange. Other compatible markup languages are being developed in
areas such as genomics (e.g. MAGE-ML) and proteomics (e.g. PEML, MIML)
which will expedite the acquisition of data by systems biology modellers.
The US FDA has long been ahead of the industry in use of models: it
employs a growing number of pharmacometric experts who are very familiar
with this technology. Modelling and simulation are actually encouraged
in some of its recently published guidances (e.g. population
pharmacokinetics, exposure-response guidances) and the Agency has already
agreed to reduced clinical trial requirements when provided with
satisfactory simulation data.
Systems biology directly addresses the challenges and bottlenecks in
pharmaceutical drug discovery and development today. One of the most
significant challenges are high compound attrition rates; drugs prove
ineffective or toxic and fail due to poor understanding of the biological
system they attempt to affect. Systems biology approaches provide a
means for identifying pathways that are critical to disease, and
discovering both on- and off-target effects of compounds.
It is not surprising therefore that while academic, government and
non-profit institutions are making ambitious plans for long-term project
work in systems biology requiring an unprecedented new level of
collaboration between scientists from diverse disciplines, companies have
already began applying their existing technological skills relevant to
systems biology to pharmaceutical development. They are playing to their
strengths and emphasising either the experimental ot the computational
side. Chapter 3 reveals how drug discovery and development is being
expedited by companies applying proprietary technologies in systems
biology to the discovery and validation of biomarkers and drug targets in
a range of complex diseases (metabolic diseases, cancer, cardiovascular
diseases, CNS disorders, inflammatory and autoimmune diseases), and to
drug toxicity prediction.
Currently few companies have collaborations involving the sharing of
enabling experimental and computational technologies in systems biology.
Future progress in systems biology will require integration of diverse
technologies and it is therefore imperative that all companies developing
drugs and diagnostics start formulating their strategies in this area
now.