Biology Reference
In-Depth Information
Chapter 19
Ribonoscopy and “Theragnostics”
The combined field of researches in drug therapy, diagnostics, and prognostics may
be referred to as “theragnostics.” Some investigators have already coined the word
“theranostics” to refer to the same but I prefer theragnostics over theranostics
because the second stem in the latter word, “nostics,” has no etymological basis.
The main purpose of this section is to propose that ribonoscopy will find important
applications in
theragnostics
.
According to Bain and Company (2007), the cost of developing a new drug is
estimated to be $1.7 billion and it takes 12-16 years to complete a drug develop-
ment process from the compound discovery stage to marketing. The overall attrition
rate for developing a drug is calculated to be 10,000:1. According to another survey,
the USA invested a total of $25 billion in 2000 on the research and development for
pharmaceuticals and produced only 11 new drugs on the market in that year, costing
the US pharmaceutical industry $2.3 billion per new drug.
In addition, once a drug is approved by FDA, the success rate of drug treatment
is only 30-60% (Ingleman-Sundberg 2010). In other words, only about 50% of the
patients treated with drugs respond favorably. The success rate (R
suc
) of a drug is
calculated as the percentage of the number of responders (N
res
) over the total
number (N
tot
) of the patients treated with a drug as explained in Fig.
19.1
.
There are two ways to improve the success rate of drug therapy - (1) to improve
the efficacy of drugs so that more patients respond to them, and (2) to develop the
companion diagnostics
and
prognostic tools
to identify those patients who are most
likely to respond to drugs, thereby lowering the number of nonresponders in clinical
trials. When these two approaches are combined into one package, we have the
example of what has been referred to as “theragnostics” or “theranostics” defined
by Wikipedia as the combination of diagnostics and therapy in order to test patients
“for possible reaction to taking a new medication and to tailor a treatment for them
based on the test results” (Wikipedia 2010).
The use of
ribonoscopy
as a theragnostic tool is illustrated in Table
19.1
, where
the top panel depicts a hypothetical set of three RNA trajectories (i.e., t-ribons) each
corresponding to one of the three cell types - normal (A), diseased and drug
resistant (B), and diseased and drug responding (C). The
x
-axis records time in
