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 Two are better than one
October 2010
SHARING OPTIONS:
The age-old saying is that two heads are better than one,
and it is proving to be true in drug research and development. Developing targeted therapies and companion diagnostics is
all about discovering and validating clinical biomarkers. PCR, microarrays and
expression profiling are being used to improve the sensitivity and selectivity
of companion diagnostics.
“The use of molecular diagnostics for detecting variations
such as mutations or amplifications of specific genes, in order to target
therapies to patients who are most likely to benefit, is becoming increasingly
common in anticancer drug development,” Jocelyn August, a senior analyst at San
Diego, Calif.-based Sagient Research Systems, says in a recent issue in the
journal Nature.
Eli Lilly & Co.
Tiffany Olson, vice president of diagnostics at Eli Lilly
& Co., says the company has announced plans to build a diagnostics
capability.
“A big part of the company’s innovation strategy is
providing improved outcomes for individual patients, which can be achieved through
tailored therapies,” she says.
“This offers many advantages from earlier understanding of
efficacy and target populations to potentially lower development costs and
improve outcomes for individual patients,” she says. “We see opportunities for
companion diagnostics across approximately 40 percent of our portfolio of
pipeline molecules, including many in cancer.”
In companion diagnostics, there are two primary categories: in
vitro and in vivo diagnostic testing.
“Tests done in vitro—literally,
‘in glass’—are performed on specimens taken from the human body to diagnose
disease or conditions,” Olson explains. “Tests would include blood glucose
testing and genetic screening. In-vivo tests use diagnostics to assess health ‘within the living body,’ such
as a CAT scan or MRI. Other specific technologies that may be used include PCR,
microarrays and expression profiling, to name a few.”
Olson also points out that there are several technologies
that enable the development of biomarkers into companion diagnostics. PCR,
microarrays and expression profiling are being used to improve the sensitivity
and selectivity of companion diagnostics.
Next-generation sequencing and
proteomics are two other growing areas of interest.
“Biomarkers that are validated have the ability to lead to
safer and more effective products, especially when developed into a companion
diagnostic,” she says.
For companies like Lilly that are developing companion
diagnostics, there are plenty of challenges on the path to success.
“There is a lot of movement within and among companies as
they buy, build and partner to access diagnostic capabilities,” Olson says.
“The market is evolving rapidly, so we’ll be ramping up quickly while ensuring
total quality.”
To be on the leading edge of companion diagnostics could
prove to be a boon to a drug company’s drug pipeline and revenue stream.
Still, there are plenty of road bumps along the way, as diagnostics
have a different FDA review and approval process from pharmaceuticals, with
different offices in the agency having regulatory oversight. Currently, only
draft guidance is available, Olson notes.
“Due to the momentum that diagnostics are gaining, the FDA
has announced plans to make a guidance document available at the end of the
year to clarify regulatory expectations,” she says.
“Diagnostic biomarkers are a measure to help determine the
characteristics of a particular patient’s disease in order to determine the
best treatment option for that specific patient,” she says. “The development
and validation of biomarkers are the fundamentals for developing a companion
diagnostic.”
Olson also points out that there are a select lucky few
biomarkers that will “grow up” to be a diagnostic, and a subset of these that will
be companion diagnostics.
“By co-developing and then launching both a pharmaceutical
and a diagnostic, our goal is to provide customers with a better benefit-risk
profile and lower total healthcare costs,” she says.
Genentech Inc.
Based in South San Francisco, Calif., Genentech’s scientists
and doctors continue to research the basic biology of cancer and look for
biomarkers that show how certain pathways are important for the growth of
particular cancers.
“Finding new biomarkers that can be measured with companion
diagnostics could help us determine what pathways are important to target with
new investigational agents,” says Amy Berry, a Genentech spokeswoman.
According to Berry, biomarkers are an important part of
cancer research and personalized medicine, “but they are only important if they
help us improve the care patients receive. We believe in the potential for biomarkers and companion
diagnostics to personalize medicine and help us develop new potential medicines
for people with cancer.At Genentech, all new agents in our pipeline include a
corresponding biomarker program that may help us determine which people are the
best candidates for clinical trials.”
Moreover, the technology used in a given companion
diagnostic depends on what the test is designed to measure, Berry adds.
“For example, to measure the amount of protein on a cancer
cell surface, immunohistochemistry (IHC) can be used to detect the protein
itself or fluorescent in situ
hybridization (FISH) can measure the number of copies of a gene present,” she
says. “When detecting specific mutations in the cancer cell DNA, often
polymerase chain reaction (PCR)-based techniques are used.”
Berry also says the field of companion diagnostics is full
of new developments and has a bright future on the horizon.
“One of the
best-known examples of how a biomarker and companion diagnostic can work to
personalize cancer treatment was pioneered at Genentech, and involves measuring
the amount of the HER2 protein or the number of corresponding genes,” Berry
says. “Women with HER2-postive breast cancer have a more aggressive form of the
disease, but also have the best chance of responding to medicines that target HER2,
like Herceptin. About a quarter of all breast cancers are HER2-positive.”
Roche/Genentech
and Plexxikon are co-developing RG7204 (PLX4032), a first-in-class
investigational molecule called a BRAF inhibitor, designed to block the
activity of the mutated form of the BRAF protein.
Another advantage of companion diagnostics is the fact that
they can lead to safer and more effective products. For example, Berry notes
that a companion diagnostic could help identify who and who is not an
appropriate candidate for a particular medicine.
Though most all cancers have common characteristics, Berry
notes that there is no “one-size-fits-all” solution to biomarker discovery
because each drug and disease are different and unique. “In order to determine which patients should and should not receive a
certain medicine, biomarkers and companion diagnostics must be rigorously
tested and validated in clinical studies,” she concludes. Code: E101027 Back  |
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