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Targeted Cancer Therapeutics
Cancer treatment is typically expensive and accompanied by a host of adverse
side effects that decrease patients' quality of life. Often, non-specific,
more broadly acting cancer therapeutic agents, including various chemotherapies
and radiotherapy, are employed as first-line and second-line therapies before more
specific, targeted therapeutics are used. Newer, targeted therapies typically
aren't tried until a patient has "failed" first- and second-line treatments,
either because of intolerable side effects or because their cancer does not respond
or has progressed.
An estimated 300 pharmaceutical and biotechnology companies are currently
developing cancer therapeutics. Several targeted biotherapeutics and small
molecule drugs have been developed and approved for patients with advanced
stages of specific types of solid tumors. These targeted medications include
Herceptin®, Avastin™, Erbitux™, Gleevec®,
Iressa®, and Tarceva™. Over the next decade, significant
growth in the number of approved targeted therapies is likely, based on the drug
pipelines of the major pharmaceutical and biotechnology companies.
These novel therapeutics are designed to block activated protein pathways that are
driving cell proliferation and tumor development. These targeted therapies are
very effective when matched with patients who have the specific target
protein for the drug in question, but are dramatically less effective when the
patient either lacks the target protein, the target protein is not in an activated form, or
there are several activated pathways contributing to tumor cell growth and the
drug in question does not impact the most critical ones.
Because cancer is such a complex disease, most of the new targeted therapies, while
extremely effective in some individual patients, have exhibited limited
effectiveness, often with response rates in the range of 10%-20%, in the general
patient population for a particular cancer. Without being able to read the map
of biological protein expression and activated protein targets in a patient's
tumor, healthcare providers are unlikely to select an effective targeted therapy
for that patient.
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