Chemotherapy
without side effects?
New drugs
that target the microbiological mechanisms that tumor cells use to grow
may provide a more successful and gentle chemotherapy experience.
Current chemotherapy
agents target all fast growing cells. That means that hair, nail and
other healthy tissue are just as much a target as the tumor cells. The
hope is that the cancer will be more damaged by the treatments than the
rest of the patient. Thankfully, this is usually the case, but there are
instances where the damage to the heart and other organs is so severe
that the treatments need to be discontinued.
If specific
cells could be targeted, the cytotoxic side effects that are associated
with chemotherapy could be eliminated.
Discoveries
in tumor microbiology are creating these drug therapies based on targeting
specific cells. Breakthroughs in the field of molecular biology have lead
to pharmacological agents that target areas found only on the cancer cells.
Drugs based on these findings are being investigated. They interfere with
the 'normal' functions of tumor cells. Proliferation, angiogenesis and
metastasis are the leading areas of vunerability being explored in the
cancer cell.
Proliferation
can be interfered with by drugs that target the growth factor receptors
and HER-2/neu receptors on cancer cells. This prevents the cells from
continuing their abnormal growth patterns. In some cases the drugs prevent
the drug from reproducing and eliminate the tumor. Many of these have
been tested on animal models and in the lab and some are now entering
clinical trials for humans. One, herceptin,
which targets HER-2/neu receptors has been approved and has made a major
impact on the success of breast cancer treatment.
The vascular
endothelial growth factor receptor and the basic fibroblast growth factor
receptor are necessary for angiogenesis. Tumors require a very rich blood
supply and blocking these receptors prevents the tumor from establishing
the food supply that it needs.
Onyx Pharmaceuticals
and Bayer announced trials for a drug that targets the oncogenic GTP-binding
protein Ras. The ras pathway sends signals that cause cells to grow and
reproduce. A mutated gene in the pathway can cause uncontrolled cell proliferation,
leading to tumor growth.
Cyclin-dependent
kinases and protein kinase C which are involved in proliferation and drug
resistance, and matrix metalloproteinases and angiogenin, which assist
in angiogenesis and metastasis are other areas being looked at for targeted
drug therapies.
What these
complicated and hard to pronounce terms have in common are the hope for
future generations of effective and less toxic chemotherapy drugs.
July 25, 2000
Last
updated April 1, 2006
Elsewhere
on the Web:
Doctors
pioneer new chemotherapy treatment to reduce side-effects
Preventing
Chemotherapy Toxicities And Other Issues On Drugs Used In Oncology
Treatment
by Breast Cancer Stage
