http://www.eurekalert.org/pub_releases/2004-03/aafc-lcr032604.php

In vivo cfficacy of CX-3543, a novel c-Myc oncogene inhibitor: Abstract No.
LB-243

Cancer researchers today unveiled a new small molecule drug that specifically
targets c-Myc, a key growth promoting regulator in cancers and a gene that has
escaped all efforts to control it.

William Rice, Ph.D., the presenting author on a team of scientists from Cylene
Pharmaceuticals, San Diego, Calif., said that the small molecule CX-3543
effectively reduced cMyc mRNA expression by 85 percent in colorectal tumor
animal models. The small molecule inhibited growth of prostate and pancreatic
tumor models in mice as well. Each of those tumor cell types are known to
produce high levels of cMyc during tumor growth.

"We have identified a small molecule with drug-like properties that is a
candidate for further preclinical development," Rice said.

CX-3543 selectively suppresses cMyc activity by specifically binding to the cMyc
quadruplex, he said. G-quadruplex structures are four stranded DNA secondary
structures. Certain G-quadruplexes regulate transcription of specific oncogenes,
including cMyc. The quadruplex cluster that includes cMyc also includes VEGF, a
growth factor that regulates development of blood vessels to tumors. CX-3543
inhibits VEGF expression as well as cMyc.

"We selected CX-3543 as the first 'Oncogene Inhibitor' class of small molecule
compounds that specifically target the G-quadruplex regulatory elements in the
genes involved in growth and proliferation of tumors," Rice said.

Small molecule drugs such as CX-3543 are compelling because they can be targeted
to previously "undruggable" genes such as cMyc, Rice said. Furthermore,
bioassays are already established to identify the efficacy of the small molecule
action on their respective targets, and biomarkers are available to follow
drug-induced responses in preclinical and clinical studies.


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