June 3, 2006
Combination “smart bombs” future of cancer therapy
By Toni Clarke
ATLANTA (Reuters) - Using combinations of "smart bomb"
cancer drugs that target specific proteins and avoid the
indiscriminate cell destruction of chemotherapy may be the wave
of the future for cancer patients, experts say.
Early studies show that combining targeted treatments such
as Genentech Inc.'s breast cancer drug Herceptin with
GlaxoSmithKline Plc's experimental treatment Tykerb, may be
helpful in patients who do not respond to Herceptin alone, said
Dr. Jose Baselga, chief of medical oncology service at Vall
d'Hebron University Hospital in Barcelona, Spain.
Targeted therapies act like smart bombs by crippling or
knocking out deadly cancer cells while leaving healthy cells in
tact, unlike the scorched earth approach of chemotherapy which
kills both healthy and unhealthy cells.
Using Herceptin and Tykerb together is just one of many
drug combinations that could improve on results seen with
existing targeted therapies such as ImClone Systems Inc.'s
colon cancer drug Erbitux and OSI Pharmaceuticals Inc.'s lung
cancer drug Tarceva.
"All the chemical models suggest that combinations will be
superior, though the data still has to prove it," Baselga said
at the annual meeting of the American Society of Clinical
Investigators on Saturday released promising results from a
mid-stage trial on lung cancer patients of Pfizer Inc.'s kidney
cancer drug Sutent. Now they are planning to test it in
combination with Tarceva.
"Most of us feel that except for in very rare instances,
tumors are driven by multiple pathways and therefore it makes
sense that a multi-targeted approach makes most sense," said
Mark Socinski, associate professor of medicine at the
University of North Carolina at Chapel Hill.
The first targeted therapies isolated single targets.
Genentech's Avastin targets a protein known as vascular
endothelial growth factor (VEGF), which cuts off the oxygen and
nutrients tumors need to survive. Erbitux attacks the epidermal
growth factor receptor (EGFR), which curtails tumor growth.
But drugs such as Sutent hit multiple targets, as does
Bayer AG and Onyx Pharmaceuticals' kidney cancer drug Nexavar.
In the colorectal field, behind Avastin and Erbitux, comes
Amgen Inc's. panitumumab, which has not yet been approved.
"The compelling argument for panitumumab is that it is
multi-targeting whereas Avastin only targets VEGF and Erbitux
only targets EGFR," said Dr. William Li, head of the
Angiogenesis Foundation. "This raises the exciting possibility
that it might have better coverage and could be a competitor to