June 5, 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 as 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 Oncology.
This weekend, investigators at the annual meeting of the American Society of Clinical Oncology in Atlanta released data 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.
Researchers say they now also plan to test combinations of Novartis AG's drug Gleevec with Bristol-Myers Squibb Co.'s Sprycel in chronic myelogenous leukemia. A U.S. advisory panel recently recommended that Sprycel be approved.
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 also targets EGFR, but has not yet been approved.
As more is learned about drugs that are directed at single targets, evidence is emerging that they may hit more than initially thought.
"New research indicates that targeting EGFR can affect multiple growth factors as well, representing a sort of sideways approach to inhibiting other proteins like VEGF," said Dr. William Li, head of the Angiogenesis Foundation.