New drugs chip away at cancer

Little by little, new targeted therapies are helping cancer patients live longer, even if they do not offer miraculous cures, researchers said on Sunday.

They are learning how to combine the best new targeted therapies with older drugs to eke out a few extra months or even years for cancer patients - which can mean a lot to a patient hoping to live long enough to see a child graduate or marry.

And each small step builds on earlier progress, so that the overall five-year survival rate for all cancers combined is now 63 percent, according to the American Cancer Society, up from 51 percent in 1975.

"It is sort of like a glacier - you have this slow but extremely powerful movement. But it's not a fast movement," Dr. Michael Friedman, chief executive officer of the City of Hope Cancer Center in California, said in an interview.

At first cancer researchers hoped the targeted therapies would prove to be magic bullets that could kill cancer cells without causing too many toxic side-effects, as current chemotherapy and radiation does.

Dr. Margaret Tempero, president of the American Society of Clinical Oncology, said reality was kicking in. Targeted therapies are far too specific to affect a disease that has as many different causes as cancer, she said.

"You can't expect to hit one part of the pathway and expect everything to regress," she said in an interview.

"Miraculous effects like Gleevec and CML are probably few and far between."

But several studies presented at an ongoing ASCO meeting in New Orleans show the new drugs can buy valuable time.

SYNERGISTIC EFFECTS

For instance, adding ImClone Systems Inc.'s. drug Erbitux to radiation therapy helped head and neck cancer patients live longer without their cancer spreading.

Combining two targeted drugs, Avastin and Tarceva, both made by Genentech with Roche and OSI Pharmaceuticals Inc., kept 71 percent of patients with a hopeless type of kidney cancer alive for six months or more.

And combining Avastin with Pfizer Inc.'s Camptosar and an older drug called 5-FU helped colon cancer patients live 25.1 months versus 15.8 months for those on more standard therapy.

"There is an idea that these drugs - Erbitux, Tarceva - these drugs that act on cancer's cellular product are pro-apoptotic. They lead the cell down a pathway that makes it more sensitive to traditional chemotherapy or radiation," Tempero said.

Apoptosis is programmed cell death, in which a cell self-destructs. This normal process is disrupted in cancer.

"We hope to understand how to put them together thoughtfully as opposed to how it used to be put together - 1 plus 1 equals 2 but now 1 plus 1 is more than 2."

Some of the targeted drugs also have significant effects on their own when used in the right patients.