Oncologist calls new colon cancer drug a ‘landmark’

For the first time in four decades, oncologists treating colon cancer say they have a new experimental drug in their arsenal. It’s called Camptosar.

Clinical trials testing its effectiveness for patients with stage three colon cancer are set to begin this month.

Colon cancer is the second leading cause of cancer deaths in Canada.

About 1200 people with colon cancer that has spread to the lymph nodes will receive Camptosar in addition to standard chemotherapy. About 250 of the test group will be Canadians, according to Dr. Anthony Fields.

He’s director of the Cross-Cancer Institute of Alberta and head of the gastrointestinal committee of the National Cancer Institute of Canada. He says Camptosar is the biggest treatment breakthrough in 40 years.

“With most other cancers, we were able to develop combination chemotherapy drug treatment that was more effective than single drug treatment. But we were never able to achieve that with colorectal cancer. The first time was with Camptosar, so this is a landmark.”

Early Test Results

So far, Camptosar has been tested on people with late stage or incurable colon cancer which had spre to other parts of the body.

They received the standard chemotherapy. This consists of a drug called 5-flourouracil (5-FU), boosted by another drug called leucovorin. Dr. Fields calls this treatment “an engine with a turbocharger.”

In clinical trials in Canada, the United States and Europe, these cancer patients also received Camptosar.Dr. Fields says this was like adding another engine to the turbocharger engine.

He says in these earlier trials, about 40 to 45 of every 100 patients receiving the three-drug combination lived three months longer on average. That’s compared to those who received the standard chemotherapy of 5-FU plus leucovorin.

“Now we’re looking at patients who are at an earlier stage, whose colon cancer has spread to the lymph nodes but can still be potentially cured. They have surgery removing all the visible cancer. But the risk that the cancer will subsequently appear somewhere else is quite high.”

“What we know so far is that if we treat these patients with 5-FU and leucovorin after surgery, that increases their chances of cure. And the question now— if we use the new combination treatment, is it a further step forward?”

Random Groups

Dr. Fields says the people participating in the clinical trial for Camptosar will be divided randomly into two groups. One group will get the standard chemotherapy of 5-FU with leucovorin and the other group will get those drugs plus Camptosar.

All the participants will be volunteers.

“Oncologists will select patients who might be candidates and invite them to join the trial. Treatment has to start about 8 weeks after surgery.”

“Any patient has a 50-50 chance of getting the new drug, and maybe the new drug won’t work out to make a difference. But it’ll advance the state of knowledge, and maybe help people in the future.”

Dr. Fields says it will take two to four years to gather the results.

Camptosar use in Canada

Camptosar is the brand name for irinotecan, manufactured by Pharmacia&Upjohn.

In Canada, it’s licensed as a second-line treatment, that is, for patients whose cancer has not responded to standard chemotherapy.

In the U.S., an advisory committee to the Food and Drug Administration has recommended that Camptosar be approved as a first-line therapy for patients whose colon cancer has spread to other parts of the body.

Dr. Fields says “I feel that it would be wrong for someone with stage three, the potentially curable cancer, to try and get Camptosar without being in the clinical trial because we don’t know the potential for long term harm. So we shouldn’t simply assume it’s the better treatment, we should prove it.”

In earlier clinical trials with Camptosar, the side effects were diarrhea, nausea and vomiting.

Dr. Jean Macoun, head of medical oncology at the Ottawa Regional Cancer Centre, is preparing the test groups. He says the clinical trial set to begin will have two phases.

In the first phase, doctors will seek out the right combination dose for patients. Then, in the second phase, doctors will evaluate the benefits of the three-drug combination.