By Maggie Fox, Health and Science Correspondent
NEW ORLEANS (Reuters) - A drug that has shown surprising effects against some of the most incurable cancers is continuing to help people who had no hope of treatment, researchers said on Sunday.
They said ImClone's experimental drug IMC-225, which had already worked well in a few patients with seemingly incurable head and neck cancer, was also showing promise against colorectal cancer.
The drug helps other cancer drugs work better, ImClone researchers told a meeting of the American Society of Clinical Oncology (ASCO) in New Orleans.
It said 12 patients with head and neck cancer and six patients with colorectal cancer who had not responded to standard chemotherapy showed either a complete remission or a partial response -- which means their tumor shrank by at least 50 percent -- when IMC-225 was added to their chemotherapy.
``We are seeing about a 20 percent response rate in colorectal cancer,'' Dr. Harlan Waksal, M.D., executive vice president and chief operating officer of ImClone Systems, said in an interview.
``The expected response is zero.''
He said he was excited but cautious. ``These are encouraging data but they are early data,'' he said.
The company, working with researchers at M.D. Anderson Cancer Center in Houston, New York Presbyterian Hospital and Florida Cancer Specialists in Bonita Springs, hopes to eventually enroll 125 patients in their trial. All will have cancer that has not responded to the standard chemotherapy treatment.
``What has made people excited about these data is we have only been talking about IMC-225 in squamous cell head and neck cancer,'' Waksal said.
Now it is working against a different kind of tumor -- adenocarcinoma.
Most cancer drugs are strong poisons that target rapidly dividing cells such as tumor cells. But IMC-225 is a monoclonal antibody -- a genetically engineered protein that recognizes specific parts of cells.
In this case the target is the epidermal growth factor receptor (EGFr), which is involved in the growth of tumor cells and their ability to repair the damage done to them by chemotherapy drugs.
``It is blocking the ability of the tumor cell to overcome the DNA damage of chemotherapy,'' Waksal said. Cancer cells are able to turn on genes that can stop mechanisms that are meant to kill them. The drug essentially lets the cells die, the way they are supposed to.
ImClone says 90 percent of head and neck cancers over express EGFr, which means they use it to recover from the damage done by chemotherapy.
The company estimates that 92 percent of esophageal cancers, 67 percent of colorectal cancers, 65 percent of prostate and bladder cancers, 60 percent of ovarian and cervical cancers and 50 percent of pancreatic, kidney and lung cancers over express EGFr and thus might respond to IMC-225.
The researchers reported on one interesting case in their study -- a woman with lung cancer who had failed several attempts at chemotherapy and who had given up. Unlike other patients, she got IMC-225 alone and while her tumor has not shrunk, it has stopped growing.
``It has now been 40 weeks and she has had stable lung cancer on IMC-225 alone,'' Waksal said. ``She's doing extremely well. Her quality of life has been excellent.''
He said this might suggest that IMC-225 can stabilize cancer on its own.