New immunoassay detects early-stage pancreatic cancer

ORLANDO (Reuters Health) - A new immunoassay can detect pancreatic cancer at an early stage, when the potential for cure is greater, researchers announced at the American Society of Clinical Oncology's 2010 Gastrointestinal Cancers Symposium in Orlando, Florida.

The assay uses the PAM4 monoclonal antibody (also called clivatuzumab), which identifies a unique biomarker that is highly specific for a mucin glycoprotein expressed by pancreatic cancer.

"The antigen is not present in normal pancreas or other normal organs, or in other types of malignancies, such as breast, lung, brain, et cetera. It is also very unlikely to be found in chronic pancreatitis," said the lead author, Dr. David V. Gold, at a press briefing.

Dr. Gold, of the Garden State Cancer Center in Belleville, New Jersey, and his colleagues tested the assay in a group of 68 patients who had undergone surgery for pancreatic cancer and in 19 healthy volunteers. They found that the sensitivity of the PAM4 immunoassay was 62% for detecting pancreatic cancer confined to the organ, 86% for disease that has spread locally, and 91% for detecting disease with local and distant spread.

Overall, the sensitivity and specificity for discrimination of all stages of pancreatic cancer were 81% and 95%, respectively, Dr. Gold reported.

The test could be used as a surveillance screen in individuals at high risk for pancreatic cancer, such as people with long-term diabetes and chronic pancreatitis, Dr. Gold told Reuters Health. He would like to see the test used more widely for screening, but he admitted such a program is unlikely.

"I would love to see it being used like that, but let's face it, all of this costs money and we are in enough financial problems already."

If the results of this small study are confirmed in larger studies, this test might replace the CA19-9 assay biomarker, which is currently the gold standard for monitoring pancreatic cancer, Dr. Gold said. "PAM4 is specific for pancreatic cancer, but CA19-9 is affected by whether or not you smoke, and it cannot tell the difference between pancreatic cancer and pancreatitis. This new assay can. It not only detects, it provides the diagnosis."

The PAM4 monoclonal antibody also has therapeutic potential, Dr. Gold said. In a related study presented here as a poster, he and his colleagues reported that 21 patients with stage III/IV pancreatic cancer who were treated with radiolabeled PAM4 plus low dose gemcitabine showed a 68% overall response rate, with 23% showing a partial response of at least a 30% decrease in the size of the tumor, and 45% showing stable disease by CT-RECIST criteria.

"We use the antibody to administer targeted radiotherapy, rather than having the patient stay under a beam of radiation. The antibody targets right to the tumor because it is specific," Dr. Gold explained. "We've been getting very nice results with stage III and IV patients. If we can translate that to patients who are detected in earlier stages, we may be able to improve the survival rate. Both early detection and improved therapy go hand in hand."

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