New Diagnostic Tool for Leukemia Uncovered at UCSD

Using what may prove to be a new device for understanding the complexities of leukemia, a team of researchers in San Diego has identified a previously unknown group of adult leukemia patients for whom standard therapy appears to be likely to fail.

Their findings, reported today in the New England Journal of Medicine, illustrate the limitations of traditional techniques for diagnosing leukemia and the need to target experimental forms of therapy to the newly identified group, researchers said.

‘New Insight’ on Effective Therapy

“Our study identified a subgroup of . . . patients with a poor prognosis who could not be identified using conventional diagnostic techniques,” said Dr. Robert E. Sobol, an investigator at the UC San Diego Cancer Center, where much of the work was done.

“Our findings may also provide new insight regarding more effective therapy for these patients.”

In the study, which involved 76 adult patients suffering from acute lymphoblastic leukemia, bone marrow and blood samples were tested using monoclonal antibodies--highly selective proteins that attach themselves to specific targets.

Using that method, the researchers discovered a protein called a myeloid antigen in the cells of 25 of the patients.

They found that those patients experienced fewer remissions (when the disease is not active) and shorter survival times than patients without the antigen.

About one-third of the patients showing the antigen experienced complete remission, compared to more than two-thirds of the other patients. The average survival time for most of the patients with the antigen was eight months, compared to 26 months for the others.

Conventional Techniques ‘Incomplete’

“It shows how incomplete our conventional techniques are for diagnosing leukemia,” said Dr. Ivor Royston, associate professor of medicine at UCSD Cancer Center and vice chairman of the National Cancer Institute study group that conducted the study.

“We can no longer depend just on the microscope, as we have for 100 years,” he said.

“The real value is we’ve identified a group that doesn’t do well,” Sobol said during a briefing Tuesday. “It really earmarks a group of patients for whom experimental therapies need to be designed.”

Royston said such therapies might include drugs used traditionally for acute myelogenous leukemia, which accounts for 85% of adult leukemia cases.

Myeloid antigens had been found previously only in patients with that form of the disease.

However, Royston said researchers do not know why the myeloid antigen “marker” is present or what purpose it serves.

Leukemia is a disease of the blood-forming organs, characterized by unrestrained growth of white corpuscles.

According to Royston, six new cases of acute lymphoblastic leukemia are diagnosed per every 100,000 population each year.

Leukemia is the most common cancer in children and acute lymphoblastic leukemia accounts for 95% of all cases.