Targeted Drugs Emerging for Chronic Lymphocytic Leukemia

A promising new class of drugs may shift treatment of the most common form of adult leukemia from combination chemotherapies to a more customized approach.

One such B cell receptor inhibitor, called PCI-32765, continues to show improved effectiveness in an ongoing clinical trial with relatively mild side effects compared to existing treatment.

Susan O'Brien, M.D., professor in MD Anderson's Department of Leukemia, will present updated results of a Phase II clinical trial of 61 patients with relapsed or resistant CLL Tuesday at the 53rd Annual Meeting of the American Society of Hematology. She spoke about the results at a news briefing today.

The hallmarks of the drug so far are a steady increase in patients achieving either complete or partial remission over time, low toxicity and lack of myelosuppression - the inhibition of bone marrow function that causes reduced blood cell production, O'Brien says.

"When we first reported results of this trial at ASH a year ago, 25% or patients had a partial response," O'Brien says. "By the time we presented in June at the American Society of Clinical Oncology meeting, the overall response rate was 48%. Now it's approaching 70% with either complete or partial remission.

"Lack of myelosuppression is exciting, because the most important complication we face treating CLL now is infection caused by myelosuppression," O'Brien says, "and these patients have compromised immune systems already." Infections spring from suppression of white blood cell production.

Chronic lymphocytic leukemia is caused by overproduction of defective B cell lymphocytes, white blood cells that fight infection by producing antibodies.

Additional resources: 

Patient Power video interview.

ASH Abstract 983 (Click OK on the prompt from ASH to view the abstract.)

MD Anderson news release