Drug combination acts against aggressive chronic lymphocytic leukemia

December 10, 2012

ATLANTA - A two-prong approach combining ibrutinib and rituximab (Rituxin®) to treat aggressive chronic lymphocytic leukemia (CLL) produced profound responses with minor side effects in a Phase 2 clinical trial at the University of Texas MD Anderson Cancer Center.

Researchers presented the results today at the 54th annual meeting of the American Society of Hematology (ASH).

"This is a patient population with a great need for more targeted therapies," said Jan Burger, M.D., Ph.D., associate professor in MD Anderson's Department of Leukemia. Burger was lead author of the study.

"Many CLL patients, especially those with indolent or non-aggressive disease, do well on the standard treatment of chemotherapy and antibodies," he said. "But for a certain subset of high-risk patients, treatment often fails, and remissions, if they are achieved, are short."

According to the National Cancer Institute's Surveillance Epidemiology and End Results database, CLL is the most common type of adult leukemia in the United States. An estimated 16,000 new cases will be diagnosed this year, and about 4,600 people will die because of the disease. Median age of diagnosis is 72, and it is more common in men than women.

Although chemotherapy combinations have improved the cure rate for CLL, side effects often are severe. A sizeable number of CLL deaths are from secondary cancers caused by treatment.

Early studies showed potential

Ibrutinib, a tyrosine kinase inhibitor that thwarts B-cell receptor signaling, is a promising new targeted therapy for mature B-cell malignancies, including certain types of myeloma and lymphoma. It has been shown to be especially effective in CLL.

Over the past two years, Phase 1/2 trials at MD Anderson and other sites showed high-risk CLL patients responded as well as low-risk patients to ibrutinib. However, the response often is lessened because of persistent lymphocytosis, an increase in leukemia cells in the blood due to release of CLL cells from the tissues (lymph glands) into the blood stream. Rituximab, a well-established antibody, was added to capture the CLL cells in the blood and thereby accelerate and improve response.

"When we looked at how well the high-risk patients were doing on ibrutinib - even though it was a small number - we saw a great opportunity to find out if combining the two drugs would have a positive impact on these patients," Burger said.

Combination tolerated well

Forty patients with high-risk CLL were enrolled in the study earlier this year. They received: At a median follow up of four months, 38 patients remained on ibrutinib therapy without disease progression. One patient died from an unrelated infectious complication, and one patient discontinued therapy due to oral ulcers.

Preliminary results: 85 percent response rate

Of 20 patients evaluated for early response at three months, 17 achieved partial remission for an overall response rate of 85%. Three achieved partial remission with persistent lymphocytosis.

Interestingly, lymphocytosis peaked earlier and the duration was shorter than with ibrutinib alone.

Treatment was well tolerated, with 13 cases of grade 3 or grade 4 toxicities, including neutropenia, fatigue, pneumonia, insomnia and bone aches. Most side effects were unrelated and transient. Many patients reported improved overall health and quality of life after three cycles of treatment.

"Although this study has a short follow-up time, we are encouraged by the fact that the vast majority of patients are responding and are able to continue on treatment, Burger said.

Development of ibrutinib for CLL crucial

Researchers said these data, together with the previous Phase 1/2 studies, emphasize the need for rapid further development of ibrutinib for high-risk CLL patients.

Pharmacyclics, the company that is developing ibrutinib, is proceeding with a Phase 3 multi-center clinical trial, in which MD Anderson will participate. Additionally, MD Anderson researchers will conduct a follow-up study on their research in high-risk CLL patients.
-end-
Other research team members from MD Anderson's Department of Leukemia included Michael Keating, M.D.; William Wierda, M.D., Ph.D.; Julia Hoellenriegel, M.S.; Alessandra Ferrajoli, M.D.; Stefan Faderl, M.D.; Susan Lerner, M.S.; Gracy Zacharian; Hagop Kantarjian, M.D.; and Susan O'Brien, M.D. Also participating were Xuelin Huang, Ph.D., of the Department of Biostatistics at MD Anderson; and Danelle James, M.D. and Joseph Buggy, Ph.D., of Pharmacyclics, Inc, Sunnyvale, CA.

Support for the study was provided by Pharmacyclics and CLL Global Research Foundation.

About MD Anderson

The University of Texas MD Anderson Cancer Center in Houston ranks as one of the world's most respected centers focused on cancer patient care, research, education and prevention. MD Anderson is one of only 41 comprehensive cancer centers designated by the National Cancer Institute. For nine of the past 11 years, including 2012, MD Anderson has ranked No. 1 in cancer care in "America's Best Hospitals," a survey published annually in U.S. News & World Report.

University of Texas M. D. Anderson Cancer Center

Related Leukemia Articles from Brightsurf:

New therapeutic approach against leukemia
Using an RNA molecule complex, researchers can prevent retention of cancer stem cell in their tumor supporting niche

Nanoparticle for overcoming leukemia treatment resistance
One of the largest problems with cancer treatment is the development of resistance to anticancer therapies.

Key gene in leukemia discovered
Acute myeloid leukemia (AML) is one of the most common forms of blood cancer among adults and is associated with a low survival rate, and leads to the inhibition of normal blood formation.

Vitamin B6, leukemia's deadly addiction
Researchers from CSHL and Memorial Sloan Kettering Cancer Center have discovered how Acute Myeloid Leukemia is addicted to vitamin B6.

Artificial intelligence tracks down leukemia
Artificial intelligence can detect one of the most common forms of blood cancer - acute myeloid leukemia -- with high reliability.

Milestone reached in new leukemia drug
Using a chemical compound called YKL-05-099, a team of cancer researchers from CSHL and the Dana Farber Institute was able to target the Salt-Inducible Kinase 3 (SIK3) pathway and extend survival in mice with MLL leukemia.

The drug combination effective against bovine leukemia
Scientists have succeeded in reducing levels of the bovine leukemia virus (BLV) in cows with severe infections by combining an immune checkpoint inhibitor and an enzyme inhibitor.

Towards a safer treatment for leukemia
An international team of researchers at VIB-KU Leuven, Belgium, the UK Dementia Institute and the Children's Cancer Institute, Australia, have found a safer treatment for a specific type of leukemia.

Research paves way for new source for leukemia drug
Chemistry researchers have patented a method for making anti-leukemia compounds that until now have only been available via an Asian tree that produces them.

An atlas of an aggressive leukemia
A team of researchers led by Bradley Bernstein at the Ludwig Center at Harvard has used single-cell technologies and machine learning to create a detailed 'atlas of cell states' for acute myeloid leukemia (AML) that could help improve treatment of the aggressive cancer.

Read More: Leukemia News and Leukemia Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.