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FDA Expands Approved Use of Imbruvica (ibrutinib) for Waldenström’s Macroglobulinemia

January 29, 2015 -- The U.S. Food and Drug Administration today expanded the approved use of Imbruvica (ibrutinib) for patients with Waldenström’s macroglobulinemia (WM), a rare form of cancer that begins in the body’s immune system. The drug received a breakthrough therapy designation for this use.

A type of non-Hodgkin lymphoma, WM usually gets worse slowly over time and causes abnormal blood cells, known as B lymphocytes (B-cells), to grow within the bone marrow, lymph nodes, liver, and spleen. In WM, abnormal B-cells also overproduce a protein known as immunoglobulin M or IgM (macroglobulin) that may lead to excess bleeding, problems with vision and with the nervous system.

According to the National Cancer Institute, approximately 70,800 Americans were diagnosed and 18,990 died from non-Hodgkin lymphomas in 2014. Imbruvica works by blocking the enzyme that allows the abnormal B-cells in WM to grow and divide.

“Today’s approval highlights the importance of development of drugs for supplemental indications,” said Richard Pazdur, M.D., director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research. “Continued research has discovered new uses of Imbruvica.”

The FDA initially granted Imbruvica accelerated approval in November 2013 for use in patients with mantle cell lymphoma who received one prior therapy. In February 2014, the FDA granted accelerated approval to Imbruvica for use in patients with previously treated chronic lymphocytic leukemia (CLL), and then in July 2014, expanded its use to include treatment of CLL patients who carry a deletion in chromosome 17.

The FDA based its approval of Imbruvica for WM on a clinical study of 63 previously treated participants. All study participants received a daily 420 milligram orally administered dose of the medication until disease progression or side effects became intolerable. Results showed 62 percent of participants had their cancer shrink after treatment (overall response rate). At the time of the study, the duration of response ranged from 2.8 months to approximately 18.8 months.

The most common side effects associated with the drug are low blood platelet counts (thrombocytopenia), a decrease in infection-fighting white blood cells (neutropenia), diarrhea, low red blood cell counts (anemia), lack of energy (fatigue), musculoskeletal pain, bruising, nausea, upper respiratory tract infection, and rash. Healthcare professionals should inform patients of the risk for bleeding (hemorrhage), infections, abnormal heartbeat (atrial fibrillation), development of new cancers (second primary malignancies), metabolic disturbances following treatment (tumor lysis syndrome), and toxic effects on an embryo (embryo-fetal toxicity) associated with the use of Imbruvica.

The FDA granted Imbruvica for WM breakthrough therapy designation, priority review, and orphan product designation because the company demonstrated through preliminary clinical evidence that the drug may offer a substantial improvement over available therapies; has potential, at the time of the application was submitted, to be a significant improvement in safety or effectiveness in the treatment of a serious condition; and the drug is intended to treat a rare disease, respectively.

The product’s new use is being approved more than two months ahead of its prescription drug user fee goal date of April 17, 2015, the date the FDA was scheduled to complete review of the drug application.

Imbruvica is co-marketed by Pharmacyclics, based in Sunnyvale, California, and Janssen Biotech, based in Horsham, Pennsylvania.

Source: FDA

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