FDA expands use of Imbruvica to treat rare form of blood cancer
By Natalie Grover (Reuters) - The U.S. Food and Drug Administration approved the expanded use of Imbruvica, sold by Johnson & Johnson and Pharmacyclics Inc, to treat Waldenström's macroglobulinemia (WM), a rare form of blood cancer for which no specific pharmaceutical therapy exists. The decision, announced more than two months before the scheduled review date, marks the fourth indication for the drug. WM, a type of non-Hodgkin lymphoma, was discovered more than 70 years ago. It usually worsens 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. Imbruvica works by blocking the enzyme that allows abnormal B-cells to grow and divide. Since WM was first described, doctors have had to rely on therapies borrowed from similar cancers, said Steven Treon, who led the trial that led to the approval for expanded use. The FDA granted Imbruvica breakthrough therapy designation for WM, a status given to drugs seen as important advances in the treatment of serious diseases, but it added a warning that it could cause tumor lysis syndrome (TLS). TLS is a potentially life-threatening disorder that occurs when a treatment kills cancer cells so quickly that the kidneys cannot expel the breakdown products from the blood. Since its initial approval in late 2013, the number of safety warnings associated with Imbruvica have increased, said Elliot Favus of Favus Institutional Research, adding that the number of cases of TLS for Imbruvica had risen in the past year. "We're learning a lot more about the safety of the drug and it's not as good as people originally thought when it was first approved," Favus said. In contrast, a potential rival drug being developed by AbbVie Inc and Roche Holding AG, ABT-199, has reduced the number of TLS cases in recent trials, he said. Imbruvica is already used to fight chronic lymphocytic leukemia and Mantle cell lymphoma. The approval for WM highlights the strength of the franchise, although the disease occurs only in up to 1,500 patients in the United States each year, Roth Capital Partner's Joseph Pantginis wrote in a note. Pharmacyclics anticipates U.S. net product revenue of about $1 billion for the drug in 2015, up from $492 million in 2014, the company said earlier this month. Pharmacyclics shares closed 1.25 percent higher at $167.47, while J&J's stock ended up about 0.9 percent at $102.38. (Editing by Sriraj Kalluvila, Simon Jennings and Ted Kerr)
