The same therapeutic that is offering patients hope against lymphoma and a number of other deadly diseases has been linked to an often lethal brain-eating viral infection, according to new research from Northwestern’s Feinberg School of Medicine.
The infection, known as progressive multifocal leukoencephalitis (PML), eats away at the brain’s white matter and leads to a rapid deterioration of various cognitive abilities, said Charles Bennett, lead author of the study and the A.C. Buehler Professor in Economics and Aging at Feinberg.
The drug, Rituxan, is a widely prescribed and effective “magic bullet” against treating lymphoma, a group of cancers that affects the body’s white blood cells, said Bennett, who is also a hematologist and oncologist at the Jesse Brown VA Medical Center in Chicago. Lymphoma is the most common type of blood cancer in the United States and is the sixth most common cancer overall in adults. The annual incidence of lymphomas in the United States is rising dramatically and affects people of all ages, even children, said Muthu Vaduganathan, a first-year student at Feinberg.
Rituxan has also been approved for treatment of rheumatoid arthritis and a number of autoimmune diseases such as lupus erythematosus and multiple sclerosis.
“Rituxan is unbelievably successful,” Bennett said. “It’s become so good that it’s used for treating diseases other than cancer – its potential market is spreading rapidly.”
The therapeutic works by targeting a specific protein on the outside of cancerous B-cells. When healthy, these white blood cells play a role in the human immune response. When Rituxan binds to the protein, the cancerous cell is destroyed, said Steve Rosen, director of NU’s Robert H. Lurie Comprehensive Cancer Center.
Despite its efficacy in combating cancer, Rituxan has also been known to moderately weaken the body’s immune system, which may cause complications in some patients. The drug has the potential to suppress the immune system enough to allow a virus that usually lies dormant in the body to grow and attack brain cells, which may cause PML and its associated cognitive deficiencies like memory loss and confusion. But in a body protected with a healthy immune system, this virus is harmless, Bennett said.
“The human body is loaded with tons of bacteria, viruses and fungi,” said Andrew Evens, professor of medicine at Feinberg and co-author of the research study. “But as long as you have a competent immune system, typically those viruses and bacteria stay at very low levels.”
Despite the risks associated with Rituxan, only about one in 4,000 users developed PML – however, those who do contract the virus must battle a fatality rate of about 95 percent. But when considering the drug’s success in treating a number of diseases, Bennett, Evens and Rosen said they all believe Rituxan’s benefits outweigh the risks and would continue to prescribe the drug.
“We would still use (Rituxan) because it’s the most effective agent for a number of diseases and is still better-tolerated than many other drugs,” Rosen said. “We would still use it, but it will still need to be monitored closely.”
