The US Food and Drug Administration (FDA) has prompted the pharmaceutical company, Genentech, to revise the labeling of the widely selling drug – Rituxan – after a fatal case of ‘Progressive Multifocal Leukoencephalopathy’, or PML, in an arthritis patient treated with the drug. The case was a complicated one, and the patient had been on immunosuppressive therapy for a long time.

The FDA has also directed healthcare providers to ‘maintain an index of suspicion’ for PML, in Rituxan patients with neurological symptoms.

PML is a viralus infection that often occurs in patients with impaired cell-mediated immunity. It was previously registered in patients taking Rituxan for unapproved uses. However, this happens to be the first case when PML occurred in a patient who was taking the drug for arthritis. It was more than one and a half years after discontinuing treatment with Rituxan that the infection had developed in the patient.

Genentech asserted that Rituxan, or rituximab, is a blockbuster drug. In 1997, it was approved for the treatment of non-Hodgkin’s lymphoma, and in 2006, for treating rheumatoid arthritis. The drug’s label already mentions thea risk of PML. Mentioning the complicated nature of the fatal case, the company said that the role Rituxan played in the patient’s death could not be ascertained. In fact, there was no clear indication that PML was aggravated by Rituxan, and the patient had also received chemotherapy agents some months back.

Tara Cooper, a representative for Genentech specifically tried to reiterate the fact that the risk of developing PML already finds a mention on the label of Rituxan. She said, “The patient had a number of confounding factors that make it difficult to assess the potential role, if any, that Rituxan exposure may have played”.