PML cases prompts boxed warning for brentuximab vedotin

Two additional cases of progressive multifocal leukoencephalopathy, a serious brain infection that can be fatal, have been reported in patients taking the lymphoma drug brentuximab vedotin, according to the FDA.

Consequently, a new boxed warning highlighting potential risk has been added to the drug label for brentuximab vedotin (Adcetris, Seattle Genetics).

In addition, the FDA added to the drug label a new contraindication warning against the use of brentuximab vedotin with the cancer drug bleomycin due to heightened risk of pulmonary toxicity.

At the time the FDA approved brentuximab vedotin in August 2011, the warnings and precautions section of the drug label described one case of progressive multifocal leukoencephalopathy (PML).

Symptoms of PML may develop over several weeks or months. The can include mood changes, memory loss, confusion, weakness in one side of the body, or changes in speech, vision or walking.

The FDA recommended that health care professionals:

Consider a possible diagnosis of PML in any patient who is taking or has taken brentuximab vedotin and presents with new signs or symptoms of central nervous system abnormalities.
Suspend brentuximab vedotin dosing for any suspected case of PML and discontinue dosing if PML is confirmed.
Report adverse events involving brentuximab vedotin to the FDA MedWatch program.

"Our first priority is patient safety," Tom Reynolds, Seattle Genetics' chief medical officer, said in a statement. "By developing these agreed-upon label updates with the FDA regarding PML and the contraindication with bleomycin, we aim to heighten awareness among health care professionals in order to most safely treat their patients with Adcetris. Although PML in lymphoma patients can be caused by factors such as underlying disease and prior therapies that affect the immune system, a contributory role of Adcetris cannot be excluded."

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