Summary Safety Review - ZYDELIG (idelalisib) - Assessing the potential risk of a rare brain infection (progressive multifocal leukoencephalopathy)

 

December 15, 2017

Product

Zydelig (idelalisib)

Potential Safety Issue

Rare brain infection (progressive multifocal leukoencephalopathy [PML])

Key Messages

  • Zydelig (idelalisib) is a prescription drug authorized for sale in Canada to treat certain types of blood cancer.
  • Health Canada reviewed the potential risk of progressive multifocal leukoencephalopathy (PML) with the use of Zydelig, following the publication of reports of PML in patients taking Zydelig.   
  • Health Canada’s review concluded that there was a possible link between Zydelig and PML. Health Canada is working with the manufacturer to update the product safety information with a warning about the risk of this rare brain infection.

Overview

Health Canada reviewed the potential risk of a rare brain infection known as PML with the use of Zydelig following the publication of reports of PML in patients taking Zydelig. In 2016, the product safety information for Zydelig was updated to include a warning about the risk of serious infections; however, the potential risk of PML was not identified at that time.

Use in Canada

  • Zydelig (idelalisib) is a prescription drug authorized for sale in Canada to treat 2 types of  cancers:
    • chronic lymphocytic leukemia (cancer of the blood and bone marrow), when used together with rituximab (another anti-cancer drug), in patients previously treated with other drugs.
    • follicular lymphoma (cancer of the blood), when used alone, in patients who have received at least two other types of treatment that no longer work for them. This indication was authorized by Health Canada with the condition that the manufacturer undertakes additional studies to verify the clinical benefit of Zydelig.
  • Zydelig has been marketed in Canada since April 2015. It is available as a tablet that is taken by mouth.
  • In 2016, approximately 500 prescriptions were filled in Canada.

Safety Review Findings

  • At the time of the review, Health Canada had not received any Canadian reports of PML linked to the use of Zydelig.
  • The safety review identified 9 international reports of PML in patients treated with Zydelig. In 8 of the 9 reports, the link between PML and the use of Zydelig was considered to be possible. However, other factors such as the type of cancer of the patient and the use of other medications at the same time or in the recent past may have also played a role. The remaining report could not be assessed because there was not enough information.
  • The review of the literature suggested that a possible link may be explained by the actions of idelalisib on the immune system. Zydelig is known to suppress the immune system and PML occurs generally in patients that have a weak immune system.

Conclusions and Actions

  • Health Canada’s review concluded that there was a possible link between Zydelig and PML.
  • Health Canada is working with the manufacturer to update the product safety information to include a warning about the risk of this rare brain infection.
  • Health Canada encourages consumers and healthcare professionals to report any side effects related to the use of this health product.
  • Health Canada will continue to monitor the side effects of Zydelig, as it does for all health products on the Canadian market, to identify and assess potential harms. Health Canada will take appropriate and timely action if or when new health risks are identified.

Additional Information

The analysis that contributed to this safety review included scientific and medical literature, international adverse reaction reports and what is known about the use of this drug both in Canada and internationally.

For additional information, contact the Marketed Health Products Directorate.

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