EU regulators initiate review of Gilead Sciences' blood cancer drug Zydelig on safety concerns

The European Medicines Agency said Friday that it launched a review of Gilead Sciences' Zydelig (idelalisib), which is approved in the EU for chronic lymphocytic leukaemia (CLL) and follicular lymphoma, because of an increased rate of serious adverse events, including deaths, mostly due to infections, observed in three clinical studies. As part of the review done at the European Commission's request, the EMA will evaluate data from the studies to determine if the findings have any impact on currently authorised uses of Zydelig, adding that patients who are receiving or starting treatment with the PI3K delta inhibitor should be carefully monitored for signs of infection.

According to the agency, the higher rates of adverse events were observed in trials investigating Zydelig in combination with other cancer therapies. Specifically, one trial involving patients with CLLinvestigated combination regimens that are not yet approved, while studies in non-Hodgkin lymphoma included patients whose disease characteristics differed from those covered by the drug's currently approved indications. The EMA indicated it will consider whether immediate measures are needed during the ongoing review.

Zydelig is currently cleared in Europe for use in combination with Roche's MabThera (rituximab) to treat CLL patients who received at least one prior therapy, or as first-line treatment in those deemed unsuitable for chemo-immunotherapy due to certain genetic mutations. The drug is also authorised for use as monotherapy in patients with follicular lymphoma who are refractory to two prior lines of treatment.

Gilead spokeswoman Sonia Choi stated that the company is aware of the study findings and has halted several studies examining the use of Zydelig for the same blood cancers in which severe side effects were observed. However, Choi said Gilead still believes the drug is a good option for patients with both cancer types whose disease has recurred and that it is discussing its next steps with regulators.

Zydelig, which analysts forecast will generate sales of $821 million in 2020, has also been approved in the US in combination with Rituxan (rituximab) for patients with relapsed CLL, and as monotherapy for patients with relapsed follicular B-cell non-Hodgkin lymphoma and relapsed small lymphocytic lymphoma who received at least two prior systemic therapies.

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