Gilead Sciences, Inc. (NASDAQ:GILD)’s new drug, for the treatment of leukemia, has come under review, from EU regulators. The review was initiated, after several adverse effects were observed, during the trial. Zydelig, the drug in question, was undergoing clinical trials at three locations, with other cancer medicines, when increased rates of harmful events, including death, were observed.

The EMA has issued guidance for patients using the drug, stating that they should be monitored for any sign of infections. Added to this, the regulatory body is looking at the results of the Zydelig studies, in order to determine if the drugs approval should be withdrawn. Furthermore, the news has already spread to the US, where the FDA is monitoring the situation. The FDA has stated that it would release guidelines for the drug, once more data is made available to them. Gilead Sciences, on the other hand, has halted all planned studies of the drug, which targeted the kind of cancers that the effected patients were suffering from.

Zydelig was expected to bring in an estimated $821 million in sales, by 2020, before the unfortunate incidents. However, the regulators have also highlighted the fact that the patients suffering from the infections, were being administered the drug, along with unapproved drugs. This indicates that the real problem could be the unapproved drugs, rather than Zydelig itself. Moreover, the EMA has also advised doctors to continue treating patients with the drug, if they are displaying signs of improvement.

Regardless of the outcome, Gilead Sciences still has a hold of 94% of the hepatitis-C market, as per a recent IMS report. Although this figure was slightly below that of the previous quarter, the company still has a commanding lead over the new competition. The IMS expects the company to report $2.16 billion worth sales, during the 1Q2016.

Gilead Sciences, Inc. (NASDAQ:GILD) reported a gain of 1.14% in terms of its share value, to reach a close at $89.65, after having a trade volume of 10.58 million, during the March 11 session.