Sesen, still reeling from FDA rejection, pulls filing for EU approval of cancer drug

The rapid unraveling of Sesen Bio goes on. Two weeks ago, the biotech was on the cusp of winning FDA approval for cancer drug Vicineum and working its way toward authorization in Europe. Now, with the FDA rejecting Vicineum days before a media report of misconduct, Sesen has pulled its filing to the European Medicines Agency (EMA). 

Massachusetts-based Sesen withdrew its EMA submission Aug. 20, a week after the FDA rejection and two days after the Stat report of misconduct, but only disclosed the action in a regulatory filing on Wednesday. The filing is light on details.

Sesen said “certain components” of the EMA are “interrelated with elements” of the FDA’s decision to reject Vicineum, without providing further details. Given the links, Sesen has hit pause on plans to seek approval in the EU until it has “more clarity” on the next steps in the U.S. Sesen expects to be able to “better synchronize” the two reviews once it gets feedback from the FDA. 

The EMA filing is critical to the commercial prospects of Vicineum, a drug designed to get a protein payload into cancer cells. When Sesen filed for EMA approval in a form of bladder cancer in March, it tipped sales in Europe to peak as high as $1.1 billion. Sesen put peak global sales at $3 billion. 

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The first sales of Vicineum will now arrive later than expected, at best. At this stage, it is publicly unclear why the FDA rejected the application for approval or what Sesen needs to do to get the drug to market. Sesen plans to meet with the FDA before setting out the next steps. 

Stat’s report, which is based on leaked internal documents, contains allegations about the effect of Vicineum on liver enzymes that, if true, could indicate concerns about the toxicity of the medicine.